While writing a selftest with kselftest_harness.h, I often want to
check which paths are actually exercised.
Let's support generating KCOV coverage data.
We can specify the output directory via the KCOV_OUTPUT environment
variable, and the number of instructions to collect via the KCOV_SLOTS
environment variable.
# KCOV_OUTPUT=$PWD/kcov KCOV_SLOTS=$((4096 * 2)) \
./tools/testing/selftests/net/af_unix/scm_inq
Both variables can also be specified as the make variable.
# make -C tools/testing/selftests/ \
KCOV_OUTPUT=$PWD/kcov KCOV_SLOTS=$((4096 * 4)) \
kselftest_override_timeout=60 TARGETS=net/af_unix run_tests
The coverage data can be simply decoded with addr2line:
$ cat kcov/* | sort | uniq | addr2line -e vmlinux | grep unix
net/unix/af_unix.c:1056
net/unix/af_unix.c:3138
net/unix/af_unix.c:3834
net/unix/af_unix.c:3838
net/unix/af_unix.c:311 (discriminator 2)
...
or more nicely with a script embedded in vock [0]:
$ cat kcov/* | sort | uniq > local.log
$ python3 ~/kernel/tools/vock/report.py \
--kernel-src ./ --vmlinux ./vmlinux \
--mode local --local-log local.log --filter unix
...
------------------------------- Coverage Report
--------------------------------
📄 net/unix/af_unix.c (276 lines)
...
942 | static int unix_setsockopt(struct socket *sock, int level, int optname,
943 | sockptr_t optval, unsigned int optlen)
944 | {
...
961 | switch (optname) {
962 | case SO_INQ:
963 > if (sk->sk_type != SOCK_STREAM)
964 | return -EINVAL;
965 |
966 > if (val > 1 || val < 0)
967 | return -EINVAL;
968 |
969 > WRITE_ONCE(u->recvmsg_inq, val);
970 | break;
Link:
https://github.com/kzall0c/vock/blob/f3d97de9954f9df758c0ab287ca7e24e654288c7/report.py
#[0]
Signed-off-by: Kuniyuki Iwashima <[email protected]>
---
v2: Support TEST()
v1:
https://lore.kernel.org/linux-kselftest/[email protected]/
---
Documentation/dev-tools/kselftest.rst | 41 ++++++
tools/testing/selftests/Makefile | 14 ++-
tools/testing/selftests/kselftest_harness.h | 133 +++++++++++++++++++-
3 files changed, 178 insertions(+), 10 deletions(-)
diff --git a/Documentation/dev-tools/kselftest.rst
b/Documentation/dev-tools/kselftest.rst
index 18c2da67fae4..5c2b92ac4a30 100644
--- a/Documentation/dev-tools/kselftest.rst
+++ b/Documentation/dev-tools/kselftest.rst
@@ -200,6 +200,47 @@ You can look at the TAP output to see if you ran into the
timeout. Test
runners which know a test must run under a specific time can then optionally
treat these timeouts then as fatal.
+KCOV for selftests
+==================
+
+Selftests built with `kselftest_harness.h` natively support generating
+KCOV coverage data. See :doc:`KCOV: code coverage for fuzzing
</dev-tools/kcov>`
+for prerequisites.
+
+You can specify the output directory with the `KCOV_OUTPUT` environment
+variable. Additionally, you can specify the number of instructions to
+collect with the `KCOV_SLOTS` environment variable ::
+
+ # KCOV_OUTPUT=$PWD/kcov KCOV_SLOTS=$((4096 * 2)) \
+ ./tools/testing/selftests/net/af_unix/scm_inq
+
+In the output directory, a coverage file is generated for each test
+case in the selftest ::
+
+ $ ls kcov/
+ scm_inq.dgram.basic scm_inq.seqpacket.basic scm_inq.stream.basic
+
+The default value of `KCOV_SLOTS` is `4096`, and `KCOV_SLOTS` multiplied
+by `sizeof(unsigned long)` must be multiple of `4096`, so the smallest
+value is `512`.
+
+Both `KCOV_OUTPUT` and `KCOV_SLOTS` can be specified as the variables
+on the `make` command line ::
+
+ # make -C tools/testing/selftests/ \
+ kselftest_override_timeout=60 \
+ KCOV_OUTPUT=$PWD/kcov KCOV_SLOTS=$((4096 * 4)) \
+ TARGETS=net/af_unix run_tests
+
+The collected data can be decoded with `addr2line` ::
+
+ $ cat kcov/* | sort | uniq | addr2line -e vmlinux | grep unix
+ net/unix/af_unix.c:1056
+ net/unix/af_unix.c:3138
+ net/unix/af_unix.c:3834
+ net/unix/af_unix.c:3838
+ ...
+
Packaging selftests
===================
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index c46ebdb9b8ef..40e70fb1a347 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -218,12 +218,14 @@ all:
done; exit $$ret;
run_tests: all
- @for TARGET in $(TARGETS); do \
- BUILD_TARGET=$$BUILD/$$TARGET; \
- $(MAKE) OUTPUT=$$BUILD_TARGET -C $$TARGET run_tests \
- SRC_PATH=$(shell readlink -e $$(pwd)) \
- OBJ_PATH=$(BUILD) \
- O=$(abs_objtree); \
+ @for TARGET in $(TARGETS); do \
+ BUILD_TARGET=$$BUILD/$$TARGET; \
+ $(MAKE) OUTPUT=$$BUILD_TARGET \
+ KCOV_OUTPUT=$(abspath $(KCOV_OUTPUT)) \
+ -C $$TARGET run_tests \
+ SRC_PATH=$(shell readlink -e $$(pwd)) \
+ OBJ_PATH=$(BUILD) \
+ O=$(abs_objtree); \
done;
hotplug:
diff --git a/tools/testing/selftests/kselftest_harness.h
b/tools/testing/selftests/kselftest_harness.h
index 3f66e862e83e..5b7a01722981 100644
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -56,6 +56,8 @@
#include <asm/types.h>
#include <ctype.h>
#include <errno.h>
+#include <fcntl.h>
+#include <linux/kcov.h>
#include <linux/unistd.h>
#include <poll.h>
#include <stdbool.h>
@@ -63,7 +65,9 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/ioctl.h>
#include <sys/mman.h>
+#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
@@ -175,9 +179,12 @@
static void test_name(struct __test_metadata *_metadata); \
static void wrapper_##test_name( \
struct __test_metadata *_metadata, \
- struct __fixture_variant_metadata __attribute__((unused))
*variant) \
+ struct __fixture_variant_metadata __attribute__((unused))
*variant, \
+ char *test_full_name) \
{ \
+ enable_kcov(_metadata); \
test_name(_metadata); \
+ disable_kcov(_metadata, test_full_name); \
} \
static struct __test_metadata _##test_name##_object = \
{ .name = #test_name, \
@@ -401,7 +408,8 @@
const FIXTURE_VARIANT(fixture_name) *variant); \
static void wrapper_##fixture_name##_##test_name( \
struct __test_metadata *_metadata, \
- struct __fixture_variant_metadata *variant) \
+ struct __fixture_variant_metadata *variant, \
+ char *test_full_name) \
{ \
/* fixture data is alloced, setup, and torn down per call. */ \
FIXTURE_DATA(fixture_name) self_private, *self = NULL; \
@@ -430,7 +438,9 @@
if (_metadata->exit_code) \
_exit(0); \
*_metadata->no_teardown = false; \
+ enable_kcov(_metadata); \
fixture_name##_##test_name(_metadata, self,
variant->data); \
+ disable_kcov(_metadata, test_full_name); \
_metadata->teardown_fn(false, _metadata, self,
variant->data); \
_exit(0); \
} else if (child < 0 || child != waitpid(child, &status, 0)) { \
@@ -470,6 +480,8 @@
object->teardown_fn =
&wrapper_##fixture_name##_##test_name##_teardown; \
object->termsig = signal; \
object->timeout = tmout; \
+ object->kcov_fd = -1; \
+ object->kcov_slots = -1; \
_##fixture_name##_##test_name##_object = object; \
__register_test(object); \
} \
@@ -908,7 +920,8 @@ __register_fixture_variant(struct __fixture_metadata *f,
struct __test_metadata {
const char *name;
void (*fn)(struct __test_metadata *,
- struct __fixture_variant_metadata *);
+ struct __fixture_variant_metadata *,
+ char *test_name);
pid_t pid; /* pid of test when being run */
struct __fixture_metadata *fixture;
void (*teardown_fn)(bool in_parent, struct __test_metadata *_metadata,
@@ -923,6 +936,10 @@ struct __test_metadata {
const void *variant;
struct __test_results *results;
struct __test_metadata *prev, *next;
+ int kcov_fd;
+ int kcov_slots;
+ char *kcov_dir;
+ unsigned long *kcov_mem;
};
static inline bool __test_passed(struct __test_metadata *metadata)
@@ -1185,6 +1202,114 @@ static bool test_enabled(int argc, char **argv,
return !has_positive;
}
+#define KCOV_SLOTS 4096
+
+static void enable_kcov(struct __test_metadata *t)
+{
+ char *slots;
+ int err;
+
+ t->kcov_dir = getenv("KCOV_OUTPUT");
+ if (!t->kcov_dir || *t->kcov_dir == '\0')
+ return;
+
+ slots = getenv("KCOV_SLOTS");
+ if (slots && *slots != '\0')
+ sscanf(slots, "%d", &t->kcov_slots);
+ if (t->kcov_slots <= 0)
+ t->kcov_slots = KCOV_SLOTS;
+
+ t->kcov_fd = open("/sys/kernel/debug/kcov", O_RDWR);
+ if (t->kcov_fd < 0) {
+ ksft_print_msg("ERROR OPENING KCOV FD\n");
+ goto err;
+ }
+
+ err = ioctl(t->kcov_fd, KCOV_INIT_TRACE, t->kcov_slots);
+ if (err) {
+ ksft_print_msg("ERROR INITIALISING KCOV\n");
+ goto err;
+ }
+
+ t->kcov_mem = mmap(NULL, sizeof(unsigned long) * t->kcov_slots,
+ PROT_READ | PROT_WRITE, MAP_SHARED, t->kcov_fd, 0);
+ if ((void *)t->kcov_mem == MAP_FAILED) {
+ ksft_print_msg("ERROR ALLOCATING MEMORY FOR KCOV\n");
+ goto err;
+ }
+
+ err = ioctl(t->kcov_fd, KCOV_ENABLE, KCOV_TRACE_PC);
+ if (err) {
+ ksft_print_msg("ERROR ENABLING KCOV\n");
+ goto err;
+ }
+
+ __atomic_store_n(&t->kcov_mem[0], 0, __ATOMIC_RELAXED);
+ return;
+err:
+ t->exit_code = KSFT_FAIL;
+ _exit(KSFT_FAIL);
+}
+
+static void disable_kcov(struct __test_metadata *t, char *test_name)
+{
+ int slots, err, dir, fd, i;
+
+ if (t->kcov_fd == -1)
+ return;
+
+ slots = __atomic_load_n(&t->kcov_mem[0], __ATOMIC_RELAXED);
+ if (slots == t->kcov_slots - 1)
+ ksft_print_msg("Set KCOV_SLOTS to a value greater than %d\n",
t->kcov_slots);
+
+ err = ioctl(t->kcov_fd, KCOV_DISABLE, 0);
+ if (err) {
+ ksft_print_msg("ERROR DISABLING KCOV\n");
+ goto out;
+ }
+
+ err = mkdir(t->kcov_dir, 0755);
+ if (err == -1 && errno != EEXIST) {
+ ksft_print_msg("ERROR CREATING '%s'\n", t->kcov_dir);
+ goto out;
+ }
+ err = 0;
+
+ dir = open(t->kcov_dir, O_DIRECTORY);
+ if (dir < 0) {
+ ksft_print_msg("ERROR OPENING %s\n", t->kcov_dir);
+ err = dir;
+ goto out;
+ }
+
+ fd = openat(dir, test_name, O_RDWR | O_CREAT | O_TRUNC);
+
+ close(dir);
+
+ if (fd == -1) {
+ ksft_print_msg("ERROR CREATING '%s' at '%s'\n", test_name,
t->kcov_dir);
+ err = fd;
+ goto out;
+ }
+
+ for (i = 0; i < slots; i++) {
+ char buf[64];
+ int size;
+
+ size = snprintf(buf, 64, "0x%lx\n", t->kcov_mem[i + 1]);
+ write(fd, buf, size);
+ }
+
+out:
+ munmap(t->kcov_mem, sizeof(t->kcov_mem[0]) * t->kcov_slots);
+ close(t->kcov_fd);
+
+ if (err) {
+ t->exit_code = KSFT_FAIL;
+ _exit(KSFT_FAIL);
+ }
+}
+
static void __run_test(struct __fixture_metadata *f,
struct __fixture_variant_metadata *variant,
struct __test_metadata *t)
@@ -1216,7 +1341,7 @@ static void __run_test(struct __fixture_metadata *f,
t->exit_code = KSFT_FAIL;
} else if (child == 0) {
setpgrp();
- t->fn(t, variant);
+ t->fn(t, variant, test_name);
_exit(t->exit_code);
} else {
t->pid = child;
--
2.51.1.838.g19442a804e-goog
