From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- drivers/nvmem/rmem.c | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 178 insertions(+) create mode 100644 drivers/nvmem/rmem.c (limited to 'drivers/nvmem/rmem.c') diff --git a/drivers/nvmem/rmem.c b/drivers/nvmem/rmem.c new file mode 100644 index 000000000..b39d628cb --- /dev/null +++ b/drivers/nvmem/rmem.c @@ -0,0 +1,178 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2020 Nicolas Saenz Julienne + */ + +#include +#include +#include +#include +#include +#include +#include + +struct rmem { + struct device *dev; + struct nvmem_device *nvmem; + struct reserved_mem *mem; +}; + +struct rmem_match_data { + int (*checksum)(struct rmem *priv); +}; + +struct __packed rmem_eyeq5_header { + u32 magic; + u32 version; + u32 size; +}; + +#define RMEM_EYEQ5_MAGIC ((u32)0xDABBAD00) + +static int rmem_read(void *context, unsigned int offset, + void *val, size_t bytes) +{ + struct rmem *priv = context; + void *addr; + + if ((phys_addr_t)offset + bytes > priv->mem->size) + return -EIO; + + /* + * Only map the reserved memory at this point to avoid potential rogue + * kernel threads inadvertently modifying it. Based on the current + * uses-cases for this driver, the performance hit isn't a concern. + * Nor is likely to be, given the nature of the subsystem. Most nvmem + * devices operate over slow buses to begin with. + * + * An alternative would be setting the memory as RO, set_memory_ro(), + * but as of Dec 2020 this isn't possible on arm64. + */ + addr = memremap(priv->mem->base, priv->mem->size, MEMREMAP_WB); + if (!addr) { + dev_err(priv->dev, "Failed to remap memory region\n"); + return -ENOMEM; + } + + memcpy(val, addr + offset, bytes); + + memunmap(addr); + + return 0; +} + +static int rmem_eyeq5_checksum(struct rmem *priv) +{ + void *buf __free(kfree) = NULL; + struct rmem_eyeq5_header header; + u32 computed_crc, *target_crc; + size_t data_size; + int ret; + + ret = rmem_read(priv, 0, &header, sizeof(header)); + if (ret) + return ret; + + if (header.magic != RMEM_EYEQ5_MAGIC) + return -EINVAL; + + /* + * Avoid massive kmalloc() if header read is invalid; + * the check would be done by the next rmem_read() anyway. + */ + if (header.size > priv->mem->size) + return -EINVAL; + + /* + * 0 +-------------------+ + * | Header (12 bytes) | \ + * +-------------------+ | + * | | | data to be CRCed + * | ... | | + * | | / + * data_size +-------------------+ + * | CRC (4 bytes) | + * header.size +-------------------+ + */ + + buf = kmalloc(header.size, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + ret = rmem_read(priv, 0, buf, header.size); + if (ret) + return ret; + + data_size = header.size - sizeof(*target_crc); + target_crc = buf + data_size; + computed_crc = crc32(U32_MAX, buf, data_size) ^ U32_MAX; + + if (computed_crc == *target_crc) + return 0; + + dev_err(priv->dev, + "checksum failed: computed %#x, expected %#x, header (%#x, %#x, %#x)\n", + computed_crc, *target_crc, header.magic, header.version, header.size); + return -EINVAL; +} + +static int rmem_probe(struct platform_device *pdev) +{ + struct nvmem_config config = { }; + struct device *dev = &pdev->dev; + const struct rmem_match_data *match_data = device_get_match_data(dev); + struct reserved_mem *mem; + struct rmem *priv; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + priv->dev = dev; + + mem = of_reserved_mem_lookup(dev->of_node); + if (!mem) { + dev_err(dev, "Failed to lookup reserved memory\n"); + return -EINVAL; + } + priv->mem = mem; + + config.dev = dev; + config.priv = priv; + config.name = "rmem"; + config.id = NVMEM_DEVID_AUTO; + config.size = mem->size; + config.reg_read = rmem_read; + + if (match_data && match_data->checksum) { + int ret = match_data->checksum(priv); + + if (ret) + return ret; + } + + return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config)); +} + +static const struct rmem_match_data rmem_eyeq5_match_data = { + .checksum = rmem_eyeq5_checksum, +}; + +static const struct of_device_id rmem_match[] = { + { .compatible = "mobileye,eyeq5-bootloader-config", .data = &rmem_eyeq5_match_data }, + { .compatible = "nvmem-rmem", }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, rmem_match); + +static struct platform_driver rmem_driver = { + .probe = rmem_probe, + .driver = { + .name = "rmem", + .of_match_table = rmem_match, + }, +}; +module_platform_driver(rmem_driver); + +MODULE_AUTHOR("Nicolas Saenz Julienne "); +MODULE_DESCRIPTION("Reserved Memory Based nvmem Driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1