ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 311 insertions, 0 deletions

diff --git a/tools/perf/util/kvm-stat.c b/tools/perf/util/kvm-stat.c
new file mode 100644
index 000000000..c571d2ed7
--- /dev/null
+++ b/tools/perf/util/kvm-stat.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "debug.h"
+#include "env.h"
+#include "evsel.h"
+#include "kvm-stat.h"
+#include <dwarf-regs.h>
+#include <subcmd/parse-options.h>
+
+bool kvm_exit_event(struct evsel *evsel)
+{
+	uint16_t e_machine = evsel__e_machine(evsel, /*e_flags=*/NULL);
+
+	return evsel__name_is(evsel, kvm_exit_trace(e_machine));
+}
+
+void exit_event_get_key(struct perf_sample *sample,
+			struct event_key *key)
+{
+	uint16_t e_machine = evsel__e_machine(sample->evsel, /*e_flags=*/NULL);
+
+	key->info = 0;
+	key->key  = perf_sample__intval(sample, kvm_exit_reason(e_machine));
+}
+
+
+bool exit_event_begin(struct perf_sample *sample, struct event_key *key)
+{
+	if (kvm_exit_event(sample->evsel)) {
+		exit_event_get_key(sample, key);
+		return true;
+	}
+
+	return false;
+}
+
+bool kvm_entry_event(struct evsel *evsel)
+{
+	uint16_t e_machine = evsel__e_machine(evsel, /*e_flags=*/NULL);
+
+	return evsel__name_is(evsel, kvm_entry_trace(e_machine));
+}
+
+bool exit_event_end(struct perf_sample *sample,
+		    struct event_key *key __maybe_unused)
+{
+	return kvm_entry_event(sample->evsel);
+}
+
+static const char *get_exit_reason(struct perf_kvm_stat *kvm,
+				   struct exit_reasons_table *tbl,
+				   u64 exit_code)
+{
+	while (tbl->reason != NULL) {
+		if (tbl->exit_code == exit_code)
+			return tbl->reason;
+		tbl++;
+	}
+
+	pr_err("unknown kvm exit code:%lld on %s\n",
+		(unsigned long long)exit_code, kvm->exit_reasons_isa);
+	return "UNKNOWN";
+}
+
+void exit_event_decode_key(struct perf_kvm_stat *kvm,
+			   struct event_key *key,
+			   char *decode)
+{
+	const char *exit_reason = get_exit_reason(kvm, key->exit_reasons,
+						  key->key);
+
+	scnprintf(decode, KVM_EVENT_NAME_LEN, "%s", exit_reason);
+}
+
+int setup_kvm_events_tp(struct perf_kvm_stat *kvm, uint16_t e_machine)
+{
+	switch (e_machine) {
+	case EM_PPC:
+	case EM_PPC64:
+		return __setup_kvm_events_tp_powerpc(kvm);
+	default:
+		return 0;
+	}
+}
+
+int cpu_isa_init(struct perf_kvm_stat *kvm, uint16_t e_machine, const char *cpuid)
+{
+	switch (e_machine) {
+	case EM_AARCH64:
+		return __cpu_isa_init_arm64(kvm);
+	case EM_LOONGARCH:
+		return __cpu_isa_init_loongarch(kvm);
+	case EM_PPC:
+	case EM_PPC64:
+		return __cpu_isa_init_powerpc(kvm);
+	case EM_RISCV:
+		return __cpu_isa_init_riscv(kvm);
+	case EM_S390:
+		return __cpu_isa_init_s390(kvm, cpuid);
+	case EM_X86_64:
+	case EM_386:
+		return __cpu_isa_init_x86(kvm, cpuid);
+	default:
+		pr_err("Unsupported kvm-stat host %d\n", e_machine);
+		return -1;
+	}
+}
+
+const char *vcpu_id_str(uint16_t e_machine)
+{
+	switch (e_machine) {
+	case EM_AARCH64:
+	case EM_RISCV:
+	case EM_S390:
+		return "id";
+	case EM_LOONGARCH:
+	case EM_PPC:
+	case EM_PPC64:
+	case EM_X86_64:
+	case EM_386:
+		return "vcpu_id";
+	default:
+		pr_err("Unsupported kvm-stat host %d\n", e_machine);
+		return NULL;
+	}
+}
+
+const char *kvm_exit_reason(uint16_t e_machine)
+{
+	switch (e_machine) {
+	case EM_AARCH64:
+		return "ret";
+	case EM_LOONGARCH:
+		return "reason";
+	case EM_PPC:
+	case EM_PPC64:
+		return "trap";
+	case EM_RISCV:
+		return "scause";
+	case EM_S390:
+		return "icptcode";
+	case EM_X86_64:
+	case EM_386:
+		return "exit_reason";
+	default:
+		pr_err("Unsupported kvm-stat host %d\n", e_machine);
+		return NULL;
+	}
+}
+
+const char *kvm_entry_trace(uint16_t e_machine)
+{
+	switch (e_machine) {
+	case EM_AARCH64:
+	case EM_RISCV:
+	case EM_X86_64:
+	case EM_386:
+		return "kvm:kvm_entry";
+	case EM_LOONGARCH:
+		return "kvm:kvm_enter";
+	case EM_PPC:
+	case EM_PPC64:
+		return "kvm_hv:kvm_guest_enter";
+	case EM_S390:
+		return "kvm:kvm_s390_sie_enter";
+	default:
+		pr_err("Unsupported kvm-stat host %d\n", e_machine);
+		return NULL;
+	}
+}
+
+const char *kvm_exit_trace(uint16_t e_machine)
+{
+	switch (e_machine) {
+	case EM_AARCH64:
+	case EM_LOONGARCH:
+	case EM_RISCV:
+	case EM_X86_64:
+	case EM_386:
+		return "kvm:kvm_exit";
+	case EM_PPC:
+	case EM_PPC64:
+		return "kvm_hv:kvm_guest_exit";
+	case EM_S390:
+		return "kvm:kvm_s390_sie_exit";
+	default:
+		pr_err("Unsupported kvm-stat host %d\n", e_machine);
+		return NULL;
+	}
+}
+
+const char * const *kvm_events_tp(uint16_t e_machine)
+{
+	switch (e_machine) {
+	case EM_AARCH64:
+		return __kvm_events_tp_arm64();
+	case EM_LOONGARCH:
+		return __kvm_events_tp_loongarch();
+	case EM_PPC:
+	case EM_PPC64:
+		return __kvm_events_tp_powerpc();
+	case EM_RISCV:
+		return __kvm_events_tp_riscv();
+	case EM_S390:
+		return __kvm_events_tp_s390();
+	case EM_X86_64:
+	case EM_386:
+		return __kvm_events_tp_x86();
+	default:
+		pr_err("Unsupported kvm-stat host %d\n", e_machine);
+		return NULL;
+	}
+}
+
+const struct kvm_reg_events_ops *kvm_reg_events_ops(uint16_t e_machine)
+{
+	switch (e_machine) {
+	case EM_AARCH64:
+		return __kvm_reg_events_ops_arm64();
+	case EM_LOONGARCH:
+		return __kvm_reg_events_ops_loongarch();
+	case EM_PPC:
+	case EM_PPC64:
+		return __kvm_reg_events_ops_powerpc();
+	case EM_RISCV:
+		return __kvm_reg_events_ops_riscv();
+	case EM_S390:
+		return __kvm_reg_events_ops_s390();
+	case EM_X86_64:
+	case EM_386:
+		return __kvm_reg_events_ops_x86();
+	default:
+		pr_err("Unsupported kvm-stat host %d\n", e_machine);
+		return NULL;
+	}
+}
+
+const char * const *kvm_skip_events(uint16_t e_machine)
+{
+	switch (e_machine) {
+	case EM_AARCH64:
+		return __kvm_skip_events_arm64();
+	case EM_LOONGARCH:
+		return __kvm_skip_events_loongarch();
+	case EM_PPC:
+	case EM_PPC64:
+		return __kvm_skip_events_powerpc();
+	case EM_RISCV:
+		return __kvm_skip_events_riscv();
+	case EM_S390:
+		return __kvm_skip_events_s390();
+	case EM_X86_64:
+	case EM_386:
+		return __kvm_skip_events_x86();
+	default:
+		pr_err("Unsupported kvm-stat host %d\n", e_machine);
+		return NULL;
+	}
+}
+
+int kvm_add_default_arch_event(uint16_t e_machine, int *argc, const char **argv)
+{
+	switch (e_machine) {
+	case EM_PPC:
+	case EM_PPC64:
+		return __kvm_add_default_arch_event_powerpc(argc, argv);
+	case EM_X86_64:
+	case EM_386:
+		return __kvm_add_default_arch_event_x86(argc, argv);
+	default:
+		return 0;
+	}
+}
+
+bool kvm_need_default_arch_event(uint16_t e_machine, int argc, const char **argv)
+{
+	const char **tmp_argv;
+	bool event = false;
+	int i;
+
+	const struct option event_options[] = {
+		OPT_BOOLEAN('e', "event", &event, NULL),
+		OPT_BOOLEAN(0, "pfm-events", &event, NULL),
+		OPT_END()
+	};
+
+	switch (e_machine) {
+	case EM_PPC:
+	case EM_PPC64:
+		break;
+	case EM_X86_64:
+	case EM_386:
+		if (!x86__is_intel_cpu())
+			return false;
+		break;
+	default:
+		return false;
+	}
+
+	/* parse_options() may change the argv, let's make a copy */
+	tmp_argv = calloc(argc + 1, sizeof(char *));
+	if (!tmp_argv)
+		return false;
+
+	for (i = 0; i < argc; i++)
+		tmp_argv[i] = argv[i];
+
+	parse_options(argc, tmp_argv, event_options, NULL, PARSE_OPT_KEEP_UNKNOWN);
+	free(tmp_argv);
+
+	return !event;
+}