diff options
| author | Jan Beulich <JBeulich@novell.com> | 2009-12-18 16:12:56 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-12-30 11:57:31 +0100 |
| commit | 1b1d9258181bae199dc940f4bd0298126b9a73d9 (patch) | |
| tree | b17ca149d943051fc76e79b75fc4b89c61b524a2 /arch/x86/include/asm/uaccess_64.h | |
| parent | 499a5f1efa0b0ac56ec5d060412aed84ae68e63e (diff) | |
x86-64: Modify copy_user_generic() alternatives mechanism
In order to avoid unnecessary chains of branches, rather than
implementing copy_user_generic() as a function consisting of
just a single (possibly patched) branch, instead properly deal
with patching call instructions in the alternative instructions
framework, and move the patching into the callers.
As a follow-on, one could also introduce something like
__EXPORT_SYMBOL_ALT() to avoid patching call sites in modules.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4B2BB8180200007800026AE7@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/uaccess_64.h')
| -rw-r--r-- | arch/x86/include/asm/uaccess_64.h | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h index 46324c6a4f6e..a78c40305447 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -8,6 +8,8 @@ #include <linux/errno.h> #include <linux/prefetch.h> #include <linux/lockdep.h> +#include <asm/alternative.h> +#include <asm/cpufeature.h> #include <asm/page.h> /* @@ -16,7 +18,24 @@ /* Handles exceptions in both to and from, but doesn't do access_ok */ __must_check unsigned long -copy_user_generic(void *to, const void *from, unsigned len); +copy_user_generic_string(void *to, const void *from, unsigned len); +__must_check unsigned long +copy_user_generic_unrolled(void *to, const void *from, unsigned len); + +static __always_inline __must_check unsigned long +copy_user_generic(void *to, const void *from, unsigned len) +{ + unsigned ret; + + alternative_call(copy_user_generic_unrolled, + copy_user_generic_string, + X86_FEATURE_REP_GOOD, + ASM_OUTPUT2("=a" (ret), "=D" (to), "=S" (from), + "=d" (len)), + "1" (to), "2" (from), "3" (len) + : "memory", "rcx", "r8", "r9", "r10", "r11"); + return ret; +} __must_check unsigned long _copy_to_user(void __user *to, const void *from, unsigned len); |