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@xxxxxxxxxx>
---
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
--
To unsubscribe from this list: send the line "unsubscribe live-patching" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
