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authorNick Piggin <npiggin@suse.de>2008-09-10 13:37:17 +0200
committerIngo Molnar <mingo@elte.hu>2008-09-10 13:48:49 +0200
commitc10d38dda1774ed4540380333cabd229eff37094 (patch)
treebe9649dab7c0017c0a700f146db70f730ad819a7 /arch/x86/lib
parent76b189e91845eab3a9d52bb97f971d312d25652d (diff)
x86: some lock annotations for user copy paths
copy_to/from_user and all its variants (except the atomic ones) can take a page fault and perform non-trivial work like taking mmap_sem and entering the filesyste/pagecache. Unfortunately, this often escapes lockdep because a common pattern is to use it to read in some arguments just set up from userspace, or write data back to a hot buffer. In those cases, it will be unlikely for page reclaim to get a window in to cause copy_*_user to fault. With the new might_lock primitives, add some annotations to x86. I don't know if I caught all possible faulting points (it's a bit of a maze, and I didn't really look at 32-bit). But this is a starting point. Boots and runs OK so far. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/lib')
-rw-r--r--arch/x86/lib/usercopy_32.c7
-rw-r--r--arch/x86/lib/usercopy_64.c4
2 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 24e60944971..8eedde2a9ca 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -33,6 +33,8 @@ static inline int __movsl_is_ok(unsigned long a1, unsigned long a2, unsigned lon
do { \
int __d0, __d1, __d2; \
might_sleep(); \
+ if (current->mm) \
+ might_lock_read(&current->mm->mmap_sem); \
__asm__ __volatile__( \
" testl %1,%1\n" \
" jz 2f\n" \
@@ -120,6 +122,8 @@ EXPORT_SYMBOL(strncpy_from_user);
do { \
int __d0; \
might_sleep(); \
+ if (current->mm) \
+ might_lock_read(&current->mm->mmap_sem); \
__asm__ __volatile__( \
"0: rep; stosl\n" \
" movl %2,%0\n" \
@@ -148,7 +152,6 @@ do { \
unsigned long
clear_user(void __user *to, unsigned long n)
{
- might_sleep();
if (access_ok(VERIFY_WRITE, to, n))
__do_clear_user(to, n);
return n;
@@ -191,6 +194,8 @@ long strnlen_user(const char __user *s, long n)
unsigned long res, tmp;
might_sleep();
+ if (current->mm)
+ might_lock_read(&current->mm->mmap_sem);
__asm__ __volatile__(
" testl %0, %0\n"
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index f4df6e7c718..847d1294599 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -16,6 +16,8 @@
do { \
long __d0, __d1, __d2; \
might_sleep(); \
+ if (current->mm) \
+ might_lock_read(&current->mm->mmap_sem); \
__asm__ __volatile__( \
" testq %1,%1\n" \
" jz 2f\n" \
@@ -65,6 +67,8 @@ unsigned long __clear_user(void __user *addr, unsigned long size)
{
long __d0;
might_sleep();
+ if (current->mm)
+ might_lock_read(&current->mm->mmap_sem);
/* no memory constraint because it doesn't change any memory gcc knows
about */
asm volatile(