include/linux/kcsan.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 /*
0003  * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. Public interface and
0004  * data structures to set up runtime. See kcsan-checks.h for explicit checks and
0005  * modifiers. For more info please see Documentation/dev-tools/kcsan.rst.
0006  *
0007  * Copyright (C) 2019, Google LLC.
0008  */
0009
0010 #ifndef _LINUX_KCSAN_H
0011 #define _LINUX_KCSAN_H
0012
0013 #include <linux/kcsan-checks.h>
0014 #include <linux/types.h>
0015
0016 #ifdef CONFIG_KCSAN
0017
0018 /*
0019  * Context for each thread of execution: for tasks, this is stored in
0020  * task_struct, and interrupts access internal per-CPU storage.
0021  */
0022 struct kcsan_ctx {
0023     int disable_count; /* disable counter */
0024     int disable_scoped; /* disable scoped access counter */
0025     int atomic_next; /* number of following atomic ops */
0026
0027     /*
0028      * We distinguish between: (a) nestable atomic regions that may contain
0029      * other nestable regions; and (b) flat atomic regions that do not keep
0030      * track of nesting. Both (a) and (b) are entirely independent of each
0031      * other, and a flat region may be started in a nestable region or
0032      * vice-versa.
0033      *
0034      * This is required because, for example, in the annotations for
0035      * seqlocks, we declare seqlock writer critical sections as (a) nestable
0036      * atomic regions, but reader critical sections as (b) flat atomic
0037      * regions, but have encountered cases where seqlock reader critical
0038      * sections are contained within writer critical sections (the opposite
0039      * may be possible, too).
0040      *
0041      * To support these cases, we independently track the depth of nesting
0042      * for (a), and whether the leaf level is flat for (b).
0043      */
0044     int atomic_nest_count;
0045     bool in_flat_atomic;
0046
0047     /*
0048      * Access mask for all accesses if non-zero.
0049      */
0050     unsigned long access_mask;
0051
0052     /* List of scoped accesses; likely to be empty. */
0053     struct list_head scoped_accesses;
0054
0055 #ifdef CONFIG_KCSAN_WEAK_MEMORY
0056     /*
0057      * Scoped access for modeling access reordering to detect missing memory
0058      * barriers; only keep 1 to keep fast-path complexity manageable.
0059      */
0060     struct kcsan_scoped_access reorder_access;
0061 #endif
0062 };
0063
0064 /**
0065  * kcsan_init - initialize KCSAN runtime
0066  */
0067 void kcsan_init(void);
0068
0069 #else /* CONFIG_KCSAN */
0070
0071 static inline void kcsan_init(void)         { }
0072
0073 #endif /* CONFIG_KCSAN */
0074
0075 #endif /* _LINUX_KCSAN_H */