linux-kernel - Re: [PATCH] xtensa: Increase size of gcc stack frame check

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Date:   Sat, 11 Sep 2021 22:16:51 -0700
From:   Max Filippov <jcmvbkbc@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        "open list:TENSILICA XTENSA PORT (xtensa)" 
        <linux-xtensa@...ux-xtensa.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Chris Zankel <chris@...kel.net>
Subject: Re: [PATCH] xtensa: Increase size of gcc stack frame check

On Sat, Sep 11, 2021 at 9:02 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> On 9/11/21 8:05 PM, Max Filippov wrote:
> > On Sat, Sep 11, 2021 at 7:52 PM Guenter Roeck <linux@...ck-us.net> wrote:
> >>
> >> xtensa frame size is larger than the frame size for almost all other
> >> architectures. This results in more than 50 "the frame size of <n> is
> >> larger than 1024 bytes" errors when trying to build xtensa:allmodconfig.
> >>
> >> Increase frame size for xtensa to 1536 bytes to avoid compile errors
> >> due to frame size limits.
> >>
> >> Cc: Chris Zankel <chris@...kel.net>
> >> Cc: Max Filippov <jcmvbkbc@...il.com>
> >> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> >> ---
> >>   lib/Kconfig.debug | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> >> index ed4a31e34098..afad11e57d6b 100644
> >> --- a/lib/Kconfig.debug
> >> +++ b/lib/Kconfig.debug
> >> @@ -346,7 +346,7 @@ config FRAME_WARN
> >>          int "Warn for stack frames larger than"
> >>          range 0 8192
> >>          default 2048 if GCC_PLUGIN_LATENT_ENTROPY
> >> -       default 1536 if (!64BIT && PARISC)
> >> +       default 1536 if (!64BIT && (PARISC || XTENSA))
> >>          default 1024 if (!64BIT && !PARISC)
> >
> > Shouldn't that line also be changed to
> >    default 1024 if (!64BIT && !(PARISC || XTENSA))
> > ?
>
> I could do that, but I tested it and it looks like the evaluation
> is top-down, so it didn't seem necessary or useful. For example,
> the default value is 2048 for 32-bit systems (such as arm, riscv32,
> or i386) if GCC_PLUGIN_LATENT_ENTROPY is enabled, even though the
> line with the default of 1024 matches as well.

Reviewed-by: Max Filippov <jcmvbkbc@...il.com>

-- 
Thanks.
-- Max