Messages in this thread | | | Date | Thu, 26 Jun 2014 21:56:29 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH] x86_64,entry: Fix RCX for traced syscalls |
| |
> show RCX == RIP even under strace.
If you think it's really worth the extra instruction?
It's not wrong, but it's not clear if it's useful.
-Andi
> > Signed-off-by: Andy Lutomirski <luto@amacapital.net> > --- > arch/x86/kernel/entry_64.S | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S > index b25ca96..6624e18 100644 > --- a/arch/x86/kernel/entry_64.S > +++ b/arch/x86/kernel/entry_64.S > @@ -143,7 +143,8 @@ ENDPROC(native_usergs_sysret64) > movq \tmp,RSP+\offset(%rsp) > movq $__USER_DS,SS+\offset(%rsp) > movq $__USER_CS,CS+\offset(%rsp) > - movq $-1,RCX+\offset(%rsp) > + movq RIP+\offset(%rsp),\tmp /* get rip */ > + movq \tmp,RCX+\offset(%rsp) /* copy it to rcx as sysret would do */ > movq R11+\offset(%rsp),\tmp /* get eflags */ > movq \tmp,EFLAGS+\offset(%rsp) > .endm > -- > 1.9.3 >
-- ak@linux.intel.com -- Speaking for myself only.
| |