TIF_NOTIFY_SIGNAL handling in xtensa assembly is implemented
incorrectly: there should be a call to do_notify_resume when either
TIF_SIGPENDING, TIF_NOTIFY_RESUME or TIF_NOTIFY_SIGNAL bit is set in the
thread_info::flags. The straightforward way to do it would be
_bbsi.l a4, TIF_NEED_RESCHED, 3f
_bbsi.l a4, TIF_NOTIFY_RESUME, 2f
_bbsi.l a4, TIF_NOTIFY_SIGNAL, 2f
_bbci.l a4, TIF_SIGPENDING, 5f
Optimize it a little bit and use bit mask and bnone opcode to skip
do_notify_resume invocation. Shuffle _TIF_* flags a bit so that used bit
mask fits into the immediate field of movi opcode.
Fixes: 4c6a9dcd4d13 ("xtensa: add support for TIF_NOTIFY_SIGNAL")
Cc: Jens Axboe <[email protected]>
Signed-off-by: Max Filippov <[email protected]>
---
Changes v1->v2:
- use more canonical order of bnone arguments: tested value first,
bit mask second.
arch/xtensa/include/asm/thread_info.h | 7 ++++---
arch/xtensa/kernel/entry.S | 5 ++---
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/xtensa/include/asm/thread_info.h b/arch/xtensa/include/asm/thread_info.h
index 6ea521b8e2ec..a312333a9add 100644
--- a/arch/xtensa/include/asm/thread_info.h
+++ b/arch/xtensa/include/asm/thread_info.h
@@ -111,22 +111,23 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_SINGLESTEP 3 /* restore singlestep on return to user mode */
#define TIF_SYSCALL_TRACEPOINT 4 /* syscall tracepoint instrumentation */
-#define TIF_MEMDIE 5 /* is terminating due to OOM killer */
+#define TIF_NOTIFY_SIGNAL 5 /* signal notifications exist */
#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
#define TIF_NOTIFY_RESUME 7 /* callback before returning to user */
#define TIF_DB_DISABLED 8 /* debug trap disabled for syscall */
#define TIF_SYSCALL_AUDIT 9 /* syscall auditing active */
#define TIF_SECCOMP 10 /* secure computing */
-#define TIF_NOTIFY_SIGNAL 11 /* signal notifications exist */
+#define TIF_MEMDIE 11 /* is terminating due to OOM killer */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
+#define _TIF_NOTIFY_SIGNAL (1<<TIF_NOTIFY_SIGNAL)
+#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
-#define _TIF_NOTIFY_SIGNAL (1<<TIF_NOTIFY_SIGNAL)
#define _TIF_WORK_MASK (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | \
_TIF_SYSCALL_TRACEPOINT | \
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 7f733f40fef0..647b162f959b 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -500,9 +500,8 @@ common_exception_return:
*/
_bbsi.l a4, TIF_NEED_RESCHED, 3f
- _bbsi.l a4, TIF_NOTIFY_RESUME, 2f
- _bbci.l a4, TIF_SIGPENDING, 5f
- _bbci.l a4, TIF_NOTIFY_SIGNAL, 5f
+ movi a2, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL
+ bnone a4, a2, 5f
2: l32i a4, a1, PT_DEPC
bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
--
2.20.1
On 11/11/20 1:53 PM, Max Filippov wrote:
> TIF_NOTIFY_SIGNAL handling in xtensa assembly is implemented
> incorrectly: there should be a call to do_notify_resume when either
> TIF_SIGPENDING, TIF_NOTIFY_RESUME or TIF_NOTIFY_SIGNAL bit is set in the
> thread_info::flags. The straightforward way to do it would be
>
> _bbsi.l a4, TIF_NEED_RESCHED, 3f
> _bbsi.l a4, TIF_NOTIFY_RESUME, 2f
> _bbsi.l a4, TIF_NOTIFY_SIGNAL, 2f
> _bbci.l a4, TIF_SIGPENDING, 5f
>
> Optimize it a little bit and use bit mask and bnone opcode to skip
> do_notify_resume invocation. Shuffle _TIF_* flags a bit so that used bit
> mask fits into the immediate field of movi opcode.
Thanks - do you mind if I fold this in with a reference to your
changes? Seems like that'd be a better option than leaving it
broken for a bit.
--
Jens Axboe
On Wed, Nov 11, 2020 at 1:05 PM Jens Axboe <[email protected]> wrote:
>
> On 11/11/20 1:53 PM, Max Filippov wrote:
> > TIF_NOTIFY_SIGNAL handling in xtensa assembly is implemented
> > incorrectly: there should be a call to do_notify_resume when either
> > TIF_SIGPENDING, TIF_NOTIFY_RESUME or TIF_NOTIFY_SIGNAL bit is set in the
> > thread_info::flags. The straightforward way to do it would be
> >
> > _bbsi.l a4, TIF_NEED_RESCHED, 3f
> > _bbsi.l a4, TIF_NOTIFY_RESUME, 2f
> > _bbsi.l a4, TIF_NOTIFY_SIGNAL, 2f
> > _bbci.l a4, TIF_SIGPENDING, 5f
> >
> > Optimize it a little bit and use bit mask and bnone opcode to skip
> > do_notify_resume invocation. Shuffle _TIF_* flags a bit so that used bit
> > mask fits into the immediate field of movi opcode.
>
> Thanks - do you mind if I fold this in with a reference to your
> changes? Seems like that'd be a better option than leaving it
> broken for a bit.
Sure Jens, by all means!
--
Thanks.
-- Max
On 11/12/20 2:12 AM, Max Filippov wrote:
> On Wed, Nov 11, 2020 at 1:05 PM Jens Axboe <[email protected]> wrote:
>>
>> On 11/11/20 1:53 PM, Max Filippov wrote:
>>> TIF_NOTIFY_SIGNAL handling in xtensa assembly is implemented
>>> incorrectly: there should be a call to do_notify_resume when either
>>> TIF_SIGPENDING, TIF_NOTIFY_RESUME or TIF_NOTIFY_SIGNAL bit is set in the
>>> thread_info::flags. The straightforward way to do it would be
>>>
>>> _bbsi.l a4, TIF_NEED_RESCHED, 3f
>>> _bbsi.l a4, TIF_NOTIFY_RESUME, 2f
>>> _bbsi.l a4, TIF_NOTIFY_SIGNAL, 2f
>>> _bbci.l a4, TIF_SIGPENDING, 5f
>>>
>>> Optimize it a little bit and use bit mask and bnone opcode to skip
>>> do_notify_resume invocation. Shuffle _TIF_* flags a bit so that used bit
>>> mask fits into the immediate field of movi opcode.
>>
>> Thanks - do you mind if I fold this in with a reference to your
>> changes? Seems like that'd be a better option than leaving it
>> broken for a bit.
>
> Sure Jens, by all means!
Thanks! Done.
--
Jens Axboe