linux-kernel - Re: [PATCH] mips: lib: uncached: fix uninitialized variable 'sp'

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Message-ID: <CAKwvOdkbPCaJO8c+Zj_BSwfkwcVuMQSFhnxj6PXGo5i86NQ_Zg@mail.gmail.com>
Date:   Mon, 30 Nov 2020 12:22:07 -0800
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Anders Roxell <anders.roxell@...aro.org>
Cc:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Nathan Chancellor <natechancellor@...il.com>,
        linux-mips@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] mips: lib: uncached: fix uninitialized variable 'sp'

On Fri, Nov 27, 2020 at 12:39 AM Anders Roxell <anders.roxell@...aro.org> wrote:
>
> When building mips tinyconfig with clang the following warning show up:
>
> /tmp/arch/mips/lib/uncached.c:40:18: note: initialize the variable 'sp' to silence this warning
>         register long sp __asm__("$sp");
>                         ^
>                          = 0

Hi Anders, thank you for sending the patch. Do you have the full text
of the warning; it looks like only the note was included?

>
> Rework to make an explicit inline move.
>
> Signed-off-by: Anders Roxell <anders.roxell@...aro.org>
> ---
>  arch/mips/lib/uncached.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/mips/lib/uncached.c b/arch/mips/lib/uncached.c
> index 09d5deea747f..21a4b94a0558 100644
> --- a/arch/mips/lib/uncached.c
> +++ b/arch/mips/lib/uncached.c
> @@ -37,10 +37,11 @@
>   */
>  unsigned long run_uncached(void *func)
>  {
> -       register long sp __asm__("$sp");
>         register long ret __asm__("$2");
>         long lfunc = (long)func, ufunc;
>         long usp;
> +       long sp;
> +       asm ("move %0, $sp" : "=r" (sp));
>
>         if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)
>                 usp = CKSEG1ADDR(sp);
> --
> 2.29.2
>


--
Thanks,
~Nick Desaulniers