Messages in this thread Patch in this message | | | From | Miguel Bernal Marin <> | Subject | [PATCH v3 2/6] locking/rwsem/x86: Add stack frame dependency for __up_write() | Date | Tue, 19 Sep 2017 18:37:41 -0500 |
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kernel/locking/rwsem.o: warning: objtool: up_write()+0x17: call without frame pointer save/setup
The warning means gcc 7.2.0 placed the __up_write() inline asm (and its call instruction) before the frame pointer setup in up_write(), which breaks frame pointer convention and can result in incorrect stack traces.
Force a stack frame to be created before the call instruction by listing the stack pointer as an output operand in the inline asm statement.
Signed-off-by: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com> --- arch/x86/include/asm/rwsem.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h index 762167afaec0..d26b6916b935 100644 --- a/arch/x86/include/asm/rwsem.h +++ b/arch/x86/include/asm/rwsem.h @@ -186,14 +186,16 @@ static inline void __up_read(struct rw_semaphore *sem) static inline void __up_write(struct rw_semaphore *sem) { long tmp; + register void *__sp asm(_ASM_SP); + asm volatile("# beginning __up_write\n\t" - LOCK_PREFIX " xadd %1,(%2)\n\t" + LOCK_PREFIX " xadd %1,(%3)\n\t" /* subtracts 0xffff0001, returns the old value */ " jns 1f\n\t" " call call_rwsem_wake\n" /* expects old value in %edx */ "1:\n\t" "# ending __up_write\n" - : "+m" (sem->count), "=d" (tmp) + : "+m" (sem->count), "=d" (tmp), "+r" (__sp) : "a" (sem), "1" (-RWSEM_ACTIVE_WRITE_BIAS) : "memory", "cc"); } -- 2.14.1
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