[PATCH 14/29] perf tests: Enforce LLVM test for BPF test

[Wang Nan]

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

The newly introduced BPF program attaches a BPF program at
'sys_epoll_pwait()', and collect half samples from it. perf itself never
use that syscall, so further test can verify their result with it.

Since BPF program require LINUX_VERSION_CODE of runtime kernel, this
patch computes that code from uname.

Since the resuling BPF object is useful for further testcases, this patch
introduces 'prepare' and 'cleanup' method to tests, and makes test__llvm()
create a MAP_SHARED memory array to hold the resulting object.

Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
 tools/perf/tests/Build          |   9 +++-
 tools/perf/tests/builtin-test.c |   8 ++++
 tools/perf/tests/llvm.c         | 104 +++++++++++++++++++++++++++++++++++-----
 tools/perf/tests/llvm.h         |  14 ++++++
 tools/perf/tests/tests.h        |   2 +
 5 files changed, 123 insertions(+), 14 deletions(-)
 create mode 100644 tools/perf/tests/llvm.h

diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index c1518bd..8c98409 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -32,7 +32,14 @@ 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.o
+
+$(OUTPUT)tests/llvm-src.c: tests/bpf-script-example.c
+	$(Q)echo '#include <tests/llvm.h>' > $@
+	$(Q)echo 'const char test_llvm__bpf_prog[] =' >> $@
+	$(Q)sed -e 's/"/\\"/g' -e 's/\(.*\)/"\1\\n"/g' $< >> $@
+	$(Q)echo ';' >> $@
+
 
 perf-$(CONFIG_X86) += perf-time-to-tsc.o
 
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 136cd93..1a349e8 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -17,6 +17,8 @@
 static struct test {
 	const char *desc;
 	int (*func)(void);
+	void (*prepare)(void);
+	void (*cleanup)(void);
 } tests[] = {
 	{
 		.desc = "vmlinux symtab matches kallsyms",
@@ -177,6 +179,8 @@ static struct test {
 	{
 		.desc = "Test LLVM searching and compiling",
 		.func = test__llvm,
+		.prepare = test__llvm_prepare,
+		.cleanup = test__llvm_cleanup,
 	},
 	{
 		.func = NULL,
@@ -265,7 +269,11 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
 		}
 
 		pr_debug("\n--- start ---\n");
+		if (tests[curr].prepare)
+			tests[curr].prepare();
 		err = run_test(&tests[curr]);
+		if (tests[curr].cleanup)
+			tests[curr].cleanup();
 		pr_debug("---- end ----\n%s:", tests[curr].desc);
 
 		switch (err) {
diff --git a/tools/perf/tests/llvm.c b/tools/perf/tests/llvm.c
index a337356..e48eb64 100644
--- a/tools/perf/tests/llvm.c
+++ b/tools/perf/tests/llvm.c
@@ -1,9 +1,13 @@
 #include <stdio.h>
+#include <sys/utsname.h>
 #include <bpf/libbpf.h>
 #include <util/llvm-utils.h>
 #include <util/cache.h>
+#include <util/util.h>
+#include <sys/mman.h>
 #include "tests.h"
 #include "debug.h"
+#include "llvm.h"
 
 static int perf_config_cb(const char *var, const char *val,
 			  void *arg __maybe_unused)
@@ -11,16 +15,6 @@ 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)
 {
@@ -41,12 +35,44 @@ static int test__bpf_parsing(void *obj_buf __maybe_unused,
 }
 #endif
 
+static char *
+compose_source(void)
+{
+	struct utsname utsname;
+	int version, patchlevel, sublevel, err;
+	unsigned long version_code;
+	char *code;
+
+	if (uname(&utsname))
+		return NULL;
+
+	err = sscanf(utsname.release, "%d.%d.%d",
+		     &version, &patchlevel, &sublevel);
+	if (err != 3) {
+		fprintf(stderr, " (Can't get kernel version from uname '%s')",
+			utsname.release);
+		return NULL;
+	}
+
+	version_code = (version << 16) + (patchlevel << 8) + sublevel;
+	err = asprintf(&code, "#define LINUX_VERSION_CODE 0x%08lx;\n%s",
+		       version_code, test_llvm__bpf_prog);
+	if (err < 0)
+		return NULL;
+
+	return code;
+}
+
+#define SHARED_BUF_INIT_SIZE	(1 << 20)
+struct test_llvm__bpf_result *p_test_llvm__bpf_result;
+
 int test__llvm(void)
 {
 	char *tmpl_new, *clang_opt_new;
 	void *obj_buf;
 	size_t obj_buf_sz;
 	int err, old_verbose;
+	char *source;
 
 	perf_config(perf_config_cb, NULL);
 
@@ -73,10 +99,22 @@ int test__llvm(void)
 	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);
-	if (err < 0)
+	source = compose_source();
+	if (!source) {
+		pr_err("Failed to compose source code\n");
+		return -1;
+	}
+
+	/* Quote __EOF__ so strings in source won't be expanded by shell */
+	err = asprintf(&tmpl_new, "cat << '__EOF__' | %s\n%s\n__EOF__\n",
+		       llvm_param.clang_bpf_cmd_template, source);
+	free(source);
+	source = NULL;
+	if (err < 0) {
+		pr_err("Failed to alloc new template\n");
 		return -1;
+	}
+
 	err = asprintf(&clang_opt_new, "-xc %s", llvm_param.clang_opt);
 	if (err < 0)
 		return -1;
@@ -93,6 +131,46 @@ int test__llvm(void)
 	}
 
 	err = test__bpf_parsing(obj_buf, obj_buf_sz);
+	if (!err && p_test_llvm__bpf_result) {
+		if (obj_buf_sz > SHARED_BUF_INIT_SIZE) {
+			pr_err("Resulting object too large\n");
+		} else {
+			p_test_llvm__bpf_result->size = obj_buf_sz;
+			memcpy(p_test_llvm__bpf_result->object,
+			       obj_buf, obj_buf_sz);
+		}
+	}
 	free(obj_buf);
 	return err;
 }
+
+void test__llvm_prepare(void)
+{
+	p_test_llvm__bpf_result = mmap(NULL, SHARED_BUF_INIT_SIZE,
+				       PROT_READ | PROT_WRITE,
+				       MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	if (!p_test_llvm__bpf_result)
+		return;
+	memset((void *)p_test_llvm__bpf_result, '\0', SHARED_BUF_INIT_SIZE);
+}
+
+void test__llvm_cleanup(void)
+{
+	unsigned long boundary, buf_end;
+
+	if (!p_test_llvm__bpf_result)
+		return;
+	if (p_test_llvm__bpf_result->size == 0) {
+		munmap((void *)p_test_llvm__bpf_result, SHARED_BUF_INIT_SIZE);
+		p_test_llvm__bpf_result = NULL;
+		return;
+	}
+
+	buf_end = (unsigned long)p_test_llvm__bpf_result + SHARED_BUF_INIT_SIZE;
+
+	boundary = (unsigned long)(p_test_llvm__bpf_result);
+	boundary += p_test_llvm__bpf_result->size;
+	boundary = (boundary + (page_size - 1)) &
+			(~((unsigned long)page_size - 1));
+	munmap((void *)boundary, buf_end - boundary);
+}
diff --git a/tools/perf/tests/llvm.h b/tools/perf/tests/llvm.h
new file mode 100644
index 0000000..1e89e46
--- /dev/null
+++ b/tools/perf/tests/llvm.h
@@ -0,0 +1,14 @@
+#ifndef PERF_TEST_LLVM_H
+#define PERF_TEST_LLVM_H
+
+#include <stddef.h> /* for size_t */
+
+struct test_llvm__bpf_result {
+	size_t size;
+	char object[];
+};
+
+extern struct test_llvm__bpf_result *p_test_llvm__bpf_result;
+extern const char test_llvm__bpf_prog[];
+
+#endif
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index bf113a2..0d79f04 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -63,6 +63,8 @@ int test__fdarray__add(void);
 int test__kmod_path__parse(void);
 int test__thread_map(void);
 int test__llvm(void);
+void test__llvm_prepare(void);
+void test__llvm_cleanup(void);
 
 #if defined(__x86_64__) || defined(__i386__) || defined(__arm__) || defined(__aarch64__)
 #ifdef HAVE_DWARF_UNWIND_SUPPORT
-- 
2.1.0

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