include/linux/kcov.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_KCOV_H
   3 #define _LINUX_KCOV_H
   4
   5 #include <linux/sched.h>
   6 #include <uapi/linux/kcov.h>
   7
   8 struct task_struct;
   9
  10 #ifdef CONFIG_KCOV
  11
  12 enum kcov_mode {
  13         /* Coverage collection is not enabled yet. */
  14         KCOV_MODE_DISABLED = 0,
  15         /* KCOV was initialized, but tracing mode hasn't been chosen yet. */
  16         KCOV_MODE_INIT = 1,
  17         /*
  18          * Tracing coverage collection mode.
  19          * Covered PCs are collected in a per-task buffer.
  20          */
  21         KCOV_MODE_TRACE_PC = 2,
  22         /* Collecting comparison operands mode. */
  23         KCOV_MODE_TRACE_CMP = 3,
  24         /* The process owns a KCOV remote reference. */
  25         KCOV_MODE_REMOTE = 4,
  26 };
  27
  28 #define KCOV_IN_CTXSW   (1 << 30)
  29
  30 void kcov_task_init(struct task_struct *t);
  31 void kcov_task_exit(struct task_struct *t);
  32
  33 #define kcov_prepare_switch(t)                  \
  34 do {                                            \
  35         (t)->kcov_mode |= KCOV_IN_CTXSW;        \
  36 } while (0)
  37
  38 #define kcov_finish_switch(t)                   \
  39 do {                                            \
  40         (t)->kcov_mode &= ~KCOV_IN_CTXSW;       \
  41 } while (0)
  42
  43 /* See Documentation/dev-tools/kcov.rst for usage details. */
  44 void kcov_remote_start(u64 handle);
  45 void kcov_remote_stop(void);
  46 u64 kcov_common_handle(void);
  47
  48 static inline void kcov_remote_start_common(u64 id)
  49 {
  50         kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_COMMON, id));
  51 }
  52
  53 static inline void kcov_remote_start_usb(u64 id)
  54 {
  55         kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_USB, id));
  56 }
  57
  58 /*
  59  * The softirq flavor of kcov_remote_*() functions is introduced as a temporary
  60  * workaround for KCOV's lack of nested remote coverage sections support.
  61  *
  62  * Adding support is tracked in https://bugzilla.kernel.org/show_bug.cgi?id=210337.
  63  *
  64  * kcov_remote_start_usb_softirq():
  65  *
  66  * 1. Only collects coverage when called in the softirq context. This allows
  67  *    avoiding nested remote coverage collection sections in the task context.
  68  *    For example, USB/IP calls usb_hcd_giveback_urb() in the task context
  69  *    within an existing remote coverage collection section. Thus, KCOV should
  70  *    not attempt to start collecting coverage within the coverage collection
  71  *    section in __usb_hcd_giveback_urb() in this case.
  72  *
  73  * 2. Disables interrupts for the duration of the coverage collection section.
  74  *    This allows avoiding nested remote coverage collection sections in the
  75  *    softirq context (a softirq might occur during the execution of a work in
  76  *    the BH workqueue, which runs with in_serving_softirq() > 0).
  77  *    For example, usb_giveback_urb_bh() runs in the BH workqueue with
  78  *    interrupts enabled, so __usb_hcd_giveback_urb() might be interrupted in
  79  *    the middle of its remote coverage collection section, and the interrupt
  80  *    handler might invoke __usb_hcd_giveback_urb() again.
  81  */
  82
  83 static inline unsigned long kcov_remote_start_usb_softirq(u64 id)
  84 {
  85         unsigned long flags = 0;
  86
  87         if (in_serving_softirq()) {
  88                 local_irq_save(flags);
  89                 kcov_remote_start_usb(id);
  90         }
  91
  92         return flags;
  93 }
  94
  95 static inline void kcov_remote_stop_softirq(unsigned long flags)
  96 {
  97         if (in_serving_softirq()) {
  98                 kcov_remote_stop();
  99                 local_irq_restore(flags);
 100         }
 101 }
 102
 103 #ifdef CONFIG_64BIT
 104 typedef unsigned long kcov_u64;
 105 #else
 106 typedef unsigned long long kcov_u64;
 107 #endif
 108
 109 void __sanitizer_cov_trace_pc(void);
 110 void __sanitizer_cov_trace_cmp1(u8 arg1, u8 arg2);
 111 void __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2);
 112 void __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2);
 113 void __sanitizer_cov_trace_cmp8(kcov_u64 arg1, kcov_u64 arg2);
 114 void __sanitizer_cov_trace_const_cmp1(u8 arg1, u8 arg2);
 115 void __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2);
 116 void __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2);
 117 void __sanitizer_cov_trace_const_cmp8(kcov_u64 arg1, kcov_u64 arg2);
 118 void __sanitizer_cov_trace_switch(kcov_u64 val, void *cases);
 119
 120 #else
 121
 122 static inline void kcov_task_init(struct task_struct *t) {}
 123 static inline void kcov_task_exit(struct task_struct *t) {}
 124 static inline void kcov_prepare_switch(struct task_struct *t) {}
 125 static inline void kcov_finish_switch(struct task_struct *t) {}
 126 static inline void kcov_remote_start(u64 handle) {}
 127 static inline void kcov_remote_stop(void) {}
 128 static inline u64 kcov_common_handle(void)
 129 {
 130         return 0;
 131 }
 132 static inline void kcov_remote_start_common(u64 id) {}
 133 static inline void kcov_remote_start_usb(u64 id) {}
 134 static inline unsigned long kcov_remote_start_usb_softirq(u64 id)
 135 {
 136         return 0;
 137 }
 138 static inline void kcov_remote_stop_softirq(unsigned long flags) {}
 139
 140 #endif /* CONFIG_KCOV */
 141 #endif /* _LINUX_KCOV_H */