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>
---
 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..dac76d03f741 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);
 
 		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;
-- 
2.52.0.457.g6b5491de43-goog