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>

2 files changed, 225 insertions, 0 deletions

diff --git a/tools/wmi/Makefile b/tools/wmi/Makefile
new file mode 100644
index 000000000..e161ff59e
--- /dev/null
+++ b/tools/wmi/Makefile
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0-only
+PREFIX ?= /usr
+SBINDIR ?= sbin
+INSTALL ?= install
+CFLAGS += -D__EXPORTED_HEADERS__ -I../../include/uapi -I../../include
+
+TARGET = dell-smbios-example
+
+all: $(TARGET)
+
+%: %.c
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $<
+
+clean:
+	$(RM) $(TARGET)
+
+install: dell-smbios-example
+	$(INSTALL) -D -m 755 $(TARGET) $(DESTDIR)$(PREFIX)/$(SBINDIR)/$(TARGET)
diff --git a/tools/wmi/dell-smbios-example.c b/tools/wmi/dell-smbios-example.c
new file mode 100644
index 000000000..1f3e7ab14
--- /dev/null
+++ b/tools/wmi/dell-smbios-example.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Sample application for SMBIOS communication over WMI interface
+ *  Performs the following:
+ *  - Simple cmd_class/cmd_select lookup for TPM information
+ *  - Simple query of known tokens and their values
+ *  - Simple activation of a token
+ *
+ *  Copyright (C) 2017 Dell, Inc.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+/* if uapi header isn't installed, this might not yet exist */
+#ifndef __packed
+#define __packed __attribute__((packed))
+#endif
+#include <linux/wmi.h>
+
+/* It would be better to discover these using udev, but for a simple
+ * application they're hardcoded
+ */
+static const char *ioctl_devfs = "/dev/wmi/dell-smbios";
+static const char *token_sysfs =
+			"/sys/bus/platform/devices/dell-smbios.0/tokens";
+
+static void show_buffer(struct dell_wmi_smbios_buffer *buffer)
+{
+	printf("Call: %x/%x [%x,%x,%x,%x]\nResults: [%8x,%8x,%8x,%8x]\n",
+	buffer->std.cmd_class, buffer->std.cmd_select,
+	buffer->std.input[0], buffer->std.input[1],
+	buffer->std.input[2], buffer->std.input[3],
+	buffer->std.output[0], buffer->std.output[1],
+	buffer->std.output[2], buffer->std.output[3]);
+}
+
+static int run_wmi_smbios_cmd(struct dell_wmi_smbios_buffer *buffer)
+{
+	int fd;
+	int ret;
+
+	fd = open(ioctl_devfs, O_NONBLOCK);
+	ret = ioctl(fd, DELL_WMI_SMBIOS_CMD, buffer);
+	close(fd);
+	return ret;
+}
+
+static int find_token(__u16 token, __u16 *location, __u16 *value)
+{
+	char location_sysfs[60];
+	char value_sysfs[57];
+	char buf[4096];
+	FILE *f;
+	int ret;
+
+	ret = sprintf(value_sysfs, "%s/%04x_value", token_sysfs, token);
+	if (ret < 0) {
+		printf("sprintf value failed\n");
+		return 2;
+	}
+	f = fopen(value_sysfs, "rb");
+	if (!f) {
+		printf("failed to open %s\n", value_sysfs);
+		return 2;
+	}
+	fread(buf, 1, 4096, f);
+	fclose(f);
+	*value = (__u16) strtol(buf, NULL, 16);
+
+	ret = sprintf(location_sysfs, "%s/%04x_location", token_sysfs, token);
+	if (ret < 0) {
+		printf("sprintf location failed\n");
+		return 1;
+	}
+	f = fopen(location_sysfs, "rb");
+	if (!f) {
+		printf("failed to open %s\n", location_sysfs);
+		return 2;
+	}
+	fread(buf, 1, 4096, f);
+	fclose(f);
+	*location = (__u16) strtol(buf, NULL, 16);
+
+	if (*location)
+		return 0;
+	return 2;
+}
+
+static int token_is_active(__u16 *location, __u16 *cmpvalue,
+			   struct dell_wmi_smbios_buffer *buffer)
+{
+	int ret;
+
+	buffer->std.cmd_class = CLASS_TOKEN_READ;
+	buffer->std.cmd_select = SELECT_TOKEN_STD;
+	buffer->std.input[0] = *location;
+	ret = run_wmi_smbios_cmd(buffer);
+	if (ret != 0 || buffer->std.output[0] != 0)
+		return ret;
+	ret = (buffer->std.output[1] == *cmpvalue);
+	return ret;
+}
+
+static int query_token(__u16 token, struct dell_wmi_smbios_buffer *buffer)
+{
+	__u16 location;
+	__u16 value;
+	int ret;
+
+	ret = find_token(token, &location, &value);
+	if (ret != 0) {
+		printf("unable to find token %04x\n", token);
+		return 1;
+	}
+	return token_is_active(&location, &value, buffer);
+}
+
+static int activate_token(struct dell_wmi_smbios_buffer *buffer,
+		   __u16 token)
+{
+	__u16 location;
+	__u16 value;
+	int ret;
+
+	ret = find_token(token, &location, &value);
+	if (ret != 0) {
+		printf("unable to find token %04x\n", token);
+		return 1;
+	}
+	buffer->std.cmd_class = CLASS_TOKEN_WRITE;
+	buffer->std.cmd_select = SELECT_TOKEN_STD;
+	buffer->std.input[0] = location;
+	buffer->std.input[1] = 1;
+	ret = run_wmi_smbios_cmd(buffer);
+	return ret;
+}
+
+static int query_buffer_size(__u64 *buffer_size)
+{
+	FILE *f;
+
+	f = fopen(ioctl_devfs, "rb");
+	if (!f)
+		return -EINVAL;
+	fread(buffer_size, sizeof(__u64), 1, f);
+	fclose(f);
+	return EXIT_SUCCESS;
+}
+
+int main(void)
+{
+	struct dell_wmi_smbios_buffer *buffer;
+	int ret;
+	__u64 value = 0;
+
+	ret = query_buffer_size(&value);
+	if (ret == EXIT_FAILURE || !value) {
+		printf("Unable to read buffer size\n");
+		goto out;
+	}
+	printf("Detected required buffer size %lld\n", value);
+
+	buffer = malloc(value);
+	if (buffer == NULL) {
+		printf("failed to alloc memory for ioctl\n");
+		ret = -ENOMEM;
+		goto out;
+	}
+	buffer->length = value;
+
+	/* simple SMBIOS call for looking up TPM info */
+	buffer->std.cmd_class = CLASS_FLASH_INTERFACE;
+	buffer->std.cmd_select = SELECT_FLASH_INTERFACE;
+	buffer->std.input[0] = 2;
+	ret = run_wmi_smbios_cmd(buffer);
+	if (ret) {
+		printf("smbios ioctl failed: %d\n", ret);
+		ret = EXIT_FAILURE;
+		goto out;
+	}
+	show_buffer(buffer);
+
+	/* query some tokens */
+	ret = query_token(CAPSULE_EN_TOKEN, buffer);
+	printf("UEFI Capsule enabled token is: %d\n", ret);
+	ret = query_token(CAPSULE_DIS_TOKEN, buffer);
+	printf("UEFI Capsule disabled token is: %d\n", ret);
+
+	/* activate UEFI capsule token if disabled */
+	if (ret) {
+		printf("Enabling UEFI capsule token");
+		if (activate_token(buffer, CAPSULE_EN_TOKEN)) {
+			printf("activate failed\n");
+			ret = -1;
+			goto out;
+		}
+	}
+	ret = EXIT_SUCCESS;
+out:
+	free(buffer);
+	return ret;
+}