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, 204 insertions, 0 deletions

diff --git a/drivers/ssb/sprom.c b/drivers/ssb/sprom.c
new file mode 100644
index 000000000..7cd553127
--- /dev/null
+++ b/drivers/ssb/sprom.c
@@ -0,0 +1,204 @@
+/*
+ * Sonics Silicon Backplane
+ * Common SPROM support routines
+ *
+ * Copyright (C) 2005-2008 Michael Buesch <m@bues.ch>
+ * Copyright (C) 2005 Martin Langer <martin-langer@gmx.de>
+ * Copyright (C) 2005 Stefano Brivio <st3@riseup.net>
+ * Copyright (C) 2005 Danny van Dyk <kugelfang@gentoo.org>
+ * Copyright (C) 2005 Andreas Jaggi <andreas.jaggi@waterwave.ch>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include "ssb_private.h"
+
+#include <linux/ctype.h>
+#include <linux/slab.h>
+
+
+static int(*get_fallback_sprom)(struct ssb_bus *dev, struct ssb_sprom *out);
+
+
+static int sprom2hex(const u16 *sprom, char *buf, size_t buf_len,
+		     size_t sprom_size_words)
+{
+	int i, pos = 0;
+
+	for (i = 0; i < sprom_size_words; i++)
+		pos += scnprintf(buf + pos, buf_len - pos - 1,
+				"%04X", swab16(sprom[i]) & 0xFFFF);
+	pos += scnprintf(buf + pos, buf_len - pos - 1, "\n");
+
+	return pos + 1;
+}
+
+static int hex2sprom(u16 *sprom, const char *dump, size_t len,
+		     size_t sprom_size_words)
+{
+	char c, tmp[5] = { 0 };
+	int err, cnt = 0;
+	unsigned long parsed;
+
+	/* Strip whitespace at the end. */
+	while (len) {
+		c = dump[len - 1];
+		if (!isspace(c) && c != '\0')
+			break;
+		len--;
+	}
+	/* Length must match exactly. */
+	if (len != sprom_size_words * 4)
+		return -EINVAL;
+
+	while (cnt < sprom_size_words) {
+		memcpy(tmp, dump, 4);
+		dump += 4;
+		err = kstrtoul(tmp, 16, &parsed);
+		if (err)
+			return err;
+		sprom[cnt++] = swab16((u16)parsed);
+	}
+
+	return 0;
+}
+
+/* Common sprom device-attribute show-handler */
+ssize_t ssb_attr_sprom_show(struct ssb_bus *bus, char *buf,
+			    int (*sprom_read)(struct ssb_bus *bus, u16 *sprom))
+{
+	u16 *sprom;
+	int err = -ENOMEM;
+	ssize_t count = 0;
+	size_t sprom_size_words = bus->sprom_size;
+
+	sprom = kcalloc(sprom_size_words, sizeof(u16), GFP_KERNEL);
+	if (!sprom)
+		goto out;
+
+	/* Use interruptible locking, as the SPROM write might
+	 * be holding the lock for several seconds. So allow userspace
+	 * to cancel operation.
+	 */
+	err = -ERESTARTSYS;
+	if (mutex_lock_interruptible(&bus->sprom_mutex))
+		goto out_kfree;
+	err = sprom_read(bus, sprom);
+	mutex_unlock(&bus->sprom_mutex);
+
+	if (!err)
+		count = sprom2hex(sprom, buf, PAGE_SIZE, sprom_size_words);
+
+out_kfree:
+	kfree(sprom);
+out:
+	return err ? err : count;
+}
+
+/* Common sprom device-attribute store-handler */
+ssize_t ssb_attr_sprom_store(struct ssb_bus *bus,
+			     const char *buf, size_t count,
+			     int (*sprom_check_crc)(const u16 *sprom, size_t size),
+			     int (*sprom_write)(struct ssb_bus *bus, const u16 *sprom))
+{
+	u16 *sprom;
+	int res = 0, err = -ENOMEM;
+	size_t sprom_size_words = bus->sprom_size;
+	struct ssb_freeze_context freeze;
+
+	sprom = kcalloc(bus->sprom_size, sizeof(u16), GFP_KERNEL);
+	if (!sprom)
+		goto out;
+	err = hex2sprom(sprom, buf, count, sprom_size_words);
+	if (err) {
+		err = -EINVAL;
+		goto out_kfree;
+	}
+	err = sprom_check_crc(sprom, sprom_size_words);
+	if (err) {
+		err = -EINVAL;
+		goto out_kfree;
+	}
+
+	/* Use interruptible locking, as the SPROM write might
+	 * be holding the lock for several seconds. So allow userspace
+	 * to cancel operation.
+	 */
+	err = -ERESTARTSYS;
+	if (mutex_lock_interruptible(&bus->sprom_mutex))
+		goto out_kfree;
+	err = ssb_devices_freeze(bus, &freeze);
+	if (err) {
+		pr_err("SPROM write: Could not freeze all devices\n");
+		goto out_unlock;
+	}
+	res = sprom_write(bus, sprom);
+	err = ssb_devices_thaw(&freeze);
+	if (err)
+		pr_err("SPROM write: Could not thaw all devices\n");
+out_unlock:
+	mutex_unlock(&bus->sprom_mutex);
+out_kfree:
+	kfree(sprom);
+out:
+	if (res)
+		return res;
+	return err ? err : count;
+}
+
+/**
+ * ssb_arch_register_fallback_sprom - Registers a method providing a
+ * fallback SPROM if no SPROM is found.
+ *
+ * @sprom_callback: The callback function.
+ *
+ * With this function the architecture implementation may register a
+ * callback handler which fills the SPROM data structure. The fallback is
+ * only used for PCI based SSB devices, where no valid SPROM can be found
+ * in the shadow registers.
+ *
+ * This function is useful for weird architectures that have a half-assed
+ * SSB device hardwired to their PCI bus.
+ *
+ * Note that it does only work with PCI attached SSB devices. PCMCIA
+ * devices currently don't use this fallback.
+ * Architectures must provide the SPROM for native SSB devices anyway, so
+ * the fallback also isn't used for native devices.
+ *
+ * This function is available for architecture code, only. So it is not
+ * exported.
+ */
+int ssb_arch_register_fallback_sprom(int (*sprom_callback)(struct ssb_bus *bus,
+				     struct ssb_sprom *out))
+{
+	if (get_fallback_sprom)
+		return -EEXIST;
+	get_fallback_sprom = sprom_callback;
+
+	return 0;
+}
+
+int ssb_fill_sprom_with_fallback(struct ssb_bus *bus, struct ssb_sprom *out)
+{
+	if (!get_fallback_sprom)
+		return -ENOENT;
+
+	return get_fallback_sprom(bus, out);
+}
+
+/* https://bcm-v4.sipsolutions.net/802.11/IsSpromAvailable */
+bool ssb_is_sprom_available(struct ssb_bus *bus)
+{
+	/* status register only exists on chipcomon rev >= 11 and we need check
+	 * for >= 31 only
+	 */
+	/* this routine differs from specs as we do not access SPROM directly
+	 * on PCMCIA
+	 */
+	if (bus->bustype == SSB_BUSTYPE_PCI &&
+	    bus->chipco.dev &&	/* can be unavailable! */
+	    bus->chipco.dev->id.revision >= 31)
+		return bus->chipco.capabilities & SSB_CHIPCO_CAP_SPROM;
+
+	return true;
+}