From c10d38dda1774ed4540380333cabd229eff37094 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 10 Sep 2008 13:37:17 +0200 Subject: [PATCH] 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 --- arch/x86/lib/usercopy_32.c | 7 ++++++- arch/x86/lib/usercopy_64.c | 4 ++++ include/asm-x86/uaccess.h | 14 ++++++++++++++ include/asm-x86/uaccess_32.h | 10 ++++++++-- include/asm-x86/uaccess_64.h | 12 ++++++++++++ 5 files changed, 44 insertions(+), 3 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" diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index f4df6e7c718b..847d12945998 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(¤t->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(¤t->mm->mmap_sem); /* no memory constraint because it doesn't change any memory gcc knows about */ asm volatile( diff --git a/include/asm-x86/uaccess.h b/include/asm-x86/uaccess.h index 5f702d1d5218..ad29752a1713 100644 --- a/include/asm-x86/uaccess.h +++ b/include/asm-x86/uaccess.h @@ -8,6 +8,8 @@ #include #include #include +#include +#include #include #include @@ -157,6 +159,9 @@ extern int __get_user_bad(void); int __ret_gu; \ unsigned long __val_gu; \ __chk_user_ptr(ptr); \ + might_sleep(); \ + if (current->mm) \ + might_lock_read(¤t->mm->mmap_sem); \ switch (sizeof(*(ptr))) { \ case 1: \ __get_user_x(1, __ret_gu, __val_gu, ptr); \ @@ -241,6 +246,9 @@ extern void __put_user_8(void); int __ret_pu; \ __typeof__(*(ptr)) __pu_val; \ __chk_user_ptr(ptr); \ + might_sleep(); \ + if (current->mm) \ + might_lock_read(¤t->mm->mmap_sem); \ __pu_val = x; \ switch (sizeof(*(ptr))) { \ case 1: \ @@ -265,6 +273,9 @@ extern void __put_user_8(void); #define __put_user_size(x, ptr, size, retval, errret) \ do { \ retval = 0; \ + might_sleep(); \ + if (current->mm) \ + might_lock_read(¤t->mm->mmap_sem); \ __chk_user_ptr(ptr); \ switch (size) { \ case 1: \ @@ -317,6 +328,9 @@ do { \ #define __get_user_size(x, ptr, size, retval, errret) \ do { \ retval = 0; \ + might_sleep(); \ + if (current->mm) \ + might_lock_read(¤t->mm->mmap_sem); \ __chk_user_ptr(ptr); \ switch (size) { \ case 1: \ 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; diff --git a/include/asm-x86/uaccess_64.h b/include/asm-x86/uaccess_64.h index 515d4dce96b5..40a7205fe576 100644 --- a/include/asm-x86/uaccess_64.h +++ b/include/asm-x86/uaccess_64.h @@ -28,6 +28,10 @@ static __always_inline __must_check int __copy_from_user(void *dst, const void __user *src, unsigned size) { int ret = 0; + + might_sleep(); + if (current->mm) + might_lock_read(¤t->mm->mmap_sem); if (!__builtin_constant_p(size)) return copy_user_generic(dst, (__force void *)src, size); switch (size) { @@ -70,6 +74,10 @@ static __always_inline __must_check int __copy_to_user(void __user *dst, const void *src, unsigned size) { int ret = 0; + + might_sleep(); + if (current->mm) + might_lock_read(¤t->mm->mmap_sem); if (!__builtin_constant_p(size)) return copy_user_generic((__force void *)dst, src, size); switch (size) { @@ -112,6 +120,10 @@ static __always_inline __must_check int __copy_in_user(void __user *dst, const void __user *src, unsigned size) { int ret = 0; + + might_sleep(); + if (current->mm) + might_lock_read(¤t->mm->mmap_sem); if (!__builtin_constant_p(size)) return copy_user_generic((__force void *)dst, (__force void *)src, size); -- 2.20.1