From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave.Martin@arm.com (Dave Martin) Date: Thu, 11 Jun 2015 16:29:24 +0100 Subject: [PATCH 10/10] arm64/BUG: Show explicit backtrace for WARNs In-Reply-To: <1434036566-9848-1-git-send-email-Dave.Martin@arm.com> References: <1434036566-9848-1-git-send-email-Dave.Martin@arm.com> Message-ID: <1434036566-9848-11-git-send-email-Dave.Martin@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The generic slowpath WARN implementation prints a backtrace, but the report_bug() based implementation does not, opting to print the registers instead which is generally not as useful. Ideally, report_bug() should be fixed to make the behaviour more consistent, but in the meantime this patch generates a backtrace directly from the arm64 backend instead so that this functionality is not lost with the migration to report_bug(). As a side-effect, the backtrace will be outside the oops end marker, but that's hard to avoid without modifying generic code. This patch can go away if report_bug() grows the ability in the future to generate a backtrace directly or call an arch hook at the appropriate time. Signed-off-by: Dave Martin --- arch/arm64/kernel/traps.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 5fdf776..8929c16 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -489,6 +489,9 @@ static int bug_handler(struct pt_regs *regs, unsigned int esr) /* die() does not return */ case BUG_TRAP_TYPE_WARN: + /* Ideally, report_bug() should backtrace for us... but no. */ + dump_backtrace(regs, NULL); + regs->pc += AARCH64_INSN_SIZE; /* skip BRK and resume */ return DBG_HOOK_HANDLED; -- 1.7.10.4