diff options
| author | Dima Zavin <dima@android.com> | 2012-02-14 12:09:09 +0000 |
|---|---|---|
| committer | Marc Zyngier <marc.zyngier@arm.com> | 2012-04-16 16:07:51 +0100 |
| commit | d4740183794d464765685beb5b37de85409a290c (patch) | |
| tree | bda6e24da1b808fe0fbd937afb237e4346738553 | |
| parent | d276e473ccc94255bd1181e291b8670c4a71581f (diff) | |
ARM: Do not call flush_cache_user_range with mmap_sem held
We can't be holding the mmap_sem while calling flush_cache_user_range
because the flush can fault. If we fault on a user address, the
page fault handler will try to take mmap_sem again. Since both places
acquire the read lock, most of the time it succeeds. However, if another
thread tries to acquire the write lock on the mmap_sem (e.g. mmap) in
between the call to flush_cache_user_range and the fault, the down_read
in do_page_fault will deadlock.
Also, since we really can't be holding the mmap_sem while calling
flush_cache_user_range AND vma is actually unused by the flush itself,
get rid of vma as an argument.
Signed-off-by: Dima Zavin <dima@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
| -rw-r--r-- | arch/arm/include/asm/cacheflush.h | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/traps.c | 4 |
2 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h index d5d8d5c72682..1252a2675ca9 100644 --- a/arch/arm/include/asm/cacheflush.h +++ b/arch/arm/include/asm/cacheflush.h @@ -249,7 +249,7 @@ extern void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr * Harvard caches are synchronised for the user space address range. * This is used for the ARM private sys_cacheflush system call. */ -#define flush_cache_user_range(vma,start,end) \ +#define flush_cache_user_range(start,end) \ __cpuc_coherent_user_range((start) & PAGE_MASK, PAGE_ALIGN(end)) /* diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index 356f1197d90c..a31187b59f33 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -491,7 +491,9 @@ do_cache_op(unsigned long start, unsigned long end, int flags) if (end > vma->vm_end) end = vma->vm_end; - flush_cache_user_range(vma, start, end); + up_read(&mm->mmap_sem); + flush_cache_user_range(start, end); + return; } up_read(&mm->mmap_sem); } |