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 <rost...@goodmis.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Brian Gerst <brge...@gmail.com>
Cc: Andi Kleen <a...@linux.intel.com>
Cc: H. Peter Anvin <h...@linux.intel.com>
Signed-off-by: Mathias Krause <mini...@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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