Subject: [PATCH bpf-next v2 6/9] samples/bpf: move common-purpose perf_event functions to bpf_load.c

From: Yonghong Song <[email-masked]>
Date: Wed, 18 Apr 2018 09:54:41 -0700

There is no functionality change in this patch. The common-purpose
perf_event functions are moved from trace_output_user.c to bpf_load.c
so that these function can be reused later.

Signed-off-by: Yonghong Song <[email-masked]>
---
 samples/bpf/bpf_load.c          | 104 ++++++++++++++++++++++++++++++++++++
 samples/bpf/bpf_load.h          |   5 ++
 samples/bpf/trace_output_user.c | 113 ++++------------------------------------
 3 files changed, 118 insertions(+), 104 deletions(-)

diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index bebe418..62aa5cc 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -713,3 +713,107 @@ struct ksym *ksym_search(long key)
 	return &syms[0];
 }
 
+static int page_size;
+static int page_cnt = 8;
+static volatile struct perf_event_mmap_page *header;
+
+static int perf_event_mmap(int fd)
+{
+	void *base;
+	int mmap_size;
+
+	page_size = getpagesize();
+	mmap_size = page_size * (page_cnt + 1);
+
+	base = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	if (base == MAP_FAILED) {
+		printf("mmap err\n");
+		return -1;
+	}
+
+	header = base;
+	return 0;
+}
+
+static int perf_event_poll(int fd)
+{
+	struct pollfd pfd = { .fd = fd, .events = POLLIN };
+
+	return poll(&pfd, 1, 1000);
+}
+
+struct perf_event_sample {
+	struct perf_event_header header;
+	__u32 size;
+	char data[];
+};
+
+static void perf_event_read(perf_event_print_fn fn)
+{
+	__u64 data_tail = header->data_tail;
+	__u64 data_head = header->data_head;
+	__u64 buffer_size = page_cnt * page_size;
+	void *base, *begin, *end;
+	char buf[256];
+
+	asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */
+	if (data_head == data_tail)
+		return;
+
+	base = ((char *)header) + page_size;
+
+	begin = base + data_tail % buffer_size;
+	end = base + data_head % buffer_size;
+
+	while (begin != end) {
+		struct perf_event_sample *e;
+
+		e = begin;
+		if (begin + e->header.size > base + buffer_size) {
+			long len = base + buffer_size - begin;
+
+			assert(len < e->header.size);
+			memcpy(buf, begin, len);
+			memcpy(buf + len, base, e->header.size - len);
+			e = (void *) buf;
+			begin = base + e->header.size - len;
+		} else if (begin + e->header.size == base + buffer_size) {
+			begin = base;
+		} else {
+			begin += e->header.size;
+		}
+
+		if (e->header.type == PERF_RECORD_SAMPLE) {
+			fn(e->data, e->size);
+		} else if (e->header.type == PERF_RECORD_LOST) {
+			struct {
+				struct perf_event_header header;
+				__u64 id;
+				__u64 lost;
+			} *lost = (void *) e;
+			printf("lost %lld events\n", lost->lost);
+		} else {
+			printf("unknown event type=%d size=%d\n",
+			       e->header.type, e->header.size);
+		}
+	}
+
+	__sync_synchronize(); /* smp_mb() */
+	header->data_tail = data_head;
+}
+
+int perf_event_poller(int fd, perf_event_exec_fn exec_fn,
+		      perf_event_print_fn output_fn)
+{
+	if (perf_event_mmap(fd) < 0)
+		return 1;
+
+	exec_fn();
+
+	for (;;) {
+		perf_event_poll(fd);
+		perf_event_read(output_fn);
+	}
+
+	return 0;
+}
diff --git a/samples/bpf/bpf_load.h b/samples/bpf/bpf_load.h
index 453c200..d618750 100644
--- a/samples/bpf/bpf_load.h
+++ b/samples/bpf/bpf_load.h
@@ -62,4 +62,9 @@ struct ksym {
 int load_kallsyms(void);
 struct ksym *ksym_search(long key);
 int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);
+
+typedef void (*perf_event_exec_fn)(void);
+typedef void (*perf_event_print_fn)(void *data, int size);
+int perf_event_poller(int fd, perf_event_exec_fn exec_fn,
+		      perf_event_print_fn output_fn);
 #endif
diff --git a/samples/bpf/trace_output_user.c b/samples/bpf/trace_output_user.c
index ccca1e3..3d3991f 100644
--- a/samples/bpf/trace_output_user.c
+++ b/samples/bpf/trace_output_user.c
@@ -24,97 +24,6 @@
 
 static int pmu_fd;
 
-int page_size;
-int page_cnt = 8;
-volatile struct perf_event_mmap_page *header;
-
-typedef void (*print_fn)(void *data, int size);
-
-static int perf_event_mmap(int fd)
-{
-	void *base;
-	int mmap_size;
-
-	page_size = getpagesize();
-	mmap_size = page_size * (page_cnt + 1);
-
-	base = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	if (base == MAP_FAILED) {
-		printf("mmap err\n");
-		return -1;
-	}
-
-	header = base;
-	return 0;
-}
-
-static int perf_event_poll(int fd)
-{
-	struct pollfd pfd = { .fd = fd, .events = POLLIN };
-
-	return poll(&pfd, 1, 1000);
-}
-
-struct perf_event_sample {
-	struct perf_event_header header;
-	__u32 size;
-	char data[];
-};
-
-static void perf_event_read(print_fn fn)
-{
-	__u64 data_tail = header->data_tail;
-	__u64 data_head = header->data_head;
-	__u64 buffer_size = page_cnt * page_size;
-	void *base, *begin, *end;
-	char buf[256];
-
-	asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */
-	if (data_head == data_tail)
-		return;
-
-	base = ((char *)header) + page_size;
-
-	begin = base + data_tail % buffer_size;
-	end = base + data_head % buffer_size;
-
-	while (begin != end) {
-		struct perf_event_sample *e;
-
-		e = begin;
-		if (begin + e->header.size > base + buffer_size) {
-			long len = base + buffer_size - begin;
-
-			assert(len < e->header.size);
-			memcpy(buf, begin, len);
-			memcpy(buf + len, base, e->header.size - len);
-			e = (void *) buf;
-			begin = base + e->header.size - len;
-		} else if (begin + e->header.size == base + buffer_size) {
-			begin = base;
-		} else {
-			begin += e->header.size;
-		}
-
-		if (e->header.type == PERF_RECORD_SAMPLE) {
-			fn(e->data, e->size);
-		} else if (e->header.type == PERF_RECORD_LOST) {
-			struct {
-				struct perf_event_header header;
-				__u64 id;
-				__u64 lost;
-			} *lost = (void *) e;
-			printf("lost %lld events\n", lost->lost);
-		} else {
-			printf("unknown event type=%d size=%d\n",
-			       e->header.type, e->header.size);
-		}
-	}
-
-	__sync_synchronize(); /* smp_mb() */
-	header->data_tail = data_head;
-}
-
 static __u64 time_get_ns(void)
 {
 	struct timespec ts;
@@ -166,10 +75,17 @@ static void test_bpf_perf_event(void)
 	ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
 }
 
+static void exec_action(void)
+{
+	FILE *f;
+
+	f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
+	(void) f;
+}
+
 int main(int argc, char **argv)
 {
 	char filename[256];
-	FILE *f;
 
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 
@@ -180,17 +96,6 @@ int main(int argc, char **argv)
 
 	test_bpf_perf_event();
 
-	if (perf_event_mmap(pmu_fd) < 0)
-		return 1;
-
-	f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
-	(void) f;
-
 	start_time = time_get_ns();
-	for (;;) {
-		perf_event_poll(pmu_fd);
-		perf_event_read(print_bpf_output);
-	}
-
-	return 0;
+	return perf_event_poller(pmu_fd, exec_action, print_bpf_output);
 }
-- 
2.9.5