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Subject: Re: [PATCH] s390: add support for TIF_NOTIFY_SIGNAL
To:     Sven Schnelle <svens@linux.ibm.com>
Cc:     linux-s390@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
        linux-kernel@vger.kernel.org, peterz@infradead.org,
        oleg@redhat.com, tglx@linutronix.de,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Linux-Next Mailing List <linux-next@vger.kernel.org>
References: <yt9do8ke4seh.fsf@linux.ibm.com>
 <75a238c7-fc37-21dd-bd89-d4c87a206eaa@kernel.dk>
 <yt9dk0v21o0i.fsf@linux.ibm.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <f3ef071a-bbbc-1133-ed7b-6307919c4c3c@kernel.dk>
Date:   Tue, 3 Nov 2020 08:12:19 -0700
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On 11/3/20 8:03 AM, Sven Schnelle wrote:
> Hi Jens,
> 
> Jens Axboe <axboe@kernel.dk> writes:
> 
>> On 11/3/20 4:00 AM, Sven Schnelle wrote:
>>> Hi Jens,
>>>
>>> Heiko Carstens <hca () linux ! ibm ! com> writes:
>>>
>>>> On Thu, Oct 29, 2020 at 10:21:11AM -0600, Jens Axboe wrote:
>>>>> Wire up TIF_NOTIFY_SIGNAL handling for s390.
>>>>>
>>>>> Cc: linux-s390@vger.kernel.org
>>>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>>>> ---
>>>>>
>>>>> 5.11 has support queued up for TIF_NOTIFY_SIGNAL, see this posting
>>>>> for details:
>>>>>
>>>>> https://lore.kernel.org/io-uring/20201026203230.386348-1-axboe@kernel.dk/
>>>>>
>>>>> As part of that work, I'm adding TIF_NOTIFY_SIGNAL support to all archs,
>>>>> as that will enable a set of cleanups once all of them support it. I'm
>>>>> happy carrying this patch if need be, or it can be funelled through the
>>>>> arch tree. Let me know.
>>>>>
>>>>>  arch/s390/include/asm/thread_info.h | 2 ++
>>>>>  arch/s390/kernel/entry.S            | 7 ++++++-
>>>>>  2 files changed, 8 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
>>>>> index 13a04fcf7762..0045341ade48 100644
>>>>> --- a/arch/s390/include/asm/thread_info.h
>>>>> +++ b/arch/s390/include/asm/thread_info.h
>>>>> @@ -65,6 +65,7 @@ void arch_setup_new_exec(void);
>>>>>  #define TIF_GUARDED_STORAGE	4	/* load guarded storage control block */
>>>>>  #define TIF_PATCH_PENDING	5	/* pending live patching update */
>>>>>  #define TIF_PGSTE		6	/* New mm's will use 4K page tables */
>>>>> +#define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
>>>>>  #define TIF_ISOLATE_BP		8	/* Run process with isolated BP */
>>>>>  #define TIF_ISOLATE_BP_GUEST	9	/* Run KVM guests with isolated BP */
>>>>>  
>>>>> @@ -82,6 +83,7 @@ void arch_setup_new_exec(void);
>>>>>  #define TIF_SYSCALL_TRACEPOINT	27	/* syscall tracepoint instrumentation */
>>>>>  
>>>>>  #define _TIF_NOTIFY_RESUME	BIT(TIF_NOTIFY_RESUME)
>>>>> +#define _TIF_NOTIFY_SIGNAL	BIT(TIF_NOTIFY_SIGNAL)
>>>>>  #define _TIF_SIGPENDING		BIT(TIF_SIGPENDING)
>>>>>  #define _TIF_NEED_RESCHED	BIT(TIF_NEED_RESCHED)
>>>>>  #define _TIF_UPROBE		BIT(TIF_UPROBE)
>>>>> diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
>>>>> index 86235919c2d1..a30d891e8045 100644
>>>>> --- a/arch/s390/kernel/entry.S
>>>>> +++ b/arch/s390/kernel/entry.S
>>>>> @@ -52,7 +52,8 @@ STACK_SIZE  = 1 << STACK_SHIFT
>>>>>  STACK_INIT = STACK_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE
>>>>>  
>>>>>  _TIF_WORK	= (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
>>>>> -		   _TIF_UPROBE | _TIF_GUARDED_STORAGE | _TIF_PATCH_PENDING)
>>>>> +		   _TIF_UPROBE | _TIF_GUARDED_STORAGE | _TIF_PATCH_PENDING | \
>>>>> +		   _TIF_NOTIFY_SIGNAL)
>>>>>  _TIF_TRACE	= (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
>>>>>  		   _TIF_SYSCALL_TRACEPOINT)
>>>>>  _CIF_WORK	= (_CIF_ASCE_PRIMARY | _CIF_ASCE_SECONDARY | _CIF_FPU)
>>>>> @@ -463,6 +464,8 @@ ENTRY(system_call)
>>>>>  #endif
>>>>>  	TSTMSK	__PT_FLAGS(%r11),_PIF_SYSCALL_RESTART
>>>>>  	jo	.Lsysc_syscall_restart
>>>>> +	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_SIGNAL
>>>>> +	jo	.Lsysc_sigpending
>>>>>  	TSTMSK	__TI_flags(%r12),_TIF_SIGPENDING
>>>>>  	jo	.Lsysc_sigpending
>>>>>  	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_RESUME
>>>>> @@ -857,6 +860,8 @@ ENTRY(io_int_handler)
>>>>>  #endif
>>>>>  	TSTMSK	__TI_flags(%r12),_TIF_SIGPENDING
>>>>>  	jo	.Lio_sigpending
>>>>> +	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_SIGNAL
>>>>> +	jo	.Lio_sigpending
>>>>>  	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_RESUME
>>>>>  	jo	.Lio_notify_resume
>>>>>  	TSTMSK	__TI_flags(%r12),_TIF_GUARDED_STORAGE
>>>>
>>>> (full quote so you can make sense of the patch below).
>>>>
>>>> Please merge the patch below into this one. With that:
>>>>
>>>> Acked-by: Heiko Carstens <hca@linux.ibm.com>
>>>>
>>>> diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
>>>> index a30d891e8045..31f16d903ef3 100644
>>>> --- a/arch/s390/kernel/entry.S
>>>> +++ b/arch/s390/kernel/entry.S
>>>> @@ -464,9 +464,7 @@ ENTRY(system_call)
>>>>  #endif
>>>>  	TSTMSK	__PT_FLAGS(%r11),_PIF_SYSCALL_RESTART
>>>>  	jo	.Lsysc_syscall_restart
>>>> -	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_SIGNAL
>>>> -	jo	.Lsysc_sigpending
>>>> -	TSTMSK	__TI_flags(%r12),_TIF_SIGPENDING
>>>> +	TSTMSK	__TI_flags(%r12),(_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)
>>>>  	jo	.Lsysc_sigpending
>>>
>>> We need to also change the jo to jnz - in combination with tm, jo means
>>> 'jump if all tested bits are set' while jnz means 'jump if at least one
>>> bit is set'
>>
>> Ah thanks, good catch. And you also caught the braino in signal.c, here's
>> the end result:
>>
>>
>> commit 0eb7d372d5319970bd15f2dbc18264ea576214d4
>> Author: Jens Axboe <axboe@kernel.dk>
>> Date:   Fri Oct 9 15:34:12 2020 -0600
>>
>>     s390: add support for TIF_NOTIFY_SIGNAL
>>     
>>     Wire up TIF_NOTIFY_SIGNAL handling for s390.
>>     
>>     Cc: linux-s390@vger.kernel.org
>>     Acked-by: Heiko Carstens <hca@linux.ibm.com>
>>     Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
>> index 13a04fcf7762..0045341ade48 100644
>> --- a/arch/s390/include/asm/thread_info.h
>> +++ b/arch/s390/include/asm/thread_info.h
>> @@ -65,6 +65,7 @@ void arch_setup_new_exec(void);
>>  #define TIF_GUARDED_STORAGE	4	/* load guarded storage control block */
>>  #define TIF_PATCH_PENDING	5	/* pending live patching update */
>>  #define TIF_PGSTE		6	/* New mm's will use 4K page tables */
>> +#define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
>>  #define TIF_ISOLATE_BP		8	/* Run process with isolated BP */
>>  #define TIF_ISOLATE_BP_GUEST	9	/* Run KVM guests with isolated BP */
>>  
>> @@ -82,6 +83,7 @@ void arch_setup_new_exec(void);
>>  #define TIF_SYSCALL_TRACEPOINT	27	/* syscall tracepoint instrumentation */
>>  
>>  #define _TIF_NOTIFY_RESUME	BIT(TIF_NOTIFY_RESUME)
>> +#define _TIF_NOTIFY_SIGNAL	BIT(TIF_NOTIFY_SIGNAL)
>>  #define _TIF_SIGPENDING		BIT(TIF_SIGPENDING)
>>  #define _TIF_NEED_RESCHED	BIT(TIF_NEED_RESCHED)
>>  #define _TIF_UPROBE		BIT(TIF_UPROBE)
>> diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
>> index 86235919c2d1..19a89f292290 100644
>> --- a/arch/s390/kernel/entry.S
>> +++ b/arch/s390/kernel/entry.S
>> @@ -52,7 +52,8 @@ STACK_SIZE  = 1 << STACK_SHIFT
>>  STACK_INIT = STACK_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE
>>  
>>  _TIF_WORK	= (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
>> -		   _TIF_UPROBE | _TIF_GUARDED_STORAGE | _TIF_PATCH_PENDING)
>> +		   _TIF_UPROBE | _TIF_GUARDED_STORAGE | _TIF_PATCH_PENDING | \
>> +		   _TIF_NOTIFY_SIGNAL)
>>  _TIF_TRACE	= (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
>>  		   _TIF_SYSCALL_TRACEPOINT)
>>  _CIF_WORK	= (_CIF_ASCE_PRIMARY | _CIF_ASCE_SECONDARY | _CIF_FPU)
>> @@ -463,8 +464,8 @@ ENTRY(system_call)
>>  #endif
>>  	TSTMSK	__PT_FLAGS(%r11),_PIF_SYSCALL_RESTART
>>  	jo	.Lsysc_syscall_restart
>> -	TSTMSK	__TI_flags(%r12),_TIF_SIGPENDING
>> -	jo	.Lsysc_sigpending
>> +	TSTMSK	__TI_flags(%r12),(_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)
>> +	jnz	.Lsysc_sigpending
>>  	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_RESUME
>>  	jo	.Lsysc_notify_resume
>>  	TSTMSK	__LC_CPU_FLAGS,(_CIF_ASCE_PRIMARY|_CIF_ASCE_SECONDARY)
>> @@ -855,8 +856,8 @@ ENTRY(io_int_handler)
>>  	TSTMSK	__TI_flags(%r12),_TIF_PATCH_PENDING
>>  	jo	.Lio_patch_pending
>>  #endif
>> -	TSTMSK	__TI_flags(%r12),_TIF_SIGPENDING
>> -	jo	.Lio_sigpending
>> +	TSTMSK	__TI_flags(%r12),(_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)
>> +	jnz	.Lio_sigpending
>>  	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_RESUME
>>  	jo	.Lio_notify_resume
>>  	TSTMSK	__TI_flags(%r12),_TIF_GUARDED_STORAGE
>> diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
>> index 9e900a8977bd..b27b6c1f058d 100644
>> --- a/arch/s390/kernel/signal.c
>> +++ b/arch/s390/kernel/signal.c
>> @@ -472,7 +472,7 @@ void do_signal(struct pt_regs *regs)
>>  	current->thread.system_call =
>>  		test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
>>  
>> -	if (get_signal(&ksig)) {
>> +	if (test_thread_flag(TIF_SIGPENDING) && get_signal(&ksig)) {
>>  		/* Whee!  Actually deliver the signal.  */
>>  		if (current->thread.system_call) {
>>  			regs->int_code = current->thread.system_call;
> 
> Looks good, feel free to add my Acked-by.

Thanks for your help! Added.

-- 
Jens Axboe