3.2.81-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Andi Kleen <[email protected]> commit ff47ab4ff3cddfa7bc1b25b990e24abe2ae474ff upstream. The 64bit __copy_{from,to}_user_inatomic always called copy_from_user_generic, but skipped the special optimizations for 1/2/4/8 byte accesses. This especially hurts the futex call, which accesses the 4 byte futex user value with a complicated fast string operation in a function call, instead of a single movl. Use __copy_{from,to}_user for _inatomic instead to get the same optimizations. The only problem was the might_fault() in those functions. So move that to new wrapper and call __copy_{f,t}_user_nocheck() from *_inatomic directly. 32bit already did this correctly by duplicating the code. Signed-off-by: Andi Kleen <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: H. Peter Anvin <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> Cc: Jaccon Bastiaansen <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: Peter Zijlstra <[email protected]> Cc: [email protected] --- arch/x86/include/asm/uaccess_64.h | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -68,11 +68,10 @@ int copy_to_user(void __user *dst, const } static __always_inline __must_check -int __copy_from_user(void *dst, const void __user *src, unsigned size) +int __copy_from_user_nocheck(void *dst, const void __user *src, unsigned size) { int ret = 0; - might_fault(); if (!__builtin_constant_p(size)) return copy_user_generic(dst, (__force void *)src, size); switch (size) { @@ -112,11 +111,17 @@ int __copy_from_user(void *dst, const vo } static __always_inline __must_check -int __copy_to_user(void __user *dst, const void *src, unsigned size) +int __copy_from_user(void *dst, const void __user *src, unsigned size) +{ + might_fault(); + return __copy_from_user_nocheck(dst, src, size); +} + +static __always_inline __must_check +int __copy_to_user_nocheck(void __user *dst, const void *src, unsigned size) { int ret = 0; - might_fault(); if (!__builtin_constant_p(size)) return copy_user_generic((__force void *)dst, src, size); switch (size) { @@ -156,6 +161,13 @@ int __copy_to_user(void __user *dst, con } static __always_inline __must_check +int __copy_to_user(void __user *dst, const void *src, unsigned size) +{ + might_fault(); + return __copy_to_user_nocheck(dst, src, size); +} + +static __always_inline __must_check int __copy_in_user(void __user *dst, const void __user *src, unsigned size) { int ret = 0; @@ -221,13 +233,13 @@ __must_check unsigned long __clear_user( static __must_check __always_inline int __copy_from_user_inatomic(void *dst, const void __user *src, unsigned size) { - return copy_user_generic(dst, (__force const void *)src, size); + return __copy_from_user_nocheck(dst, (__force const void *)src, size); } static __must_check __always_inline int __copy_to_user_inatomic(void __user *dst, const void *src, unsigned size) { - return copy_user_generic((__force void *)dst, src, size); + return __copy_to_user_nocheck((__force void *)dst, src, size); } extern long __copy_user_nocache(void *dst, const void __user *src,
