diff options
| author | Nick Piggin <npiggin@suse.de> | 2008-09-10 13:37:17 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-09-10 13:48:49 +0200 |
| commit | c10d38dda1774ed4540380333cabd229eff37094 (patch) | |
| tree | be9649dab7c0017c0a700f146db70f730ad819a7 /arch/x86/lib/usercopy_32.c | |
| parent | 76b189e91845eab3a9d52bb97f971d312d25652d (diff) | |
| download | linux-rt-c10d38dda1774ed4540380333cabd229eff37094.tar.gz | |
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/usercopy_32.c')
| -rw-r--r-- | arch/x86/lib/usercopy_32.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c index 24e60944971a..8eedde2a9cac 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(¤t->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(¤t->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(¤t->mm->mmap_sem); __asm__ __volatile__( " testl %0, %0\n" |