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, 267 insertions, 0 deletions

diff --git a/drivers/nvmem/brcm_nvram.c b/drivers/nvmem/brcm_nvram.c
new file mode 100644
index 000000000..9f77aee37
--- /dev/null
+++ b/drivers/nvmem/brcm_nvram.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
+ */
+
+#include <linux/bcm47xx_nvram.h>
+#include <linux/etherdevice.h>
+#include <linux/hex.h>
+#include <linux/if_ether.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define NVRAM_MAGIC			"FLSH"
+
+/**
+ * struct brcm_nvram - driver state internal struct
+ *
+ * @dev:		NVMEM device pointer
+ * @nvmem_size:		Size of the whole space available for NVRAM
+ * @data:		NVRAM data copy stored to avoid poking underlying flash controller
+ * @data_len:		NVRAM data size
+ * @padding_byte:	Padding value used to fill remaining space
+ * @cells:		Array of discovered NVMEM cells
+ * @ncells:		Number of elements in cells
+ */
+struct brcm_nvram {
+	struct device *dev;
+	size_t nvmem_size;
+	uint8_t *data;
+	size_t data_len;
+	uint8_t padding_byte;
+	struct nvmem_cell_info *cells;
+	int ncells;
+};
+
+struct brcm_nvram_header {
+	char magic[4];
+	__le32 len;
+	__le32 crc_ver_init;	/* 0:7 crc, 8:15 ver, 16:31 sdram_init */
+	__le32 config_refresh;	/* 0:15 sdram_config, 16:31 sdram_refresh */
+	__le32 config_ncdl;	/* ncdl values for memc */
+};
+
+static int brcm_nvram_read(void *context, unsigned int offset, void *val,
+			   size_t bytes)
+{
+	struct brcm_nvram *priv = context;
+	size_t to_copy;
+
+	if (offset + bytes > priv->data_len)
+		to_copy = max_t(ssize_t, (ssize_t)priv->data_len - offset, 0);
+	else
+		to_copy = bytes;
+
+	memcpy(val, priv->data + offset, to_copy);
+
+	memset((uint8_t *)val + to_copy, priv->padding_byte, bytes - to_copy);
+
+	return 0;
+}
+
+static int brcm_nvram_copy_data(struct brcm_nvram *priv, struct platform_device *pdev)
+{
+	struct resource *res;
+	void __iomem *base;
+
+	base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	priv->nvmem_size = resource_size(res);
+
+	priv->padding_byte = readb(base + priv->nvmem_size - 1);
+	for (priv->data_len = priv->nvmem_size;
+	     priv->data_len;
+	     priv->data_len--) {
+		if (readb(base + priv->data_len - 1) != priv->padding_byte)
+			break;
+	}
+	WARN(priv->data_len > SZ_128K, "Unexpected (big) NVRAM size: %zu B\n", priv->data_len);
+
+	if (priv->data_len < sizeof(struct brcm_nvram_header)) {
+		dev_err(priv->dev, "NVRAM data too small (%zu)\n", priv->data_len);
+		return -EINVAL;
+	}
+
+	priv->data = devm_kzalloc(priv->dev, priv->data_len, GFP_KERNEL);
+	if (!priv->data)
+		return -ENOMEM;
+
+	memcpy_fromio(priv->data, base, priv->data_len);
+
+	bcm47xx_nvram_init_from_iomem(base, priv->data_len);
+
+	return 0;
+}
+
+static int brcm_nvram_read_post_process_macaddr(void *context, const char *id, int index,
+						unsigned int offset, void *buf, size_t bytes)
+{
+	u8 mac[ETH_ALEN];
+
+	if (bytes != MAC_ADDR_STR_LEN)
+		return -EINVAL;
+
+	if (!mac_pton(buf, mac))
+		return -EINVAL;
+
+	if (index)
+		eth_addr_add(mac, index);
+
+	ether_addr_copy(buf, mac);
+
+	return 0;
+}
+
+static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
+				size_t len)
+{
+	struct device *dev = priv->dev;
+	char *var, *value;
+	uint8_t tmp;
+	int idx;
+	int err = 0;
+
+	tmp = priv->data[len - 1];
+	priv->data[len - 1] = '\0';
+
+	priv->ncells = 0;
+	for (var = data + sizeof(struct brcm_nvram_header);
+	     var < (char *)data + len && *var;
+	     var += strlen(var) + 1) {
+		priv->ncells++;
+	}
+
+	priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
+	if (!priv->cells) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
+	     var < (char *)data + len && *var;
+	     var = value + strlen(value) + 1, idx++) {
+		char *eq, *name;
+
+		eq = strchr(var, '=');
+		if (!eq)
+			break;
+		*eq = '\0';
+		name = devm_kstrdup(dev, var, GFP_KERNEL);
+		*eq = '=';
+		if (!name) {
+			err = -ENOMEM;
+			goto out;
+		}
+		value = eq + 1;
+
+		priv->cells[idx].name = name;
+		priv->cells[idx].offset = value - (char *)data;
+		priv->cells[idx].bytes = strlen(value);
+		priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
+		if (!strcmp(name, "et0macaddr") ||
+		    !strcmp(name, "et1macaddr") ||
+		    !strcmp(name, "et2macaddr")) {
+			priv->cells[idx].raw_len = strlen(value);
+			priv->cells[idx].bytes = ETH_ALEN;
+			priv->cells[idx].read_post_process = brcm_nvram_read_post_process_macaddr;
+		}
+	}
+
+out:
+	priv->data[len - 1] = tmp;
+	return err;
+}
+
+static int brcm_nvram_parse(struct brcm_nvram *priv)
+{
+	struct brcm_nvram_header *header = (struct brcm_nvram_header *)priv->data;
+	struct device *dev = priv->dev;
+	size_t len;
+	int err;
+
+	if (memcmp(header->magic, NVRAM_MAGIC, 4)) {
+		dev_err(dev, "Invalid NVRAM magic\n");
+		return -EINVAL;
+	}
+
+	len = le32_to_cpu(header->len);
+	if (len < sizeof(*header)) {
+		dev_err(dev, "NVRAM length (%zd) too small\n", len);
+		return -EINVAL;
+	}
+	if (len > priv->data_len) {
+		dev_err(dev, "NVRAM length (%zd) exceeds data size (%zd)\n", len,
+			priv->data_len);
+		return -EINVAL;
+	}
+
+	err = brcm_nvram_add_cells(priv, priv->data, len);
+	if (err)
+		dev_err(dev, "Failed to add cells: %d\n", err);
+
+	return 0;
+}
+
+static int brcm_nvram_probe(struct platform_device *pdev)
+{
+	struct nvmem_config config = {
+		.name = "brcm-nvram",
+		.reg_read = brcm_nvram_read,
+	};
+	struct device *dev = &pdev->dev;
+	struct brcm_nvram *priv;
+	int err;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	priv->dev = dev;
+
+	err = brcm_nvram_copy_data(priv, pdev);
+	if (err)
+		return err;
+
+	err = brcm_nvram_parse(priv);
+	if (err)
+		return err;
+
+	config.dev = dev;
+	config.cells = priv->cells;
+	config.ncells = priv->ncells;
+	config.priv = priv;
+	config.size = priv->nvmem_size;
+
+	return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
+}
+
+static const struct of_device_id brcm_nvram_of_match_table[] = {
+	{ .compatible = "brcm,nvram", },
+	{},
+};
+
+static struct platform_driver brcm_nvram_driver = {
+	.probe = brcm_nvram_probe,
+	.driver = {
+		.name = "brcm_nvram",
+		.of_match_table = brcm_nvram_of_match_table,
+	},
+};
+
+static int __init brcm_nvram_init(void)
+{
+	return platform_driver_register(&brcm_nvram_driver);
+}
+
+subsys_initcall_sync(brcm_nvram_init);
+
+MODULE_AUTHOR("Rafał Miłecki");
+MODULE_DESCRIPTION("Broadcom I/O-mapped NVRAM support driver");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);