linux-kernel - Re: [PATCH v2 04/24] arm64/cpu: Mark cpu_die() _

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230215194538.aiiris3uabnuvkkg@treble>
Date:   Wed, 15 Feb 2023 11:45:38 -0800
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Philippe Mathieu-Daudé <philmd@...aro.org>,
        juri.lelli@...hat.com, dalias@...c.org, linux-ia64@...r.kernel.org,
        linux-sh@...r.kernel.org, peterz@...radead.org,
        catalin.marinas@....com, dave.hansen@...ux.intel.com,
        x86@...nel.org, jiaxun.yang@...goat.com,
        linux-mips@...r.kernel.org, bsegall@...gle.com, jcmvbkbc@...il.com,
        guoren@...nel.org, hpa@...or.com, sparclinux@...r.kernel.org,
        kernel@...0n.name, will@...nel.org, vschneid@...hat.com,
        f.fainelli@...il.com, vincent.guittot@...aro.org,
        ysato@...rs.sourceforge.jp, chenhuacai@...nel.org,
        linux@...linux.org.uk, linux-csky@...r.kernel.org,
        dietmar.eggemann@....com, mingo@...hat.com,
        bcm-kernel-feedback-list@...adcom.com, mgorman@...e.de,
        mattst88@...il.com, linux-xtensa@...ux-xtensa.org,
        paulmck@...nel.org, richard.henderson@...aro.org,
        npiggin@...il.com, ink@...assic.park.msu.ru, rostedt@...dmis.org,
        loongarch@...ts.linux.dev, tglx@...utronix.de,
        linux-arm-kernel@...ts.infradead.org, jgross@...e.com,
        chris@...kel.net, tsbogend@...ha.franken.de, bristot@...hat.com,
        linux-kernel@...r.kernel.org, linux-alpha@...r.kernel.org,
        bp@...en8.de, linuxppc-dev@...ts.ozlabs.org, davem@...emloft.net
Subject: Re: [PATCH v2 04/24] arm64/cpu: Mark cpu_die() __noreturn

On Wed, Feb 15, 2023 at 01:09:21PM +0000, Mark Rutland wrote:
> On Tue, Feb 14, 2023 at 09:13:08AM +0100, Philippe Mathieu-Daudé wrote:
> > On 14/2/23 08:05, Josh Poimboeuf wrote:
> > > cpu_die() doesn't return.  Annotate it as such.  By extension this also
> > > makes arch_cpu_idle_dead() noreturn.
> > > 
> > > Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
> > > ---
> > >   arch/arm64/include/asm/smp.h | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
> > > index fc55f5a57a06..5733a31bab08 100644
> > > --- a/arch/arm64/include/asm/smp.h
> > > +++ b/arch/arm64/include/asm/smp.h
> > > @@ -100,7 +100,7 @@ static inline void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
> > >   extern int __cpu_disable(void);
> > >   extern void __cpu_die(unsigned int cpu);
> > > -extern void cpu_die(void);
> > > +extern void __noreturn cpu_die(void);
> > >   extern void cpu_die_early(void);
> > 
> > Shouldn't cpu_operations::cpu_die() be declared noreturn first?
> 
> The cpu_die() function ends with a BUG(), and so does not return, even if a
> cpu_operations::cpu_die() function that it calls erroneously returned.
> 
> We *could* mark cpu_operations::cpu_die() as noreturn, but I'd prefer that we
> did not so that the compiler doesn't optimize away the BUG() which is there to
> catch such erroneous returns.
> 
> That said, could we please add __noreturn to the implementation of cpu_die() in
> arch/arm64/kernel/smp.c? i.e. the fixup below.

Done.

> With that fixup:
> 
> Acked-by: Mark Rutland <mark.rutland@....com>

Thanks!

-- 
Josh