kernel/kcsan/kcsan.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
   4  * see Documentation/dev-tools/kcsan.rst.
   5  *
   6  * Copyright (C) 2019, Google LLC.
   7  */
   8
   9 #ifndef _KERNEL_KCSAN_KCSAN_H
  10 #define _KERNEL_KCSAN_KCSAN_H
  11
  12 #include <linux/atomic.h>
  13 #include <linux/kcsan.h>
  14 #include <linux/sched.h>
  15
  16 /* The number of adjacent watchpoints to check. */
  17 #define KCSAN_CHECK_ADJACENT 1
  18 #define NUM_SLOTS (1 + 2*KCSAN_CHECK_ADJACENT)
  19
  20 extern unsigned int kcsan_udelay_task;
  21 extern unsigned int kcsan_udelay_interrupt;
  22
  23 /*
  24  * Globally enable and disable KCSAN.
  25  */
  26 extern bool kcsan_enabled;
  27
  28 /*
  29  * Save/restore IRQ flags state trace dirtied by KCSAN.
  30  */
  31 void kcsan_save_irqtrace(struct task_struct *task);
  32 void kcsan_restore_irqtrace(struct task_struct *task);
  33
  34 /*
  35  * Statistics counters displayed via debugfs; should only be modified in
  36  * slow-paths.
  37  */
  38 enum kcsan_counter_id {
  39         /*
  40          * Number of watchpoints currently in use.
  41          */
  42         KCSAN_COUNTER_USED_WATCHPOINTS,
  43
  44         /*
  45          * Total number of watchpoints set up.
  46          */
  47         KCSAN_COUNTER_SETUP_WATCHPOINTS,
  48
  49         /*
  50          * Total number of data races.
  51          */
  52         KCSAN_COUNTER_DATA_RACES,
  53
  54         /*
  55          * Total number of ASSERT failures due to races. If the observed race is
  56          * due to two conflicting ASSERT type accesses, then both will be
  57          * counted.
  58          */
  59         KCSAN_COUNTER_ASSERT_FAILURES,
  60
  61         /*
  62          * Number of times no watchpoints were available.
  63          */
  64         KCSAN_COUNTER_NO_CAPACITY,
  65
  66         /*
  67          * A thread checking a watchpoint raced with another checking thread;
  68          * only one will be reported.
  69          */
  70         KCSAN_COUNTER_REPORT_RACES,
  71
  72         /*
  73          * Observed data value change, but writer thread unknown.
  74          */
  75         KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN,
  76
  77         /*
  78          * The access cannot be encoded to a valid watchpoint.
  79          */
  80         KCSAN_COUNTER_UNENCODABLE_ACCESSES,
  81
  82         /*
  83          * Watchpoint encoding caused a watchpoint to fire on mismatching
  84          * accesses.
  85          */
  86         KCSAN_COUNTER_ENCODING_FALSE_POSITIVES,
  87
  88         KCSAN_COUNTER_COUNT, /* number of counters */
  89 };
  90 extern atomic_long_t kcsan_counters[KCSAN_COUNTER_COUNT];
  91
  92 /*
  93  * Returns true if data races in the function symbol that maps to func_addr
  94  * (offsets are ignored) should *not* be reported.
  95  */
  96 extern bool kcsan_skip_report_debugfs(unsigned long func_addr);
  97
  98 /*
  99  * Value-change states.
 100  */
 101 enum kcsan_value_change {
 102         /*
 103          * Did not observe a value-change, however, it is valid to report the
 104          * race, depending on preferences.
 105          */
 106         KCSAN_VALUE_CHANGE_MAYBE,
 107
 108         /*
 109          * Did not observe a value-change, and it is invalid to report the race.
 110          */
 111         KCSAN_VALUE_CHANGE_FALSE,
 112
 113         /*
 114          * The value was observed to change, and the race should be reported.
 115          */
 116         KCSAN_VALUE_CHANGE_TRUE,
 117 };
 118
 119 /*
 120  * The calling thread hit and consumed a watchpoint: set the access information
 121  * to be consumed by the reporting thread. No report is printed yet.
 122  */
 123 void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,
 124                            unsigned long ip, int watchpoint_idx);
 125
 126 /*
 127  * The calling thread observed that the watchpoint it set up was hit and
 128  * consumed: print the full report based on information set by the racing
 129  * thread.
 130  */
 131 void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
 132                                unsigned long ip, enum kcsan_value_change value_change,
 133                                int watchpoint_idx, u64 old, u64 new, u64 mask);
 134
 135 /*
 136  * No other thread was observed to race with the access, but the data value
 137  * before and after the stall differs. Reports a race of "unknown origin".
 138  */
 139 void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type,
 140                                  unsigned long ip, u64 old, u64 new, u64 mask);
 141
 142 #endif /* _KERNEL_KCSAN_KCSAN_H */