From c10d38dda1774ed4540380333cabd229eff37094 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 10 Sep 2008 13:37:17 +0200 Subject: 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 Acked-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- include/asm-x86/uaccess_32.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'include/asm-x86/uaccess_32.h') diff --git a/include/asm-x86/uaccess_32.h b/include/asm-x86/uaccess_32.h index 6fdef39a0bcb..d725e2d703f7 100644 --- a/include/asm-x86/uaccess_32.h +++ b/include/asm-x86/uaccess_32.h @@ -82,8 +82,10 @@ __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) static __always_inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n) { - might_sleep(); - return __copy_to_user_inatomic(to, from, n); + might_sleep(); + if (current->mm) + might_lock_read(¤t->mm->mmap_sem); + return __copy_to_user_inatomic(to, from, n); } static __always_inline unsigned long @@ -138,6 +140,8 @@ static __always_inline unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n) { might_sleep(); + if (current->mm) + might_lock_read(¤t->mm->mmap_sem); if (__builtin_constant_p(n)) { unsigned long ret; @@ -160,6 +164,8 @@ static __always_inline unsigned long __copy_from_user_nocache(void *to, const void __user *from, unsigned long n) { might_sleep(); + if (current->mm) + might_lock_read(¤t->mm->mmap_sem); if (__builtin_constant_p(n)) { unsigned long ret; -- cgit v1.2.2