linux/arch/powerpc/mm/hash_utils_64.c

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/*
* PowerPC64 port by Mike Corrigan and Dave Engebretsen
* {mikejc|engebret}@us.ibm.com
*
* Copyright (c) 2000 Mike Corrigan <mikejc@us.ibm.com>
*
* SMP scalability work:
* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
*
* Module name: htab.c
*
* Description:
* PowerPC Hashed Page Table functions
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#undef DEBUG
#undef DEBUG_LOW
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/sysctl.h>
#include <linux/ctype.h>
#include <linux/cache.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/memblock.h>
#include <asm/processor.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/page.h>
#include <asm/types.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/machdep.h>
#include <asm/prom.h>
#include <asm/abs_addr.h>
#include <asm/tlbflush.h>
#include <asm/io.h>
#include <asm/eeh.h>
#include <asm/tlb.h>
#include <asm/cacheflush.h>
#include <asm/cputable.h>
#include <asm/sections.h>
[POWERPC] Introduce address space "slices" The basic issue is to be able to do what hugetlbfs does but with different page sizes for some other special filesystems; more specifically, my need is: - Huge pages - SPE local store mappings using 64K pages on a 4K base page size kernel on Cell - Some special 4K segments in 64K-page kernels for mapping a dodgy type of powerpc-specific infiniband hardware that requires 4K MMU mappings for various reasons I won't explain here. The main issues are: - To maintain/keep track of the page size per "segment" (as we can only have one page size per segment on powerpc, which are 256MB divisions of the address space). - To make sure special mappings stay within their allotted "segments" (including MAP_FIXED crap) - To make sure everybody else doesn't mmap/brk/grow_stack into a "segment" that is used for a special mapping Some of the necessary mechanisms to handle that were present in the hugetlbfs code, but mostly in ways not suitable for anything else. The patch relies on some changes to the generic get_unmapped_area() that just got merged. It still hijacks hugetlb callbacks here or there as the generic code hasn't been entirely cleaned up yet but that shouldn't be a problem. So what is a slice ? Well, I re-used the mechanism used formerly by our hugetlbfs implementation which divides the address space in "meta-segments" which I called "slices". The division is done using 256MB slices below 4G, and 1T slices above. Thus the address space is divided currently into 16 "low" slices and 16 "high" slices. (Special case: high slice 0 is the area between 4G and 1T). Doing so simplifies significantly the tracking of segments and avoids having to keep track of all the 256MB segments in the address space. While I used the "concepts" of hugetlbfs, I mostly re-implemented everything in a more generic way and "ported" hugetlbfs to it. Slices can have an associated page size, which is encoded in the mmu context and used by the SLB miss handler to set the segment sizes. The hash code currently doesn't care, it has a specific check for hugepages, though I might add a mechanism to provide per-slice hash mapping functions in the future. The slice code provide a pair of "generic" get_unmapped_area() (bottomup and topdown) functions that should work with any slice size. There is some trickiness here so I would appreciate people to have a look at the implementation of these and let me know if I got something wrong. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-05-08 14:27:27 +08:00
#include <asm/spu.h>
#include <asm/udbg.h>
#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif
#ifdef DEBUG_LOW
#define DBG_LOW(fmt...) udbg_printf(fmt)
#else
#define DBG_LOW(fmt...)
#endif
#define KB (1024)
#define MB (1024*KB)
#define GB (1024L*MB)
/*
* Note: pte --> Linux PTE
* HPTE --> PowerPC Hashed Page Table Entry
*
* Execution context:
* htab_initialize is called with the MMU off (of course), but
* the kernel has been copied down to zero so it can directly
* reference global data. At this point it is very difficult
* to print debug info.
*
*/
#ifdef CONFIG_U3_DART
extern unsigned long dart_tablebase;
#endif /* CONFIG_U3_DART */
static unsigned long _SDR1;
struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT];
struct hash_pte *htab_address;
unsigned long htab_size_bytes;
unsigned long htab_hash_mask;
EXPORT_SYMBOL_GPL(htab_hash_mask);
int mmu_linear_psize = MMU_PAGE_4K;
int mmu_virtual_psize = MMU_PAGE_4K;
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
int mmu_vmalloc_psize = MMU_PAGE_4K;
#ifdef CONFIG_SPARSEMEM_VMEMMAP
int mmu_vmemmap_psize = MMU_PAGE_4K;
#endif
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
int mmu_io_psize = MMU_PAGE_4K;
int mmu_kernel_ssize = MMU_SEGSIZE_256M;
int mmu_highuser_ssize = MMU_SEGSIZE_256M;
u16 mmu_slb_size = 64;
EXPORT_SYMBOL_GPL(mmu_slb_size);
#ifdef CONFIG_HUGETLB_PAGE
unsigned int HPAGE_SHIFT;
#endif
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
#ifdef CONFIG_PPC_64K_PAGES
int mmu_ci_restrictions;
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
static u8 *linear_map_hash_slots;
static unsigned long linear_map_hash_count;
static DEFINE_SPINLOCK(linear_map_hash_lock);
#endif /* CONFIG_DEBUG_PAGEALLOC */
/* There are definitions of page sizes arrays to be used when none
* is provided by the firmware.
*/
/* Pre-POWER4 CPUs (4k pages only)
*/
static struct mmu_psize_def mmu_psize_defaults_old[] = {
[MMU_PAGE_4K] = {
.shift = 12,
.sllp = 0,
.penc = 0,
.avpnm = 0,
.tlbiel = 0,
},
};
/* POWER4, GPUL, POWER5
*
* Support for 16Mb large pages
*/
static struct mmu_psize_def mmu_psize_defaults_gp[] = {
[MMU_PAGE_4K] = {
.shift = 12,
.sllp = 0,
.penc = 0,
.avpnm = 0,
.tlbiel = 1,
},
[MMU_PAGE_16M] = {
.shift = 24,
.sllp = SLB_VSID_L,
.penc = 0,
.avpnm = 0x1UL,
.tlbiel = 0,
},
};
static unsigned long htab_convert_pte_flags(unsigned long pteflags)
{
unsigned long rflags = pteflags & 0x1fa;
/* _PAGE_EXEC -> NOEXEC */
if ((pteflags & _PAGE_EXEC) == 0)
rflags |= HPTE_R_N;
/* PP bits. PAGE_USER is already PP bit 0x2, so we only
* need to add in 0x1 if it's a read-only user page
*/
if ((pteflags & _PAGE_USER) && !((pteflags & _PAGE_RW) &&
(pteflags & _PAGE_DIRTY)))
rflags |= 1;
/* Always add C */
return rflags | HPTE_R_C;
}
int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
unsigned long pstart, unsigned long prot,
int psize, int ssize)
{
unsigned long vaddr, paddr;
unsigned int step, shift;
int ret = 0;
shift = mmu_psize_defs[psize].shift;
step = 1 << shift;
prot = htab_convert_pte_flags(prot);
DBG("htab_bolt_mapping(%lx..%lx -> %lx (%lx,%d,%d)\n",
vstart, vend, pstart, prot, psize, ssize);
for (vaddr = vstart, paddr = pstart; vaddr < vend;
vaddr += step, paddr += step) {
unsigned long hash, hpteg;
unsigned long vsid = get_kernel_vsid(vaddr, ssize);
unsigned long va = hpt_va(vaddr, vsid, ssize);
unsigned long tprot = prot;
/* Make kernel text executable */
2008-08-30 09:43:47 +08:00
if (overlaps_kernel_text(vaddr, vaddr + step))
tprot &= ~HPTE_R_N;
hash = hpt_hash(va, shift, ssize);
hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
BUG_ON(!ppc_md.hpte_insert);
ret = ppc_md.hpte_insert(hpteg, va, paddr, tprot,
HPTE_V_BOLTED, psize, ssize);
if (ret < 0)
break;
#ifdef CONFIG_DEBUG_PAGEALLOC
if ((paddr >> PAGE_SHIFT) < linear_map_hash_count)
linear_map_hash_slots[paddr >> PAGE_SHIFT] = ret | 0x80;
#endif /* CONFIG_DEBUG_PAGEALLOC */
}
return ret < 0 ? ret : 0;
}
#ifdef CONFIG_MEMORY_HOTPLUG
static int htab_remove_mapping(unsigned long vstart, unsigned long vend,
int psize, int ssize)
{
unsigned long vaddr;
unsigned int step, shift;
shift = mmu_psize_defs[psize].shift;
step = 1 << shift;
if (!ppc_md.hpte_removebolted) {
printk(KERN_WARNING "Platform doesn't implement "
"hpte_removebolted\n");
return -EINVAL;
}
for (vaddr = vstart; vaddr < vend; vaddr += step)
ppc_md.hpte_removebolted(vaddr, psize, ssize);
return 0;
}
#endif /* CONFIG_MEMORY_HOTPLUG */
static int __init htab_dt_scan_seg_sizes(unsigned long node,
const char *uname, int depth,
void *data)
{
char *type = of_get_flat_dt_prop(node, "device_type", NULL);
u32 *prop;
unsigned long size = 0;
/* We are scanning "cpu" nodes only */
if (type == NULL || strcmp(type, "cpu") != 0)
return 0;
prop = (u32 *)of_get_flat_dt_prop(node, "ibm,processor-segment-sizes",
&size);
if (prop == NULL)
return 0;
for (; size >= 4; size -= 4, ++prop) {
if (prop[0] == 40) {
DBG("1T segment support detected\n");
cur_cpu_spec->cpu_features |= CPU_FTR_1T_SEGMENT;
return 1;
}
}
cur_cpu_spec->cpu_features &= ~CPU_FTR_NO_SLBIE_B;
return 0;
}
static void __init htab_init_seg_sizes(void)
{
of_scan_flat_dt(htab_dt_scan_seg_sizes, NULL);
}
static int __init htab_dt_scan_page_sizes(unsigned long node,
const char *uname, int depth,
void *data)
{
char *type = of_get_flat_dt_prop(node, "device_type", NULL);
u32 *prop;
unsigned long size = 0;
/* We are scanning "cpu" nodes only */
if (type == NULL || strcmp(type, "cpu") != 0)
return 0;
prop = (u32 *)of_get_flat_dt_prop(node,
"ibm,segment-page-sizes", &size);
if (prop != NULL) {
DBG("Page sizes from device-tree:\n");
size /= 4;
cur_cpu_spec->cpu_features &= ~(CPU_FTR_16M_PAGE);
while(size > 0) {
unsigned int shift = prop[0];
unsigned int slbenc = prop[1];
unsigned int lpnum = prop[2];
unsigned int lpenc = 0;
struct mmu_psize_def *def;
int idx = -1;
size -= 3; prop += 3;
while(size > 0 && lpnum) {
if (prop[0] == shift)
lpenc = prop[1];
prop += 2; size -= 2;
lpnum--;
}
switch(shift) {
case 0xc:
idx = MMU_PAGE_4K;
break;
case 0x10:
idx = MMU_PAGE_64K;
break;
case 0x14:
idx = MMU_PAGE_1M;
break;
case 0x18:
idx = MMU_PAGE_16M;
cur_cpu_spec->cpu_features |= CPU_FTR_16M_PAGE;
break;
case 0x22:
idx = MMU_PAGE_16G;
break;
}
if (idx < 0)
continue;
def = &mmu_psize_defs[idx];
def->shift = shift;
if (shift <= 23)
def->avpnm = 0;
else
def->avpnm = (1 << (shift - 23)) - 1;
def->sllp = slbenc;
def->penc = lpenc;
/* We don't know for sure what's up with tlbiel, so
* for now we only set it for 4K and 64K pages
*/
if (idx == MMU_PAGE_4K || idx == MMU_PAGE_64K)
def->tlbiel = 1;
else
def->tlbiel = 0;
DBG(" %d: shift=%02x, sllp=%04lx, avpnm=%08lx, "
"tlbiel=%d, penc=%d\n",
idx, shift, def->sllp, def->avpnm, def->tlbiel,
def->penc);
}
return 1;
}
return 0;
}
#ifdef CONFIG_HUGETLB_PAGE
/* Scan for 16G memory blocks that have been set aside for huge pages
* and reserve those blocks for 16G huge pages.
*/
static int __init htab_dt_scan_hugepage_blocks(unsigned long node,
const char *uname, int depth,
void *data) {
char *type = of_get_flat_dt_prop(node, "device_type", NULL);
unsigned long *addr_prop;
u32 *page_count_prop;
unsigned int expected_pages;
long unsigned int phys_addr;
long unsigned int block_size;
/* We are scanning "memory" nodes only */
if (type == NULL || strcmp(type, "memory") != 0)
return 0;
/* This property is the log base 2 of the number of virtual pages that
* will represent this memory block. */
page_count_prop = of_get_flat_dt_prop(node, "ibm,expected#pages", NULL);
if (page_count_prop == NULL)
return 0;
expected_pages = (1 << page_count_prop[0]);
addr_prop = of_get_flat_dt_prop(node, "reg", NULL);
if (addr_prop == NULL)
return 0;
phys_addr = addr_prop[0];
block_size = addr_prop[1];
if (block_size != (16 * GB))
return 0;
printk(KERN_INFO "Huge page(16GB) memory: "
"addr = 0x%lX size = 0x%lX pages = %d\n",
phys_addr, block_size, expected_pages);
if (phys_addr + (16 * GB) <= memblock_end_of_DRAM()) {
memblock_reserve(phys_addr, block_size * expected_pages);
add_gpage(phys_addr, block_size, expected_pages);
}
return 0;
}
#endif /* CONFIG_HUGETLB_PAGE */
static void __init htab_init_page_sizes(void)
{
int rc;
/* Default to 4K pages only */
memcpy(mmu_psize_defs, mmu_psize_defaults_old,
sizeof(mmu_psize_defaults_old));
/*
* Try to find the available page sizes in the device-tree
*/
rc = of_scan_flat_dt(htab_dt_scan_page_sizes, NULL);
if (rc != 0) /* Found */
goto found;
/*
* Not in the device-tree, let's fallback on known size
* list for 16M capable GP & GR
*/
if (cpu_has_feature(CPU_FTR_16M_PAGE))
memcpy(mmu_psize_defs, mmu_psize_defaults_gp,
sizeof(mmu_psize_defaults_gp));
found:
#ifndef CONFIG_DEBUG_PAGEALLOC
/*
* Pick a size for the linear mapping. Currently, we only support
* 16M, 1M and 4K which is the default
*/
if (mmu_psize_defs[MMU_PAGE_16M].shift)
mmu_linear_psize = MMU_PAGE_16M;
else if (mmu_psize_defs[MMU_PAGE_1M].shift)
mmu_linear_psize = MMU_PAGE_1M;
#endif /* CONFIG_DEBUG_PAGEALLOC */
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
#ifdef CONFIG_PPC_64K_PAGES
/*
* Pick a size for the ordinary pages. Default is 4K, we support
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
* 64K for user mappings and vmalloc if supported by the processor.
* We only use 64k for ioremap if the processor
* (and firmware) support cache-inhibited large pages.
* If not, we use 4k and set mmu_ci_restrictions so that
* hash_page knows to switch processes that use cache-inhibited
* mappings to 4k pages.
*/
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
if (mmu_psize_defs[MMU_PAGE_64K].shift) {
mmu_virtual_psize = MMU_PAGE_64K;
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
mmu_vmalloc_psize = MMU_PAGE_64K;
if (mmu_linear_psize == MMU_PAGE_4K)
mmu_linear_psize = MMU_PAGE_64K;
if (cpu_has_feature(CPU_FTR_CI_LARGE_PAGE)) {
/*
* Don't use 64k pages for ioremap on pSeries, since
* that would stop us accessing the HEA ethernet.
*/
if (!machine_is(pseries))
mmu_io_psize = MMU_PAGE_64K;
} else
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
mmu_ci_restrictions = 1;
}
#endif /* CONFIG_PPC_64K_PAGES */
#ifdef CONFIG_SPARSEMEM_VMEMMAP
/* We try to use 16M pages for vmemmap if that is supported
* and we have at least 1G of RAM at boot
*/
if (mmu_psize_defs[MMU_PAGE_16M].shift &&
memblock_phys_mem_size() >= 0x40000000)
mmu_vmemmap_psize = MMU_PAGE_16M;
else if (mmu_psize_defs[MMU_PAGE_64K].shift)
mmu_vmemmap_psize = MMU_PAGE_64K;
else
mmu_vmemmap_psize = MMU_PAGE_4K;
#endif /* CONFIG_SPARSEMEM_VMEMMAP */
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
printk(KERN_DEBUG "Page orders: linear mapping = %d, "
"virtual = %d, io = %d"
#ifdef CONFIG_SPARSEMEM_VMEMMAP
", vmemmap = %d"
#endif
"\n",
mmu_psize_defs[mmu_linear_psize].shift,
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
mmu_psize_defs[mmu_virtual_psize].shift,
mmu_psize_defs[mmu_io_psize].shift
#ifdef CONFIG_SPARSEMEM_VMEMMAP
,mmu_psize_defs[mmu_vmemmap_psize].shift
#endif
);
#ifdef CONFIG_HUGETLB_PAGE
/* Reserve 16G huge page memory sections for huge pages */
of_scan_flat_dt(htab_dt_scan_hugepage_blocks, NULL);
#endif /* CONFIG_HUGETLB_PAGE */
}
static int __init htab_dt_scan_pftsize(unsigned long node,
const char *uname, int depth,
void *data)
{
char *type = of_get_flat_dt_prop(node, "device_type", NULL);
u32 *prop;
/* We are scanning "cpu" nodes only */
if (type == NULL || strcmp(type, "cpu") != 0)
return 0;
prop = (u32 *)of_get_flat_dt_prop(node, "ibm,pft-size", NULL);
if (prop != NULL) {
/* pft_size[0] is the NUMA CEC cookie */
ppc64_pft_size = prop[1];
return 1;
}
return 0;
}
static unsigned long __init htab_get_table_size(void)
{
unsigned long mem_size, rnd_mem_size, pteg_count, psize;
/* If hash size isn't already provided by the platform, we try to
* retrieve it from the device-tree. If it's not there neither, we
* calculate it now based on the total RAM size
*/
if (ppc64_pft_size == 0)
of_scan_flat_dt(htab_dt_scan_pftsize, NULL);
if (ppc64_pft_size)
return 1UL << ppc64_pft_size;
/* round mem_size up to next power of 2 */
mem_size = memblock_phys_mem_size();
rnd_mem_size = 1UL << __ilog2(mem_size);
if (rnd_mem_size < mem_size)
rnd_mem_size <<= 1;
/* # pages / 2 */
psize = mmu_psize_defs[mmu_virtual_psize].shift;
pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11);
return pteg_count << 7;
}
#ifdef CONFIG_MEMORY_HOTPLUG
void create_section_mapping(unsigned long start, unsigned long end)
{
BUG_ON(htab_bolt_mapping(start, end, __pa(start),
pgprot_val(PAGE_KERNEL), mmu_linear_psize,
mmu_kernel_ssize));
}
int remove_section_mapping(unsigned long start, unsigned long end)
{
return htab_remove_mapping(start, end, mmu_linear_psize,
mmu_kernel_ssize);
}
#endif /* CONFIG_MEMORY_HOTPLUG */
static inline void make_bl(unsigned int *insn_addr, void *func)
{
unsigned long funcp = *((unsigned long *)func);
int offset = funcp - (unsigned long)insn_addr;
*insn_addr = (unsigned int)(0x48000001 | (offset & 0x03fffffc));
flush_icache_range((unsigned long)insn_addr, 4+
(unsigned long)insn_addr);
}
static void __init htab_finish_init(void)
{
extern unsigned int *htab_call_hpte_insert1;
extern unsigned int *htab_call_hpte_insert2;
extern unsigned int *htab_call_hpte_remove;
extern unsigned int *htab_call_hpte_updatepp;
#ifdef CONFIG_PPC_HAS_HASH_64K
extern unsigned int *ht64_call_hpte_insert1;
extern unsigned int *ht64_call_hpte_insert2;
extern unsigned int *ht64_call_hpte_remove;
extern unsigned int *ht64_call_hpte_updatepp;
make_bl(ht64_call_hpte_insert1, ppc_md.hpte_insert);
make_bl(ht64_call_hpte_insert2, ppc_md.hpte_insert);
make_bl(ht64_call_hpte_remove, ppc_md.hpte_remove);
make_bl(ht64_call_hpte_updatepp, ppc_md.hpte_updatepp);
#endif /* CONFIG_PPC_HAS_HASH_64K */
make_bl(htab_call_hpte_insert1, ppc_md.hpte_insert);
make_bl(htab_call_hpte_insert2, ppc_md.hpte_insert);
make_bl(htab_call_hpte_remove, ppc_md.hpte_remove);
make_bl(htab_call_hpte_updatepp, ppc_md.hpte_updatepp);
}
static void __init htab_initialize(void)
{
unsigned long table;
unsigned long pteg_count;
unsigned long prot;
unsigned long base = 0, size = 0, limit;
struct memblock_region *reg;
DBG(" -> htab_initialize()\n");
/* Initialize segment sizes */
htab_init_seg_sizes();
/* Initialize page sizes */
htab_init_page_sizes();
if (cpu_has_feature(CPU_FTR_1T_SEGMENT)) {
mmu_kernel_ssize = MMU_SEGSIZE_1T;
mmu_highuser_ssize = MMU_SEGSIZE_1T;
printk(KERN_INFO "Using 1TB segments\n");
}
/*
* Calculate the required size of the htab. We want the number of
* PTEGs to equal one half the number of real pages.
*/
htab_size_bytes = htab_get_table_size();
pteg_count = htab_size_bytes >> 7;
htab_hash_mask = pteg_count - 1;
if (firmware_has_feature(FW_FEATURE_LPAR)) {
/* Using a hypervisor which owns the htab */
htab_address = NULL;
_SDR1 = 0;
} else {
/* Find storage for the HPT. Must be contiguous in
* the absolute address space. On cell we want it to be
* in the first 2 Gig so we can use it for IOMMU hacks.
*/
if (machine_is(cell))
limit = 0x80000000;
else
limit = MEMBLOCK_ALLOC_ANYWHERE;
table = memblock_alloc_base(htab_size_bytes, htab_size_bytes, limit);
DBG("Hash table allocated at %lx, size: %lx\n", table,
htab_size_bytes);
htab_address = abs_to_virt(table);
/* htab absolute addr + encoded htabsize */
_SDR1 = table + __ilog2(pteg_count) - 11;
/* Initialize the HPT with no entries */
memset((void *)table, 0, htab_size_bytes);
/* Set SDR1 */
mtspr(SPRN_SDR1, _SDR1);
}
prot = pgprot_val(PAGE_KERNEL);
#ifdef CONFIG_DEBUG_PAGEALLOC
linear_map_hash_count = memblock_end_of_DRAM() >> PAGE_SHIFT;
linear_map_hash_slots = __va(memblock_alloc_base(linear_map_hash_count,
1, memblock.rmo_size));
memset(linear_map_hash_slots, 0, linear_map_hash_count);
#endif /* CONFIG_DEBUG_PAGEALLOC */
/* On U3 based machines, we need to reserve the DART area and
* _NOT_ map it to avoid cache paradoxes as it's remapped non
* cacheable later on
*/
/* create bolted the linear mapping in the hash table */
for_each_memblock(memory, reg) {
base = (unsigned long)__va(reg->base);
size = reg->size;
DBG("creating mapping for region: %lx..%lx (prot: %lx)\n",
base, size, prot);
#ifdef CONFIG_U3_DART
/* Do not map the DART space. Fortunately, it will be aligned
* in such a way that it will not cross two memblock regions and
* will fit within a single 16Mb page.
* The DART space is assumed to be a full 16Mb region even if
* we only use 2Mb of that space. We will use more of it later
* for AGP GART. We have to use a full 16Mb large page.
*/
DBG("DART base: %lx\n", dart_tablebase);
if (dart_tablebase != 0 && dart_tablebase >= base
&& dart_tablebase < (base + size)) {
unsigned long dart_table_end = dart_tablebase + 16 * MB;
if (base != dart_tablebase)
BUG_ON(htab_bolt_mapping(base, dart_tablebase,
__pa(base), prot,
mmu_linear_psize,
mmu_kernel_ssize));
if ((base + size) > dart_table_end)
BUG_ON(htab_bolt_mapping(dart_tablebase+16*MB,
base + size,
__pa(dart_table_end),
prot,
mmu_linear_psize,
mmu_kernel_ssize));
continue;
}
#endif /* CONFIG_U3_DART */
BUG_ON(htab_bolt_mapping(base, base + size, __pa(base),
prot, mmu_linear_psize, mmu_kernel_ssize));
}
memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
/*
* If we have a memory_limit and we've allocated TCEs then we need to
* explicitly map the TCE area at the top of RAM. We also cope with the
* case that the TCEs start below memory_limit.
* tce_alloc_start/end are 16MB aligned so the mapping should work
* for either 4K or 16MB pages.
*/
if (tce_alloc_start) {
tce_alloc_start = (unsigned long)__va(tce_alloc_start);
tce_alloc_end = (unsigned long)__va(tce_alloc_end);
if (base + size >= tce_alloc_start)
tce_alloc_start = base + size + 1;
BUG_ON(htab_bolt_mapping(tce_alloc_start, tce_alloc_end,
__pa(tce_alloc_start), prot,
mmu_linear_psize, mmu_kernel_ssize));
}
htab_finish_init();
DBG(" <- htab_initialize()\n");
}
#undef KB
#undef MB
void __init early_init_mmu(void)
{
/* Setup initial STAB address in the PACA */
get_paca()->stab_real = __pa((u64)&initial_stab);
get_paca()->stab_addr = (u64)&initial_stab;
/* Initialize the MMU Hash table and create the linear mapping
* of memory. Has to be done before stab/slb initialization as
* this is currently where the page size encoding is obtained
*/
htab_initialize();
/* Initialize stab / SLB management except on iSeries
*/
if (cpu_has_feature(CPU_FTR_SLB))
slb_initialize();
else if (!firmware_has_feature(FW_FEATURE_ISERIES))
stab_initialize(get_paca()->stab_real);
}
#ifdef CONFIG_SMP
void __cpuinit early_init_mmu_secondary(void)
{
/* Initialize hash table for that CPU */
if (!firmware_has_feature(FW_FEATURE_LPAR))
mtspr(SPRN_SDR1, _SDR1);
/* Initialize STAB/SLB. We use a virtual address as it works
* in real mode on pSeries and we want a virutal address on
* iSeries anyway
*/
if (cpu_has_feature(CPU_FTR_SLB))
slb_initialize();
else
stab_initialize(get_paca()->stab_addr);
}
#endif /* CONFIG_SMP */
/*
* Called by asm hashtable.S for doing lazy icache flush
*/
unsigned int hash_page_do_lazy_icache(unsigned int pp, pte_t pte, int trap)
{
struct page *page;
if (!pfn_valid(pte_pfn(pte)))
return pp;
page = pte_page(pte);
/* page is dirty */
if (!test_bit(PG_arch_1, &page->flags) && !PageReserved(page)) {
if (trap == 0x400) {
flush_dcache_icache_page(page);
set_bit(PG_arch_1, &page->flags);
} else
pp |= HPTE_R_N;
}
return pp;
}
#ifdef CONFIG_PPC_MM_SLICES
unsigned int get_paca_psize(unsigned long addr)
{
unsigned long index, slices;
if (addr < SLICE_LOW_TOP) {
slices = get_paca()->context.low_slices_psize;
index = GET_LOW_SLICE_INDEX(addr);
} else {
slices = get_paca()->context.high_slices_psize;
index = GET_HIGH_SLICE_INDEX(addr);
}
return (slices >> (index * 4)) & 0xF;
}
#else
unsigned int get_paca_psize(unsigned long addr)
{
return get_paca()->context.user_psize;
}
#endif
[POWERPC] Allow drivers to map individual 4k pages to userspace Some drivers have resources that they want to be able to map into userspace that are 4k in size. On a kernel configured with 64k pages we currently end up mapping the 4k we want plus another 60k of physical address space, which could contain anything. This can introduce security problems, for example in the case of an infiniband adaptor where the other 60k could contain registers that some other program is using for its communications. This patch adds a new function, remap_4k_pfn, which drivers can use to map a single 4k page to userspace regardless of whether the kernel is using a 4k or a 64k page size. Like remap_pfn_range, it would typically be called in a driver's mmap function. It only maps a single 4k page, which on a 64k page kernel appears replicated 16 times throughout a 64k page. On a 4k page kernel it reduces to a call to remap_pfn_range. The way this works on a 64k kernel is that a new bit, _PAGE_4K_PFN, gets set on the linux PTE. This alters the way that __hash_page_4K computes the real address to put in the HPTE. The RPN field of the linux PTE becomes the 4k RPN directly rather than being interpreted as a 64k RPN. Since the RPN field is 32 bits, this means that physical addresses being mapped with remap_4k_pfn have to be below 2^44, i.e. 0x100000000000. The patch also factors out the code in arch/powerpc/mm/hash_utils_64.c that deals with demoting a process to use 4k pages into one function that gets called in the various different places where we need to do that. There were some discrepancies between exactly what was done in the various places, such as a call to spu_flush_all_slbs in one case but not in others. Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-04-03 19:24:02 +08:00
/*
* Demote a segment to using 4k pages.
* For now this makes the whole process use 4k pages.
*/
#ifdef CONFIG_PPC_64K_PAGES
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
void demote_segment_4k(struct mm_struct *mm, unsigned long addr)
{
if (get_slice_psize(mm, addr) == MMU_PAGE_4K)
[POWERPC] Allow drivers to map individual 4k pages to userspace Some drivers have resources that they want to be able to map into userspace that are 4k in size. On a kernel configured with 64k pages we currently end up mapping the 4k we want plus another 60k of physical address space, which could contain anything. This can introduce security problems, for example in the case of an infiniband adaptor where the other 60k could contain registers that some other program is using for its communications. This patch adds a new function, remap_4k_pfn, which drivers can use to map a single 4k page to userspace regardless of whether the kernel is using a 4k or a 64k page size. Like remap_pfn_range, it would typically be called in a driver's mmap function. It only maps a single 4k page, which on a 64k page kernel appears replicated 16 times throughout a 64k page. On a 4k page kernel it reduces to a call to remap_pfn_range. The way this works on a 64k kernel is that a new bit, _PAGE_4K_PFN, gets set on the linux PTE. This alters the way that __hash_page_4K computes the real address to put in the HPTE. The RPN field of the linux PTE becomes the 4k RPN directly rather than being interpreted as a 64k RPN. Since the RPN field is 32 bits, this means that physical addresses being mapped with remap_4k_pfn have to be below 2^44, i.e. 0x100000000000. The patch also factors out the code in arch/powerpc/mm/hash_utils_64.c that deals with demoting a process to use 4k pages into one function that gets called in the various different places where we need to do that. There were some discrepancies between exactly what was done in the various places, such as a call to spu_flush_all_slbs in one case but not in others. Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-04-03 19:24:02 +08:00
return;
slice_set_range_psize(mm, addr, 1, MMU_PAGE_4K);
#ifdef CONFIG_SPU_BASE
[POWERPC] Allow drivers to map individual 4k pages to userspace Some drivers have resources that they want to be able to map into userspace that are 4k in size. On a kernel configured with 64k pages we currently end up mapping the 4k we want plus another 60k of physical address space, which could contain anything. This can introduce security problems, for example in the case of an infiniband adaptor where the other 60k could contain registers that some other program is using for its communications. This patch adds a new function, remap_4k_pfn, which drivers can use to map a single 4k page to userspace regardless of whether the kernel is using a 4k or a 64k page size. Like remap_pfn_range, it would typically be called in a driver's mmap function. It only maps a single 4k page, which on a 64k page kernel appears replicated 16 times throughout a 64k page. On a 4k page kernel it reduces to a call to remap_pfn_range. The way this works on a 64k kernel is that a new bit, _PAGE_4K_PFN, gets set on the linux PTE. This alters the way that __hash_page_4K computes the real address to put in the HPTE. The RPN field of the linux PTE becomes the 4k RPN directly rather than being interpreted as a 64k RPN. Since the RPN field is 32 bits, this means that physical addresses being mapped with remap_4k_pfn have to be below 2^44, i.e. 0x100000000000. The patch also factors out the code in arch/powerpc/mm/hash_utils_64.c that deals with demoting a process to use 4k pages into one function that gets called in the various different places where we need to do that. There were some discrepancies between exactly what was done in the various places, such as a call to spu_flush_all_slbs in one case but not in others. Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-04-03 19:24:02 +08:00
spu_flush_all_slbs(mm);
#endif
if (get_paca_psize(addr) != MMU_PAGE_4K) {
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
get_paca()->context = mm->context;
slb_flush_and_rebolt();
}
[POWERPC] Allow drivers to map individual 4k pages to userspace Some drivers have resources that they want to be able to map into userspace that are 4k in size. On a kernel configured with 64k pages we currently end up mapping the 4k we want plus another 60k of physical address space, which could contain anything. This can introduce security problems, for example in the case of an infiniband adaptor where the other 60k could contain registers that some other program is using for its communications. This patch adds a new function, remap_4k_pfn, which drivers can use to map a single 4k page to userspace regardless of whether the kernel is using a 4k or a 64k page size. Like remap_pfn_range, it would typically be called in a driver's mmap function. It only maps a single 4k page, which on a 64k page kernel appears replicated 16 times throughout a 64k page. On a 4k page kernel it reduces to a call to remap_pfn_range. The way this works on a 64k kernel is that a new bit, _PAGE_4K_PFN, gets set on the linux PTE. This alters the way that __hash_page_4K computes the real address to put in the HPTE. The RPN field of the linux PTE becomes the 4k RPN directly rather than being interpreted as a 64k RPN. Since the RPN field is 32 bits, this means that physical addresses being mapped with remap_4k_pfn have to be below 2^44, i.e. 0x100000000000. The patch also factors out the code in arch/powerpc/mm/hash_utils_64.c that deals with demoting a process to use 4k pages into one function that gets called in the various different places where we need to do that. There were some discrepancies between exactly what was done in the various places, such as a call to spu_flush_all_slbs in one case but not in others. Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-04-03 19:24:02 +08:00
}
#endif /* CONFIG_PPC_64K_PAGES */
[POWERPC] Allow drivers to map individual 4k pages to userspace Some drivers have resources that they want to be able to map into userspace that are 4k in size. On a kernel configured with 64k pages we currently end up mapping the 4k we want plus another 60k of physical address space, which could contain anything. This can introduce security problems, for example in the case of an infiniband adaptor where the other 60k could contain registers that some other program is using for its communications. This patch adds a new function, remap_4k_pfn, which drivers can use to map a single 4k page to userspace regardless of whether the kernel is using a 4k or a 64k page size. Like remap_pfn_range, it would typically be called in a driver's mmap function. It only maps a single 4k page, which on a 64k page kernel appears replicated 16 times throughout a 64k page. On a 4k page kernel it reduces to a call to remap_pfn_range. The way this works on a 64k kernel is that a new bit, _PAGE_4K_PFN, gets set on the linux PTE. This alters the way that __hash_page_4K computes the real address to put in the HPTE. The RPN field of the linux PTE becomes the 4k RPN directly rather than being interpreted as a 64k RPN. Since the RPN field is 32 bits, this means that physical addresses being mapped with remap_4k_pfn have to be below 2^44, i.e. 0x100000000000. The patch also factors out the code in arch/powerpc/mm/hash_utils_64.c that deals with demoting a process to use 4k pages into one function that gets called in the various different places where we need to do that. There were some discrepancies between exactly what was done in the various places, such as a call to spu_flush_all_slbs in one case but not in others. Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-04-03 19:24:02 +08:00
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
#ifdef CONFIG_PPC_SUBPAGE_PROT
/*
* This looks up a 2-bit protection code for a 4k subpage of a 64k page.
* Userspace sets the subpage permissions using the subpage_prot system call.
*
* Result is 0: full permissions, _PAGE_RW: read-only,
* _PAGE_USER or _PAGE_USER|_PAGE_RW: no access.
*/
static int subpage_protection(struct mm_struct *mm, unsigned long ea)
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
{
struct subpage_prot_table *spt = &mm->context.spt;
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
u32 spp = 0;
u32 **sbpm, *sbpp;
if (ea >= spt->maxaddr)
return 0;
if (ea < 0x100000000) {
/* addresses below 4GB use spt->low_prot */
sbpm = spt->low_prot;
} else {
sbpm = spt->protptrs[ea >> SBP_L3_SHIFT];
if (!sbpm)
return 0;
}
sbpp = sbpm[(ea >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)];
if (!sbpp)
return 0;
spp = sbpp[(ea >> PAGE_SHIFT) & (SBP_L1_COUNT - 1)];
/* extract 2-bit bitfield for this 4k subpage */
spp >>= 30 - 2 * ((ea >> 12) & 0xf);
/* turn 0,1,2,3 into combination of _PAGE_USER and _PAGE_RW */
spp = ((spp & 2) ? _PAGE_USER : 0) | ((spp & 1) ? _PAGE_RW : 0);
return spp;
}
#else /* CONFIG_PPC_SUBPAGE_PROT */
static inline int subpage_protection(struct mm_struct *mm, unsigned long ea)
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
{
return 0;
}
#endif
void hash_failure_debug(unsigned long ea, unsigned long access,
unsigned long vsid, unsigned long trap,
int ssize, int psize, unsigned long pte)
{
if (!printk_ratelimit())
return;
pr_info("mm: Hashing failure ! EA=0x%lx access=0x%lx current=%s\n",
ea, access, current->comm);
pr_info(" trap=0x%lx vsid=0x%lx ssize=%d psize=%d pte=0x%lx\n",
trap, vsid, ssize, psize, pte);
}
/* Result code is:
* 0 - handled
* 1 - normal page fault
* -1 - critical hash insertion error
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
* -2 - access not permitted by subpage protection mechanism
*/
int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
{
pgd_t *pgdir;
unsigned long vsid;
struct mm_struct *mm;
pte_t *ptep;
powerpc/mm: Allow more flexible layouts for hugepage pagetables Currently each available hugepage size uses a slightly different pagetable layout: that is, the bottem level table of pointers to hugepages is a different size, and may branch off from the normal page tables at a different level. Every hugepage aware path that needs to walk the pagetables must therefore look up the hugepage size from the slice info first, and work out the correct way to walk the pagetables accordingly. Future hardware is likely to add more possible hugepage sizes, more layout options and more mess. This patch, therefore reworks the handling of hugepage pagetables to reduce this complexity. In the new scheme, instead of having to consult the slice mask, pagetable walking code can check a flag in the PGD/PUD/PMD entries to see where to branch off to hugepage pagetables, and the entry also contains the information (eseentially hugepage shift) necessary to then interpret that table without recourse to the slice mask. This scheme can be extended neatly to handle multiple levels of self-describing "special" hugepage pagetables, although for now we assume only one level exists. This approach means that only the pagetable allocation path needs to know how the pagetables should be set out. All other (hugepage) pagetable walking paths can just interpret the structure as they go. There already was a flag bit in PGD/PUD/PMD entries for hugepage directory pointers, but it was only used for debug. We alter that flag bit to instead be a 0 in the MSB to indicate a hugepage pagetable pointer (normally it would be 1 since the pointer lies in the linear mapping). This means that asm pagetable walking can test for (and punt on) hugepage pointers with the same test that checks for unpopulated page directory entries (beq becomes bge), since hugepage pointers will always be positive, and normal pointers always negative. While we're at it, we get rid of the confusing (and grep defeating) #defining of hugepte_shift to be the same thing as mmu_huge_psizes. Signed-off-by: David Gibson <dwg@au1.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-10-27 03:24:31 +08:00
unsigned hugeshift;
const struct cpumask *tmp;
int rc, user_region = 0, local = 0;
int psize, ssize;
DBG_LOW("hash_page(ea=%016lx, access=%lx, trap=%lx\n",
ea, access, trap);
if ((ea & ~REGION_MASK) >= PGTABLE_RANGE) {
DBG_LOW(" out of pgtable range !\n");
return 1;
}
/* Get region & vsid */
switch (REGION_ID(ea)) {
case USER_REGION_ID:
user_region = 1;
mm = current->mm;
if (! mm) {
DBG_LOW(" user region with no mm !\n");
return 1;
}
psize = get_slice_psize(mm, ea);
ssize = user_segment_size(ea);
vsid = get_vsid(mm->context.id, ea, ssize);
break;
case VMALLOC_REGION_ID:
mm = &init_mm;
vsid = get_kernel_vsid(ea, mmu_kernel_ssize);
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
if (ea < VMALLOC_END)
psize = mmu_vmalloc_psize;
else
psize = mmu_io_psize;
ssize = mmu_kernel_ssize;
break;
default:
/* Not a valid range
* Send the problem up to do_page_fault
*/
return 1;
}
DBG_LOW(" mm=%p, mm->pgdir=%p, vsid=%016lx\n", mm, mm->pgd, vsid);
/* Get pgdir */
pgdir = mm->pgd;
if (pgdir == NULL)
return 1;
/* Check CPU locality */
tmp = cpumask_of(smp_processor_id());
if (user_region && cpumask_equal(mm_cpumask(mm), tmp))
local = 1;
#ifndef CONFIG_PPC_64K_PAGES
powerpc/mm: Allow more flexible layouts for hugepage pagetables Currently each available hugepage size uses a slightly different pagetable layout: that is, the bottem level table of pointers to hugepages is a different size, and may branch off from the normal page tables at a different level. Every hugepage aware path that needs to walk the pagetables must therefore look up the hugepage size from the slice info first, and work out the correct way to walk the pagetables accordingly. Future hardware is likely to add more possible hugepage sizes, more layout options and more mess. This patch, therefore reworks the handling of hugepage pagetables to reduce this complexity. In the new scheme, instead of having to consult the slice mask, pagetable walking code can check a flag in the PGD/PUD/PMD entries to see where to branch off to hugepage pagetables, and the entry also contains the information (eseentially hugepage shift) necessary to then interpret that table without recourse to the slice mask. This scheme can be extended neatly to handle multiple levels of self-describing "special" hugepage pagetables, although for now we assume only one level exists. This approach means that only the pagetable allocation path needs to know how the pagetables should be set out. All other (hugepage) pagetable walking paths can just interpret the structure as they go. There already was a flag bit in PGD/PUD/PMD entries for hugepage directory pointers, but it was only used for debug. We alter that flag bit to instead be a 0 in the MSB to indicate a hugepage pagetable pointer (normally it would be 1 since the pointer lies in the linear mapping). This means that asm pagetable walking can test for (and punt on) hugepage pointers with the same test that checks for unpopulated page directory entries (beq becomes bge), since hugepage pointers will always be positive, and normal pointers always negative. While we're at it, we get rid of the confusing (and grep defeating) #defining of hugepte_shift to be the same thing as mmu_huge_psizes. Signed-off-by: David Gibson <dwg@au1.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-10-27 03:24:31 +08:00
/* If we use 4K pages and our psize is not 4K, then we might
* be hitting a special driver mapping, and need to align the
* address before we fetch the PTE.
*
* It could also be a hugepage mapping, in which case this is
* not necessary, but it's not harmful, either.
*/
if (psize != MMU_PAGE_4K)
ea &= ~((1ul << mmu_psize_defs[psize].shift) - 1);
#endif /* CONFIG_PPC_64K_PAGES */
/* Get PTE and page size from page tables */
powerpc/mm: Allow more flexible layouts for hugepage pagetables Currently each available hugepage size uses a slightly different pagetable layout: that is, the bottem level table of pointers to hugepages is a different size, and may branch off from the normal page tables at a different level. Every hugepage aware path that needs to walk the pagetables must therefore look up the hugepage size from the slice info first, and work out the correct way to walk the pagetables accordingly. Future hardware is likely to add more possible hugepage sizes, more layout options and more mess. This patch, therefore reworks the handling of hugepage pagetables to reduce this complexity. In the new scheme, instead of having to consult the slice mask, pagetable walking code can check a flag in the PGD/PUD/PMD entries to see where to branch off to hugepage pagetables, and the entry also contains the information (eseentially hugepage shift) necessary to then interpret that table without recourse to the slice mask. This scheme can be extended neatly to handle multiple levels of self-describing "special" hugepage pagetables, although for now we assume only one level exists. This approach means that only the pagetable allocation path needs to know how the pagetables should be set out. All other (hugepage) pagetable walking paths can just interpret the structure as they go. There already was a flag bit in PGD/PUD/PMD entries for hugepage directory pointers, but it was only used for debug. We alter that flag bit to instead be a 0 in the MSB to indicate a hugepage pagetable pointer (normally it would be 1 since the pointer lies in the linear mapping). This means that asm pagetable walking can test for (and punt on) hugepage pointers with the same test that checks for unpopulated page directory entries (beq becomes bge), since hugepage pointers will always be positive, and normal pointers always negative. While we're at it, we get rid of the confusing (and grep defeating) #defining of hugepte_shift to be the same thing as mmu_huge_psizes. Signed-off-by: David Gibson <dwg@au1.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-10-27 03:24:31 +08:00
ptep = find_linux_pte_or_hugepte(pgdir, ea, &hugeshift);
if (ptep == NULL || !pte_present(*ptep)) {
DBG_LOW(" no PTE !\n");
return 1;
}
/* Add _PAGE_PRESENT to the required access perm */
access |= _PAGE_PRESENT;
/* Pre-check access permissions (will be re-checked atomically
* in __hash_page_XX but this pre-check is a fast path
*/
if (access & ~pte_val(*ptep)) {
DBG_LOW(" no access !\n");
return 1;
}
powerpc/mm: Allow more flexible layouts for hugepage pagetables Currently each available hugepage size uses a slightly different pagetable layout: that is, the bottem level table of pointers to hugepages is a different size, and may branch off from the normal page tables at a different level. Every hugepage aware path that needs to walk the pagetables must therefore look up the hugepage size from the slice info first, and work out the correct way to walk the pagetables accordingly. Future hardware is likely to add more possible hugepage sizes, more layout options and more mess. This patch, therefore reworks the handling of hugepage pagetables to reduce this complexity. In the new scheme, instead of having to consult the slice mask, pagetable walking code can check a flag in the PGD/PUD/PMD entries to see where to branch off to hugepage pagetables, and the entry also contains the information (eseentially hugepage shift) necessary to then interpret that table without recourse to the slice mask. This scheme can be extended neatly to handle multiple levels of self-describing "special" hugepage pagetables, although for now we assume only one level exists. This approach means that only the pagetable allocation path needs to know how the pagetables should be set out. All other (hugepage) pagetable walking paths can just interpret the structure as they go. There already was a flag bit in PGD/PUD/PMD entries for hugepage directory pointers, but it was only used for debug. We alter that flag bit to instead be a 0 in the MSB to indicate a hugepage pagetable pointer (normally it would be 1 since the pointer lies in the linear mapping). This means that asm pagetable walking can test for (and punt on) hugepage pointers with the same test that checks for unpopulated page directory entries (beq becomes bge), since hugepage pointers will always be positive, and normal pointers always negative. While we're at it, we get rid of the confusing (and grep defeating) #defining of hugepte_shift to be the same thing as mmu_huge_psizes. Signed-off-by: David Gibson <dwg@au1.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-10-27 03:24:31 +08:00
#ifdef CONFIG_HUGETLB_PAGE
if (hugeshift)
return __hash_page_huge(ea, access, vsid, ptep, trap, local,
ssize, hugeshift, psize);
#endif /* CONFIG_HUGETLB_PAGE */
#ifndef CONFIG_PPC_64K_PAGES
DBG_LOW(" i-pte: %016lx\n", pte_val(*ptep));
#else
DBG_LOW(" i-pte: %016lx %016lx\n", pte_val(*ptep),
pte_val(*(ptep + PTRS_PER_PTE)));
#endif
/* Do actual hashing */
#ifdef CONFIG_PPC_64K_PAGES
[POWERPC] Allow drivers to map individual 4k pages to userspace Some drivers have resources that they want to be able to map into userspace that are 4k in size. On a kernel configured with 64k pages we currently end up mapping the 4k we want plus another 60k of physical address space, which could contain anything. This can introduce security problems, for example in the case of an infiniband adaptor where the other 60k could contain registers that some other program is using for its communications. This patch adds a new function, remap_4k_pfn, which drivers can use to map a single 4k page to userspace regardless of whether the kernel is using a 4k or a 64k page size. Like remap_pfn_range, it would typically be called in a driver's mmap function. It only maps a single 4k page, which on a 64k page kernel appears replicated 16 times throughout a 64k page. On a 4k page kernel it reduces to a call to remap_pfn_range. The way this works on a 64k kernel is that a new bit, _PAGE_4K_PFN, gets set on the linux PTE. This alters the way that __hash_page_4K computes the real address to put in the HPTE. The RPN field of the linux PTE becomes the 4k RPN directly rather than being interpreted as a 64k RPN. Since the RPN field is 32 bits, this means that physical addresses being mapped with remap_4k_pfn have to be below 2^44, i.e. 0x100000000000. The patch also factors out the code in arch/powerpc/mm/hash_utils_64.c that deals with demoting a process to use 4k pages into one function that gets called in the various different places where we need to do that. There were some discrepancies between exactly what was done in the various places, such as a call to spu_flush_all_slbs in one case but not in others. Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-04-03 19:24:02 +08:00
/* If _PAGE_4K_PFN is set, make sure this is a 4k segment */
if ((pte_val(*ptep) & _PAGE_4K_PFN) && psize == MMU_PAGE_64K) {
[POWERPC] Allow drivers to map individual 4k pages to userspace Some drivers have resources that they want to be able to map into userspace that are 4k in size. On a kernel configured with 64k pages we currently end up mapping the 4k we want plus another 60k of physical address space, which could contain anything. This can introduce security problems, for example in the case of an infiniband adaptor where the other 60k could contain registers that some other program is using for its communications. This patch adds a new function, remap_4k_pfn, which drivers can use to map a single 4k page to userspace regardless of whether the kernel is using a 4k or a 64k page size. Like remap_pfn_range, it would typically be called in a driver's mmap function. It only maps a single 4k page, which on a 64k page kernel appears replicated 16 times throughout a 64k page. On a 4k page kernel it reduces to a call to remap_pfn_range. The way this works on a 64k kernel is that a new bit, _PAGE_4K_PFN, gets set on the linux PTE. This alters the way that __hash_page_4K computes the real address to put in the HPTE. The RPN field of the linux PTE becomes the 4k RPN directly rather than being interpreted as a 64k RPN. Since the RPN field is 32 bits, this means that physical addresses being mapped with remap_4k_pfn have to be below 2^44, i.e. 0x100000000000. The patch also factors out the code in arch/powerpc/mm/hash_utils_64.c that deals with demoting a process to use 4k pages into one function that gets called in the various different places where we need to do that. There were some discrepancies between exactly what was done in the various places, such as a call to spu_flush_all_slbs in one case but not in others. Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-04-03 19:24:02 +08:00
demote_segment_4k(mm, ea);
psize = MMU_PAGE_4K;
}
/* If this PTE is non-cacheable and we have restrictions on
* using non cacheable large pages, then we switch to 4k
*/
if (mmu_ci_restrictions && psize == MMU_PAGE_64K &&
(pte_val(*ptep) & _PAGE_NO_CACHE)) {
if (user_region) {
demote_segment_4k(mm, ea);
psize = MMU_PAGE_4K;
} else if (ea < VMALLOC_END) {
/*
* some driver did a non-cacheable mapping
* in vmalloc space, so switch vmalloc
* to 4k pages
*/
printk(KERN_ALERT "Reducing vmalloc segment "
"to 4kB pages because of "
"non-cacheable mapping\n");
psize = mmu_vmalloc_psize = MMU_PAGE_4K;
#ifdef CONFIG_SPU_BASE
spu_flush_all_slbs(mm);
#endif
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
}
}
if (user_region) {
if (psize != get_paca_psize(ea)) {
get_paca()->context = mm->context;
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
slb_flush_and_rebolt();
}
} else if (get_paca()->vmalloc_sllp !=
mmu_psize_defs[mmu_vmalloc_psize].sllp) {
get_paca()->vmalloc_sllp =
mmu_psize_defs[mmu_vmalloc_psize].sllp;
slb_vmalloc_update();
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
}
#endif /* CONFIG_PPC_64K_PAGES */
#ifdef CONFIG_PPC_HAS_HASH_64K
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
if (psize == MMU_PAGE_64K)
rc = __hash_page_64K(ea, access, vsid, ptep, trap, local, ssize);
else
#endif /* CONFIG_PPC_HAS_HASH_64K */
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
{
int spp = subpage_protection(mm, ea);
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
if (access & spp)
rc = -2;
else
rc = __hash_page_4K(ea, access, vsid, ptep, trap,
local, ssize, spp);
}
/* Dump some info in case of hash insertion failure, they should
* never happen so it is really useful to know if/when they do
*/
if (rc == -1)
hash_failure_debug(ea, access, vsid, trap, ssize, psize,
pte_val(*ptep));
#ifndef CONFIG_PPC_64K_PAGES
DBG_LOW(" o-pte: %016lx\n", pte_val(*ptep));
#else
DBG_LOW(" o-pte: %016lx %016lx\n", pte_val(*ptep),
pte_val(*(ptep + PTRS_PER_PTE)));
#endif
DBG_LOW(" -> rc=%d\n", rc);
return rc;
}
EXPORT_SYMBOL_GPL(hash_page);
void hash_preload(struct mm_struct *mm, unsigned long ea,
unsigned long access, unsigned long trap)
{
unsigned long vsid;
void *pgdir;
pte_t *ptep;
unsigned long flags;
int rc, ssize, local = 0;
[POWERPC] Introduce address space "slices" The basic issue is to be able to do what hugetlbfs does but with different page sizes for some other special filesystems; more specifically, my need is: - Huge pages - SPE local store mappings using 64K pages on a 4K base page size kernel on Cell - Some special 4K segments in 64K-page kernels for mapping a dodgy type of powerpc-specific infiniband hardware that requires 4K MMU mappings for various reasons I won't explain here. The main issues are: - To maintain/keep track of the page size per "segment" (as we can only have one page size per segment on powerpc, which are 256MB divisions of the address space). - To make sure special mappings stay within their allotted "segments" (including MAP_FIXED crap) - To make sure everybody else doesn't mmap/brk/grow_stack into a "segment" that is used for a special mapping Some of the necessary mechanisms to handle that were present in the hugetlbfs code, but mostly in ways not suitable for anything else. The patch relies on some changes to the generic get_unmapped_area() that just got merged. It still hijacks hugetlb callbacks here or there as the generic code hasn't been entirely cleaned up yet but that shouldn't be a problem. So what is a slice ? Well, I re-used the mechanism used formerly by our hugetlbfs implementation which divides the address space in "meta-segments" which I called "slices". The division is done using 256MB slices below 4G, and 1T slices above. Thus the address space is divided currently into 16 "low" slices and 16 "high" slices. (Special case: high slice 0 is the area between 4G and 1T). Doing so simplifies significantly the tracking of segments and avoids having to keep track of all the 256MB segments in the address space. While I used the "concepts" of hugetlbfs, I mostly re-implemented everything in a more generic way and "ported" hugetlbfs to it. Slices can have an associated page size, which is encoded in the mmu context and used by the SLB miss handler to set the segment sizes. The hash code currently doesn't care, it has a specific check for hugepages, though I might add a mechanism to provide per-slice hash mapping functions in the future. The slice code provide a pair of "generic" get_unmapped_area() (bottomup and topdown) functions that should work with any slice size. There is some trickiness here so I would appreciate people to have a look at the implementation of these and let me know if I got something wrong. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-05-08 14:27:27 +08:00
BUG_ON(REGION_ID(ea) != USER_REGION_ID);
#ifdef CONFIG_PPC_MM_SLICES
/* We only prefault standard pages for now */
if (unlikely(get_slice_psize(mm, ea) != mm->context.user_psize))
return;
[POWERPC] Introduce address space "slices" The basic issue is to be able to do what hugetlbfs does but with different page sizes for some other special filesystems; more specifically, my need is: - Huge pages - SPE local store mappings using 64K pages on a 4K base page size kernel on Cell - Some special 4K segments in 64K-page kernels for mapping a dodgy type of powerpc-specific infiniband hardware that requires 4K MMU mappings for various reasons I won't explain here. The main issues are: - To maintain/keep track of the page size per "segment" (as we can only have one page size per segment on powerpc, which are 256MB divisions of the address space). - To make sure special mappings stay within their allotted "segments" (including MAP_FIXED crap) - To make sure everybody else doesn't mmap/brk/grow_stack into a "segment" that is used for a special mapping Some of the necessary mechanisms to handle that were present in the hugetlbfs code, but mostly in ways not suitable for anything else. The patch relies on some changes to the generic get_unmapped_area() that just got merged. It still hijacks hugetlb callbacks here or there as the generic code hasn't been entirely cleaned up yet but that shouldn't be a problem. So what is a slice ? Well, I re-used the mechanism used formerly by our hugetlbfs implementation which divides the address space in "meta-segments" which I called "slices". The division is done using 256MB slices below 4G, and 1T slices above. Thus the address space is divided currently into 16 "low" slices and 16 "high" slices. (Special case: high slice 0 is the area between 4G and 1T). Doing so simplifies significantly the tracking of segments and avoids having to keep track of all the 256MB segments in the address space. While I used the "concepts" of hugetlbfs, I mostly re-implemented everything in a more generic way and "ported" hugetlbfs to it. Slices can have an associated page size, which is encoded in the mmu context and used by the SLB miss handler to set the segment sizes. The hash code currently doesn't care, it has a specific check for hugepages, though I might add a mechanism to provide per-slice hash mapping functions in the future. The slice code provide a pair of "generic" get_unmapped_area() (bottomup and topdown) functions that should work with any slice size. There is some trickiness here so I would appreciate people to have a look at the implementation of these and let me know if I got something wrong. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-05-08 14:27:27 +08:00
#endif
DBG_LOW("hash_preload(mm=%p, mm->pgdir=%p, ea=%016lx, access=%lx,"
" trap=%lx\n", mm, mm->pgd, ea, access, trap);
/* Get Linux PTE if available */
pgdir = mm->pgd;
if (pgdir == NULL)
return;
ptep = find_linux_pte(pgdir, ea);
if (!ptep)
return;
#ifdef CONFIG_PPC_64K_PAGES
/* If either _PAGE_4K_PFN or _PAGE_NO_CACHE is set (and we are on
* a 64K kernel), then we don't preload, hash_page() will take
* care of it once we actually try to access the page.
* That way we don't have to duplicate all of the logic for segment
* page size demotion here
*/
if (pte_val(*ptep) & (_PAGE_4K_PFN | _PAGE_NO_CACHE))
return;
#endif /* CONFIG_PPC_64K_PAGES */
/* Get VSID */
ssize = user_segment_size(ea);
vsid = get_vsid(mm->context.id, ea, ssize);
/* Hash doesn't like irqs */
local_irq_save(flags);
/* Is that local to this CPU ? */
if (cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
local = 1;
/* Hash it in */
#ifdef CONFIG_PPC_HAS_HASH_64K
powerpc: Use 64k pages without needing cache-inhibited large pages Some POWER5+ machines can do 64k hardware pages for normal memory but not for cache-inhibited pages. This patch lets us use 64k hardware pages for most user processes on such machines (assuming the kernel has been configured with CONFIG_PPC_64K_PAGES=y). User processes start out using 64k pages and get switched to 4k pages if they use any non-cacheable mappings. With this, we use 64k pages for the vmalloc region and 4k pages for the imalloc region. If anything creates a non-cacheable mapping in the vmalloc region, the vmalloc region will get switched to 4k pages. I don't know of any driver other than the DRM that would do this, though, and these machines don't have AGP. When a region gets switched from 64k pages to 4k pages, we do not have to clear out all the 64k HPTEs from the hash table immediately. We use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page was hashed in as a 64k page or a set of 4k pages. If hash_page is trying to insert a 4k page for a Linux PTE and it sees that it has already been inserted as a 64k page, it first invalidates the 64k HPTE before inserting the 4k HPTE. The hash invalidation routines also use the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a set of 4k HPTEs to remove. With those two changes, we can tolerate a mix of 4k and 64k HPTEs in the hash table, and they will all get removed when the address space is torn down. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 08:45:18 +08:00
if (mm->context.user_psize == MMU_PAGE_64K)
rc = __hash_page_64K(ea, access, vsid, ptep, trap, local, ssize);
else
#endif /* CONFIG_PPC_HAS_HASH_64K */
rc = __hash_page_4K(ea, access, vsid, ptep, trap, local, ssize,
subpage_protection(pgdir, ea));
/* Dump some info in case of hash insertion failure, they should
* never happen so it is really useful to know if/when they do
*/
if (rc == -1)
hash_failure_debug(ea, access, vsid, trap, ssize,
mm->context.user_psize, pte_val(*ptep));
local_irq_restore(flags);
}
/* WARNING: This is called from hash_low_64.S, if you change this prototype,
* do not forget to update the assembly call site !
*/
void flush_hash_page(unsigned long va, real_pte_t pte, int psize, int ssize,
int local)
{
unsigned long hash, index, shift, hidx, slot;
DBG_LOW("flush_hash_page(va=%016lx)\n", va);
pte_iterate_hashed_subpages(pte, psize, va, index, shift) {
hash = hpt_hash(va, shift, ssize);
hidx = __rpte_to_hidx(pte, index);
if (hidx & _PTEIDX_SECONDARY)
hash = ~hash;
slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
slot += hidx & _PTEIDX_GROUP_IX;
DBG_LOW(" sub %ld: hash=%lx, hidx=%lx\n", index, slot, hidx);
ppc_md.hpte_invalidate(slot, va, psize, ssize, local);
} pte_iterate_hashed_end();
}
void flush_hash_range(unsigned long number, int local)
{
if (ppc_md.flush_hash_range)
ppc_md.flush_hash_range(number, local);
else {
int i;
struct ppc64_tlb_batch *batch =
&__get_cpu_var(ppc64_tlb_batch);
for (i = 0; i < number; i++)
flush_hash_page(batch->vaddr[i], batch->pte[i],
batch->psize, batch->ssize, local);
}
}
/*
* low_hash_fault is called when we the low level hash code failed
* to instert a PTE due to an hypervisor error
*/
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
void low_hash_fault(struct pt_regs *regs, unsigned long address, int rc)
{
if (user_mode(regs)) {
[POWERPC] Provide a way to protect 4k subpages when using 64k pages Using 64k pages on 64-bit PowerPC systems makes life difficult for emulators that are trying to emulate an ISA, such as x86, which use a smaller page size, since the emulator can no longer use the MMU and the normal system calls for controlling page protections. Of course, the emulator can emulate the MMU by checking and possibly remapping the address for each memory access in software, but that is pretty slow. This provides a facility for such programs to control the access permissions on individual 4k sub-pages of 64k pages. The idea is that the emulator supplies an array of protection masks to apply to a specified range of virtual addresses. These masks are applied at the level where hardware PTEs are inserted into the hardware page table based on the Linux PTEs, so the Linux PTEs are not affected. Note that this new mechanism does not allow any access that would otherwise be prohibited; it can only prohibit accesses that would otherwise be allowed. This new facility is only available on 64-bit PowerPC and only when the kernel is configured for 64k pages. The masks are supplied using a new subpage_prot system call, which takes a starting virtual address and length, and a pointer to an array of protection masks in memory. The array has a 32-bit word per 64k page to be protected; each 32-bit word consists of 16 2-bit fields, for which 0 allows any access (that is otherwise allowed), 1 prevents write accesses, and 2 or 3 prevent any access. Implicit in this is that the regions of the address space that are protected are switched to use 4k hardware pages rather than 64k hardware pages (on machines with hardware 64k page support). In fact the whole process is switched to use 4k hardware pages when the subpage_prot system call is used, but this could be improved in future to switch only the affected segments. The subpage protection bits are stored in a 3 level tree akin to the page table tree. The top level of this tree is stored in a structure that is appended to the top level of the page table tree, i.e., the pgd array. Since it will often only be 32-bit addresses (below 4GB) that are protected, the pointers to the first four bottom level pages are also stored in this structure (each bottom level page contains the protection bits for 1GB of address space), so the protection bits for addresses below 4GB can be accessed with one fewer loads than those for higher addresses. Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-01-24 05:35:13 +08:00
#ifdef CONFIG_PPC_SUBPAGE_PROT
if (rc == -2)
_exception(SIGSEGV, regs, SEGV_ACCERR, address);
else
#endif
_exception(SIGBUS, regs, BUS_ADRERR, address);
} else
bad_page_fault(regs, address, SIGBUS);
}
#ifdef CONFIG_DEBUG_PAGEALLOC
static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
{
unsigned long hash, hpteg;
unsigned long vsid = get_kernel_vsid(vaddr, mmu_kernel_ssize);
unsigned long va = hpt_va(vaddr, vsid, mmu_kernel_ssize);
unsigned long mode = htab_convert_pte_flags(PAGE_KERNEL);
int ret;
hash = hpt_hash(va, PAGE_SHIFT, mmu_kernel_ssize);
hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
ret = ppc_md.hpte_insert(hpteg, va, __pa(vaddr),
mode, HPTE_V_BOLTED,
mmu_linear_psize, mmu_kernel_ssize);
BUG_ON (ret < 0);
spin_lock(&linear_map_hash_lock);
BUG_ON(linear_map_hash_slots[lmi] & 0x80);
linear_map_hash_slots[lmi] = ret | 0x80;
spin_unlock(&linear_map_hash_lock);
}
static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi)
{
unsigned long hash, hidx, slot;
unsigned long vsid = get_kernel_vsid(vaddr, mmu_kernel_ssize);
unsigned long va = hpt_va(vaddr, vsid, mmu_kernel_ssize);
hash = hpt_hash(va, PAGE_SHIFT, mmu_kernel_ssize);
spin_lock(&linear_map_hash_lock);
BUG_ON(!(linear_map_hash_slots[lmi] & 0x80));
hidx = linear_map_hash_slots[lmi] & 0x7f;
linear_map_hash_slots[lmi] = 0;
spin_unlock(&linear_map_hash_lock);
if (hidx & _PTEIDX_SECONDARY)
hash = ~hash;
slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
slot += hidx & _PTEIDX_GROUP_IX;
ppc_md.hpte_invalidate(slot, va, mmu_linear_psize, mmu_kernel_ssize, 0);
}
void kernel_map_pages(struct page *page, int numpages, int enable)
{
unsigned long flags, vaddr, lmi;
int i;
local_irq_save(flags);
for (i = 0; i < numpages; i++, page++) {
vaddr = (unsigned long)page_address(page);
lmi = __pa(vaddr) >> PAGE_SHIFT;
if (lmi >= linear_map_hash_count)
continue;
if (enable)
kernel_map_linear_page(vaddr, lmi);
else
kernel_unmap_linear_page(vaddr, lmi);
}
local_irq_restore(flags);
}
#endif /* CONFIG_DEBUG_PAGEALLOC */