[ Added Michal to Cc ]
On Tue, 2010-05-25 at 15:06 -0400, Jason Baron wrote:
> On Mon, May 24, 2010 at 09:27:52PM +0200, Ingo Molnar wrote:
> > * Jason Baron <jbaron@xxxxxxxxxx> wrote:
> >
> > > On Sun, May 23, 2010 at 11:18:56AM +0200, Ingo Molnar wrote:
> > > > hi Jason,
> > > >
> > > > * Jason Baron <jbaron@xxxxxxxxxx> wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > updates for -v8:
> > > >
> > > > I wanted to try your feature, but even after updating to
> > > > latest rawhide i have:
> > > >
> > > > lyra:~> rpm -q gcc
> > > > gcc-4.4.4-3.fc14.x86_64
> > > >
> > > > and IIRC the asm goto feature is new in GCC 4.5, right?
> > > >
> > > > Do you know when there's going to be a GCC 4.5 package for
> > > > Fedora? I wanted to see how this feature works in
> > > > practice, with a GCC packaged up for a distro.
> > > >
> > > > Is there perhaps some repo somewhere with more
> > > > experimental GCC builds for rawhide or so?
> > > >
> > > > Thanks,
> > > >
> > > > Ingo
> > >
> > > Hi Ingo,
> > >
> > > right. So the gcc feature is officially in gcc 4.5 which
> > > i believe has been released. however, it has been
> > > bacported to the latest fedora gcc even though its 4.4
> > > based. Thus, if you apply something like like the
> > > following you can test it out on fedora.
> >
> > Hm, could you please add a build-time check to check for
> > the GCC feature instead? That way we'll be able to support
> > any backports straight out of box.
> >
> > We do this for various GCC features: stackprotector, cfi,
> > etc., so it's a standard technique.
> >
> > Ingo
>
> ok, here's what we've come up with based on Ingo's suggestion. Any
> chance this feature can be considered for 2.6.35? I've a got a few
> other small fixes too...
>
> thanks,
>
> -Jason
>
> diff --git a/Makefile b/Makefile
> index 85edb67..b51ddfb 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -582,6 +582,11 @@ KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm)
> # conserve stack if available
> KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)
>
> +# check for 'asm goto'
> +ifeq ($(shell sh -c "(echo 'int main(void) { entry: asm goto (\"\"::::entry); return 0; }') | $(CC) -x c - >/dev/null 2>&1 && echo y"), y)
> + KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
> +endif
Yeah, also this would help prevent bugs with other archs where the GCC
version may not have supported it either.
Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
-- Steve
> +
> # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
> # But warn user when we do so
> warn-assign = \
> diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
> index 1eaf884..ebe19ae 100644
> --- a/include/linux/jump_label.h
> +++ b/include/linux/jump_label.h
> @@ -1,11 +1,9 @@
> #ifndef _LINUX_JUMP_LABEL_H
> #define _LINUX_JUMP_LABEL_H
>
> -#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5))
> -# ifdef CONFIG_HAVE_ARCH_JUMP_LABEL
> -# include <asm/jump_label.h>
> -# define HAVE_JUMP_LABEL 1
> -# endif
> +#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_HAVE_ARCH_JUMP_LABEL)
> +# include <asm/jump_label.h>
> +# define HAVE_JUMP_LABEL
> #endif
>
> enum jump_label_type {
--
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