linux-kernel - Re: [PATCH] s390: add support for TIF_NOTIFY

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Date:   Tue, 03 Nov 2020 12:00:06 +0100
From:   Sven Schnelle <svens@...ux.ibm.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-s390@...r.kernel.org, Heiko Carstens <hca@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        oleg@...hat.com, tglx@...utronix.de,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux-Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: [PATCH] s390: add support for TIF_NOTIFY_SIGNAL

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@...r.kernel.org
>> Signed-off-by: Jens Axboe <axboe@...nel.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@...ux.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'

>  	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_RESUME
>  	jo	.Lsysc_notify_resume
> @@ -858,9 +856,7 @@ 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_NOTIFY_SIGNAL
> +	TSTMSK	__TI_flags(%r12),(_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)

Same here.

>  	jo	.Lio_sigpending
>  	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_RESUME
>  	jo	.Lio_notify_resume

PS: I didn't get the previous emails, so i replied to a raw download
from marc.info. Not sure whether Threading will work out.