170 lines
6.0 KiB
Diff
170 lines
6.0 KiB
Diff
From: Ingo Molnar <mingo@kernel.org>
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Date: Tue, 15 Oct 2013 08:23:51 +0200
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Subject: [PATCH] compiler/gcc4: Add quirk for 'asm goto' miscompilation bug
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Origin: https://lkml.kernel.org/g/20131015062933.GB4666@gmail.com
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Fengguang Wu, Oleg Nesterov and Peter Zijlstra tracked down
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a kernel crash to a GCC bug: GCC miscompiles certain 'asm goto'
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constructs, as outlined here:
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
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Implement a workaround suggested by Jakub Jelinek.
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Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
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Reported-by: Oleg Nesterov <oleg@redhat.com>
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Reported-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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Suggested-by: Jakub Jelinek <jakub@redhat.com>
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Reviewed-by: Richard Henderson <rth@twiddle.net>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Andrew Morton <akpm@linux-foundation.org>
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Cc: <stable@kernel.org>
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Link: http://lkml.kernel.org/r/20131015062351.GA4666@gmail.com
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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---
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arch/arm/include/asm/jump_label.h | 2 +-
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arch/mips/include/asm/jump_label.h | 2 +-
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arch/powerpc/include/asm/jump_label.h | 2 +-
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arch/s390/include/asm/jump_label.h | 2 +-
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arch/sparc/include/asm/jump_label.h | 2 +-
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arch/x86/include/asm/cpufeature.h | 6 +++---
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arch/x86/include/asm/jump_label.h | 2 +-
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include/linux/compiler-gcc4.h | 15 +++++++++++++++
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8 files changed, 24 insertions(+), 9 deletions(-)
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diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
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index bfc198c..863c892 100644
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--- a/arch/arm/include/asm/jump_label.h
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+++ b/arch/arm/include/asm/jump_label.h
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@@ -16,7 +16,7 @@
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static __always_inline bool arch_static_branch(struct static_key *key)
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{
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- asm goto("1:\n\t"
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+ asm_volatile_goto("1:\n\t"
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JUMP_LABEL_NOP "\n\t"
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".pushsection __jump_table, \"aw\"\n\t"
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".word 1b, %l[l_yes], %c0\n\t"
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diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
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index 4d6d77e..e194f95 100644
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--- a/arch/mips/include/asm/jump_label.h
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+++ b/arch/mips/include/asm/jump_label.h
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@@ -22,7 +22,7 @@
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static __always_inline bool arch_static_branch(struct static_key *key)
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{
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- asm goto("1:\tnop\n\t"
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+ asm_volatile_goto("1:\tnop\n\t"
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"nop\n\t"
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".pushsection __jump_table, \"aw\"\n\t"
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WORD_INSN " 1b, %l[l_yes], %0\n\t"
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diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
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index ae098c4..f016bb6 100644
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--- a/arch/powerpc/include/asm/jump_label.h
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+++ b/arch/powerpc/include/asm/jump_label.h
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@@ -19,7 +19,7 @@
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static __always_inline bool arch_static_branch(struct static_key *key)
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{
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- asm goto("1:\n\t"
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+ asm_volatile_goto("1:\n\t"
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"nop\n\t"
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".pushsection __jump_table, \"aw\"\n\t"
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JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
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diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
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index 6c32190..346b1c8 100644
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--- a/arch/s390/include/asm/jump_label.h
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+++ b/arch/s390/include/asm/jump_label.h
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@@ -15,7 +15,7 @@
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static __always_inline bool arch_static_branch(struct static_key *key)
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{
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- asm goto("0: brcl 0,0\n"
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+ asm_volatile_goto("0: brcl 0,0\n"
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".pushsection __jump_table, \"aw\"\n"
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ASM_ALIGN "\n"
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ASM_PTR " 0b, %l[label], %0\n"
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diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h
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index 5080d16..ec2e2e2 100644
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--- a/arch/sparc/include/asm/jump_label.h
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+++ b/arch/sparc/include/asm/jump_label.h
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@@ -9,7 +9,7 @@
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static __always_inline bool arch_static_branch(struct static_key *key)
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{
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- asm goto("1:\n\t"
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+ asm_volatile_goto("1:\n\t"
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"nop\n\t"
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"nop\n\t"
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".pushsection __jump_table, \"aw\"\n\t"
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diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
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index 47538a6..7290585 100644
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--- a/arch/x86/include/asm/cpufeature.h
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+++ b/arch/x86/include/asm/cpufeature.h
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@@ -373,7 +373,7 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
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* Catch too early usage of this before alternatives
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* have run.
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*/
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- asm goto("1: jmp %l[t_warn]\n"
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+ asm_volatile_goto("1: jmp %l[t_warn]\n"
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"2:\n"
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".section .altinstructions,\"a\"\n"
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" .long 1b - .\n"
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@@ -386,7 +386,7 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
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: : "i" (X86_FEATURE_ALWAYS) : : t_warn);
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#endif
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- asm goto("1: jmp %l[t_no]\n"
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+ asm_volatile_goto("1: jmp %l[t_no]\n"
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"2:\n"
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".section .altinstructions,\"a\"\n"
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" .long 1b - .\n"
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@@ -448,7 +448,7 @@ static __always_inline __pure bool _static_cpu_has_safe(u16 bit)
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* have. Thus, we force the jump to the widest, 4-byte, signed relative
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* offset even though the last would often fit in less bytes.
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*/
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- asm goto("1: .byte 0xe9\n .long %l[t_dynamic] - 2f\n"
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+ asm_volatile_goto("1: .byte 0xe9\n .long %l[t_dynamic] - 2f\n"
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"2:\n"
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".section .altinstructions,\"a\"\n"
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" .long 1b - .\n" /* src offset */
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diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
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index 3a16c14..0297669 100644
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--- a/arch/x86/include/asm/jump_label.h
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+++ b/arch/x86/include/asm/jump_label.h
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@@ -13,7 +13,7 @@
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static __always_inline bool arch_static_branch(struct static_key *key)
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{
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- asm goto("1:"
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+ asm_volatile_goto("1:"
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STATIC_KEY_INITIAL_NOP
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".pushsection __jump_table, \"aw\" \n\t"
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_ASM_ALIGN "\n\t"
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diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
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index 842de22..ded4299 100644
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--- a/include/linux/compiler-gcc4.h
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+++ b/include/linux/compiler-gcc4.h
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@@ -65,6 +65,21 @@
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#define __visible __attribute__((externally_visible))
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#endif
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+/*
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+ * GCC 'asm goto' miscompiles certain code sequences:
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+ *
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+ * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
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+ *
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+ * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
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+ * Fixed in GCC 4.8.2 and later versions.
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+ *
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+ * (asm goto is automatically volatile - the naming reflects this.)
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+ */
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+#if GCC_VERSION <= 40801
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+# define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
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+#else
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+# define asm_volatile_goto(x...) do { asm goto(x); } while (0)
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+#endif
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#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
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#if GCC_VERSION >= 40400
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