| Message ID | 20211129142849.3056714-4-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: stacktrace: unify unwind code | expand |
On Mon, Nov 29, 2021 at 02:28:43PM +0000, Mark Rutland wrote: > Unlike most architectures (and only in keeping with powerpc), arm64 has > a non __sched() function on the path to our cpu_switch_to() assembly > function. Reviewed-by: Mark Brown <broonie@kernel.org>
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index aacf2f5559a8..980cad7292af 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -490,7 +490,8 @@ void update_sctlr_el1(u64 sctlr) /* * Thread switching. */ -__notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, +__notrace_funcgraph __sched +struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next) { struct task_struct *last;
Unlike most architectures (and only in keeping with powerpc), arm64 has a non __sched() function on the path to our cpu_switch_to() assembly function. It is expected that for a blocked task, in_sched_functions() can be used to skip all functions between the raw context switch assembly and the scheduler functions that call into __switch_to(). This is the behaviour expected by stack_trace_consume_entry_nosched(), and the behaviour we'd like to have such that we an simplify arm64's __get_wchan() implementation to use arch_stack_walk(). This patch mark's arm64's __switch_to as __sched. This *will not* change the behaviour of arm64's current __get_wchan() implementation, which always performs an initial unwind step which skips __switch_to(). This *will* change the behaviour of stack_trace_consume_entry_nosched() and stack_trace_save_tsk() to match their expected behaviour on blocked tasks, skipping all scheduler-internal functions including __switch_to(). Other than the above, there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> --- arch/arm64/kernel/process.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)