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linux-next/arch/s390/mm/hugetlbpage.c
Linus Torvalds 6b008640db mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area() 
Instead of having callers care about the mmap_min_addr logic for the
lowest valid mapping address (and some of them getting it wrong), just
move the logic into vm_unmapped_area() itself.  One less thing for various
architecture cases (and generic helpers) to worry about.

We should really try to make much more of this be common code, but baby
steps..

Without this, vm_unmapped_area() could return an address below
mmap_min_addr (because some caller forgot about that).  That then causes
the mmap machinery to think it has found a workable address, but then
later security_mmap_addr(addr) is unhappy about it and the mmap() returns
with a nonsensical error (EPERM).

The proper action is to either return ENOMEM (if the virtual address space
is exhausted), or try to find another address (ie do a bottom-up search
for free addresses after the top-down one failed).

See commit 2afc745f3e ("mm: ensure get_unmapped_area() returns higher
address than mmap_min_addr"), which fixed this for one call site (the
generic arch_get_unmapped_area_topdown() fallback) but left other cases
alone.

Link: https://lkml.kernel.org/r/20230418214009.1142926-1-Liam.Howlett@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-21 14:52:05 -07:00

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// SPDX-License-Identifier: GPL-2.0
/*
* IBM System z Huge TLB Page Support for Kernel.
*
* Copyright IBM Corp. 2007,2020
* Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
*/
#define KMSG_COMPONENT "hugetlb"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <asm/pgalloc.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/sched/mm.h>
#include <linux/security.h>
/*
* If the bit selected by single-bit bitmask "a" is set within "x", move
* it to the position indicated by single-bit bitmask "b".
*/
#define move_set_bit(x, a, b) (((x) & (a)) >> ilog2(a) << ilog2(b))
static inline unsigned long __pte_to_rste(pte_t pte)
{
unsigned long rste;
/*
* Convert encoding pte bits pmd / pud bits
* lIR.uswrdy.p dy..R...I...wr
* empty 010.000000.0 -> 00..0...1...00
* prot-none, clean, old 111.000000.1 -> 00..1...1...00
* prot-none, clean, young 111.000001.1 -> 01..1...1...00
* prot-none, dirty, old 111.000010.1 -> 10..1...1...00
* prot-none, dirty, young 111.000011.1 -> 11..1...1...00
* read-only, clean, old 111.000100.1 -> 00..1...1...01
* read-only, clean, young 101.000101.1 -> 01..1...0...01
* read-only, dirty, old 111.000110.1 -> 10..1...1...01
* read-only, dirty, young 101.000111.1 -> 11..1...0...01
* read-write, clean, old 111.001100.1 -> 00..1...1...11
* read-write, clean, young 101.001101.1 -> 01..1...0...11
* read-write, dirty, old 110.001110.1 -> 10..0...1...11
* read-write, dirty, young 100.001111.1 -> 11..0...0...11
* HW-bits: R read-only, I invalid
* SW-bits: p present, y young, d dirty, r read, w write, s special,
* u unused, l large
*/
if (pte_present(pte)) {
rste = pte_val(pte) & PAGE_MASK;
rste |= move_set_bit(pte_val(pte), _PAGE_READ,
_SEGMENT_ENTRY_READ);
rste |= move_set_bit(pte_val(pte), _PAGE_WRITE,
_SEGMENT_ENTRY_WRITE);
rste |= move_set_bit(pte_val(pte), _PAGE_INVALID,
_SEGMENT_ENTRY_INVALID);
rste |= move_set_bit(pte_val(pte), _PAGE_PROTECT,
_SEGMENT_ENTRY_PROTECT);
rste |= move_set_bit(pte_val(pte), _PAGE_DIRTY,
_SEGMENT_ENTRY_DIRTY);
rste |= move_set_bit(pte_val(pte), _PAGE_YOUNG,
_SEGMENT_ENTRY_YOUNG);
#ifdef CONFIG_MEM_SOFT_DIRTY
rste |= move_set_bit(pte_val(pte), _PAGE_SOFT_DIRTY,
_SEGMENT_ENTRY_SOFT_DIRTY);
#endif
rste |= move_set_bit(pte_val(pte), _PAGE_NOEXEC,
_SEGMENT_ENTRY_NOEXEC);
} else
rste = _SEGMENT_ENTRY_EMPTY;
return rste;
}
static inline pte_t __rste_to_pte(unsigned long rste)
{
unsigned long pteval;
int present;
if ((rste & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
present = pud_present(__pud(rste));
else
present = pmd_present(__pmd(rste));
/*
* Convert encoding pmd / pud bits pte bits
* dy..R...I...wr lIR.uswrdy.p
* empty 00..0...1...00 -> 010.000000.0
* prot-none, clean, old 00..1...1...00 -> 111.000000.1
* prot-none, clean, young 01..1...1...00 -> 111.000001.1
* prot-none, dirty, old 10..1...1...00 -> 111.000010.1
* prot-none, dirty, young 11..1...1...00 -> 111.000011.1
* read-only, clean, old 00..1...1...01 -> 111.000100.1
* read-only, clean, young 01..1...0...01 -> 101.000101.1
* read-only, dirty, old 10..1...1...01 -> 111.000110.1
* read-only, dirty, young 11..1...0...01 -> 101.000111.1
* read-write, clean, old 00..1...1...11 -> 111.001100.1
* read-write, clean, young 01..1...0...11 -> 101.001101.1
* read-write, dirty, old 10..0...1...11 -> 110.001110.1
* read-write, dirty, young 11..0...0...11 -> 100.001111.1
* HW-bits: R read-only, I invalid
* SW-bits: p present, y young, d dirty, r read, w write, s special,
* u unused, l large
*/
if (present) {
pteval = rste & _SEGMENT_ENTRY_ORIGIN_LARGE;
pteval |= _PAGE_LARGE | _PAGE_PRESENT;
pteval |= move_set_bit(rste, _SEGMENT_ENTRY_READ, _PAGE_READ);
pteval |= move_set_bit(rste, _SEGMENT_ENTRY_WRITE, _PAGE_WRITE);
pteval |= move_set_bit(rste, _SEGMENT_ENTRY_INVALID, _PAGE_INVALID);
pteval |= move_set_bit(rste, _SEGMENT_ENTRY_PROTECT, _PAGE_PROTECT);
pteval |= move_set_bit(rste, _SEGMENT_ENTRY_DIRTY, _PAGE_DIRTY);
pteval |= move_set_bit(rste, _SEGMENT_ENTRY_YOUNG, _PAGE_YOUNG);
#ifdef CONFIG_MEM_SOFT_DIRTY
pteval |= move_set_bit(rste, _SEGMENT_ENTRY_SOFT_DIRTY, _PAGE_SOFT_DIRTY);
#endif
pteval |= move_set_bit(rste, _SEGMENT_ENTRY_NOEXEC, _PAGE_NOEXEC);
} else
pteval = _PAGE_INVALID;
return __pte(pteval);
}
static void clear_huge_pte_skeys(struct mm_struct *mm, unsigned long rste)
{
struct page *page;
unsigned long size, paddr;
if (!mm_uses_skeys(mm) ||
rste & _SEGMENT_ENTRY_INVALID)
return;
if ((rste & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3) {
page = pud_page(__pud(rste));
size = PUD_SIZE;
paddr = rste & PUD_MASK;
} else {
page = pmd_page(__pmd(rste));
size = PMD_SIZE;
paddr = rste & PMD_MASK;
}
if (!test_and_set_bit(PG_arch_1, &page->flags))
__storage_key_init_range(paddr, paddr + size - 1);
}
void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
unsigned long rste;
rste = __pte_to_rste(pte);
if (!MACHINE_HAS_NX)
rste &= ~_SEGMENT_ENTRY_NOEXEC;
/* Set correct table type for 2G hugepages */
if ((pte_val(*ptep) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3) {
if (likely(pte_present(pte)))
rste |= _REGION3_ENTRY_LARGE;
rste |= _REGION_ENTRY_TYPE_R3;
} else if (likely(pte_present(pte)))
rste |= _SEGMENT_ENTRY_LARGE;
clear_huge_pte_skeys(mm, rste);
set_pte(ptep, __pte(rste));
}
pte_t huge_ptep_get(pte_t *ptep)
{
return __rste_to_pte(pte_val(*ptep));
}
pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
pte_t pte = huge_ptep_get(ptep);
pmd_t *pmdp = (pmd_t *) ptep;
pud_t *pudp = (pud_t *) ptep;
if ((pte_val(*ptep) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
pudp_xchg_direct(mm, addr, pudp, __pud(_REGION3_ENTRY_EMPTY));
else
pmdp_xchg_direct(mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_EMPTY));
return pte;
}
pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long sz)
{
pgd_t *pgdp;
p4d_t *p4dp;
pud_t *pudp;
pmd_t *pmdp = NULL;
pgdp = pgd_offset(mm, addr);
p4dp = p4d_alloc(mm, pgdp, addr);
if (p4dp) {
pudp = pud_alloc(mm, p4dp, addr);
if (pudp) {
if (sz == PUD_SIZE)
return (pte_t *) pudp;
else if (sz == PMD_SIZE)
pmdp = pmd_alloc(mm, pudp, addr);
}
}
return (pte_t *) pmdp;
}
pte_t *huge_pte_offset(struct mm_struct *mm,
unsigned long addr, unsigned long sz)
{
pgd_t *pgdp;
p4d_t *p4dp;
pud_t *pudp;
pmd_t *pmdp = NULL;
pgdp = pgd_offset(mm, addr);
if (pgd_present(*pgdp)) {
p4dp = p4d_offset(pgdp, addr);
if (p4d_present(*p4dp)) {
pudp = pud_offset(p4dp, addr);
if (pud_present(*pudp)) {
if (pud_large(*pudp))
return (pte_t *) pudp;
pmdp = pmd_offset(pudp, addr);
}
}
}
return (pte_t *) pmdp;
}
int pmd_huge(pmd_t pmd)
{
return pmd_large(pmd);
}
int pud_huge(pud_t pud)
{
return pud_large(pud);
}
bool __init arch_hugetlb_valid_size(unsigned long size)
{
if (MACHINE_HAS_EDAT1 && size == PMD_SIZE)
return true;
else if (MACHINE_HAS_EDAT2 && size == PUD_SIZE)
return true;
else
return false;
}
static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
unsigned long addr, unsigned long len,
unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
struct vm_unmapped_area_info info;
info.flags = 0;
info.length = len;
info.low_limit = current->mm->mmap_base;
info.high_limit = TASK_SIZE;
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
info.align_offset = 0;
return vm_unmapped_area(&info);
}
static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
unsigned long addr0, unsigned long len,
unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
struct vm_unmapped_area_info info;
unsigned long addr;
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
info.low_limit = PAGE_SIZE;
info.high_limit = current->mm->mmap_base;
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
info.align_offset = 0;
addr = vm_unmapped_area(&info);
/*
* A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario
* can happen with large stack limits and large mmap()
* allocations.
*/
if (addr & ~PAGE_MASK) {
VM_BUG_ON(addr != -ENOMEM);
info.flags = 0;
info.low_limit = TASK_UNMAPPED_BASE;
info.high_limit = TASK_SIZE;
addr = vm_unmapped_area(&info);
}
return addr;
}
unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
if (len & ~huge_page_mask(h))
return -EINVAL;
if (len > TASK_SIZE - mmap_min_addr)
return -ENOMEM;
if (flags & MAP_FIXED) {
if (prepare_hugepage_range(file, addr, len))
return -EINVAL;
goto check_asce_limit;
}
if (addr) {
addr = ALIGN(addr, huge_page_size(h));
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
(!vma || addr + len <= vm_start_gap(vma)))
goto check_asce_limit;
}
if (mm->get_unmapped_area == arch_get_unmapped_area)
addr = hugetlb_get_unmapped_area_bottomup(file, addr, len,
pgoff, flags);
else
addr = hugetlb_get_unmapped_area_topdown(file, addr, len,
pgoff, flags);
if (offset_in_page(addr))
return addr;
check_asce_limit:
return check_asce_limit(mm, addr, len);
}
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