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Date: Tue, 24 May 2016 01:08:39 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, Scott Wood <oss@buserror.net>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc: inline current_stack_pointer()
Message-ID: <20160524060839.GA6492@gate.crashing.org>
References: <20160523084602.53F771A239A@localhost.localdomain> <20160523202214.GB11583@gate.crashing.org> <61305e9e-ed63-6915-709c-dd8797ff1fba@c-s.fr>
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On Tue, May 24, 2016 at 07:39:59AM +0200, Christophe Leroy wrote:
> >>+static inline unsigned long current_stack_pointer(void)
> >>+{
> >>+	register unsigned long *ptr asm("r1");
> >>+
> >>+	return *ptr;
> >>+}
> >Register asm is only guaranteed to work as input to inline asm.  NAK.
> >
> Does it mean that the following declaration in 
> arch/powerpc/include/asm/paca.h is wrong too ?
> 
> register struct paca_struct *local_paca asm("r13");

That one is fine, because it is a global var.

https://gcc.gnu.org/onlinedocs/gcc/Explicit-Register-Variables.html


Segher