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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_KCSAN_CHECKS_H
#define _LINUX_KCSAN_CHECKS_H
#include <linux/types.h>
/*
* ACCESS TYPE MODIFIERS
*
* <none>: normal read access;
* WRITE : write access;
* ATOMIC: access is atomic;
* ASSERT: access is not a regular access, but an assertion;
*/
#define KCSAN_ACCESS_WRITE 0x1
#define KCSAN_ACCESS_ATOMIC 0x2
#define KCSAN_ACCESS_ASSERT 0x4
/*
* __kcsan_*: Always calls into the runtime when KCSAN is enabled. This may be used
* even in compilation units that selectively disable KCSAN, but must use KCSAN
* to validate access to an address. Never use these in header files!
*/
#ifdef CONFIG_KCSAN
/**
* __kcsan_check_access - check generic access for races
*
* @ptr address of access
* @size size of access
* @type access type modifier
*/
void __kcsan_check_access(const volatile void *ptr, size_t size, int type);
/**
* kcsan_nestable_atomic_begin - begin nestable atomic region
*
* Accesses within the atomic region may appear to race with other accesses but
* should be considered atomic.
*/
void kcsan_nestable_atomic_begin(void);
/**
* kcsan_nestable_atomic_end - end nestable atomic region
*/
void kcsan_nestable_atomic_end(void);
/**
* kcsan_flat_atomic_begin - begin flat atomic region
*
* Accesses within the atomic region may appear to race with other accesses but
* should be considered atomic.
*/
void kcsan_flat_atomic_begin(void);
/**
* kcsan_flat_atomic_end - end flat atomic region
*/
void kcsan_flat_atomic_end(void);
/**
* kcsan_atomic_next - consider following accesses as atomic
*
* Force treating the next n memory accesses for the current context as atomic
* operations.
*
* @n number of following memory accesses to treat as atomic.
*/
void kcsan_atomic_next(int n);
#else /* CONFIG_KCSAN */
static inline void __kcsan_check_access(const volatile void *ptr, size_t size,
int type) { }
static inline void kcsan_nestable_atomic_begin(void) { }
static inline void kcsan_nestable_atomic_end(void) { }
static inline void kcsan_flat_atomic_begin(void) { }
static inline void kcsan_flat_atomic_end(void) { }
static inline void kcsan_atomic_next(int n) { }
#endif /* CONFIG_KCSAN */
/*
* kcsan_*: Only calls into the runtime when the particular compilation unit has
* KCSAN instrumentation enabled. May be used in header files.
*/
#ifdef __SANITIZE_THREAD__
#define kcsan_check_access __kcsan_check_access
#else
static inline void kcsan_check_access(const volatile void *ptr, size_t size,
int type) { }
#endif
/**
* __kcsan_check_read - check regular read access for races
*
* @ptr address of access
* @size size of access
*/
#define __kcsan_check_read(ptr, size) __kcsan_check_access(ptr, size, 0)
/**
* __kcsan_check_write - check regular write access for races
*
* @ptr address of access
* @size size of access
*/
#define __kcsan_check_write(ptr, size) \
__kcsan_check_access(ptr, size, KCSAN_ACCESS_WRITE)
/**
* kcsan_check_read - check regular read access for races
*
* @ptr address of access
* @size size of access
*/
#define kcsan_check_read(ptr, size) kcsan_check_access(ptr, size, 0)
/**
* kcsan_check_write - check regular write access for races
*
* @ptr address of access
* @size size of access
*/
#define kcsan_check_write(ptr, size) \
kcsan_check_access(ptr, size, KCSAN_ACCESS_WRITE)
/*
* Check for atomic accesses: if atomic accesses are not ignored, this simply
* aliases to kcsan_check_access(), otherwise becomes a no-op.
*/
#ifdef CONFIG_KCSAN_IGNORE_ATOMICS
#define kcsan_check_atomic_read(...) do { } while (0)
#define kcsan_check_atomic_write(...) do { } while (0)
#else
#define kcsan_check_atomic_read(ptr, size) \
kcsan_check_access(ptr, size, KCSAN_ACCESS_ATOMIC)
#define kcsan_check_atomic_write(ptr, size) \
kcsan_check_access(ptr, size, KCSAN_ACCESS_ATOMIC | KCSAN_ACCESS_WRITE)
#endif
/**
* ASSERT_EXCLUSIVE_WRITER - assert no other threads are writing @var
*
* Assert that there are no other threads writing @var; other readers are
* allowed. This assertion can be used to specify properties of concurrent code,
* where violation cannot be detected as a normal data race.
*
* For example, if a per-CPU variable is only meant to be written by a single
* CPU, but may be read from other CPUs; in this case, reads and writes must be
* marked properly, however, if an off-CPU WRITE_ONCE() races with the owning
* CPU's WRITE_ONCE(), would not constitute a data race but could be a harmful
* race condition. Using this macro allows specifying this property in the code
* and catch such bugs.
*
* @var variable to assert on
*/
#define ASSERT_EXCLUSIVE_WRITER(var) \
__kcsan_check_access(&(var), sizeof(var), KCSAN_ACCESS_ASSERT)
/**
* ASSERT_EXCLUSIVE_ACCESS - assert no other threads are accessing @var
*
* Assert that no other thread is accessing @var (no readers nor writers). This
* assertion can be used to specify properties of concurrent code, where
* violation cannot be detected as a normal data race.
*
* For example, in a reference-counting algorithm where exclusive access is
* expected after the refcount reaches 0. We can check that this property
* actually holds as follows:
*
* if (refcount_dec_and_test(&obj->refcnt)) {
* ASSERT_EXCLUSIVE_ACCESS(*obj);
* safely_dispose_of(obj);
* }
*
* @var variable to assert on
*/
#define ASSERT_EXCLUSIVE_ACCESS(var) \
__kcsan_check_access(&(var), sizeof(var), KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT)
#endif /* _LINUX_KCSAN_CHECKS_H */
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