Messages in this thread Patch in this message | | | From | Mathias Krause <> | Subject | [PATCH] x86: redo "x86: Use inline assembler to get sp" | Date | Fri, 7 Mar 2014 08:52:32 +0100 |
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This patch restores the changes of commit dff38e3e93 "x86: Use inline assembler instead of global register variable to get sp". They got lost in commit 198d208df4 "x86: Keep thread_info on thread stack in x86_32" while moving the code to arch/x86/kernel/irq_32.c.
Quoting Andi from commit dff38e3e93:
""" 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. """
Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Mathias Krause <minipli@googlemail.com> ---
If it's not obvious, this patch should be applied to tip.git on top of tip/x86/threadinfo.
arch/x86/kernel/irq_32.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c index 988dc8bcae..63ce838e5a 100644 --- a/arch/x86/kernel/irq_32.c +++ b/arch/x86/kernel/irq_32.c @@ -70,7 +70,11 @@ static void call_on_stack(void *func, void *stack) } /* 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; \ +}) static inline void *current_stack(void) { -- 1.7.10.4
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