linux-kernel - Re: [PATCH] arm64/debug: Fix registers on sleeping tasks

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Message-ID: <20180305110143.nfffbftqplrba7wu@lakrids.cambridge.arm.com>
Date:   Mon, 5 Mar 2018 11:01:44 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Brian Norris <briannorris@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>, evgreen@...omium.org,
        Ingo Molnar <mingo@...nel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] arm64/debug: Fix registers on sleeping tasks

On Fri, Mar 02, 2018 at 10:45:25AM -0800, Doug Anderson wrote:
> Hi,
> 
> On Fri, Mar 2, 2018 at 10:16 AM, Mark Rutland <mark.rutland@....com> wrote:
> > On Fri, Mar 02, 2018 at 06:01:31PM +0000, Will Deacon wrote:
> >> On Thu, Mar 01, 2018 at 11:38:03AM -0800, Douglas Anderson wrote:

> >> >     /* Initialize to zero */
> >> >     memset((char *)gdb_regs, 0, NUMREGBYTES);
> >> > -   thread_regs = task_pt_regs(task);
> >> > -   memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES);
> >> > -   /* Special case for PSTATE (check comments in asm/kgdb.h for details) */
> >> > -   dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs);
> >> > +
> >> > +   gdb_regs[19] = cpu_context->x19;
> >> > +   gdb_regs[20] = cpu_context->x20;
> >> > +   gdb_regs[21] = cpu_context->x21;
> >> > +   gdb_regs[22] = cpu_context->x22;
> >> > +   gdb_regs[23] = cpu_context->x23;
> >> > +   gdb_regs[24] = cpu_context->x24;
> >> > +   gdb_regs[25] = cpu_context->x25;
> >> > +   gdb_regs[26] = cpu_context->x26;
> >> > +   gdb_regs[27] = cpu_context->x27;
> >> > +   gdb_regs[28] = cpu_context->x28;
> >> > +   gdb_regs[29] = cpu_context->fp;
> >> > +
> >> > +   gdb_regs[31] = cpu_context->sp;
> >> > +   gdb_regs[32] = cpu_context->pc;
> >
> > Are the other reg fields initialised elsewhere?
> >
> > We might want to zero them here.
> 
> Isn't that covered by the the "/* Initialize to zero */" comment and
> and "memset((char *)gdb_regs, 0, NUMREGBYTES);"

I'd misread the patch and thought that was part of the deleted lines.

That looks fine, then.

Mark.