[PATCH] x86: add the flag -fno-reorder-blocks-and-partition

[PATCH] x86: add the flag -fno-reorder-blocks-and-partition

[Mikulas Patocka]

GCC 8 turns on -freorder-blocks-and-partition by default, the ORC unwinder 
can't deal with it and it results in a lot of warnings "sibling call from 
callable instruction with modified stack frame". This patch adds the 
-fno-reorder-blocks-and-partition option to KBUILD_CFLAGS.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org

---
 arch/x86/Makefile |    1 +
 1 file changed, 1 insertion(+)

Index: linux-2.6/arch/x86/Makefile
===================================================================
--- linux-2.6.orig/arch/x86/Makefile	2018-05-15 07:19:40.000000000 +0200
+++ linux-2.6/arch/x86/Makefile	2018-05-15 07:19:40.000000000 +0200
@@ -59,6 +59,7 @@ endif
 #
 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
 KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
+KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks-and-partition,)
 
 ifeq ($(CONFIG_X86_32),y)
         BITS := 32

Re: [PATCH] x86: add the flag -fno-reorder-blocks-and-partition

[Ingo Molnar]

* Mikulas Patocka <mpatocka@redhat.com> wrote:

> GCC 8 turns on -freorder-blocks-and-partition by default, the ORC unwinder 
> can't deal with it and it results in a lot of warnings "sibling call from 
> callable instruction with modified stack frame". This patch adds the 
> -fno-reorder-blocks-and-partition option to KBUILD_CFLAGS.
> 
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Cc: stable@vger.kernel.org
> 
> ---
>  arch/x86/Makefile |    1 +
>  1 file changed, 1 insertion(+)
> 
> Index: linux-2.6/arch/x86/Makefile
> ===================================================================
> --- linux-2.6.orig/arch/x86/Makefile	2018-05-15 07:19:40.000000000 +0200
> +++ linux-2.6/arch/x86/Makefile	2018-05-15 07:19:40.000000000 +0200
> @@ -59,6 +59,7 @@ endif
>  #
>  KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
>  KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
> +KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks-and-partition,)

Could you check whether the latest objtool fixes in -tip:

  git git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git master

solves those warnings?

Thanks,

	Ingo

Re: [PATCH] x86: add the flag -fno-reorder-blocks-and-partition

[kbuild test robot]

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Hi Mikulas,

I love your patch! Perhaps something to improve:

[auto build test WARNING on tip/auto-latest]
[also build test WARNING on v4.17-rc6 next-20180517]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Mikulas-Patocka/x86-add-the-flag-fno-reorder-blocks-and-partition/20180515-143916
config: x86_64-randconfig-g0-05220537 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

>> drivers/net/ethernet/mellanox/mlx4/sense.o: warning: objtool: .text: unexpected end of section

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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