kernel/kcsan/kcsan.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 /*
   4  * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
   5  * see Documentation/dev-tools/kcsan.rst.
   6  */
   7
   8 #ifndef _KERNEL_KCSAN_KCSAN_H
   9 #define _KERNEL_KCSAN_KCSAN_H
  10
  11 #include <linux/atomic.h>
  12 #include <linux/kcsan.h>
  13 #include <linux/sched.h>
  14
  15 /* The number of adjacent watchpoints to check. */
  16 #define KCSAN_CHECK_ADJACENT 1
  17 #define NUM_SLOTS (1 + 2*KCSAN_CHECK_ADJACENT)
  18
  19 extern unsigned int kcsan_udelay_task;
  20 extern unsigned int kcsan_udelay_interrupt;
  21
  22 /*
  23  * Globally enable and disable KCSAN.
  24  */
  25 extern bool kcsan_enabled;
  26
  27 /*
  28  * Save/restore IRQ flags state trace dirtied by KCSAN.
  29  */
  30 void kcsan_save_irqtrace(struct task_struct *task);
  31 void kcsan_restore_irqtrace(struct task_struct *task);
  32
  33 /*
  34  * Initialize debugfs file.
  35  */
  36 void kcsan_debugfs_init(void);
  37
  38 /*
  39  * Statistics counters displayed via debugfs; should only be modified in
  40  * slow-paths.
  41  */
  42 enum kcsan_counter_id {
  43         /*
  44          * Number of watchpoints currently in use.
  45          */
  46         KCSAN_COUNTER_USED_WATCHPOINTS,
  47
  48         /*
  49          * Total number of watchpoints set up.
  50          */
  51         KCSAN_COUNTER_SETUP_WATCHPOINTS,
  52
  53         /*
  54          * Total number of data races.
  55          */
  56         KCSAN_COUNTER_DATA_RACES,
  57
  58         /*
  59          * Total number of ASSERT failures due to races. If the observed race is
  60          * due to two conflicting ASSERT type accesses, then both will be
  61          * counted.
  62          */
  63         KCSAN_COUNTER_ASSERT_FAILURES,
  64
  65         /*
  66          * Number of times no watchpoints were available.
  67          */
  68         KCSAN_COUNTER_NO_CAPACITY,
  69
  70         /*
  71          * A thread checking a watchpoint raced with another checking thread;
  72          * only one will be reported.
  73          */
  74         KCSAN_COUNTER_REPORT_RACES,
  75
  76         /*
  77          * Observed data value change, but writer thread unknown.
  78          */
  79         KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN,
  80
  81         /*
  82          * The access cannot be encoded to a valid watchpoint.
  83          */
  84         KCSAN_COUNTER_UNENCODABLE_ACCESSES,
  85
  86         /*
  87          * Watchpoint encoding caused a watchpoint to fire on mismatching
  88          * accesses.
  89          */
  90         KCSAN_COUNTER_ENCODING_FALSE_POSITIVES,
  91
  92         KCSAN_COUNTER_COUNT, /* number of counters */
  93 };
  94 extern atomic_long_t kcsan_counters[KCSAN_COUNTER_COUNT];
  95
  96 /*
  97  * Returns true if data races in the function symbol that maps to func_addr
  98  * (offsets are ignored) should *not* be reported.
  99  */
 100 extern bool kcsan_skip_report_debugfs(unsigned long func_addr);
 101
 102 /*
 103  * Value-change states.
 104  */
 105 enum kcsan_value_change {
 106         /*
 107          * Did not observe a value-change, however, it is valid to report the
 108          * race, depending on preferences.
 109          */
 110         KCSAN_VALUE_CHANGE_MAYBE,
 111
 112         /*
 113          * Did not observe a value-change, and it is invalid to report the race.
 114          */
 115         KCSAN_VALUE_CHANGE_FALSE,
 116
 117         /*
 118          * The value was observed to change, and the race should be reported.
 119          */
 120         KCSAN_VALUE_CHANGE_TRUE,
 121 };
 122
 123 enum kcsan_report_type {
 124         /*
 125          * The thread that set up the watchpoint and briefly stalled was
 126          * signalled that another thread triggered the watchpoint.
 127          */
 128         KCSAN_REPORT_RACE_SIGNAL,
 129
 130         /*
 131          * A thread found and consumed a matching watchpoint.
 132          */
 133         KCSAN_REPORT_CONSUMED_WATCHPOINT,
 134
 135         /*
 136          * No other thread was observed to race with the access, but the data
 137          * value before and after the stall differs.
 138          */
 139         KCSAN_REPORT_RACE_UNKNOWN_ORIGIN,
 140 };
 141
 142 /*
 143  * Print a race report from thread that encountered the race.
 144  */
 145 extern void kcsan_report(const volatile void *ptr, size_t size, int access_type,
 146                          enum kcsan_value_change value_change,
 147                          enum kcsan_report_type type, int watchpoint_idx);
 148
 149 #endif /* _KERNEL_KCSAN_KCSAN_H */