Commit-ID: 6cce16f99d7be23cec7cabdf32a8166eec6e5393
Gitweb: http://git.kernel.org/tip/6cce16f99d7be23cec7cabdf32a8166eec6e5393
Author: Mathias Krause <minipli@xxxxxxxxxxxxxx>
AuthorDate: Fri, 7 Mar 2014 08:52:32 +0100
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Mon, 10 Mar 2014 17:32:01 -0700
x86, threadinfo: Redo "x86: Use inline assembler to get sp"
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@xxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1394178752-18047-1-git-send-email-minipli@xxxxxxxxxxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
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 988dc8b..63ce838 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)
{
--
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