Messages in this thread Patch in this message | | | From | Miguel Bernal Marin <> | Subject | [PATCH v2 1/3] locking/rwsem/x86: Add stack frame dependency for __up_read() | Date | Wed, 6 Sep 2017 17:44:59 -0500 |
| |
kernel/locking/rwsem.o: warning: objtool: up_read()+0x11: call without frame pointer save/setup
The warning means gcc 7.2.0 placed the __up_read() inline asm (and its call instruction) before the frame pointer setup in up_read(), 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 a34e0d4b957d..762167afaec0 100644 --- a/arch/x86/include/asm/rwsem.h +++ b/arch/x86/include/asm/rwsem.h @@ -166,14 +166,16 @@ static inline bool __down_write_trylock(struct rw_semaphore *sem) static inline void __up_read(struct rw_semaphore *sem) { long tmp; + register void *__sp asm(_ASM_SP); + asm volatile("# beginning __up_read\n\t" - LOCK_PREFIX " xadd %1,(%2)\n\t" + LOCK_PREFIX " xadd %1,(%3)\n\t" /* subtracts 1, returns the old value */ " jns 1f\n\t" " call call_rwsem_wake\n" /* expects old value in %edx */ "1:\n" "# ending __up_read\n" - : "+m" (sem->count), "=d" (tmp) + : "+m" (sem->count), "=d" (tmp), "+r" (__sp) : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS) : "memory", "cc"); } -- 2.14.1
| |