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9756f64c8f
Avoid checking scoped accesses from nested contexts (such as nested interrupts or in scheduler code) which share the same kcsan_ctx. This is to avoid detecting false positive races of accesses in the same thread with currently scoped accesses: consider setting up a watchpoint for a non-scoped (normal) access that also "conflicts" with a current scoped access. In a nested interrupt (or in the scheduler), which shares the same kcsan_ctx, we cannot check scoped accesses set up in the parent context -- simply ignore them in this case. With the introduction of kcsan_ctx::disable_scoped, we can also clean up kcsan_check_scoped_accesses()'s recursion guard, and do not need to modify the list's prev pointer. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
67 lines
1.9 KiB
C
67 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* The Kernel Concurrency Sanitizer (KCSAN) infrastructure. Public interface and
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* data structures to set up runtime. See kcsan-checks.h for explicit checks and
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* modifiers. For more info please see Documentation/dev-tools/kcsan.rst.
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*
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* Copyright (C) 2019, Google LLC.
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*/
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#ifndef _LINUX_KCSAN_H
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#define _LINUX_KCSAN_H
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#include <linux/kcsan-checks.h>
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#include <linux/types.h>
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#ifdef CONFIG_KCSAN
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/*
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* Context for each thread of execution: for tasks, this is stored in
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* task_struct, and interrupts access internal per-CPU storage.
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*/
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struct kcsan_ctx {
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int disable_count; /* disable counter */
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int disable_scoped; /* disable scoped access counter */
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int atomic_next; /* number of following atomic ops */
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/*
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* We distinguish between: (a) nestable atomic regions that may contain
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* other nestable regions; and (b) flat atomic regions that do not keep
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* track of nesting. Both (a) and (b) are entirely independent of each
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* other, and a flat region may be started in a nestable region or
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* vice-versa.
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*
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* This is required because, for example, in the annotations for
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* seqlocks, we declare seqlock writer critical sections as (a) nestable
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* atomic regions, but reader critical sections as (b) flat atomic
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* regions, but have encountered cases where seqlock reader critical
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* sections are contained within writer critical sections (the opposite
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* may be possible, too).
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*
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* To support these cases, we independently track the depth of nesting
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* for (a), and whether the leaf level is flat for (b).
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*/
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int atomic_nest_count;
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bool in_flat_atomic;
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/*
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* Access mask for all accesses if non-zero.
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*/
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unsigned long access_mask;
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/* List of scoped accesses. */
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struct list_head scoped_accesses;
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};
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/**
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* kcsan_init - initialize KCSAN runtime
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*/
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void kcsan_init(void);
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#else /* CONFIG_KCSAN */
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static inline void kcsan_init(void) { }
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#endif /* CONFIG_KCSAN */
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#endif /* _LINUX_KCSAN_H */
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