lkml.org 
[lkml]   [2010]   [Mar]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 3/5] jump label: x86 support
On Mon, Mar 22, 2010 at 12:40:25PM -0400, Steven Rostedt wrote:
> > add x86 support for jump label. I'm keeping this patch separate so its clear to
> > arch maintainers what was required for x86 support this new feature. hopefully,
> > it wouldn't be too painful for other arches.
> >
> > Signed-off-by: Jason Baron <jbaron@redhat.com>
>
>
> > +#ifdef __HAVE_ARCH_JUMP_LABEL
> > +
> > +# ifdef CONFIG_X86_64
> > +# define JUMP_LABEL_NOP P6_NOP5
> > +# else
> > +# define JUMP_LABEL_NOP ".byte 0xe9 \n\t .long 0\n\t"
> > +# endif
>
> Are you sure P6_NOP5 can't happen on non 64bit? Just because it is not
> configured does not mean that the CPU can not handle it. Look at the
> code I did in arch/x86/kernel/ftrace.c to determine what nop to use.
> Maybe we can make that generic and have at boot up, the kernel determine
> a proper 5byte nop.
>

indeed, i've looked at the ftrace nop code...I think was concerned that
I would need a baseline nop that would work for all boxes. But I guess a
jmp + 5 would be it?

-Jason


\
 
 \ /
  Last update: 2010-03-22 21:43    [W:0.047 / U:0.780 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site