* gregkh@xxxxxxxxxxxxxxxxxxx <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > The patch below does not apply to the 3.10-stable tree. If someone wants > it applied there, or to any other stable or longterm tree, then please > email the backport, including the original git commit id to > <stable@xxxxxxxxxxxxxxx>. > > thanks, > > greg k-h > > ------------------ original commit in Linus's tree ------------------ > > From 3f0116c3238a96bc18ad4b4acefe4e7be32fa861 Mon Sep 17 00:00:00 2001 > From: Ingo Molnar <mingo@xxxxxxxxxx> > Date: Thu, 10 Oct 2013 10:16:30 +0200 > Subject: [PATCH] compiler/gcc4: Add quirk for 'asm goto' miscompilation bug The patch below should resolve the conflicts. Lightly tested. Thanks, Ingo ================================> >From 7ab6ad431ae791fa862c9b68f1f04918735a591c Mon Sep 17 00:00:00 2001 From: Ingo Molnar <mingo@xxxxxxxxxx> Date: Tue, 15 Oct 2013 08:21:01 +0200 Subject: [PATCH] compiler/gcc4: Add quirk for 'asm goto' miscompilation bug Fengguang Wu, Oleg Nesterov and Peter Zijlstra tracked down a kernel crash to a GCC bug: GCC miscompiles certain 'asm goto' constructs, as outlined here: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 Implement a workaround suggested by Jakub Jelinek. Reported-and-tested-by: Fengguang Wu <fengguang.wu@xxxxxxxxx> Reported-by: Oleg Nesterov <oleg@xxxxxxxxxx> Reported-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Suggested-by: Jakub Jelinek <jakub@xxxxxxxxxx> Reviewed-by: Richard Henderson <rth@xxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Conflicts: arch/x86/include/asm/cpufeature.h arch/x86/include/asm/jump_label.h arch/x86/include/asm/mutex_64.h --- arch/arm/include/asm/jump_label.h | 2 +- arch/mips/include/asm/jump_label.h | 2 +- arch/powerpc/include/asm/jump_label.h | 2 +- arch/s390/include/asm/jump_label.h | 2 +- arch/sparc/include/asm/jump_label.h | 2 +- arch/x86/include/asm/cpufeature.h | 2 +- arch/x86/include/asm/jump_label.h | 2 +- include/linux/compiler-gcc4.h | 15 +++++++++++++++ 8 files changed, 22 insertions(+), 7 deletions(-) diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h index bfc198c..863c892 100644 --- a/arch/arm/include/asm/jump_label.h +++ b/arch/arm/include/asm/jump_label.h @@ -16,7 +16,7 @@ static __always_inline bool arch_static_branch(struct static_key *key) { - asm goto("1:\n\t" + asm_volatile_goto("1:\n\t" JUMP_LABEL_NOP "\n\t" ".pushsection __jump_table, \"aw\"\n\t" ".word 1b, %l[l_yes], %c0\n\t" diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h index 4d6d77e..e194f95 100644 --- a/arch/mips/include/asm/jump_label.h +++ b/arch/mips/include/asm/jump_label.h @@ -22,7 +22,7 @@ static __always_inline bool arch_static_branch(struct static_key *key) { - asm goto("1:\tnop\n\t" + asm_volatile_goto("1:\tnop\n\t" "nop\n\t" ".pushsection __jump_table, \"aw\"\n\t" WORD_INSN " 1b, %l[l_yes], %0\n\t" diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h index ae098c4..f016bb6 100644 --- a/arch/powerpc/include/asm/jump_label.h +++ b/arch/powerpc/include/asm/jump_label.h @@ -19,7 +19,7 @@ static __always_inline bool arch_static_branch(struct static_key *key) { - asm goto("1:\n\t" + asm_volatile_goto("1:\n\t" "nop\n\t" ".pushsection __jump_table, \"aw\"\n\t" JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t" diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h index 6c32190..346b1c8 100644 --- a/arch/s390/include/asm/jump_label.h +++ b/arch/s390/include/asm/jump_label.h @@ -15,7 +15,7 @@ static __always_inline bool arch_static_branch(struct static_key *key) { - asm goto("0: brcl 0,0\n" + asm_volatile_goto("0: brcl 0,0\n" ".pushsection __jump_table, \"aw\"\n" ASM_ALIGN "\n" ASM_PTR " 0b, %l[label], %0\n" diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h index 5080d16..ec2e2e2 100644 --- a/arch/sparc/include/asm/jump_label.h +++ b/arch/sparc/include/asm/jump_label.h @@ -9,7 +9,7 @@ static __always_inline bool arch_static_branch(struct static_key *key) { - asm goto("1:\n\t" + asm_volatile_goto("1:\n\t" "nop\n\t" "nop\n\t" ".pushsection __jump_table, \"aw\"\n\t" diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index e99ac27..4af181d 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -365,7 +365,7 @@ extern const char * const x86_power_flags[32]; static __always_inline __pure bool __static_cpu_has(u16 bit) { #if __GNUC__ > 4 || __GNUC_MINOR__ >= 5 - asm goto("1: jmp %l[t_no]\n" + asm_volatile_goto("1: jmp %l[t_no]\n" "2:\n" ".section .altinstructions,\"a\"\n" " .long 1b - .\n" diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index 3a16c14..0297669 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -13,7 +13,7 @@ static __always_inline bool arch_static_branch(struct static_key *key) { - asm goto("1:" + asm_volatile_goto("1:" STATIC_KEY_INITIAL_NOP ".pushsection __jump_table, \"aw\" \n\t" _ASM_ALIGN "\n\t" diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h index 842de22..ded4299 100644 --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -65,6 +65,21 @@ #define __visible __attribute__((externally_visible)) #endif +/* + * GCC 'asm goto' miscompiles certain code sequences: + * + * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 + * + * Work it around via a compiler barrier quirk suggested by Jakub Jelinek. + * Fixed in GCC 4.8.2 and later versions. + * + * (asm goto is automatically volatile - the naming reflects this.) + */ +#if GCC_VERSION <= 40801 +# define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) +#else +# define asm_volatile_goto(x...) do { asm goto(x); } while (0) +#endif #ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP #if GCC_VERSION >= 40400 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html