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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Zhouyi Zhou <zhouzhouyi@gmail.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v2] powerpc: Fix irq_soft_mask_set() and irq_soft_mask_return() with sanitizer
Date: Thu, 1 Sep 2022 12:48:58 -0500	[thread overview]
Message-ID: <20220901174858.GG25951@gate.crashing.org> (raw)
In-Reply-To: <24253442-9878-c5ed-cbaa-05a5c4851a6e@csgroup.eu>

On Thu, Sep 01, 2022 at 07:47:10AM +0000, Christophe Leroy wrote:
> Le 01/09/2022 à 09:37, Gabriel Paubert a écrit :
> > Agree, but there is one thing which escapes me: why is r3 listed in the
> > outputs section (actually as a read write operand with the "+"
> > constraint modifier) but is not used after the asm which is the last
> > statement of function returning void?
> > 
> > Do I miss something?
> 
> As far as I remember, that's to tell GCC that r3 register is modified by 
> the callee. As it is an input, it couldn't be listed in the clobber list.

Inputs can be clobbered just fine, in general.  But here the operand
is tied to a register variable, and that causes the error ("'asm'
specifier for variable 'r3' conflicts with 'asm' clobber list").

Marking it in/out here is more appropriate anyway :-)


Segher

WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Gabriel Paubert <paubert@iram.es>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Zhouyi Zhou <zhouzhouyi@gmail.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH v2] powerpc: Fix irq_soft_mask_set() and irq_soft_mask_return() with sanitizer
Date: Thu, 1 Sep 2022 12:48:58 -0500	[thread overview]
Message-ID: <20220901174858.GG25951@gate.crashing.org> (raw)
In-Reply-To: <24253442-9878-c5ed-cbaa-05a5c4851a6e@csgroup.eu>

On Thu, Sep 01, 2022 at 07:47:10AM +0000, Christophe Leroy wrote:
> Le 01/09/2022 à 09:37, Gabriel Paubert a écrit :
> > Agree, but there is one thing which escapes me: why is r3 listed in the
> > outputs section (actually as a read write operand with the "+"
> > constraint modifier) but is not used after the asm which is the last
> > statement of function returning void?
> > 
> > Do I miss something?
> 
> As far as I remember, that's to tell GCC that r3 register is modified by 
> the callee. As it is an input, it couldn't be listed in the clobber list.

Inputs can be clobbered just fine, in general.  But here the operand
is tied to a register variable, and that causes the error ("'asm'
specifier for variable 'r3' conflicts with 'asm' clobber list").

Marking it in/out here is more appropriate anyway :-)


Segher

  reply	other threads:[~2022-09-01 17:54 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-23 16:39 [PATCH v2] powerpc: Fix irq_soft_mask_set() and irq_soft_mask_return() with sanitizer Christophe Leroy
2022-08-23 16:39 ` Christophe Leroy
2022-08-30  5:15 ` Nicholas Piggin
2022-08-30  5:15   ` Nicholas Piggin
2022-08-30  5:24   ` Christophe Leroy
2022-08-30  5:24     ` Christophe Leroy
2022-08-30  9:01     ` Nicholas Piggin
2022-08-30  9:01       ` Nicholas Piggin
2022-08-30  9:10       ` Christophe Leroy
2022-08-30  9:10         ` Christophe Leroy
2022-08-31 22:45         ` Segher Boessenkool
2022-08-31 22:45           ` Segher Boessenkool
2022-09-01  5:22           ` Christophe Leroy
2022-09-01  5:22             ` Christophe Leroy
2022-09-01  7:37             ` Gabriel Paubert
2022-09-01  7:37               ` Gabriel Paubert
2022-09-01  7:47               ` Christophe Leroy
2022-09-01  7:47                 ` Christophe Leroy
2022-09-01 17:48                 ` Segher Boessenkool [this message]
2022-09-01 17:48                   ` Segher Boessenkool
2022-09-01 18:07               ` Segher Boessenkool
2022-09-01 18:07                 ` Segher Boessenkool
2022-09-02 15:57           ` Peter Bergner
2022-09-02 15:57             ` Peter Bergner
2022-09-02 17:10             ` Segher Boessenkool
2022-09-02 17:10               ` Segher Boessenkool

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