Hi,
As a next step, let KIOENABLE accept the desired tracing mode. The API
matches the kcov implementation found both in Linux and FreeBSD. As far
as I know, syzkaller is the only kcov consumer in the wild and I will
make sure to adapt the new API there.
Comments? OK?
Index: share/man/man4/kcov.4
===================================================================
RCS file: /cvs/src/share/man/man4/kcov.4,v
retrieving revision 1.5
diff -u -p -r1.5 kcov.4
--- share/man/man4/kcov.4 30 Sep 2018 09:14:43 -0000 1.5
+++ share/man/man4/kcov.4 27 Dec 2018 10:35:13 -0000
@@ -57,8 +57,16 @@ whereas the returned pointer must be int
entries.
The first entry contains the number of entries in the array,
excluding the first entry.
-.It Dv KIOENABLE Fa void
+.It Dv KIOENABLE Fa int *mode
Enable code coverage tracing for the current thread.
+The
+.Fa mode
+must be one of the following:
+.Pp
+.Bl -tag -width KCOV_MODE_TRACE_PC -compact
+.It KCOV_MODE_TRACE_PC
+Trace the kernel program counter.
+.El
.It Dv KIODISABLE Fa void
Disable code coverage tracing for the current thread.
.El
@@ -91,7 +99,7 @@ main(void)
{
unsigned long *cover, i;
unsigned long size = 1024;
- int fd;
+ int fd, mode;
fd = open("/dev/kcov", O_RDWR);
if (fd == -1)
@@ -104,7 +112,8 @@ main(void)
if (cover == MAP_FAILED)
err(1, "mmap");
- if (ioctl(fd, KIOENABLE) == -1)
+ mode = KCOV_MODE_TRACE_PC;
+ if (ioctl(fd, KIOENABLE, &mode) == -1)
err(1, "ioctl: KIOENABLE");
read(-1, NULL, 0);
if (ioctl(fd, KIODISABLE) == -1)
Index: sys/dev/kcov.c
===================================================================
RCS file: /cvs/src/sys/dev/kcov.c,v
retrieving revision 1.7
diff -u -p -r1.7 kcov.c
--- sys/dev/kcov.c 27 Dec 2018 10:04:16 -0000 1.7
+++ sys/dev/kcov.c 27 Dec 2018 10:35:13 -0000
@@ -155,6 +155,7 @@ int
kcovioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct proc *p)
{
struct kcov_dev *kd;
+ int mode;
int error = 0;
kd = kd_lookup(minor(dev));
@@ -171,8 +172,13 @@ kcovioctl(dev_t dev, u_long cmd, caddr_t
error = EBUSY;
break;
}
+ mode = *((int *)data);
+ if (mode != KCOV_MODE_TRACE_PC) {
+ error = EINVAL;
+ break;
+ }
kd->kd_state = KCOV_STATE_TRACE;
- kd->kd_mode = KCOV_MODE_TRACE_PC;
+ kd->kd_mode = mode;
p->p_kd = kd;
break;
case KIODISABLE:
Index: sys/sys/kcov.h
===================================================================
RCS file: /cvs/src/sys/sys/kcov.h,v
retrieving revision 1.2
diff -u -p -r1.2 kcov.h
--- sys/sys/kcov.h 27 Dec 2018 10:04:16 -0000 1.2
+++ sys/sys/kcov.h 27 Dec 2018 10:35:13 -0000
@@ -22,7 +22,7 @@
#include <sys/ioccom.h>
#define KIOSETBUFSIZE _IOW('K', 1, unsigned long)
-#define KIOENABLE _IO('K', 2)
+#define KIOENABLE _IOW('K', 2, int)
#define KIODISABLE _IO('K', 3)
#define KCOV_MODE_NONE 0
