kernel/kcsan/kcsan.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 /*
0003  * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
0004  * see Documentation/dev-tools/kcsan.rst.
0005  *
0006  * Copyright (C) 2019, Google LLC.
0007  */
0008
0009 #ifndef _KERNEL_KCSAN_KCSAN_H
0010 #define _KERNEL_KCSAN_KCSAN_H
0011
0012 #include <linux/atomic.h>
0013 #include <linux/kcsan.h>
0014 #include <linux/sched.h>
0015
0016 /* The number of adjacent watchpoints to check. */
0017 #define KCSAN_CHECK_ADJACENT 1
0018 #define NUM_SLOTS (1 + 2*KCSAN_CHECK_ADJACENT)
0019
0020 extern unsigned int kcsan_udelay_task;
0021 extern unsigned int kcsan_udelay_interrupt;
0022
0023 /*
0024  * Globally enable and disable KCSAN.
0025  */
0026 extern bool kcsan_enabled;
0027
0028 /*
0029  * Save/restore IRQ flags state trace dirtied by KCSAN.
0030  */
0031 void kcsan_save_irqtrace(struct task_struct *task);
0032 void kcsan_restore_irqtrace(struct task_struct *task);
0033
0034 /*
0035  * Statistics counters displayed via debugfs; should only be modified in
0036  * slow-paths.
0037  */
0038 enum kcsan_counter_id {
0039     /*
0040      * Number of watchpoints currently in use.
0041      */
0042     KCSAN_COUNTER_USED_WATCHPOINTS,
0043
0044     /*
0045      * Total number of watchpoints set up.
0046      */
0047     KCSAN_COUNTER_SETUP_WATCHPOINTS,
0048
0049     /*
0050      * Total number of data races.
0051      */
0052     KCSAN_COUNTER_DATA_RACES,
0053
0054     /*
0055      * Total number of ASSERT failures due to races. If the observed race is
0056      * due to two conflicting ASSERT type accesses, then both will be
0057      * counted.
0058      */
0059     KCSAN_COUNTER_ASSERT_FAILURES,
0060
0061     /*
0062      * Number of times no watchpoints were available.
0063      */
0064     KCSAN_COUNTER_NO_CAPACITY,
0065
0066     /*
0067      * A thread checking a watchpoint raced with another checking thread;
0068      * only one will be reported.
0069      */
0070     KCSAN_COUNTER_REPORT_RACES,
0071
0072     /*
0073      * Observed data value change, but writer thread unknown.
0074      */
0075     KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN,
0076
0077     /*
0078      * The access cannot be encoded to a valid watchpoint.
0079      */
0080     KCSAN_COUNTER_UNENCODABLE_ACCESSES,
0081
0082     /*
0083      * Watchpoint encoding caused a watchpoint to fire on mismatching
0084      * accesses.
0085      */
0086     KCSAN_COUNTER_ENCODING_FALSE_POSITIVES,
0087
0088     KCSAN_COUNTER_COUNT, /* number of counters */
0089 };
0090 extern atomic_long_t kcsan_counters[KCSAN_COUNTER_COUNT];
0091
0092 /*
0093  * Returns true if data races in the function symbol that maps to func_addr
0094  * (offsets are ignored) should *not* be reported.
0095  */
0096 extern bool kcsan_skip_report_debugfs(unsigned long func_addr);
0097
0098 /*
0099  * Value-change states.
0100  */
0101 enum kcsan_value_change {
0102     /*
0103      * Did not observe a value-change, however, it is valid to report the
0104      * race, depending on preferences.
0105      */
0106     KCSAN_VALUE_CHANGE_MAYBE,
0107
0108     /*
0109      * Did not observe a value-change, and it is invalid to report the race.
0110      */
0111     KCSAN_VALUE_CHANGE_FALSE,
0112
0113     /*
0114      * The value was observed to change, and the race should be reported.
0115      */
0116     KCSAN_VALUE_CHANGE_TRUE,
0117 };
0118
0119 /*
0120  * The calling thread hit and consumed a watchpoint: set the access information
0121  * to be consumed by the reporting thread. No report is printed yet.
0122  */
0123 void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,
0124                unsigned long ip, int watchpoint_idx);
0125
0126 /*
0127  * The calling thread observed that the watchpoint it set up was hit and
0128  * consumed: print the full report based on information set by the racing
0129  * thread.
0130  */
0131 void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
0132                    unsigned long ip, enum kcsan_value_change value_change,
0133                    int watchpoint_idx, u64 old, u64 new, u64 mask);
0134
0135 /*
0136  * No other thread was observed to race with the access, but the data value
0137  * before and after the stall differs. Reports a race of "unknown origin".
0138  */
0139 void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type,
0140                  unsigned long ip, u64 old, u64 new, u64 mask);
0141
0142 #endif /* _KERNEL_KCSAN_KCSAN_H */