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mm: fix cache coloring on x86_64 architecture 

Fix the x86-64 cache alignment code to take pgoff into account.  Use the
x86 and MIPS cache alignment code as the basis for a generic cache
alignment function.

The old x86 code will always align the mmap to aliasing boundaries,
even if the program mmaps the file with a non-zero pgoff.

If program A mmaps the file with pgoff 0, and program B mmaps the file
with pgoff 1.  The old code would align the mmaps, resulting in misaligned
pages:

  A:  0123
  B:  123

After this patch, they are aligned so the pages line up:

  A: 0123
  B:  123

Proposed by Rik van Riel.

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michel Lespinasse 2012-12-11 16:01:56 -08:00 committed by Linus Torvalds
parent f99024729e
commit 7d02505965
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kernel/sys_x86_64.c
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@ -136,7 +136,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
info.low_limit = begin;
info.high_limit = end;
info.align_mask = filp ? get_align_mask() : 0;
info.align_offset = 0;
info.align_offset = pgoff << PAGE_SHIFT;
return vm_unmapped_area(&info);
}
@ -175,7 +175,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
info.low_limit = PAGE_SIZE;
info.high_limit = mm->mmap_base;
info.align_mask = filp ? get_align_mask() : 0;
info.align_offset = 0;
info.align_offset = pgoff << PAGE_SHIFT;
addr = vm_unmapped_area(&info);
if (!(addr & ~PAGE_MASK))
return addr;