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linux-next/arch/powerpc/mm/slb_low.S
Benjamin Herrenschmidt 8d8997f34e powerpc/mm: Fix hang accessing top of vmalloc space 
On pSeries, we always force the IO space to be mapped using 4K
pages even with a 64K base page size to cope with some limitations
in the HV interface to some devices.

However, the SLB miss handler code to discriminate between vmalloc
and ioremap space uses a CPU feature section such that the code
is nop'ed out when the processor support large pages non-cachable
mappings.

Thus, we end up always using the ioremap page size for vmalloc
segments on such processors, causing a discrepency between the
segment and the hash table, and thus a hang continously hashing
the page.

It works for the first segment of the vmalloc space since that
segment is "bolted" in by C code correctly, and thankfully we
almost never use the vmalloc space beyond the first segment,
but the new percpu code made the bug happen.

This fixes it by removing the feature section from the assembly,
we now always do the comparison between vmalloc and ioremap.

Signed-off-by; Benjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-10-14 16:58:36 +11:00

300 lines
8.1 KiB
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/*
* Low-level SLB routines
*
* Copyright (C) 2004 David Gibson <dwg@au.ibm.com>, IBM
*
* Based on earlier C version:
* Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
* Copyright (c) 2001 Dave Engebretsen
* Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
*
* 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.
*/
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/cputable.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/firmware.h>
/* void slb_allocate_realmode(unsigned long ea);
*
* Create an SLB entry for the given EA (user or kernel).
* r3 = faulting address, r13 = PACA
* r9, r10, r11 are clobbered by this function
* No other registers are examined or changed.
*/
_GLOBAL(slb_allocate_realmode)
/* r3 = faulting address */
srdi r9,r3,60 /* get region */
srdi r10,r3,28 /* get esid */
cmpldi cr7,r9,0xc /* cmp PAGE_OFFSET for later use */
/* r3 = address, r10 = esid, cr7 = <> PAGE_OFFSET */
blt cr7,0f /* user or kernel? */
/* kernel address: proto-VSID = ESID */
/* WARNING - MAGIC: we don't use the VSID 0xfffffffff, but
* this code will generate the protoVSID 0xfffffffff for the
* top segment. That's ok, the scramble below will translate
* it to VSID 0, which is reserved as a bad VSID - one which
* will never have any pages in it. */
/* Check if hitting the linear mapping or some other kernel space
*/
bne cr7,1f
/* Linear mapping encoding bits, the "li" instruction below will
* be patched by the kernel at boot
*/
_GLOBAL(slb_miss_kernel_load_linear)
li r11,0
BEGIN_FTR_SECTION
b slb_finish_load
END_FTR_SECTION_IFCLR(CPU_FTR_1T_SEGMENT)
b slb_finish_load_1T
1:
#ifdef CONFIG_SPARSEMEM_VMEMMAP
/* Check virtual memmap region. To be patches at kernel boot */
cmpldi cr0,r9,0xf
bne 1f
_GLOBAL(slb_miss_kernel_load_vmemmap)
li r11,0
b 6f
1:
#endif /* CONFIG_SPARSEMEM_VMEMMAP */
/* vmalloc mapping gets the encoding from the PACA as the mapping
* can be demoted from 64K -> 4K dynamically on some machines
*/
clrldi r11,r10,48
cmpldi r11,(VMALLOC_SIZE >> 28) - 1
bgt 5f
lhz r11,PACAVMALLOCSLLP(r13)
b 6f
5:
/* IO mapping */
_GLOBAL(slb_miss_kernel_load_io)
li r11,0
6:
BEGIN_FTR_SECTION
b slb_finish_load
END_FTR_SECTION_IFCLR(CPU_FTR_1T_SEGMENT)
b slb_finish_load_1T
0: /* user address: proto-VSID = context << 15 | ESID. First check
* if the address is within the boundaries of the user region
*/
srdi. r9,r10,USER_ESID_BITS
bne- 8f /* invalid ea bits set */
/* when using slices, we extract the psize off the slice bitmaps
* and then we need to get the sllp encoding off the mmu_psize_defs
* array.
*
* XXX This is a bit inefficient especially for the normal case,
* so we should try to implement a fast path for the standard page
* size using the old sllp value so we avoid the array. We cannot
* really do dynamic patching unfortunately as processes might flip
* between 4k and 64k standard page size
*/
#ifdef CONFIG_PPC_MM_SLICES
cmpldi r10,16
/* Get the slice index * 4 in r11 and matching slice size mask in r9 */
ld r9,PACALOWSLICESPSIZE(r13)
sldi r11,r10,2
blt 5f
ld r9,PACAHIGHSLICEPSIZE(r13)
srdi r11,r10,(SLICE_HIGH_SHIFT - SLICE_LOW_SHIFT - 2)
andi. r11,r11,0x3c
5: /* Extract the psize and multiply to get an array offset */
srd r9,r9,r11
andi. r9,r9,0xf
mulli r9,r9,MMUPSIZEDEFSIZE
/* Now get to the array and obtain the sllp
*/
ld r11,PACATOC(r13)
ld r11,mmu_psize_defs@got(r11)
add r11,r11,r9
ld r11,MMUPSIZESLLP(r11)
ori r11,r11,SLB_VSID_USER
#else
/* paca context sllp already contains the SLB_VSID_USER bits */
lhz r11,PACACONTEXTSLLP(r13)
#endif /* CONFIG_PPC_MM_SLICES */
ld r9,PACACONTEXTID(r13)
BEGIN_FTR_SECTION
cmpldi r10,0x1000
END_FTR_SECTION_IFSET(CPU_FTR_1T_SEGMENT)
rldimi r10,r9,USER_ESID_BITS,0
BEGIN_FTR_SECTION
bge slb_finish_load_1T
END_FTR_SECTION_IFSET(CPU_FTR_1T_SEGMENT)
b slb_finish_load
8: /* invalid EA */
li r10,0 /* BAD_VSID */
li r11,SLB_VSID_USER /* flags don't much matter */
b slb_finish_load
#ifdef __DISABLED__
/* void slb_allocate_user(unsigned long ea);
*
* Create an SLB entry for the given EA (user or kernel).
* r3 = faulting address, r13 = PACA
* r9, r10, r11 are clobbered by this function
* No other registers are examined or changed.
*
* It is called with translation enabled in order to be able to walk the
* page tables. This is not currently used.
*/
_GLOBAL(slb_allocate_user)
/* r3 = faulting address */
srdi r10,r3,28 /* get esid */
crset 4*cr7+lt /* set "user" flag for later */
/* check if we fit in the range covered by the pagetables*/
srdi. r9,r3,PGTABLE_EADDR_SIZE
crnot 4*cr0+eq,4*cr0+eq
beqlr
/* now we need to get to the page tables in order to get the page
* size encoding from the PMD. In the future, we'll be able to deal
* with 1T segments too by getting the encoding from the PGD instead
*/
ld r9,PACAPGDIR(r13)
cmpldi cr0,r9,0
beqlr
rlwinm r11,r10,8,25,28
ldx r9,r9,r11 /* get pgd_t */
cmpldi cr0,r9,0
beqlr
rlwinm r11,r10,3,17,28
ldx r9,r9,r11 /* get pmd_t */
cmpldi cr0,r9,0
beqlr
/* build vsid flags */
andi. r11,r9,SLB_VSID_LLP
ori r11,r11,SLB_VSID_USER
/* get context to calculate proto-VSID */
ld r9,PACACONTEXTID(r13)
rldimi r10,r9,USER_ESID_BITS,0
/* fall through slb_finish_load */
#endif /* __DISABLED__ */
/*
* Finish loading of an SLB entry and return
*
* r3 = EA, r10 = proto-VSID, r11 = flags, clobbers r9, cr7 = <> PAGE_OFFSET
*/
slb_finish_load:
ASM_VSID_SCRAMBLE(r10,r9,256M)
rldimi r11,r10,SLB_VSID_SHIFT,16 /* combine VSID and flags */
/* r3 = EA, r11 = VSID data */
/*
* Find a slot, round robin. Previously we tried to find a
* free slot first but that took too long. Unfortunately we
* dont have any LRU information to help us choose a slot.
*/
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
/*
* On iSeries, the "bolted" stack segment can be cast out on
* shared processor switch so we need to check for a miss on
* it and restore it to the right slot.
*/
ld r9,PACAKSAVE(r13)
clrrdi r9,r9,28
clrrdi r3,r3,28
li r10,SLB_NUM_BOLTED-1 /* Stack goes in last bolted slot */
cmpld r9,r3
beq 3f
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif /* CONFIG_PPC_ISERIES */
7: ld r10,PACASTABRR(r13)
addi r10,r10,1
/* This gets soft patched on boot. */
_GLOBAL(slb_compare_rr_to_size)
cmpldi r10,0
blt+ 4f
li r10,SLB_NUM_BOLTED
4:
std r10,PACASTABRR(r13)
3:
rldimi r3,r10,0,36 /* r3= EA[0:35] | entry */
oris r10,r3,SLB_ESID_V@h /* r3 |= SLB_ESID_V */
/* r3 = ESID data, r11 = VSID data */
/*
* No need for an isync before or after this slbmte. The exception
* we enter with and the rfid we exit with are context synchronizing.
*/
slbmte r11,r10
/* we're done for kernel addresses */
crclr 4*cr0+eq /* set result to "success" */
bgelr cr7
/* Update the slb cache */
lhz r3,PACASLBCACHEPTR(r13) /* offset = paca->slb_cache_ptr */
cmpldi r3,SLB_CACHE_ENTRIES
bge 1f
/* still room in the slb cache */
sldi r11,r3,1 /* r11 = offset * sizeof(u16) */
rldicl r10,r10,36,28 /* get low 16 bits of the ESID */
add r11,r11,r13 /* r11 = (u16 *)paca + offset */
sth r10,PACASLBCACHE(r11) /* paca->slb_cache[offset] = esid */
addi r3,r3,1 /* offset++ */
b 2f
1: /* offset >= SLB_CACHE_ENTRIES */
li r3,SLB_CACHE_ENTRIES+1
2:
sth r3,PACASLBCACHEPTR(r13) /* paca->slb_cache_ptr = offset */
crclr 4*cr0+eq /* set result to "success" */
blr
/*
* Finish loading of a 1T SLB entry (for the kernel linear mapping) and return.
* We assume legacy iSeries will never have 1T segments.
*
* r3 = EA, r10 = proto-VSID, r11 = flags, clobbers r9
*/
slb_finish_load_1T:
srdi r10,r10,40-28 /* get 1T ESID */
ASM_VSID_SCRAMBLE(r10,r9,1T)
rldimi r11,r10,SLB_VSID_SHIFT_1T,16 /* combine VSID and flags */
li r10,MMU_SEGSIZE_1T
rldimi r11,r10,SLB_VSID_SSIZE_SHIFT,0 /* insert segment size */
/* r3 = EA, r11 = VSID data */
clrrdi r3,r3,SID_SHIFT_1T /* clear out non-ESID bits */
b 7b
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