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/base/regmap/regcache-flat.c | 175 ++++++++++++++++++++++++++++++++++++ 1 file changed, 175 insertions(+) create mode 100644 drivers/base/regmap/regcache-flat.c (limited to 'drivers/base/regmap/regcache-flat.c') diff --git a/drivers/base/regmap/regcache-flat.c b/drivers/base/regmap/regcache-flat.c new file mode 100644 index 000000000..be8497fd2 --- /dev/null +++ b/drivers/base/regmap/regcache-flat.c @@ -0,0 +1,175 @@ +// SPDX-License-Identifier: GPL-2.0 +// +// Register cache access API - flat caching support +// +// Copyright 2012 Wolfson Microelectronics plc +// +// Author: Mark Brown + +#include +#include +#include +#include +#include +#include +#include + +#include "internal.h" + +static inline unsigned int regcache_flat_get_index(const struct regmap *map, + unsigned int reg) +{ + return regcache_get_index_by_order(map, reg); +} + +struct regcache_flat_data { + unsigned long *valid; + unsigned int data[]; +}; + +static int regcache_flat_init(struct regmap *map) +{ + unsigned int cache_size; + struct regcache_flat_data *cache; + + if (!map || map->reg_stride_order < 0 || !map->max_register_is_set) + return -EINVAL; + + cache_size = regcache_flat_get_index(map, map->max_register) + 1; + cache = kzalloc_flex(*cache, data, cache_size, map->alloc_flags); + if (!cache) + return -ENOMEM; + + cache->valid = bitmap_zalloc(cache_size, map->alloc_flags); + if (!cache->valid) + goto err_free; + + map->cache = cache; + + return 0; + +err_free: + kfree(cache); + return -ENOMEM; +} + +static void regcache_flat_exit(struct regmap *map) +{ + struct regcache_flat_data *cache = map->cache; + + if (cache) + bitmap_free(cache->valid); + + kfree(cache); + map->cache = NULL; +} + +static int regcache_flat_populate(struct regmap *map) +{ + struct regcache_flat_data *cache = map->cache; + unsigned int i; + + for (i = 0; i < map->num_reg_defaults; i++) { + unsigned int reg = map->reg_defaults[i].reg; + unsigned int index = regcache_flat_get_index(map, reg); + + cache->data[index] = map->reg_defaults[i].def; + __set_bit(index, cache->valid); + } + + if (map->reg_default_cb) { + dev_dbg(map->dev, + "Populating regcache_flat using reg_default_cb callback\n"); + + for (i = 0; i <= map->max_register; i += map->reg_stride) { + unsigned int index = regcache_flat_get_index(map, i); + unsigned int value; + + if (test_bit(index, cache->valid)) + continue; + + if (map->reg_default_cb(map->dev, i, &value)) + continue; + + cache->data[index] = value; + __set_bit(index, cache->valid); + } + } + + return 0; +} + +static int regcache_flat_read(struct regmap *map, + unsigned int reg, unsigned int *value) +{ + struct regcache_flat_data *cache = map->cache; + unsigned int index = regcache_flat_get_index(map, reg); + + /* legacy behavior: ignore validity, but warn the user */ + if (unlikely(!test_bit(index, cache->valid))) + dev_warn_once(map->dev, + "using zero-initialized flat cache, this may cause unexpected behavior"); + + *value = cache->data[index]; + + return 0; +} + +static int regcache_flat_sparse_read(struct regmap *map, + unsigned int reg, unsigned int *value) +{ + struct regcache_flat_data *cache = map->cache; + unsigned int index = regcache_flat_get_index(map, reg); + + if (unlikely(!test_bit(index, cache->valid))) + return -ENOENT; + + *value = cache->data[index]; + + return 0; +} + +static int regcache_flat_write(struct regmap *map, unsigned int reg, + unsigned int value) +{ + struct regcache_flat_data *cache = map->cache; + unsigned int index = regcache_flat_get_index(map, reg); + + cache->data[index] = value; + __set_bit(index, cache->valid); + + return 0; +} + +static int regcache_flat_drop(struct regmap *map, unsigned int min, + unsigned int max) +{ + struct regcache_flat_data *cache = map->cache; + unsigned int bitmap_min = regcache_flat_get_index(map, min); + unsigned int bitmap_max = regcache_flat_get_index(map, max); + + bitmap_clear(cache->valid, bitmap_min, bitmap_max + 1 - bitmap_min); + + return 0; +} + +struct regcache_ops regcache_flat_ops = { + .type = REGCACHE_FLAT, + .name = "flat", + .init = regcache_flat_init, + .exit = regcache_flat_exit, + .populate = regcache_flat_populate, + .read = regcache_flat_read, + .write = regcache_flat_write, +}; + +struct regcache_ops regcache_flat_sparse_ops = { + .type = REGCACHE_FLAT_S, + .name = "flat-sparse", + .init = regcache_flat_init, + .exit = regcache_flat_exit, + .populate = regcache_flat_populate, + .read = regcache_flat_sparse_read, + .write = regcache_flat_write, + .drop = regcache_flat_drop, +}; -- cgit v1.3.1