linux-kernel - Re: [PATCH] arc: remove #ifndef CONFIG_AS_CFI_SIGNAL

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Date:   Mon, 13 Apr 2020 05:38:27 +0000
From:   Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:     Masahiro Yamada <masahiroy@...nel.org>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>
CC:     Kate Stewart <kstewart@...uxfoundation.org>,
        Kees Cook <keescook@...omium.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@...el.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Allison Randal <allison@...utok.net>
Subject: Re: [PATCH] arc: remove #ifndef CONFIG_AS_CFI_SIGNAL_FRAME

On 4/12/20 7:05 PM, Masahiro Yamada wrote:
> CONFIG_AS_CFI_SIGNAL_FRAME is never defined for ARC.
> 
> Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>

Where, how ?

> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
> 
>  arch/arc/kernel/unwind.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
> index 27ea64b1fa33..f87758a6851b 100644
> --- a/arch/arc/kernel/unwind.c
> +++ b/arch/arc/kernel/unwind.c
> @@ -1178,11 +1178,9 @@ int arc_unwind(struct unwind_frame_info *frame)
>  #endif
>  
>  	/* update frame */
> -#ifndef CONFIG_AS_CFI_SIGNAL_FRAME
>  	if (frame->call_frame
>  	    && !UNW_DEFAULT_RA(state.regs[retAddrReg], state.dataAlign))
>  		frame->call_frame = 0;
> -#endif
>  	cfa = FRAME_REG(state.cfa.reg, unsigned long) + state.cfa.offs;
>  	startLoc = min_t(unsigned long, UNW_SP(frame), cfa);
>  	endLoc = max_t(unsigned long, UNW_SP(frame), cfa);

Actually there's more scope for cleanup here. The while signal frame stuff is not
relevant here at all as this is only kernel stack frames. So all of
frame->call_frame stuff is bogus at best.

I once had an branch with ~15 patches to clean this all up. Let me go find it.

Curious though about the CC list, is this patch part of a bigger series or some
such. So many people from all over suddenly interested in ARC ;-)

-Vineet