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authorKevin Cernekee <cernekee@gmail.com>2009-09-07 11:11:31 -0700
committerRalf Baechle <ralf@linux-mips.org>2009-11-02 12:00:04 +0100
commit0f334a3e8c3586f81286345eb077ed32b375e8d6 (patch)
tree02278a0f6ef99b43c56af12ba44d964f099c70c3
parent39d2211d20518677511043d7ee16bbca6d0c5070 (diff)
downloadlinux-stericsson-0f334a3e8c3586f81286345eb077ed32b375e8d6.tar.gz
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>
-rw-r--r--arch/mips/include/asm/fixmap.h4
-rw-r--r--arch/mips/mm/init.c6
2 files changed, 7 insertions, 3 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 */
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 15aa1902a788..8d1f4f363049 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -27,6 +27,7 @@
#include <linux/swap.h>
#include <linux/proc_fs.h>
#include <linux/pfn.h>
+#include <linux/hardirq.h>
#include <asm/asm-offsets.h>
#include <asm/bootinfo.h>
@@ -132,7 +133,10 @@ void *kmap_coherent(struct page *page, unsigned long addr)
inc_preempt_count();
idx = (addr >> PAGE_SHIFT) & (FIX_N_COLOURS - 1);
#ifdef CONFIG_MIPS_MT_SMTC
- idx += FIX_N_COLOURS * smp_processor_id();
+ idx += FIX_N_COLOURS * smp_processor_id() +
+ (in_interrupt() ? (FIX_N_COLOURS * NR_CPUS) : 0);
+#else
+ idx += in_interrupt() ? FIX_N_COLOURS : 0;
#endif
vaddr = __fix_to_virt(FIX_CMAP_END - idx);
pte = mk_pte(page, PAGE_KERNEL);