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@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1446817783-86722-6-git-send-email-wangnan0@huawei.com
Signed-off-by: He Kuang <hekuang@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 129 insertions, 31 deletions

diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index 50de2253cff6..6c095b3d92a9 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 410a70b93b93..0ec9c2c03164 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 8f713f6d32f3..05683c5f183e 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 000000000000..bd63cee687b5
--- /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