1 // SPDX-License-Identifier: GPL-2.0
2 #define pr_fmt(fmt) "kcov: " fmt
4 #define DISABLE_BRANCH_PROFILING
5 #include <linux/atomic.h>
6 #include <linux/compiler.h>
7 #include <linux/errno.h>
8 #include <linux/export.h>
9 #include <linux/types.h>
10 #include <linux/file.h>
12 #include <linux/hashtable.h>
13 #include <linux/init.h>
15 #include <linux/preempt.h>
16 #include <linux/printk.h>
17 #include <linux/sched.h>
18 #include <linux/slab.h>
19 #include <linux/spinlock.h>
20 #include <linux/vmalloc.h>
21 #include <linux/debugfs.h>
22 #include <linux/uaccess.h>
23 #include <linux/kcov.h>
24 #include <linux/refcount.h>
25 #include <linux/log2.h>
26 #include <asm/setup.h>
28 #define kcov_debug(fmt, ...) pr_debug("%s: " fmt, __func__, ##__VA_ARGS__)
30 /* Number of 64-bit words written per one comparison: */
31 #define KCOV_WORDS_PER_CMP 4
34 * kcov descriptor (one per opened debugfs file).
35 * State transitions of the descriptor:
36 * - initial state after open()
37 * - then there must be a single ioctl(KCOV_INIT_TRACE) call
38 * - then, mmap() call (several calls are allowed but not useful)
39 * - then, ioctl(KCOV_ENABLE, arg), where arg is
40 * KCOV_TRACE_PC - to trace only the PCs
42 * KCOV_TRACE_CMP - to trace only the comparison operands
43 * - then, ioctl(KCOV_DISABLE) to disable the task.
44 * Enabling/disabling ioctls can be repeated (only one task a time allowed).
48 * Reference counter. We keep one for:
49 * - opened file descriptor
50 * - task with enabled coverage (we can't unwire it from another task)
51 * - each code section for remote coverage collection
54 /* The lock protects mode, size, area and t. */
57 /* Size of arena (in long's). */
59 /* Coverage buffer shared with user space. */
61 /* Task for which we collect coverage, or NULL. */
62 struct task_struct
*t
;
63 /* Collecting coverage from remote (background) threads. */
65 /* Size of remote area (in long's). */
66 unsigned int remote_size
;
68 * Sequence is incremented each time kcov is reenabled, used by
69 * kcov_remote_stop(), see the comment there.
74 struct kcov_remote_area
{
75 struct list_head list
;
82 struct hlist_node hnode
;
85 static DEFINE_SPINLOCK(kcov_remote_lock
);
86 static DEFINE_HASHTABLE(kcov_remote_map
, 4);
87 static struct list_head kcov_remote_areas
= LIST_HEAD_INIT(kcov_remote_areas
);
89 /* Must be called with kcov_remote_lock locked. */
90 static struct kcov_remote
*kcov_remote_find(u64 handle
)
92 struct kcov_remote
*remote
;
94 hash_for_each_possible(kcov_remote_map
, remote
, hnode
, handle
) {
95 if (remote
->handle
== handle
)
101 static struct kcov_remote
*kcov_remote_add(struct kcov
*kcov
, u64 handle
)
103 struct kcov_remote
*remote
;
105 if (kcov_remote_find(handle
))
106 return ERR_PTR(-EEXIST
);
107 remote
= kmalloc(sizeof(*remote
), GFP_ATOMIC
);
109 return ERR_PTR(-ENOMEM
);
110 remote
->handle
= handle
;
112 hash_add(kcov_remote_map
, &remote
->hnode
, handle
);
116 /* Must be called with kcov_remote_lock locked. */
117 static struct kcov_remote_area
*kcov_remote_area_get(unsigned int size
)
119 struct kcov_remote_area
*area
;
120 struct list_head
*pos
;
122 kcov_debug("size = %u\n", size
);
123 list_for_each(pos
, &kcov_remote_areas
) {
124 area
= list_entry(pos
, struct kcov_remote_area
, list
);
125 if (area
->size
== size
) {
126 list_del(&area
->list
);
127 kcov_debug("rv = %px\n", area
);
131 kcov_debug("rv = NULL\n");
135 /* Must be called with kcov_remote_lock locked. */
136 static void kcov_remote_area_put(struct kcov_remote_area
*area
,
139 kcov_debug("area = %px, size = %u\n", area
, size
);
140 INIT_LIST_HEAD(&area
->list
);
142 list_add(&area
->list
, &kcov_remote_areas
);
145 static notrace
bool check_kcov_mode(enum kcov_mode needed_mode
, struct task_struct
*t
)
150 * We are interested in code coverage as a function of a syscall inputs,
151 * so we ignore code executed in interrupts.
155 mode
= READ_ONCE(t
->kcov_mode
);
157 * There is some code that runs in interrupts but for which
158 * in_interrupt() returns false (e.g. preempt_schedule_irq()).
159 * READ_ONCE()/barrier() effectively provides load-acquire wrt
160 * interrupts, there are paired barrier()/WRITE_ONCE() in
164 return mode
== needed_mode
;
167 static notrace
unsigned long canonicalize_ip(unsigned long ip
)
169 #ifdef CONFIG_RANDOMIZE_BASE
170 ip
-= kaslr_offset();
176 * Entry point from instrumented code.
177 * This is called once per basic-block/edge.
179 void notrace
__sanitizer_cov_trace_pc(void)
181 struct task_struct
*t
;
183 unsigned long ip
= canonicalize_ip(_RET_IP_
);
187 if (!check_kcov_mode(KCOV_MODE_TRACE_PC
, t
))
191 /* The first 64-bit word is the number of subsequent PCs. */
192 pos
= READ_ONCE(area
[0]) + 1;
193 if (likely(pos
< t
->kcov_size
)) {
195 WRITE_ONCE(area
[0], pos
);
198 EXPORT_SYMBOL(__sanitizer_cov_trace_pc
);
200 #ifdef CONFIG_KCOV_ENABLE_COMPARISONS
201 static void notrace
write_comp_data(u64 type
, u64 arg1
, u64 arg2
, u64 ip
)
203 struct task_struct
*t
;
205 u64 count
, start_index
, end_pos
, max_pos
;
208 if (!check_kcov_mode(KCOV_MODE_TRACE_CMP
, t
))
211 ip
= canonicalize_ip(ip
);
214 * We write all comparison arguments and types as u64.
215 * The buffer was allocated for t->kcov_size unsigned longs.
217 area
= (u64
*)t
->kcov_area
;
218 max_pos
= t
->kcov_size
* sizeof(unsigned long);
220 count
= READ_ONCE(area
[0]);
222 /* Every record is KCOV_WORDS_PER_CMP 64-bit words. */
223 start_index
= 1 + count
* KCOV_WORDS_PER_CMP
;
224 end_pos
= (start_index
+ KCOV_WORDS_PER_CMP
) * sizeof(u64
);
225 if (likely(end_pos
<= max_pos
)) {
226 area
[start_index
] = type
;
227 area
[start_index
+ 1] = arg1
;
228 area
[start_index
+ 2] = arg2
;
229 area
[start_index
+ 3] = ip
;
230 WRITE_ONCE(area
[0], count
+ 1);
234 void notrace
__sanitizer_cov_trace_cmp1(u8 arg1
, u8 arg2
)
236 write_comp_data(KCOV_CMP_SIZE(0), arg1
, arg2
, _RET_IP_
);
238 EXPORT_SYMBOL(__sanitizer_cov_trace_cmp1
);
240 void notrace
__sanitizer_cov_trace_cmp2(u16 arg1
, u16 arg2
)
242 write_comp_data(KCOV_CMP_SIZE(1), arg1
, arg2
, _RET_IP_
);
244 EXPORT_SYMBOL(__sanitizer_cov_trace_cmp2
);
246 void notrace
__sanitizer_cov_trace_cmp4(u32 arg1
, u32 arg2
)
248 write_comp_data(KCOV_CMP_SIZE(2), arg1
, arg2
, _RET_IP_
);
250 EXPORT_SYMBOL(__sanitizer_cov_trace_cmp4
);
252 void notrace
__sanitizer_cov_trace_cmp8(u64 arg1
, u64 arg2
)
254 write_comp_data(KCOV_CMP_SIZE(3), arg1
, arg2
, _RET_IP_
);
256 EXPORT_SYMBOL(__sanitizer_cov_trace_cmp8
);
258 void notrace
__sanitizer_cov_trace_const_cmp1(u8 arg1
, u8 arg2
)
260 write_comp_data(KCOV_CMP_SIZE(0) | KCOV_CMP_CONST
, arg1
, arg2
,
263 EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp1
);
265 void notrace
__sanitizer_cov_trace_const_cmp2(u16 arg1
, u16 arg2
)
267 write_comp_data(KCOV_CMP_SIZE(1) | KCOV_CMP_CONST
, arg1
, arg2
,
270 EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp2
);
272 void notrace
__sanitizer_cov_trace_const_cmp4(u32 arg1
, u32 arg2
)
274 write_comp_data(KCOV_CMP_SIZE(2) | KCOV_CMP_CONST
, arg1
, arg2
,
277 EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp4
);
279 void notrace
__sanitizer_cov_trace_const_cmp8(u64 arg1
, u64 arg2
)
281 write_comp_data(KCOV_CMP_SIZE(3) | KCOV_CMP_CONST
, arg1
, arg2
,
284 EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp8
);
286 void notrace
__sanitizer_cov_trace_switch(u64 val
, u64
*cases
)
289 u64 count
= cases
[0];
291 u64 type
= KCOV_CMP_CONST
;
295 type
|= KCOV_CMP_SIZE(0);
298 type
|= KCOV_CMP_SIZE(1);
301 type
|= KCOV_CMP_SIZE(2);
304 type
|= KCOV_CMP_SIZE(3);
309 for (i
= 0; i
< count
; i
++)
310 write_comp_data(type
, cases
[i
+ 2], val
, _RET_IP_
);
312 EXPORT_SYMBOL(__sanitizer_cov_trace_switch
);
313 #endif /* ifdef CONFIG_KCOV_ENABLE_COMPARISONS */
315 static void kcov_start(struct task_struct
*t
, unsigned int size
,
316 void *area
, enum kcov_mode mode
, int sequence
)
318 kcov_debug("t = %px, size = %u, area = %px\n", t
, size
, area
);
319 /* Cache in task struct for performance. */
322 /* See comment in check_kcov_mode(). */
324 WRITE_ONCE(t
->kcov_mode
, mode
);
325 t
->kcov_sequence
= sequence
;
328 static void kcov_stop(struct task_struct
*t
)
330 WRITE_ONCE(t
->kcov_mode
, KCOV_MODE_DISABLED
);
336 static void kcov_task_reset(struct task_struct
*t
)
340 t
->kcov_sequence
= 0;
344 void kcov_task_init(struct task_struct
*t
)
347 t
->kcov_handle
= current
->kcov_handle
;
350 static void kcov_reset(struct kcov
*kcov
)
353 kcov
->mode
= KCOV_MODE_INIT
;
354 kcov
->remote
= false;
355 kcov
->remote_size
= 0;
359 static void kcov_remote_reset(struct kcov
*kcov
)
362 struct kcov_remote
*remote
;
363 struct hlist_node
*tmp
;
365 spin_lock(&kcov_remote_lock
);
366 hash_for_each_safe(kcov_remote_map
, bkt
, tmp
, remote
, hnode
) {
367 if (remote
->kcov
!= kcov
)
369 kcov_debug("removing handle %llx\n", remote
->handle
);
370 hash_del(&remote
->hnode
);
373 /* Do reset before unlock to prevent races with kcov_remote_start(). */
375 spin_unlock(&kcov_remote_lock
);
378 static void kcov_disable(struct task_struct
*t
, struct kcov
*kcov
)
382 kcov_remote_reset(kcov
);
387 static void kcov_get(struct kcov
*kcov
)
389 refcount_inc(&kcov
->refcount
);
392 static void kcov_put(struct kcov
*kcov
)
394 if (refcount_dec_and_test(&kcov
->refcount
)) {
395 kcov_remote_reset(kcov
);
401 void kcov_task_exit(struct task_struct
*t
)
409 spin_lock(&kcov
->lock
);
410 kcov_debug("t = %px, kcov->t = %px\n", t
, kcov
->t
);
412 * For KCOV_ENABLE devices we want to make sure that t->kcov->t == t,
413 * which comes down to:
414 * WARN_ON(!kcov->remote && kcov->t != t);
416 * For KCOV_REMOTE_ENABLE devices, the exiting task is either:
417 * 2. A remote task between kcov_remote_start() and kcov_remote_stop().
418 * In this case we should print a warning right away, since a task
419 * shouldn't be exiting when it's in a kcov coverage collection
420 * section. Here t points to the task that is collecting remote
421 * coverage, and t->kcov->t points to the thread that created the
422 * kcov device. Which means that to detect this case we need to
423 * check that t != t->kcov->t, and this gives us the following:
424 * WARN_ON(kcov->remote && kcov->t != t);
426 * 2. The task that created kcov exiting without calling KCOV_DISABLE,
427 * and then again we can make sure that t->kcov->t == t:
428 * WARN_ON(kcov->remote && kcov->t != t);
430 * By combining all three checks into one we get:
432 if (WARN_ON(kcov
->t
!= t
)) {
433 spin_unlock(&kcov
->lock
);
436 /* Just to not leave dangling references behind. */
437 kcov_disable(t
, kcov
);
438 spin_unlock(&kcov
->lock
);
442 static int kcov_mmap(struct file
*filep
, struct vm_area_struct
*vma
)
446 struct kcov
*kcov
= vma
->vm_file
->private_data
;
447 unsigned long size
, off
;
450 area
= vmalloc_user(vma
->vm_end
- vma
->vm_start
);
454 spin_lock(&kcov
->lock
);
455 size
= kcov
->size
* sizeof(unsigned long);
456 if (kcov
->mode
!= KCOV_MODE_INIT
|| vma
->vm_pgoff
!= 0 ||
457 vma
->vm_end
- vma
->vm_start
!= size
) {
463 vma
->vm_flags
|= VM_DONTEXPAND
;
464 spin_unlock(&kcov
->lock
);
465 for (off
= 0; off
< size
; off
+= PAGE_SIZE
) {
466 page
= vmalloc_to_page(kcov
->area
+ off
);
467 if (vm_insert_page(vma
, vma
->vm_start
+ off
, page
))
468 WARN_ONCE(1, "vm_insert_page() failed");
473 spin_unlock(&kcov
->lock
);
478 static int kcov_open(struct inode
*inode
, struct file
*filep
)
482 kcov
= kzalloc(sizeof(*kcov
), GFP_KERNEL
);
485 kcov
->mode
= KCOV_MODE_DISABLED
;
487 refcount_set(&kcov
->refcount
, 1);
488 spin_lock_init(&kcov
->lock
);
489 filep
->private_data
= kcov
;
490 return nonseekable_open(inode
, filep
);
493 static int kcov_close(struct inode
*inode
, struct file
*filep
)
495 kcov_put(filep
->private_data
);
499 static int kcov_get_mode(unsigned long arg
)
501 if (arg
== KCOV_TRACE_PC
)
502 return KCOV_MODE_TRACE_PC
;
503 else if (arg
== KCOV_TRACE_CMP
)
504 #ifdef CONFIG_KCOV_ENABLE_COMPARISONS
505 return KCOV_MODE_TRACE_CMP
;
514 * Fault in a lazily-faulted vmalloc area before it can be used by
515 * __santizer_cov_trace_pc(), to avoid recursion issues if any code on the
516 * vmalloc fault handling path is instrumented.
518 static void kcov_fault_in_area(struct kcov
*kcov
)
520 unsigned long stride
= PAGE_SIZE
/ sizeof(unsigned long);
521 unsigned long *area
= kcov
->area
;
522 unsigned long offset
;
524 for (offset
= 0; offset
< kcov
->size
; offset
+= stride
)
525 READ_ONCE(area
[offset
]);
528 static inline bool kcov_check_handle(u64 handle
, bool common_valid
,
529 bool uncommon_valid
, bool zero_valid
)
531 if (handle
& ~(KCOV_SUBSYSTEM_MASK
| KCOV_INSTANCE_MASK
))
533 switch (handle
& KCOV_SUBSYSTEM_MASK
) {
534 case KCOV_SUBSYSTEM_COMMON
:
535 return (handle
& KCOV_INSTANCE_MASK
) ?
536 common_valid
: zero_valid
;
537 case KCOV_SUBSYSTEM_USB
:
538 return uncommon_valid
;
545 static int kcov_ioctl_locked(struct kcov
*kcov
, unsigned int cmd
,
548 struct task_struct
*t
;
549 unsigned long size
, unused
;
551 struct kcov_remote_arg
*remote_arg
;
552 struct kcov_remote
*remote
;
555 case KCOV_INIT_TRACE
:
556 kcov_debug("KCOV_INIT_TRACE\n");
558 * Enable kcov in trace mode and setup buffer size.
559 * Must happen before anything else.
561 if (kcov
->mode
!= KCOV_MODE_DISABLED
)
564 * Size must be at least 2 to hold current position and one PC.
565 * Later we allocate size * sizeof(unsigned long) memory,
566 * that must not overflow.
569 if (size
< 2 || size
> INT_MAX
/ sizeof(unsigned long))
572 kcov
->mode
= KCOV_MODE_INIT
;
575 kcov_debug("KCOV_ENABLE\n");
577 * Enable coverage for the current task.
578 * At this point user must have been enabled trace mode,
579 * and mmapped the file. Coverage collection is disabled only
580 * at task exit or voluntary by KCOV_DISABLE. After that it can
581 * be enabled for another task.
583 if (kcov
->mode
!= KCOV_MODE_INIT
|| !kcov
->area
)
586 if (kcov
->t
!= NULL
|| t
->kcov
!= NULL
)
588 mode
= kcov_get_mode(arg
);
591 kcov_fault_in_area(kcov
);
593 kcov_start(t
, kcov
->size
, kcov
->area
, kcov
->mode
,
597 /* Put either in kcov_task_exit() or in KCOV_DISABLE. */
601 kcov_debug("KCOV_DISABLE\n");
602 /* Disable coverage for the current task. */
604 if (unused
!= 0 || current
->kcov
!= kcov
)
607 if (WARN_ON(kcov
->t
!= t
))
609 kcov_disable(t
, kcov
);
612 case KCOV_REMOTE_ENABLE
:
613 kcov_debug("KCOV_REMOTE_ENABLE\n");
614 if (kcov
->mode
!= KCOV_MODE_INIT
|| !kcov
->area
)
617 if (kcov
->t
!= NULL
|| t
->kcov
!= NULL
)
619 remote_arg
= (struct kcov_remote_arg
*)arg
;
620 mode
= kcov_get_mode(remote_arg
->trace_mode
);
623 if (remote_arg
->area_size
> LONG_MAX
/ sizeof(unsigned long))
629 kcov
->remote_size
= remote_arg
->area_size
;
630 spin_lock(&kcov_remote_lock
);
631 for (i
= 0; i
< remote_arg
->num_handles
; i
++) {
632 kcov_debug("handle %llx\n", remote_arg
->handles
[i
]);
633 if (!kcov_check_handle(remote_arg
->handles
[i
],
634 false, true, false)) {
635 spin_unlock(&kcov_remote_lock
);
636 kcov_disable(t
, kcov
);
639 remote
= kcov_remote_add(kcov
, remote_arg
->handles
[i
]);
640 if (IS_ERR(remote
)) {
641 spin_unlock(&kcov_remote_lock
);
642 kcov_disable(t
, kcov
);
643 return PTR_ERR(remote
);
646 if (remote_arg
->common_handle
) {
647 kcov_debug("common handle %llx\n",
648 remote_arg
->common_handle
);
649 if (!kcov_check_handle(remote_arg
->common_handle
,
650 true, false, false)) {
651 spin_unlock(&kcov_remote_lock
);
652 kcov_disable(t
, kcov
);
655 remote
= kcov_remote_add(kcov
,
656 remote_arg
->common_handle
);
657 if (IS_ERR(remote
)) {
658 spin_unlock(&kcov_remote_lock
);
659 kcov_disable(t
, kcov
);
660 return PTR_ERR(remote
);
662 t
->kcov_handle
= remote_arg
->common_handle
;
664 spin_unlock(&kcov_remote_lock
);
665 /* Put either in kcov_task_exit() or in KCOV_DISABLE. */
673 static long kcov_ioctl(struct file
*filep
, unsigned int cmd
, unsigned long arg
)
677 struct kcov_remote_arg
*remote_arg
= NULL
;
678 unsigned int remote_num_handles
;
679 unsigned long remote_arg_size
;
681 if (cmd
== KCOV_REMOTE_ENABLE
) {
682 if (get_user(remote_num_handles
, (unsigned __user
*)(arg
+
683 offsetof(struct kcov_remote_arg
, num_handles
))))
685 if (remote_num_handles
> KCOV_REMOTE_MAX_HANDLES
)
687 remote_arg_size
= struct_size(remote_arg
, handles
,
689 remote_arg
= memdup_user((void __user
*)arg
, remote_arg_size
);
690 if (IS_ERR(remote_arg
))
691 return PTR_ERR(remote_arg
);
692 if (remote_arg
->num_handles
!= remote_num_handles
) {
696 arg
= (unsigned long)remote_arg
;
699 kcov
= filep
->private_data
;
700 spin_lock(&kcov
->lock
);
701 res
= kcov_ioctl_locked(kcov
, cmd
, arg
);
702 spin_unlock(&kcov
->lock
);
709 static const struct file_operations kcov_fops
= {
711 .unlocked_ioctl
= kcov_ioctl
,
712 .compat_ioctl
= kcov_ioctl
,
714 .release
= kcov_close
,
718 * kcov_remote_start() and kcov_remote_stop() can be used to annotate a section
719 * of code in a kernel background thread to allow kcov to be used to collect
720 * coverage from that part of code.
722 * The handle argument of kcov_remote_start() identifies a code section that is
723 * used for coverage collection. A userspace process passes this handle to
724 * KCOV_REMOTE_ENABLE ioctl to make the used kcov device start collecting
725 * coverage for the code section identified by this handle.
727 * The usage of these annotations in the kernel code is different depending on
728 * the type of the kernel thread whose code is being annotated.
730 * For global kernel threads that are spawned in a limited number of instances
731 * (e.g. one USB hub_event() worker thread is spawned per USB HCD), each
732 * instance must be assigned a unique 4-byte instance id. The instance id is
733 * then combined with a 1-byte subsystem id to get a handle via
734 * kcov_remote_handle(subsystem_id, instance_id).
736 * For local kernel threads that are spawned from system calls handler when a
737 * user interacts with some kernel interface (e.g. vhost workers), a handle is
738 * passed from a userspace process as the common_handle field of the
739 * kcov_remote_arg struct (note, that the user must generate a handle by using
740 * kcov_remote_handle() with KCOV_SUBSYSTEM_COMMON as the subsystem id and an
741 * arbitrary 4-byte non-zero number as the instance id). This common handle
742 * then gets saved into the task_struct of the process that issued the
743 * KCOV_REMOTE_ENABLE ioctl. When this process issues system calls that spawn
744 * kernel threads, the common handle must be retrieved via kcov_common_handle()
745 * and passed to the spawned threads via custom annotations. Those kernel
746 * threads must in turn be annotated with kcov_remote_start(common_handle) and
747 * kcov_remote_stop(). All of the threads that are spawned by the same process
748 * obtain the same handle, hence the name "common".
750 * See Documentation/dev-tools/kcov.rst for more details.
752 * Internally, this function looks up the kcov device associated with the
753 * provided handle, allocates an area for coverage collection, and saves the
754 * pointers to kcov and area into the current task_struct to allow coverage to
755 * be collected via __sanitizer_cov_trace_pc()
756 * In turns kcov_remote_stop() clears those pointers from task_struct to stop
757 * collecting coverage and copies all collected coverage into the kcov area.
759 void kcov_remote_start(u64 handle
)
761 struct kcov_remote
*remote
;
763 struct task_struct
*t
;
768 if (WARN_ON(!kcov_check_handle(handle
, true, true, true)))
770 if (WARN_ON(!in_task()))
774 * Check that kcov_remote_start is not called twice
775 * nor called by user tasks (with enabled kcov).
777 if (WARN_ON(t
->kcov
))
780 kcov_debug("handle = %llx\n", handle
);
782 spin_lock(&kcov_remote_lock
);
783 remote
= kcov_remote_find(handle
);
785 kcov_debug("no remote found");
786 spin_unlock(&kcov_remote_lock
);
789 /* Put in kcov_remote_stop(). */
790 kcov_get(remote
->kcov
);
791 t
->kcov
= remote
->kcov
;
793 * Read kcov fields before unlock to prevent races with
794 * KCOV_DISABLE / kcov_remote_reset().
796 size
= remote
->kcov
->remote_size
;
797 mode
= remote
->kcov
->mode
;
798 sequence
= remote
->kcov
->sequence
;
799 area
= kcov_remote_area_get(size
);
800 spin_unlock(&kcov_remote_lock
);
803 area
= vmalloc(size
* sizeof(unsigned long));
806 kcov_put(remote
->kcov
);
810 /* Reset coverage size. */
813 kcov_debug("area = %px, size = %u", area
, size
);
815 kcov_start(t
, size
, area
, mode
, sequence
);
818 EXPORT_SYMBOL(kcov_remote_start
);
820 static void kcov_move_area(enum kcov_mode mode
, void *dst_area
,
821 unsigned int dst_area_size
, void *src_area
)
823 u64 word_size
= sizeof(unsigned long);
824 u64 count_size
, entry_size_log
;
825 u64 dst_len
, src_len
;
826 void *dst_entries
, *src_entries
;
827 u64 dst_occupied
, dst_free
, bytes_to_move
, entries_moved
;
829 kcov_debug("%px %u <= %px %lu\n",
830 dst_area
, dst_area_size
, src_area
, *(unsigned long *)src_area
);
833 case KCOV_MODE_TRACE_PC
:
834 dst_len
= READ_ONCE(*(unsigned long *)dst_area
);
835 src_len
= *(unsigned long *)src_area
;
836 count_size
= sizeof(unsigned long);
837 entry_size_log
= __ilog2_u64(sizeof(unsigned long));
839 case KCOV_MODE_TRACE_CMP
:
840 dst_len
= READ_ONCE(*(u64
*)dst_area
);
841 src_len
= *(u64
*)src_area
;
842 count_size
= sizeof(u64
);
843 BUILD_BUG_ON(!is_power_of_2(KCOV_WORDS_PER_CMP
));
844 entry_size_log
= __ilog2_u64(sizeof(u64
) * KCOV_WORDS_PER_CMP
);
851 /* As arm can't divide u64 integers use log of entry size. */
852 if (dst_len
> ((dst_area_size
* word_size
- count_size
) >>
855 dst_occupied
= count_size
+ (dst_len
<< entry_size_log
);
856 dst_free
= dst_area_size
* word_size
- dst_occupied
;
857 bytes_to_move
= min(dst_free
, src_len
<< entry_size_log
);
858 dst_entries
= dst_area
+ dst_occupied
;
859 src_entries
= src_area
+ count_size
;
860 memcpy(dst_entries
, src_entries
, bytes_to_move
);
861 entries_moved
= bytes_to_move
>> entry_size_log
;
864 case KCOV_MODE_TRACE_PC
:
865 WRITE_ONCE(*(unsigned long *)dst_area
, dst_len
+ entries_moved
);
867 case KCOV_MODE_TRACE_CMP
:
868 WRITE_ONCE(*(u64
*)dst_area
, dst_len
+ entries_moved
);
875 /* See the comment before kcov_remote_start() for usage details. */
876 void kcov_remote_stop(void)
878 struct task_struct
*t
= current
;
879 struct kcov
*kcov
= t
->kcov
;
880 void *area
= t
->kcov_area
;
881 unsigned int size
= t
->kcov_size
;
882 int sequence
= t
->kcov_sequence
;
885 kcov_debug("no kcov found\n");
892 spin_lock(&kcov
->lock
);
894 * KCOV_DISABLE could have been called between kcov_remote_start()
895 * and kcov_remote_stop(), hence the check.
897 kcov_debug("move if: %d == %d && %d\n",
898 sequence
, kcov
->sequence
, (int)kcov
->remote
);
899 if (sequence
== kcov
->sequence
&& kcov
->remote
)
900 kcov_move_area(kcov
->mode
, kcov
->area
, kcov
->size
, area
);
901 spin_unlock(&kcov
->lock
);
903 spin_lock(&kcov_remote_lock
);
904 kcov_remote_area_put(area
, size
);
905 spin_unlock(&kcov_remote_lock
);
909 EXPORT_SYMBOL(kcov_remote_stop
);
911 /* See the comment before kcov_remote_start() for usage details. */
912 u64
kcov_common_handle(void)
914 return current
->kcov_handle
;
916 EXPORT_SYMBOL(kcov_common_handle
);
918 static int __init
kcov_init(void)
921 * The kcov debugfs file won't ever get removed and thus,
922 * there is no need to protect it against removal races. The
923 * use of debugfs_create_file_unsafe() is actually safe here.
925 debugfs_create_file_unsafe("kcov", 0600, NULL
, NULL
, &kcov_fops
);
930 device_initcall(kcov_init
);