[PATCH 10/10] arm64/BUG: Show explicit backtrace for WARNs
will.deacon at arm.com
Tue Jun 16 07:49:44 PDT 2015
On Thu, Jun 11, 2015 at 04:29:24PM +0100, Dave P Martin wrote:
> 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.
Could you propose a patch to the core code, please? I'm happy to merge this
in the interim, but it sounds like a simple oversight.
> Signed-off-by: Dave Martin <Dave.Martin at arm.com>
> 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;
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