From: Andi Kleen Date: Tue, 22 Oct 2013 16:07:57 +0000 (-0700) Subject: x86: Use inline assembler instead of global register variable to get sp X-Git-Tag: MMI-PSA29.97-13-9~12817^2~2 X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=dff38e3e93;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git x86: Use inline assembler instead of global register variable to get sp LTO in gcc 4.6/47. has trouble with global register variables. They were used to read the stack pointer. Use a simple inline assembler statement with a mov instead. This also helps LLVM/clang, which does not support global register variables. [ hpa: Ideally this should become a builtin in both gcc and clang. ] v2: More general asm constraint. Fix description (Jan Beulich) Signed-off-by: Andi Kleen Link: http://lkml.kernel.org/r/1382458079-24450-6-git-send-email-andi@firstfloor.org Signed-off-by: H. Peter Anvin --- diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 3ba3de457d05..e1940c06ed02 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -163,9 +163,11 @@ struct thread_info { */ #ifndef __ASSEMBLY__ - -/* how to get the current stack pointer from C */ -register unsigned long current_stack_pointer asm("esp") __used; +#define current_stack_pointer ({ \ + unsigned long sp; \ + asm("mov %%esp,%0" : "=g" (sp)); \ + sp; \ +}) /* how to get the thread information struct from C */ static inline struct thread_info *current_thread_info(void)