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/regmap-ram.c | 91 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 drivers/base/regmap/regmap-ram.c (limited to 'drivers/base/regmap/regmap-ram.c') diff --git a/drivers/base/regmap/regmap-ram.c b/drivers/base/regmap/regmap-ram.c new file mode 100644 index 000000000..c7356b0d8 --- /dev/null +++ b/drivers/base/regmap/regmap-ram.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0 +// +// Register map access API - Memory region +// +// This is intended for testing only +// +// Copyright (c) 2023, Arm Ltd + +#include +#include +#include +#include +#include +#include +#include + +#include "internal.h" + +static int regmap_ram_write(void *context, unsigned int reg, unsigned int val) +{ + struct regmap_ram_data *data = context; + + data->vals[reg] = val; + data->written[reg] = true; + + return 0; +} + +static int regmap_ram_read(void *context, unsigned int reg, unsigned int *val) +{ + struct regmap_ram_data *data = context; + + *val = data->vals[reg]; + data->read[reg] = true; + + return 0; +} + +static void regmap_ram_free_context(void *context) +{ + struct regmap_ram_data *data = context; + + kfree(data->vals); + kfree(data->read); + kfree(data->written); + kfree(data); +} + +static const struct regmap_bus regmap_ram = { + .fast_io = true, + .reg_write = regmap_ram_write, + .reg_read = regmap_ram_read, + .free_context = regmap_ram_free_context, +}; + +struct regmap *__regmap_init_ram(struct device *dev, + const struct regmap_config *config, + struct regmap_ram_data *data, + struct lock_class_key *lock_key, + const char *lock_name) +{ + struct regmap *map; + + if (!config->max_register) { + pr_crit("No max_register specified for RAM regmap\n"); + return ERR_PTR(-EINVAL); + } + + data->read = kzalloc_objs(bool, config->max_register + 1); + if (!data->read) + return ERR_PTR(-ENOMEM); + + data->written = kzalloc_objs(bool, config->max_register + 1); + if (!data->written) { + kfree(data->read); + return ERR_PTR(-ENOMEM); + } + + map = __regmap_init(dev, ®map_ram, data, config, + lock_key, lock_name); + if (IS_ERR(map)) { + kfree(data->read); + kfree(data->written); + } + + return map; +} +EXPORT_SYMBOL_GPL(__regmap_init_ram); + +MODULE_DESCRIPTION("Register map access API - Memory region"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1