From: Will Deacon <will@kernel.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Jason Wessel <jason.wessel@windriver.com>,
Daniel Thompson <daniel.thompson@linaro.org>,
kgdb-bugreport@lists.sourceforge.net,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Christophe Leroy <christophe.leroy@c-s.fr>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: debug: Make 'btc' and similar work in kdb
Date: Wed, 31 Jul 2019 13:57:33 +0100 [thread overview]
Message-ID: <20190731125733.op3y5j5psuj6pet3@willie-the-truck> (raw)
In-Reply-To: <20190730221800.28326-1-dianders@chromium.org>
Hi Doug,
On Tue, Jul 30, 2019 at 03:18:00PM -0700, Douglas Anderson wrote:
> diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
> index 43119922341f..b666210fbc75 100644
> --- a/arch/arm64/kernel/kgdb.c
> +++ b/arch/arm64/kernel/kgdb.c
> @@ -148,6 +148,45 @@ sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
> gdb_regs[32] = cpu_context->pc;
> }
>
> +void kgdb_call_nmi_hook(void *ignored)
> +{
> + struct pt_regs *regs;
> +
> + /*
> + * NOTE: get_irq_regs() is supposed to get the registers from
> + * before the IPI interrupt happened and so is supposed to
> + * show where the processor was. In some situations it's
> + * possible we might be called without an IPI, so it might be
> + * safer to figure out how to make kgdb_breakpoint() work
> + * properly here.
> + */
> + regs = get_irq_regs();
> +
> + /*
> + * Some commands (like 'btc') assume that they can find info about
> + * a task in the 'cpu_context'. Unfortunately that's only valid
> + * for sleeping tasks. ...but let's make it work anyway by just
> + * writing the registers to the right place. This is safe because
> + * nobody else is using the 'cpu_context' for a running task.
> + */
> + current->thread.cpu_context.x19 = regs->regs[19];
> + current->thread.cpu_context.x20 = regs->regs[20];
> + current->thread.cpu_context.x21 = regs->regs[21];
> + current->thread.cpu_context.x22 = regs->regs[22];
> + current->thread.cpu_context.x23 = regs->regs[23];
> + current->thread.cpu_context.x24 = regs->regs[24];
> + current->thread.cpu_context.x25 = regs->regs[25];
> + current->thread.cpu_context.x26 = regs->regs[26];
> + current->thread.cpu_context.x27 = regs->regs[27];
> + current->thread.cpu_context.x28 = regs->regs[28];
> + current->thread.cpu_context.fp = regs->regs[29];
> +
> + current->thread.cpu_context.sp = regs->sp;
> + current->thread.cpu_context.pc = regs->pc;
> +
> + kgdb_nmicallback(raw_smp_processor_id(), regs);
> +}
This is really gross... :/
Can you IPI the other CPUs instead and have them backtrace locally, like we
do for things like magic sysrq (sysrq_handle_showallcpus())?
Will
next prev parent reply other threads:[~2019-07-31 12:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 22:18 [PATCH] arm64: debug: Make 'btc' and similar work in kdb Douglas Anderson
2019-07-31 12:57 ` Will Deacon [this message]
2019-07-31 18:41 ` Doug Anderson
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