From 29dc539d74abd1ec4e509fda29bc821f3586d333 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 16 Oct 2025 10:28:48 -0700 Subject: [PATCH] KVM: selftests: Report stacktraces SIGBUS, SIGSEGV, SIGILL, and SIGFPE by default Register handlers for signals for all selftests that are likely happen due to test (or kernel) bugs, and explicitly fail tests on unexpected signals so that users get a stack trace, i.e. don't have to go spelunking to do basic triage. Register the handlers as early as possible, to catch as many unexpected signals as possible, and also so that the common code doesn't clobber a handler that's installed by test (or arch) code. Tested-by: Ackerley Tng Reviewed-by: Ackerley Tng Reviewed-by: Shivank Garg Tested-by: Shivank Garg Link: https://lore.kernel.org/r/20251016172853.52451-8-seanjc@google.com Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/lib/kvm_util.c | 24 ++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index 203e33697492e..5744643d9ec3b 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -2290,11 +2290,35 @@ __weak void kvm_selftest_arch_init(void) { } +static void report_unexpected_signal(int signum) +{ +#define KVM_CASE_SIGNUM(sig) \ + case sig: TEST_FAIL("Unexpected " #sig " (%d)\n", signum) + + switch (signum) { + KVM_CASE_SIGNUM(SIGBUS); + KVM_CASE_SIGNUM(SIGSEGV); + KVM_CASE_SIGNUM(SIGILL); + KVM_CASE_SIGNUM(SIGFPE); + default: + TEST_FAIL("Unexpected signal %d\n", signum); + } +} + void __attribute((constructor)) kvm_selftest_init(void) { + struct sigaction sig_sa = { + .sa_handler = report_unexpected_signal, + }; + /* Tell stdout not to buffer its content. */ setbuf(stdout, NULL); + sigaction(SIGBUS, &sig_sa, NULL); + sigaction(SIGSEGV, &sig_sa, NULL); + sigaction(SIGILL, &sig_sa, NULL); + sigaction(SIGFPE, &sig_sa, NULL); + guest_random_seed = last_guest_seed = random(); pr_info("Random seed: 0x%x\n", guest_random_seed); -- 2.47.3