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

From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Will Deacon <will@kernel.org>, Mark Brown <broonie@kernel.org>,
	kernel-team@android.com,
	Catalin Marinas <catalin.marinas@arm.com>
Subject: [PATCH] arm64: traps: Dump registers prior to panic() in bad_mode()
Date: Mon, 15 Jun 2020 12:34:58 +0100	[thread overview]
Message-ID: <20200615113458.2884-1-will@kernel.org> (raw)

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


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