[PATCH] arm64: traps: Dump registers prior to panic() in bad_mode()

[PATCH] arm64: traps: Dump registers prior to panic() in bad_mode()

[Will Deacon]

When panicing due to an unknown/unhandled exception at EL1, dump the
registers of the faulting context so that it's easier to figure out
what went wrong. In particular, this makes it a lot easier to debug
in-kernel BTI failures since it pretty-prints PSTATE.BTYPE in the crash
log.

Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kernel/traps.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 50cc30acf106..f1869e5bd743 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -812,6 +812,8 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
 	pr_crit("Bad mode in %s handler detected on CPU%d, code 0x%08x -- %s\n",
 		handler[reason], smp_processor_id(), esr,
 		esr_get_class_string(esr));
+	if (regs)
+		__show_regs(regs);
 
 	local_daif_mask();
 	panic("bad mode");
-- 
2.27.0.290.gba653c62da-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] arm64: traps: Dump registers prior to panic() in bad_mode()

[Mark Rutland]

On Mon, Jun 15, 2020 at 12:34:58PM +0100, Will Deacon wrote:
> When panicing due to an unknown/unhandled exception at EL1, dump the
> registers of the faulting context so that it's easier to figure out
> what went wrong. In particular, this makes it a lot easier to debug
> in-kernel BTI failures since it pretty-prints PSTATE.BTYPE in the crash
> log.
> 
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  arch/arm64/kernel/traps.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 50cc30acf106..f1869e5bd743 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -812,6 +812,8 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
>  	pr_crit("Bad mode in %s handler detected on CPU%d, code 0x%08x -- %s\n",
>  		handler[reason], smp_processor_id(), esr,
>  		esr_get_class_string(esr));
> +	if (regs)
> +		__show_regs(regs);

For bad_mode() regs is never NULL, so you don't need to check that here.

Otherwise, this looks sane to me, so with the redundant check removed:

Acked-by: Mark Rutland <mark.rutland@arm.con>

Mark.

>  
>  	local_daif_mask();
>  	panic("bad mode");
> -- 
> 2.27.0.290.gba653c62da-goog
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel