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| author | Hugh Dickins <hughd@google.com> | 2013-04-29 15:07:44 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-05-07 19:51:55 -0700 |
| commit | 273a82bee94d42ba58b264bc427cd75df65b81fc (patch) | |
| tree | 29c58f1e1b209f4e6ab09fb0ea8188e52501d6db | |
| parent | ede49f3642cce1fe60ac81cb1953e7a8fd91e8ce (diff) | |
| download | lwn-273a82bee94d42ba58b264bc427cd75df65b81fc.tar.gz lwn-273a82bee94d42ba58b264bc427cd75df65b81fc.zip | |
mm: allow arch code to control the user page table ceiling
commit 6ee8630e02be6dd89926ca0fbc21af68b23dc087 upstream.
On architectures where a pgd entry may be shared between user and kernel
(e.g. ARM+LPAE), freeing page tables needs a ceiling other than 0.
This patch introduces a generic USER_PGTABLES_CEILING that arch code can
override. It is the responsibility of the arch code setting the ceiling
to ensure the complete freeing of the page tables (usually in
pgd_free()).
[catalin.marinas@arm.com: commit log; shift_arg_pages(), asm-generic/pgtables.h changes]
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/exec.c | 4 | ||||
| -rw-r--r-- | include/asm-generic/pgtable.h | 10 | ||||
| -rw-r--r-- | mm/mmap.c | 4 |
3 files changed, 14 insertions, 4 deletions
diff --git a/fs/exec.c b/fs/exec.c index e3a7e36dcd44..2b7f5ff64fb9 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -627,7 +627,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) * when the old and new regions overlap clear from new_end. */ free_pgd_range(&tlb, new_end, old_end, new_end, - vma->vm_next ? vma->vm_next->vm_start : 0); + vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); } else { /* * otherwise, clean from old_start; this is done to not touch @@ -636,7 +636,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) * for the others its just a little faster. */ free_pgd_range(&tlb, old_start, old_end, new_end, - vma->vm_next ? vma->vm_next->vm_start : 0); + vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); } tlb_finish_mmu(&tlb, new_end, old_end); diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index c7ec2cdc904d..9a6eb25b90e9 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -7,6 +7,16 @@ #include <linux/mm_types.h> #include <linux/bug.h> +/* + * On almost all architectures and configurations, 0 can be used as the + * upper ceiling to free_pgtables(): on many architectures it has the same + * effect as using TASK_SIZE. However, there is one configuration which + * must impose a more careful limit, to avoid freeing kernel pgtables. + */ +#ifndef USER_PGTABLES_CEILING +#define USER_PGTABLES_CEILING 0UL +#endif + #ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS extern int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address, pte_t *ptep, diff --git a/mm/mmap.c b/mm/mmap.c index 2add0a1a7aa6..3635d4789486 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1920,7 +1920,7 @@ static void unmap_region(struct mm_struct *mm, unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); vm_unacct_memory(nr_accounted); free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, - next ? next->vm_start : 0); + next ? next->vm_start : USER_PGTABLES_CEILING); tlb_finish_mmu(&tlb, start, end); } @@ -2308,7 +2308,7 @@ void exit_mmap(struct mm_struct *mm) unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); vm_unacct_memory(nr_accounted); - free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); + free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); tlb_finish_mmu(&tlb, 0, -1); /* |