Messages in this thread | | | Date | Fri, 15 May 2015 15:17:45 -0300 | Subject | Re: [PATCH] x86/asm/entry/64: Use shorter MOVs from segmers registers | From | Thiago Farina <> |
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On Thu, May 14, 2015 at 1:55 PM, Denys Vlasenko <dvlasenk@redhat.com> wrote: > "movw %ds,%cx" insn needs a 0x66 prefix, while "movw %ds,%ecx" does not. did you mean 'movl %ds,%ecx' here as is in your patch below?
> Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> > CC: Linus Torvalds <torvalds@linux-foundation.org> > CC: Steven Rostedt <rostedt@goodmis.org> > CC: Ingo Molnar <mingo@kernel.org> > CC: Borislav Petkov <bp@alien8.de> > CC: "H. Peter Anvin" <hpa@zytor.com> > CC: Andy Lutomirski <luto@amacapital.net> > CC: Oleg Nesterov <oleg@redhat.com> > CC: Frederic Weisbecker <fweisbec@gmail.com> > CC: Alexei Starovoitov <ast@plumgrid.com> > CC: Will Drewry <wad@chromium.org> > CC: Kees Cook <keescook@chromium.org> > CC: x86@kernel.org > CC: linux-kernel@vger.kernel.org > --- > arch/x86/kernel/entry_64.S | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S > index 62b4c5f..ef2651d 100644 > --- a/arch/x86/kernel/entry_64.S > +++ b/arch/x86/kernel/entry_64.S > @@ -1195,19 +1195,19 @@ ENTRY(xen_failsafe_callback) > /*CFI_REL_OFFSET ds,DS*/ > CFI_REL_OFFSET r11,8 > CFI_REL_OFFSET rcx,0 > - movw %ds,%cx > + movl %ds,%ecx > cmpw %cx,0x10(%rsp) > CFI_REMEMBER_STATE > jne 1f > - movw %es,%cx > + movl %es,%ecx > cmpw %cx,0x18(%rsp) > jne 1f > - movw %fs,%cx > + movl %fs,%ecx > cmpw %cx,0x20(%rsp) > jne 1f > - movw %gs,%cx > + movl %gs,%ecx > cmpw %cx,0x28(%rsp) > jne 1f > /* All segments match their saved values => Category 2 (Bad IRET). */ > movq (%rsp),%rcx > CFI_RESTORE rcx > movq 8(%rsp),%r11 > -- > 1.8.1.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
-- Thiago Farina
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