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authorAl Viro <viro@ZenIV.linux.org.uk>2013-09-01 20:35:01 +0100
committerH. Peter Anvin <hpa@linux.intel.com>2013-09-01 14:16:33 -0700
commitbd1c149aa9915b9abb6d83d0f01dfd2ace0680b5 (patch)
tree1ccdf876f778bd986a6238d379ee9e9981ed98dc /arch/x86/ia32
parent7263dda41b5a28ae6566fd126d9b06ada73dd721 (diff)
downloadlinux-bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5.tar.gz
Introduce [compat_]save_altstack_ex() to unbreak x86 SMAP
For performance reasons, when SMAP is in use, SMAP is left open for an entire put_user_try { ... } put_user_catch(); block, however, calling __put_user() in the middle of that block will close SMAP as the STAC..CLAC constructs intentionally do not nest. Furthermore, using __put_user() rather than put_user_ex() here is bad for performance. Thus, introduce new [compat_]save_altstack_ex() helpers that replace __[compat_]save_altstack() for x86, being currently the only architecture which supports put_user_try { ... } put_user_catch(). Reported-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: <stable@vger.kernel.org> # v3.8+ Link: http://lkml.kernel.org/n/tip-es5p6y64if71k8p5u08agv9n@git.kernel.org
Diffstat (limited to 'arch/x86/ia32')
-rw-r--r--arch/x86/ia32/ia32_signal.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index bccfca68430..665a730307f 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -457,7 +457,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
else
put_user_ex(0, &frame->uc.uc_flags);
put_user_ex(0, &frame->uc.uc_link);
- err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
+ compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
if (ksig->ka.sa.sa_flags & SA_RESTORER)
restorer = ksig->ka.sa.sa_restorer;