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docs: sphinxify kcov.txt and move to dev-tools

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Another document added to the dev-tools collection.

Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Jonathan Corbet 2016-08-07 15:13:00 -06:00
parent d228af5bcb
commit 758f726e7f
2 changed files with 38 additions and 37 deletions
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74
Documentation/kcov.txt → Documentation/dev-tools/kcov.rst
View File

@ -12,38 +12,38 @@ To achieve this goal it does not collect coverage in soft/hard interrupts
and instrumentation of some inherently non-deterministic parts of kernel is
disbled (e.g. scheduler, locking).
Usage:
======
Usage
-----
Configure kernel with:
Configure the kernel with::
CONFIG_KCOV=y
CONFIG_KCOV requires gcc built on revision 231296 or later.
Profiling data will only become accessible once debugfs has been mounted:
Profiling data will only become accessible once debugfs has been mounted::
mount -t debugfs none /sys/kernel/debug
The following program demonstrates kcov usage from within a test program:
The following program demonstrates kcov usage from within a test program::
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#define KCOV_INIT_TRACE _IOR('c', 1, unsigned long)
#define KCOV_ENABLE _IO('c', 100)
#define KCOV_DISABLE _IO('c', 101)
#define COVER_SIZE (64<<10)
#define KCOV_INIT_TRACE _IOR('c', 1, unsigned long)
#define KCOV_ENABLE _IO('c', 100)
#define KCOV_DISABLE _IO('c', 101)
#define COVER_SIZE (64<<10)
int main(int argc, char **argv)
{
int main(int argc, char **argv)
{
int fd;
unsigned long *cover, n, i;
@ -83,24 +83,24 @@ int main(int argc, char **argv)
if (close(fd))
perror("close"), exit(1);
return 0;
}
}
After piping through addr2line output of the program looks as follows:
After piping through addr2line output of the program looks as follows::
SyS_read
fs/read_write.c:562
__fdget_pos
fs/file.c:774
__fget_light
fs/file.c:746
__fget_light
fs/file.c:750
__fget_light
fs/file.c:760
__fdget_pos
fs/file.c:784
SyS_read
fs/read_write.c:562
SyS_read
fs/read_write.c:562
__fdget_pos
fs/file.c:774
__fget_light
fs/file.c:746
__fget_light
fs/file.c:750
__fget_light
fs/file.c:760
__fdget_pos
fs/file.c:784
SyS_read
fs/read_write.c:562
If a program needs to collect coverage from several threads (independently),
it needs to open /sys/kernel/debug/kcov in each thread separately.

1
Documentation/dev-tools/tools.rst
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@ -16,3 +16,4 @@ whole; patches welcome!
coccinelle
sparse
kcov