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Commit a0a9434d authored by Hugh Dickins's avatar Hugh Dickins Committed by Russell King
Browse files

ARM: 7701/1: mm: Allow arch code to control the user page table ceiling 



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: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org> # 3.3+
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent b361d61d

fs/exec.c

+2 −2
Original line number Diff line number Diff line
@@ -613,7 +613,7 @@ 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
@@ -622,7 +622,7 @@ 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);

include/asm-generic/pgtable.h

+10 −0
Original line number Diff line number Diff line
@@ -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,

mm/mmap.c

+2 −2
Original line number Diff line number Diff line
@@ -2303,7 +2303,7 @@ static void unmap_region(struct mm_struct *mm, 
	update_hiwater_rss(mm);

	unmap_vmas(&tlb, vma, start, end);

	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);

}
@@ -2683,7 +2683,7 @@ void exit_mmap(struct mm_struct *mm) 
	/* Use -1 here to ensure all VMAs in the mm are unmapped */

	unmap_vmas(&tlb, vma, 0, -1);



	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);

	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);

	tlb_finish_mmu(&tlb, 0, -1);



	/*