Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Josh Poimboeuf <> | Subject | [RFC PATCH 04/21] x86/hweight: Add stack frame dependency for __arch_hweight*() | Date | Fri, 17 Jul 2015 11:47:20 -0500 |
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If __arch_hweight32() or __arch_hweight64() is inlined at the beginning of a function, gcc can insert the call instruction before setting up a stack frame, which breaks frame pointer convention if CONFIG_FRAME_POINTER is enabled and can result in a bad stack trace.
Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by listing the stack pointer as an output operand for the inline asm statement.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> --- arch/x86/include/asm/arch_hweight.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/arch_hweight.h b/arch/x86/include/asm/arch_hweight.h index 9686c3d..e438a0d 100644 --- a/arch/x86/include/asm/arch_hweight.h +++ b/arch/x86/include/asm/arch_hweight.h @@ -23,10 +23,11 @@ */ static inline unsigned int __arch_hweight32(unsigned int w) { + register void *__sp asm("esp"); unsigned int res = 0; asm (ALTERNATIVE("call __sw_hweight32", POPCNT32, X86_FEATURE_POPCNT) - : "="REG_OUT (res) + : "="REG_OUT (res), "+r" (__sp) : REG_IN (w)); return res; @@ -44,6 +45,7 @@ static inline unsigned int __arch_hweight8(unsigned int w) static inline unsigned long __arch_hweight64(__u64 w) { + register void __maybe_unused *__sp asm("rsp"); unsigned long res = 0; #ifdef CONFIG_X86_32 @@ -51,7 +53,7 @@ static inline unsigned long __arch_hweight64(__u64 w) __arch_hweight32((u32)(w >> 32)); #else asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT) - : "="REG_OUT (res) + : "="REG_OUT (res), "+r" (__sp) : REG_IN (w)); #endif /* CONFIG_X86_32 */ -- 2.1.0
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