[MIPS] Fix aliasing bug in copy_to_user_page / copy_from_user_page

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The current implementation uses a sequence of a cacheflush and a copy.
This is racy in case of a multithreaded debuggee and renders GDB
virtually unusable.

Aside this fixes a performance hog rendering access to /proc/cmdline very
slow and resulting in a enough cache stalls for the 34K AP/SP programming
model to make the bare metal code on the non-Linux VPE miss RT deadlines.

The main part of this patch was originally written by Ralf Baechle;
Atushi Nemoto did the the debugging.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

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This commit is contained in:

Ralf Baechle 2006-10-21 23:17:35 +01:00

parent 224dc50ece

commit f8829caee3

5 changed files with 190 additions and 28 deletions

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167

arch/mips/mm/init.c

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7

arch/mips/mm/pgtable-32.c

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11

arch/mips/mm/pgtable-64.c

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19

include/asm-mips/cacheflush.h

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14

include/asm-mips/fixmap.h

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