From: Mark Rutland <mark.rutland@arm.com>
To: Miroslav Benes <mbenes@suse.cz>, Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Vasily Gorbik <gor@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Ingo Molnar <mingo@kernel.org>, Jiri Slaby <jirislaby@kernel.org>,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/3] arm64: stacktrace: Convert to ARCH_STACKWALK
Date: Wed, 2 Sep 2020 19:50:27 +0100 [thread overview]
Message-ID: <20200902184935.GA5875@C02TD0UTHF1T.local> (raw)
In-Reply-To: <alpine.LSU.2.21.2009021128500.23200@pobox.suse.cz>
On Wed, Sep 02, 2020 at 11:32:13AM +0200, Miroslav Benes wrote:
> Hi,
>
> it could be a silly question, but better to ask...
>
> > + if (regs)
> > + start_backtrace(&frame, regs->regs[29], regs->pc);
> > + else
> > + start_backtrace(&frame, thread_saved_fp(task),
> > + thread_saved_pc(task));
>
> Would this also work for task == current? Given that the original code had
>
> > - start_backtrace(&frame,
> > - (unsigned long)__builtin_frame_address(0),
> > - (unsigned long)__save_stack_trace);
Oh whoops; I'm annoyed I didn't spot that.
With that gone this cannot work for (task == current && regs == NULL), as
we'll erroneously use stale values from the task struct.
It looks like the LKDTM tests only trigger cases with non-NULL regs, but
IIUC this should show up with show_stack(NULL, NULL, KERN_INFO), as
drivers/tty/sysrq.c does for other cpus.
Thanks,
Mark.
next prev parent reply other threads:[~2020-09-02 18:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-19 12:49 [PATCH v2 0/3] arm64: Convert to ARCH_STACKWALK Mark Brown
2020-08-19 12:49 ` [PATCH v2 1/3] stacktrace: Remove reliable argument from arch_stack_walk() callback Mark Brown
2020-09-02 9:26 ` Miroslav Benes
2020-08-19 12:49 ` [PATCH v2 2/3] arm64: stacktrace: Make stack walk callback consistent with generic code Mark Brown
2020-09-02 9:26 ` Miroslav Benes
2020-08-19 12:49 ` [PATCH v2 3/3] arm64: stacktrace: Convert to ARCH_STACKWALK Mark Brown
2020-09-02 9:32 ` Miroslav Benes
2020-09-02 18:50 ` Mark Rutland [this message]
2020-09-10 17:34 ` Mark Brown
2020-09-01 16:06 ` [PATCH v2 0/3] arm64: " Mark Rutland
2020-09-02 17:38 ` Mark Brown
2020-09-02 19:03 ` Mark Rutland
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