On Tue, 17 Aug 2021 08:57:19 +0530
[off-list ref] wrote:

+#define oops_print(...) rte_log(RTE_LOG_ERR, RTE_LOGTYPE_EAL, __VA_ARGS__)

It is problematic to call rte_log from a signal handler.
The malloc pool maybe corrupted and rte_log can call functions that
use malloc.

Even rte_dump_stack() is unsafe from these signals.

+
+static int oops_signals[] = {SIGSEGV, SIGBUS, SIGILL, SIGABRT, SIGFPE, SIGSYS};

Should be constant.

+
+struct oops_signal {
+	int sig;

Redundant, you defined the oops_signals above.

+	bool enabled;

Redundant, you can just compare with action.

+	struct sigaction sa;
+};
+
+static struct oops_signal signals_db[RTE_DIM(oops_signals)];
+
+static void
+back_trace_dump(ucontext_t *context)
+{
+	RTE_SET_USED(context);
+
+	rte_dump_stack();
+}

rte_dump_stack() is not safe in signal handler:

Recommend backtrace_symbols_fd ??

Better yet use libunwind

+static void
+siginfo_dump(int sig, siginfo_t *info)
+{
+	oops_print("PID:           %" PRIdMAX "\n", (intmax_t)getpid());
+
+	if (info == NULL)
+		return;
+	if (sig != info->si_signo)
+		oops_print("Invalid signal info\n");
+
+	oops_print("Signal number: %d\n", info->si_signo);
+	oops_print("Fault address: %p\n", info->si_addr);
+}
+
+static void
+mem32_dump(void *ptr)

Should be const

+{
+	uint32_t *p = ptr;
+	int i;
+
+	for (i = 0; i < 16; i++)
+		oops_print("%p: 0x%x\n", p + i, rte_be_to_cpu_32(p[i]));
+}

Why reinvent hexdump?

+
+static void
+stack_dump_header(void)
+{
+	oops_print("Stack dump:\n");
+	oops_print("----------\n");
+}
+
+static void
+code_dump_header(void)
+{
+	oops_print("Code dump:\n");
+	oops_print("----------\n");
+}
+
+static void
+stack_code_dump(void *stack, void *code)
+{
+	if (stack == NULL || code == NULL)
+		return;
+
+	oops_print("\n");
+	stack_dump_header();
+	mem32_dump(stack);
+	oops_print("\n");
+
+	code_dump_header();
+	mem32_dump(code);
+	oops_print("\n");
+}
+static void
+archinfo_dump(ucontext_t *uc)
 {
-	RTE_SET_USED(sig);
-	RTE_SET_USED(info);
 	RTE_SET_USED(uc);
 
+	stack_code_dump(NULL, NULL);
+}
+
+static void
+default_signal_handler_invoke(int sig)
+{
+	unsigned int idx;
+
+	for (idx = 0; idx < RTE_DIM(oops_signals); idx++) {
+		/* Skip disabled signals */
+		if (signals_db[idx].sig != sig)
+			continue;
+		if (!signals_db[idx].enabled)
+			continue;
+		/* Replace with stored handler */
+		sigaction(sig, &signals_db[idx].sa, NULL);
+		kill(getpid(), sig);

If you use SA_RESETHAND, you don't need this stuff.

+	}
+}
+
+void
+rte_oops_decode(int sig, siginfo_t *info, ucontext_t *uc)
+{
+	oops_print("Signal info:\n");
+	oops_print("------------\n");
+	siginfo_dump(sig, info);
+	oops_print("\n");
+
+	oops_print("Backtrace:\n");
+	oops_print("----------\n");
+	back_trace_dump(uc);
+	oops_print("\n");
+
+	oops_print("Arch info:\n");
+	oops_print("----------\n");
+	if (uc)
+		archinfo_dump(uc);
+}
+
+static void
+eal_oops_handler(int sig, siginfo_t *info, void *ctx)
+{
+	ucontext_t *uc = ctx;
+
+	rte_oops_decode(sig, info, uc);
+	default_signal_handler_invoke(sig);

If you use SA_RESETHAND, then just doing raise(sig) here.

 }
 
 int
 rte_oops_signals_enabled(int *signals)

Why is this necessary and exported?

 {
-	RTE_SET_USED(signals);
+	int count = 0, sig[RTE_OOPS_SIGNALS_MAX];
+	unsigned int idx = 0;
 
-	return 0;
+	for (idx = 0; idx < RTE_DIM(oops_signals); idx++) {
+		if (signals_db[idx].enabled) {
+			sig[count] = signals_db[idx].sig;
+			count++;
+		}
+	}
+	if (signals)
+		memcpy(signals, sig, sizeof(*signals) * count);
+
+	return count;
 }
 
 int
 eal_oops_init(void)
 {
-	return 0;
+	unsigned int idx, rc = 0;
+	struct sigaction sa;
+
+	RTE_BUILD_BUG_ON(RTE_DIM(oops_signals) > RTE_OOPS_SIGNALS_MAX);
+
+	sigemptyset(&sa.sa_mask);
+	sa.sa_sigaction = &eal_oops_handler;
+	sa.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK;
+
+	for (idx = 0; idx < RTE_DIM(oops_signals); idx++) {
+		signals_db[idx].sig = oops_signals[idx];
+		/* Get exiting sigaction */
+		rc = sigaction(signals_db[idx].sig, NULL, &signals_db[idx].sa);
+		if (rc)
+			continue;
+		/* Replace with oops handler */
+		rc = sigaction(signals_db[idx].sig, &sa, NULL);
+		if (rc)
+			continue;
+		signals_db[idx].enabled = true;
+	}
+	return rc;
 }
 
 void
 eal_oops_fini(void)
 {
+	unsigned int idx;
+
+	for (idx = 0; idx < RTE_DIM(oops_signals); idx++) {
+		if (!signals_db[idx].enabled)
+			continue;
+		/* Replace with stored handler */
+		sigaction(signals_db[idx].sig, &signals_db[idx].sa, NULL);
+	}
 }