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| author | Kevin Cernekee <cernekee@gmail.com> | 2009-09-07 11:11:31 -0700 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2009-11-02 12:00:04 +0100 |
| commit | 0f334a3e8c3586f81286345eb077ed32b375e8d6 (patch) | |
| tree | 02278a0f6ef99b43c56af12ba44d964f099c70c3 /arch/mips/include/asm/fixmap.h | |
| parent | 39d2211d20518677511043d7ee16bbca6d0c5070 (diff) | |
| download | lwn-0f334a3e8c3586f81286345eb077ed32b375e8d6.tar.gz lwn-0f334a3e8c3586f81286345eb077ed32b375e8d6.zip | |
MIPS: Fix machine check exception in kmap_coherent()
On an SMP system with cache aliases, the following sequence of events may
happen:
1) copy_user_highpage() runs on CPU0, invoking kmap_coherent() to create a
temporary mapping in the fixmap region
2) copy_page() starts on CPU0
3) CPU1 sends CPU0 an IPI asking CPU0 to run local_r4k_flush_cache_page()
4) CPU0 takes the interrupt, interrupting copy_page()
5) local_r4k_flush_cache_page() on CPU0 calls kmap_coherent() again
6) The second invocation of kmap_coherent() on CPU0 tries to use the
same fixmap virtual address that was being used by copy_user_highpage()
7) CPU0 throws a machine check exception for the TLB address conflict
Fixed by creating an extra set of fixmap entries for use in interrupt
handlers. This prevents fixmap VA conflicts between copy_user_highpage()
running in user context, and local_r4k_flush_cache_page() invoked from an
SMP IPI.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include/asm/fixmap.h')
| -rw-r--r-- | arch/mips/include/asm/fixmap.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/mips/include/asm/fixmap.h b/arch/mips/include/asm/fixmap.h index efeddc8db8b1..0b89b83e2055 100644 --- a/arch/mips/include/asm/fixmap.h +++ b/arch/mips/include/asm/fixmap.h @@ -48,9 +48,9 @@ enum fixed_addresses { #define FIX_N_COLOURS 8 FIX_CMAP_BEGIN, #ifdef CONFIG_MIPS_MT_SMTC - FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS), + FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS * 2), #else - FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS, + FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * 2), #endif #ifdef CONFIG_HIGHMEM /* reserved pte's for temporary kernel mappings */ |