linux-kernel - Re: [PATCH] [ARM] Fix stack alignment when processing backtraces

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Message-ID: <20161031162631.GB28817@obsidianresearch.com>
Date:   Mon, 31 Oct 2016 10:26:31 -0600
From:   Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [ARM] Fix stack alignment when processing backtraces

On Mon, Oct 31, 2016 at 08:51:26AM +0000, Russell King - ARM Linux wrote:

> > -.Ldumpstm:	stmfd	sp!, {instr, reg, stack, r7, lr}
> > +	        /* Must maintain 8 byte stack alignment */
> > +.Ldumpstm:	stmfd	sp!, {r3, instr, reg, stack, r7, lr}
> >  		mov	stack, r0
> >  		mov	instr, r1
> >  		mov	reg, #10
> > @@ -140,7 +141,7 @@ ENDPROC(c_backtrace)
> >  		teq	r7, #0
> >  		adrne	r0, .Lcr
> >  		blne	printk
> > -		ldmfd	sp!, {instr, reg, stack, r7, pc}
> > +		ldmfd	sp!, {r3, instr, reg, stack, r7, pc}
> 
> I'd prefer r8 to get used rather than r3, as it makes it look like
> r3 is somehow required to be preserved when that's not the case.
> Makes the code slightly more difficult to understand.

Sure, I will change that and send it to your tracker.

Thanks,
Jason