Revision 1a512c0882bd311c5b5561840fcfbe4c25b8f319 authored by Arnd Bergmann on 24 April 2018, 21:19:51 UTC, committed by Thomas Gleixner on 27 April 2018, 15:06:29 UTC
A bugfix broke the x32 shmid64_ds and msqid64_ds data structure layout (as seen from user space) a few years ago: Originally, __BITS_PER_LONG was defined as 64 on x32, so we did not have padding after the 64-bit __kernel_time_t fields, After __BITS_PER_LONG got changed to 32, applications would observe extra padding. In other parts of the uapi headers we seem to have a mix of those expecting either 32 or 64 on x32 applications, so we can't easily revert the path that broke these two structures. Instead, this patch decouples x32 from the other architectures and moves it back into arch specific headers, partially reverting the even older commit 73a2d096fdf2 ("x86: remove all now-duplicate header files"). It's not clear whether this ever made any difference, since at least glibc carries its own (correct) copy of both of these header files, so possibly no application has ever observed the definitions here. Based on a suggestion from H.J. Lu, I tried out the tool from https://github.com/hjl-tools/linux-header to find other such bugs, which pointed out the same bug in statfs(), which also has a separate (correct) copy in glibc. Fixes: f4b4aae18288 ("x86/headers/uapi: Fix __BITS_PER_LONG value for x32 builds") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: "H . J . Lu" <hjl.tools@gmail.com> Cc: Jeffrey Walton <noloader@gmail.com> Cc: stable@vger.kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Link: https://lkml.kernel.org/r/20180424212013.3967461-1-arnd@arndb.de
1 parent 3db3eb2
pagewalk.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/sched.h>
#include <linux/hugetlb.h>
static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pte_t *pte;
int err = 0;
pte = pte_offset_map(pmd, addr);
for (;;) {
err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
if (err)
break;
addr += PAGE_SIZE;
if (addr == end)
break;
pte++;
}
pte_unmap(pte);
return err;
}
static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pmd_t *pmd;
unsigned long next;
int err = 0;
pmd = pmd_offset(pud, addr);
do {
again:
next = pmd_addr_end(addr, end);
if (pmd_none(*pmd) || !walk->vma) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
/*
* This implies that each ->pmd_entry() handler
* needs to know about pmd_trans_huge() pmds
*/
if (walk->pmd_entry)
err = walk->pmd_entry(pmd, addr, next, walk);
if (err)
break;
/*
* Check this here so we only break down trans_huge
* pages when we _need_ to
*/
if (!walk->pte_entry)
continue;
split_huge_pmd(walk->vma, pmd, addr);
if (pmd_trans_unstable(pmd))
goto again;
err = walk_pte_range(pmd, addr, next, walk);
if (err)
break;
} while (pmd++, addr = next, addr != end);
return err;
}
static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pud_t *pud;
unsigned long next;
int err = 0;
pud = pud_offset(p4d, addr);
do {
again:
next = pud_addr_end(addr, end);
if (pud_none(*pud) || !walk->vma) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (walk->pud_entry) {
spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
if (ptl) {
err = walk->pud_entry(pud, addr, next, walk);
spin_unlock(ptl);
if (err)
break;
continue;
}
}
split_huge_pud(walk->vma, pud, addr);
if (pud_none(*pud))
goto again;
if (walk->pmd_entry || walk->pte_entry)
err = walk_pmd_range(pud, addr, next, walk);
if (err)
break;
} while (pud++, addr = next, addr != end);
return err;
}
static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
p4d_t *p4d;
unsigned long next;
int err = 0;
p4d = p4d_offset(pgd, addr);
do {
next = p4d_addr_end(addr, end);
if (p4d_none_or_clear_bad(p4d)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (walk->pmd_entry || walk->pte_entry)
err = walk_pud_range(p4d, addr, next, walk);
if (err)
break;
} while (p4d++, addr = next, addr != end);
return err;
}
static int walk_pgd_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pgd_t *pgd;
unsigned long next;
int err = 0;
pgd = pgd_offset(walk->mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (walk->pmd_entry || walk->pte_entry)
err = walk_p4d_range(pgd, addr, next, walk);
if (err)
break;
} while (pgd++, addr = next, addr != end);
return err;
}
#ifdef CONFIG_HUGETLB_PAGE
static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
unsigned long end)
{
unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
return boundary < end ? boundary : end;
}
static int walk_hugetlb_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->vma;
struct hstate *h = hstate_vma(vma);
unsigned long next;
unsigned long hmask = huge_page_mask(h);
unsigned long sz = huge_page_size(h);
pte_t *pte;
int err = 0;
do {
next = hugetlb_entry_end(h, addr, end);
pte = huge_pte_offset(walk->mm, addr & hmask, sz);
if (pte)
err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
else if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
if (err)
break;
} while (addr = next, addr != end);
return err;
}
#else /* CONFIG_HUGETLB_PAGE */
static int walk_hugetlb_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
return 0;
}
#endif /* CONFIG_HUGETLB_PAGE */
/*
* Decide whether we really walk over the current vma on [@start, @end)
* or skip it via the returned value. Return 0 if we do walk over the
* current vma, and return 1 if we skip the vma. Negative values means
* error, where we abort the current walk.
*/
static int walk_page_test(unsigned long start, unsigned long end,
struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->vma;
if (walk->test_walk)
return walk->test_walk(start, end, walk);
/*
* vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
* range, so we don't walk over it as we do for normal vmas. However,
* Some callers are interested in handling hole range and they don't
* want to just ignore any single address range. Such users certainly
* define their ->pte_hole() callbacks, so let's delegate them to handle
* vma(VM_PFNMAP).
*/
if (vma->vm_flags & VM_PFNMAP) {
int err = 1;
if (walk->pte_hole)
err = walk->pte_hole(start, end, walk);
return err ? err : 1;
}
return 0;
}
static int __walk_page_range(unsigned long start, unsigned long end,
struct mm_walk *walk)
{
int err = 0;
struct vm_area_struct *vma = walk->vma;
if (vma && is_vm_hugetlb_page(vma)) {
if (walk->hugetlb_entry)
err = walk_hugetlb_range(start, end, walk);
} else
err = walk_pgd_range(start, end, walk);
return err;
}
/**
* walk_page_range - walk page table with caller specific callbacks
* @start: start address of the virtual address range
* @end: end address of the virtual address range
* @walk: mm_walk structure defining the callbacks and the target address space
*
* Recursively walk the page table tree of the process represented by @walk->mm
* within the virtual address range [@start, @end). During walking, we can do
* some caller-specific works for each entry, by setting up pmd_entry(),
* pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
* callbacks, the associated entries/pages are just ignored.
* The return values of these callbacks are commonly defined like below:
*
* - 0 : succeeded to handle the current entry, and if you don't reach the
* end address yet, continue to walk.
* - >0 : succeeded to handle the current entry, and return to the caller
* with caller specific value.
* - <0 : failed to handle the current entry, and return to the caller
* with error code.
*
* Before starting to walk page table, some callers want to check whether
* they really want to walk over the current vma, typically by checking
* its vm_flags. walk_page_test() and @walk->test_walk() are used for this
* purpose.
*
* struct mm_walk keeps current values of some common data like vma and pmd,
* which are useful for the access from callbacks. If you want to pass some
* caller-specific data to callbacks, @walk->private should be helpful.
*
* Locking:
* Callers of walk_page_range() and walk_page_vma() should hold
* @walk->mm->mmap_sem, because these function traverse vma list and/or
* access to vma's data.
*/
int walk_page_range(unsigned long start, unsigned long end,
struct mm_walk *walk)
{
int err = 0;
unsigned long next;
struct vm_area_struct *vma;
if (start >= end)
return -EINVAL;
if (!walk->mm)
return -EINVAL;
VM_BUG_ON_MM(!rwsem_is_locked(&walk->mm->mmap_sem), walk->mm);
vma = find_vma(walk->mm, start);
do {
if (!vma) { /* after the last vma */
walk->vma = NULL;
next = end;
} else if (start < vma->vm_start) { /* outside vma */
walk->vma = NULL;
next = min(end, vma->vm_start);
} else { /* inside vma */
walk->vma = vma;
next = min(end, vma->vm_end);
vma = vma->vm_next;
err = walk_page_test(start, next, walk);
if (err > 0) {
/*
* positive return values are purely for
* controlling the pagewalk, so should never
* be passed to the callers.
*/
err = 0;
continue;
}
if (err < 0)
break;
}
if (walk->vma || walk->pte_hole)
err = __walk_page_range(start, next, walk);
if (err)
break;
} while (start = next, start < end);
return err;
}
int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk)
{
int err;
if (!walk->mm)
return -EINVAL;
VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
VM_BUG_ON(!vma);
walk->vma = vma;
err = walk_page_test(vma->vm_start, vma->vm_end, walk);
if (err > 0)
return 0;
if (err < 0)
return err;
return __walk_page_range(vma->vm_start, vma->vm_end, walk);
}
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