From 4b870f62c5079b48a6a19c852f4db5d2569a5239 Mon Sep 17 00:00:00 2001
From: Ian Rogers <irogers@google.com>
Date: Mon, 26 Jan 2026 14:05:50 -0800
Subject: [PATCH] perf thread-stack: Switch thread_stack__init() to use
 e_machine

The architecture type is used to set the retpoline state.

Rather than use the arch string switch to using the ELF machine that's
readily available within the thread.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shimin Guo <shimin.guo@skydio.com>
Cc: Yujie Liu <yujie.liu@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/thread-stack.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
index c6a0a27b12c2..c5ce741b0744 100644
--- a/tools/perf/util/thread-stack.c
+++ b/tools/perf/util/thread-stack.c
@@ -157,10 +157,10 @@ static int thread_stack__init(struct thread_stack *ts, struct thread *thread,
 
 	if (thread__maps(thread) && maps__machine(thread__maps(thread))) {
 		struct machine *machine = maps__machine(thread__maps(thread));
-		const char *arch = perf_env__arch(machine->env);
+		uint16_t e_machine = thread__e_machine(thread, machine, /*e_flags=*/NULL);
 
 		ts->kernel_start = machine__kernel_start(machine);
-		if (!strcmp(arch, "x86"))
+		if (e_machine == EM_X86_64 || e_machine == EM_386)
 			ts->rstate = X86_RETPOLINE_POSSIBLE;
 	} else {
 		ts->kernel_start = 1ULL << 63;
-- 
2.47.3