From 0f334a3e8c3586f81286345eb077ed32b375e8d6 Mon Sep 17 00:00:00 2001 From: Kevin Cernekee Date: Mon, 7 Sep 2009 11:11:31 -0700 Subject: 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 Signed-off-by: Ralf Baechle --- arch/mips/include/asm/fixmap.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/mips/include/asm') diff --git a/arch/mips/include/asm/fixmap.h b/arch/mips/include/asm/fixmap.h index efeddc8db8b..0b89b83e205 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 */ -- cgit v1.2.3