arm64: remove EL0 exception frame record
When entering an exception from EL0, the entry code creates a synthetic frame record with a NULL PC. This was used by the code introduced in commit: 73267498 ("arm64: unwind: reference pt_regs via embedded stack frame") ... to discover exception entries on the stack and dump the associated pt_regs. Since the NULL PC was undesirable for the stacktrace, we added a special case to unwind_frame() to prevent the NULL PC from being logged. Since commit: a25ffd3a ("arm64: traps: Don't print stack or raw PC/LR values in backtraces") ... we no longer try to dump the pt_regs as part of a stacktrace, and hence no longer need the synthetic exception record. This patch removes the synthetic exception record and the associated special case in unwind_frame(). Instead, EL0 exceptions set the FP to NULL, as is the case for other terminal records (e.g. when a kernel thread starts). The synthetic record for exceptions from EL1 is retrained as this has useful unwind information for the interrupted context. To make the terminal case a bit clearer, an explicit check is added to the start of unwind_frame(). This would otherwise be caught implicitly by the on_accessible_stack() checks. Reported-by:Mark Brown <broonie@kernel.org> Signed-off-by:
Mark Rutland <mark.rutland@arm.com> Signed-off-by:
Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20210113173155.43063-1-broonie@kernel.org Signed-off-by:
Will Deacon <will@kernel.org>
parent
19c329f6
Please register or sign in to comment