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authorAl Viro <viro@ZenIV.linux.org.uk>2013-09-01 20:35:01 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-09-26 17:18:13 -0700
commita168ad2687045d24e98b2525d1ee678c4f2a9a96 (patch)
treec926544081dae0bae8e31240f745979bc0c702c1 /arch/x86
parent1159cd1ded90b41db788f84bf94644a810dd322a (diff)
downloadlinaro-lsk-a168ad2687045d24e98b2525d1ee678c4f2a9a96.tar.gz
Introduce [compat_]save_altstack_ex() to unbreak x86 SMAP
commit bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5 upstream. 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> Link: http://lkml.kernel.org/n/tip-es5p6y64if71k8p5u08agv9n@git.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/ia32/ia32_signal.c2
-rw-r--r--arch/x86/kernel/signal.c6
2 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index cf1a471a18a..10adb41f162 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -459,7 +459,7 @@ 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;
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 69562992e45..087ab2af381 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -364,7 +364,7 @@ static int __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 |= __save_altstack(&frame->uc.uc_stack, regs->sp);
+ save_altstack_ex(&frame->uc.uc_stack, regs->sp);
/* Set up to return from userspace. */
restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
@@ -429,7 +429,7 @@ static int __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 |= __save_altstack(&frame->uc.uc_stack, regs->sp);
+ save_altstack_ex(&frame->uc.uc_stack, regs->sp);
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
@@ -496,7 +496,7 @@ static int x32_setup_rt_frame(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);
put_user_ex(0, &frame->uc.uc__pad0);
if (ksig->ka.sa.sa_flags & SA_RESTORER) {