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, 229 insertions, 0 deletions

diff --git a/tools/perf/util/branch.c b/tools/perf/util/branch.c
new file mode 100644
index 000000000..3712be067
--- /dev/null
+++ b/tools/perf/util/branch.c
@@ -0,0 +1,229 @@
+#include "util/map_symbol.h"
+#include "util/branch.h"
+#include <linux/kernel.h>
+
+static bool cross_area(u64 addr1, u64 addr2, int size)
+{
+	u64 align1, align2;
+
+	align1 = addr1 & ~(size - 1);
+	align2 = addr2 & ~(size - 1);
+
+	return (align1 != align2) ? true : false;
+}
+
+#define AREA_4K		4096
+#define AREA_2M		(2 * 1024 * 1024)
+
+void branch_type_count(struct branch_type_stat *st, struct branch_flags *flags,
+		       u64 from, u64 to)
+{
+	if (flags->type == PERF_BR_UNKNOWN || from == 0)
+		return;
+
+	if (flags->type == PERF_BR_EXTEND_ABI)
+		st->new_counts[flags->new_type]++;
+	else
+		st->counts[flags->type]++;
+
+	if (flags->type == PERF_BR_COND) {
+		if (to > from)
+			st->cond_fwd++;
+		else
+			st->cond_bwd++;
+	}
+
+	if (cross_area(from, to, AREA_2M))
+		st->cross_2m++;
+	else if (cross_area(from, to, AREA_4K))
+		st->cross_4k++;
+}
+
+const char *branch_new_type_name(int new_type)
+{
+	const char *branch_new_names[PERF_BR_NEW_MAX] = {
+		"FAULT_ALGN",
+		"FAULT_DATA",
+		"FAULT_INST",
+/*
+ * TODO: This switch should happen on 'perf_session__env(session)->arch'
+ * instead, because an arm64 platform perf recording could be
+ * opened for analysis on other platforms as well.
+ */
+#ifdef __aarch64__
+		"ARM64_FIQ",
+		"ARM64_DEBUG_HALT",
+		"ARM64_DEBUG_EXIT",
+		"ARM64_DEBUG_INST",
+		"ARM64_DEBUG_DATA"
+#else
+		"ARCH_1",
+		"ARCH_2",
+		"ARCH_3",
+		"ARCH_4",
+		"ARCH_5"
+#endif
+	};
+
+	if (new_type >= 0 && new_type < PERF_BR_NEW_MAX)
+		return branch_new_names[new_type];
+
+	return NULL;
+}
+
+const char *branch_type_name(int type)
+{
+	const char *branch_names[PERF_BR_MAX] = {
+		"N/A",
+		"COND",
+		"UNCOND",
+		"IND",
+		"CALL",
+		"IND_CALL",
+		"RET",
+		"SYSCALL",
+		"SYSRET",
+		"COND_CALL",
+		"COND_RET",
+		"ERET",
+		"IRQ",
+		"SERROR",
+		"NO_TX",
+		"", // Needed for PERF_BR_EXTEND_ABI that ends up triggering some compiler warnings about NULL deref
+	};
+
+	if (type >= 0 && type < PERF_BR_MAX)
+		return branch_names[type];
+
+	return NULL;
+}
+
+const char *get_branch_type(struct branch_entry *e)
+{
+	if (e->flags.type == PERF_BR_UNKNOWN)
+		return "";
+
+	if (e->flags.type == PERF_BR_EXTEND_ABI)
+		return branch_new_type_name(e->flags.new_type);
+
+	return branch_type_name(e->flags.type);
+}
+
+void branch_type_stat_display(FILE *fp, const struct branch_type_stat *st)
+{
+	u64 total = 0;
+	int i;
+
+	for (i = 0; i < PERF_BR_MAX; i++)
+		total += st->counts[i];
+
+	if (total == 0)
+		return;
+
+	fprintf(fp, "\n#");
+	fprintf(fp, "\n# Branch Statistics:");
+	fprintf(fp, "\n#");
+
+	if (st->cond_fwd > 0) {
+		fprintf(fp, "\n%8s: %5.1f%%",
+			"COND_FWD",
+			100.0 * (double)st->cond_fwd / (double)total);
+	}
+
+	if (st->cond_bwd > 0) {
+		fprintf(fp, "\n%8s: %5.1f%%",
+			"COND_BWD",
+			100.0 * (double)st->cond_bwd / (double)total);
+	}
+
+	if (st->cross_4k > 0) {
+		fprintf(fp, "\n%8s: %5.1f%%",
+			"CROSS_4K",
+			100.0 * (double)st->cross_4k / (double)total);
+	}
+
+	if (st->cross_2m > 0) {
+		fprintf(fp, "\n%8s: %5.1f%%",
+			"CROSS_2M",
+			100.0 * (double)st->cross_2m / (double)total);
+	}
+
+	for (i = 0; i < PERF_BR_MAX; i++) {
+		if (st->counts[i] > 0)
+			fprintf(fp, "\n%8s: %5.1f%%",
+				branch_type_name(i),
+				100.0 *
+				(double)st->counts[i] / (double)total);
+	}
+
+	for (i = 0; i < PERF_BR_NEW_MAX; i++) {
+		if (st->new_counts[i] > 0)
+			fprintf(fp, "\n%8s: %5.1f%%",
+				branch_new_type_name(i),
+				100.0 *
+				(double)st->new_counts[i] / (double)total);
+	}
+
+}
+
+static int count_str_scnprintf(int idx, const char *str, char *bf, int size)
+{
+	return scnprintf(bf, size, "%s%s", (idx) ? " " : " (", str);
+}
+
+int branch_type_str(const struct branch_type_stat *st, char *bf, int size)
+{
+	int i, j = 0, printed = 0;
+	u64 total = 0;
+
+	for (i = 0; i < PERF_BR_MAX; i++)
+		total += st->counts[i];
+
+	for (i = 0; i < PERF_BR_NEW_MAX; i++)
+		total += st->new_counts[i];
+
+	if (total == 0)
+		return 0;
+
+	if (st->cond_fwd > 0)
+		printed += count_str_scnprintf(j++, "COND_FWD", bf + printed, size - printed);
+
+	if (st->cond_bwd > 0)
+		printed += count_str_scnprintf(j++, "COND_BWD", bf + printed, size - printed);
+
+	for (i = 0; i < PERF_BR_MAX; i++) {
+		if (i == PERF_BR_COND)
+			continue;
+
+		if (st->counts[i] > 0)
+			printed += count_str_scnprintf(j++, branch_type_name(i), bf + printed, size - printed);
+	}
+
+	for (i = 0; i < PERF_BR_NEW_MAX; i++) {
+		if (st->new_counts[i] > 0)
+			printed += count_str_scnprintf(j++, branch_new_type_name(i), bf + printed, size - printed);
+	}
+
+	if (st->cross_4k > 0)
+		printed += count_str_scnprintf(j++, "CROSS_4K", bf + printed, size - printed);
+
+	if (st->cross_2m > 0)
+		printed += count_str_scnprintf(j++, "CROSS_2M", bf + printed, size - printed);
+
+	return printed;
+}
+
+const char *branch_spec_desc(int spec)
+{
+	const char *branch_spec_outcomes[PERF_BR_SPEC_MAX] = {
+		"N/A",
+		"SPEC_WRONG_PATH",
+		"NON_SPEC_CORRECT_PATH",
+		"SPEC_CORRECT_PATH",
+	};
+
+	if (spec >= 0 && spec < PERF_BR_SPEC_MAX)
+		return branch_spec_outcomes[spec];
+
+	return NULL;
+}