[tip:perf/urgent] perf test: Enhance the LLVM test: update basic BPF test program

From: tip-bot for Wang Nan
Date: Sun Nov 08 2015 - 02:34:23 EST

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Commit-ID: b31de018a6284a25e0fdfeb028e724f8417ec3b1
Gitweb: http://git.kernel.org/tip/b31de018a6284a25e0fdfeb028e724f8417ec3b1
Author: Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Fri, 6 Nov 2015 13:49:41 +0000
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 6 Nov 2015 17:49:24 -0300

perf test: Enhance the LLVM test: update basic BPF test program

This patch replaces the original toy BPF program with the previously
introduced bpf-script-example.c. Dynamically embeddeding it into
'llvm-src-base.c'.

The newly introduced BPF program attaches a BPF program to
'sys_epoll_pwait()'. perf itself never use that syscall, so further test
can verify their result with it. The program would generate 1 sample in
every 2 calls of epoll_pwait() system call.

Since the resulting BPF object is useful per se for further tests,
test_llvm__fetch_bpf_obj() is introduced for creating BPF objects from
source. The LLVM test was rewritten to use it.

Committer note:

Running it:

[root@zoo wb]# perf test -v LLVM
35: Test LLVM searching and compiling :
--- start ---
test child forked, pid 17740
Kernel build dir is set to /lib/modules/4.3.0-rc1+/build
set env: KBUILD_DIR=/lib/modules/4.3.0-rc1+/build
unset env: KBUILD_OPTS
include option is set to -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.9.2/include -I/home/git/linux/arch/x86/include -Iarch/x86/include/generated/uapi -Iarch/x86/include/generated -I/home/git/linux/include -Iinclude -I/home/git/linux/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/home/git/linux/include/uapi -Iinclude/generated/uapi -include /home/git/linux/include/linux/kconfig.h
set env: NR_CPUS=4
set env: LINUX_VERSION_CODE=0x40300
set env: CLANG_EXEC=/usr/libexec/icecc/bin/clang
set env: CLANG_OPTIONS=-xc
set env: KERNEL_INC_OPTIONS= -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.9.2/include -I/home/git/linux/arch/x86/include -Iarch/x86/include/generated/uapi -Iarch/x86/include/generated -I/home/git/linux/include -Iinclude -I/home/git/linux/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/home/git/linux/include/uapi -Iinclude/generated/uapi -include /home/git/linux/include/linux/kconfig.h
set env: WORKING_DIR=/lib/modules/4.3.0-rc1+/build
set env: CLANG_SOURCE=-
llvm compiling command template: echo '/*
* bpf-script-example.c
* Test basic LLVM building
*/
#ifndef LINUX_VERSION_CODE
# error Need LINUX_VERSION_CODE
# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
#endif
#define BPF_ANY 0
#define BPF_MAP_TYPE_ARRAY 2
#define BPF_FUNC_map_lookup_elem 1
#define BPF_FUNC_map_update_elem 2

static void *(*bpf_map_lookup_elem)(void *map, void *key) =
(void *) BPF_FUNC_map_lookup_elem;
static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) =
(void *) BPF_FUNC_map_update_elem;

struct bpf_map_def {
unsigned int type;
unsigned int key_size;
unsigned int value_size;
unsigned int max_entries;
};

#define SEC(NAME) __attribute__((section(NAME), used))
struct bpf_map_def SEC("maps") flip_table = {
.type = BPF_MAP_TYPE_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(int),
.max_entries = 1,
};

SEC("func=sys_epoll_pwait")
int bpf_func__sys_epoll_pwait(void *ctx)
{
int ind =0;
int *flag = bpf_map_lookup_elem(&flip_table, &ind);
int new_flag;
if (!flag)
return 0;
/* flip flag and store back */
new_flag = !*flag;
bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
return new_flag;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
' | $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS -DLINUX_VERSION_CODE=$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -target bpf -O2 -o -
test child finished with 0
---- end ----
Test LLVM searching and compiling: Ok
[root@zoo wb]#

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1446817783-86722-6-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/tests/Build | 9 ++-
tools/perf/tests/bpf-script-example.c | 4 ++
tools/perf/tests/llvm.c | 131 ++++++++++++++++++++++++++--------
tools/perf/tests/llvm.h | 16 +++++
4 files changed, 129 insertions(+), 31 deletions(-)

diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index 50de225..6c095b3 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -31,9 +31,16 @@ perf-y += sample-parsing.o
perf-y += parse-no-sample-id-all.o
perf-y += kmod-path.o
perf-y += thread-map.o
-perf-y += llvm.o
+perf-y += llvm.o llvm-src-base.o
perf-y += topology.o

+$(OUTPUT)tests/llvm-src-base.c: tests/bpf-script-example.c
+ $(call rule_mkdir)
+ $(Q)echo '#include <tests/llvm.h>' > $@
+ $(Q)echo 'const char test_llvm__bpf_base_prog[] =' >> $@
+ $(Q)sed -e 's/"/\\"/g' -e 's/$.*$/"\1\\n"/g' $< >> $@
+ $(Q)echo ';' >> $@
+
ifeq ($(ARCH),$(filter $(ARCH),x86 arm arm64))
perf-$(CONFIG_DWARF_UNWIND) += dwarf-unwind.o
endif
diff --git a/tools/perf/tests/bpf-script-example.c b/tools/perf/tests/bpf-script-example.c
index 410a70b..0ec9c2c 100644
--- a/tools/perf/tests/bpf-script-example.c
+++ b/tools/perf/tests/bpf-script-example.c
@@ -1,3 +1,7 @@
+/*
+ * bpf-script-example.c
+ * Test basic LLVM building
+ */
#ifndef LINUX_VERSION_CODE
# error Need LINUX_VERSION_CODE
# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
diff --git a/tools/perf/tests/llvm.c b/tools/perf/tests/llvm.c
index 8f713f6..05683c5 100644
--- a/tools/perf/tests/llvm.c
+++ b/tools/perf/tests/llvm.c
@@ -2,6 +2,7 @@
#include <bpf/libbpf.h>
#include <util/llvm-utils.h>
#include <util/cache.h>
+#include "llvm.h"
#include "tests.h"
#include "debug.h"

@@ -11,16 +12,6 @@ static int perf_config_cb(const char *var, const char *val,
return perf_default_config(var, val, arg);
}

-/*
- * Randomly give it a "version" section since we don't really load it
- * into kernel
- */
-static const char test_bpf_prog[] =
- "__attribute__((section(\"do_fork\"), used)) "
- "int fork(void *ctx) {return 0;} "
- "char _license[] __attribute__((section(\"license\"), used)) = \"GPL\";"
- "int _version __attribute__((section(\"version\"), used)) = 0x40100;";
-
#ifdef HAVE_LIBBPF_SUPPORT
static int test__bpf_parsing(void *obj_buf, size_t obj_buf_sz)
{
@@ -28,25 +19,47 @@ static int test__bpf_parsing(void *obj_buf, size_t obj_buf_sz)

obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, NULL);
if (IS_ERR(obj))
- return -1;
+ return TEST_FAIL;
bpf_object__close(obj);
- return 0;
+ return TEST_OK;
}
#else
static int test__bpf_parsing(void *obj_buf __maybe_unused,
size_t obj_buf_sz __maybe_unused)
{
pr_debug("Skip bpf parsing\n");
- return 0;
+ return TEST_OK;
}
#endif

-int test__llvm(void)
+static struct {
+ const char *source;
+ const char *desc;
+} bpf_source_table[__LLVM_TESTCASE_MAX] = {
+ [LLVM_TESTCASE_BASE] = {
+ .source = test_llvm__bpf_base_prog,
+ .desc = "Basic BPF llvm compiling test",
+ },
+};
+
+
+int
+test_llvm__fetch_bpf_obj(void **p_obj_buf,
+ size_t *p_obj_buf_sz,
+ enum test_llvm__testcase index,
+ bool force)
{
- char *tmpl_new, *clang_opt_new;
- void *obj_buf;
- size_t obj_buf_sz;
- int err, old_verbose;
+ const char *source;
+ const char *desc;
+ const char *tmpl_old, *clang_opt_old;
+ char *tmpl_new = NULL, *clang_opt_new = NULL;
+ int err, old_verbose, ret = TEST_FAIL;
+
+ if (index >= __LLVM_TESTCASE_MAX)
+ return TEST_FAIL;
+
+ source = bpf_source_table[index].source;
+ desc = bpf_source_table[index].desc;

perf_config(perf_config_cb, NULL);

@@ -54,42 +67,100 @@ int test__llvm(void)
* Skip this test if user's .perfconfig doesn't set [llvm] section
* and clang is not found in $PATH, and this is not perf test -v
*/
- if (verbose == 0 && !llvm_param.user_set_param && llvm__search_clang()) {
+ if (!force && (verbose == 0 &&
+ !llvm_param.user_set_param &&
+ llvm__search_clang())) {
pr_debug("No clang and no verbosive, skip this test\n");
return TEST_SKIP;
}

- old_verbose = verbose;
/*
* llvm is verbosity when error. Suppress all error output if
* not 'perf test -v'.
*/
+ old_verbose = verbose;
if (verbose == 0)
verbose = -1;

+ *p_obj_buf = NULL;
+ *p_obj_buf_sz = 0;
+
if (!llvm_param.clang_bpf_cmd_template)
- return -1;
+ goto out;

if (!llvm_param.clang_opt)
llvm_param.clang_opt = strdup("");

- err = asprintf(&tmpl_new, "echo '%s' | %s", test_bpf_prog,
- llvm_param.clang_bpf_cmd_template);
+ err = asprintf(&tmpl_new, "echo '%s' | %s%s", source,
+ llvm_param.clang_bpf_cmd_template,
+ old_verbose ? "" : " 2>/dev/null");
if (err < 0)
- return -1;
+ goto out;
err = asprintf(&clang_opt_new, "-xc %s", llvm_param.clang_opt);
if (err < 0)
- return -1;
+ goto out;

+ tmpl_old = llvm_param.clang_bpf_cmd_template;
llvm_param.clang_bpf_cmd_template = tmpl_new;
+ clang_opt_old = llvm_param.clang_opt;
llvm_param.clang_opt = clang_opt_new;
- err = llvm__compile_bpf("-", &obj_buf, &obj_buf_sz);
+
+ err = llvm__compile_bpf("-", p_obj_buf, p_obj_buf_sz);
+
+ llvm_param.clang_bpf_cmd_template = tmpl_old;
+ llvm_param.clang_opt = clang_opt_old;

verbose = old_verbose;
if (err)
- return TEST_FAIL;
+ goto out;
+
+ ret = TEST_OK;
+out:
+ free(tmpl_new);
+ free(clang_opt_new);
+ if (ret != TEST_OK)
+ pr_debug("Failed to compile test case: '%s'\n", desc);
+ return ret;
+}

- err = test__bpf_parsing(obj_buf, obj_buf_sz);
- free(obj_buf);
- return err;
+int test__llvm(void)
+{
+ enum test_llvm__testcase i;
+
+ for (i = 0; i < __LLVM_TESTCASE_MAX; i++) {
+ int ret;
+ void *obj_buf = NULL;
+ size_t obj_buf_sz = 0;
+
+ ret = test_llvm__fetch_bpf_obj(&obj_buf, &obj_buf_sz,
+ i, false);
+
+ if (ret == TEST_OK) {
+ ret = test__bpf_parsing(obj_buf, obj_buf_sz);
+ if (ret != TEST_OK)
+ pr_debug("Failed to parse test case '%s'\n",
+ bpf_source_table[i].desc);
+ }
+ free(obj_buf);
+
+ switch (ret) {
+ case TEST_SKIP:
+ return TEST_SKIP;
+ case TEST_OK:
+ break;
+ default:
+ /*
+ * Test 0 is the basic LLVM test. If test 0
+ * fail, the basic LLVM support not functional
+ * so the whole test should fail. If other test
+ * case fail, it can be fixed by adjusting
+ * config so don't report error.
+ */
+ if (i == 0)
+ return TEST_FAIL;
+ else
+ return TEST_SKIP;
+ }
+ }
+ return TEST_OK;
}
diff --git a/tools/perf/tests/llvm.h b/tools/perf/tests/llvm.h
new file mode 100644
index 0000000..bd63cee
--- /dev/null
+++ b/tools/perf/tests/llvm.h
@@ -0,0 +1,16 @@
+#ifndef PERF_TEST_LLVM_H
+#define PERF_TEST_LLVM_H
+
+#include <stddef.h> /* for size_t */
+#include <stdbool.h> /* for bool */
+
+extern const char test_llvm__bpf_base_prog[];
+
+enum test_llvm__testcase {
+ LLVM_TESTCASE_BASE,
+ __LLVM_TESTCASE_MAX,
+};
+
+int test_llvm__fetch_bpf_obj(void **p_obj_buf, size_t *p_obj_buf_sz,
+ enum test_llvm__testcase index, bool force);
+#endif
--
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