Re: [PATCH v10 02/11] arm64: Make perf_callchain_kernel() use arch_stack_walk()

On Thu, Oct 14, 2021 at 09:58:38PM -0500, madvenka@linux.microsoft.com wrote:

From: "Madhavan T. Venkataraman" <redacted>

Currently, perf_callchain_kernel() in ARM64 code walks the stack using
start_backtrace() and walk_stackframe(). Make it use arch_stack_walk()
instead. This makes maintenance easier.

 static bool callchain_trace(void *data, unsigned long pc)
 {
 	struct perf_callchain_entry_ctx *entry = data;
-	perf_callchain_store(entry, pc);
-	return true;
+	return perf_callchain_store(entry, pc) == 0;
 }

This changes us from unconditionally doing the whole walk to returning
an error if perf_callchain_store() returns an error so it's not quite a
straight transform, though since that seems like a useful improvement
which most likely  on't have any practical impact that's fine.

Reviewed-by: Mark Brown <broonie@kernel.org>