[RFC PATCH 2/4] perf/trace-event: Write trace.dat metadata sections during parsing

[Tanushree Shah]

Perf already captures the tracing metadata as a part of
data section in perf.data

When trace_dat_fp is set, write trace.dat compatible metadata
sections using the perf provided raw buffers.

Sections written:
- Initial format header (magic, version, endian, long_size,
  page_size, compression, options_offset placeholder)
- Section 16: HEADER INFO (header_page + header_event)
- Section 17: FTRACE EVENT FORMATS
- Section 18: EVENT FORMATS (per system/event format files)
- Section 19: KALLSYMS
- Section 21: CMDLINES
- Section 15: STRINGS (written last after all sections)

Signed-off-by: Tanushree Shah <tshah@xxxxxxxxxxxxx>
---
 tools/perf/util/trace-event-read.c | 259 ++++++++++++++++++++++++++++-
 1 file changed, 252 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/trace-event-read.c b/tools/perf/util/trace-event-read.c
index ecbbb93f0185..815577703c2e 100644
--- a/tools/perf/util/trace-event-read.c
+++ b/tools/perf/util/trace-event-read.c
@@ -19,6 +19,7 @@
 #include "trace-event.h"
 #include "debug.h"
 #include "util.h"
+#include "trace-dat.h"
 
 static int input_fd;
 
@@ -145,10 +146,9 @@ static char *read_string(void)
 static int read_proc_kallsyms(struct tep_handle *pevent)
 {
 	unsigned int size;
+	char *buf;
 
 	size = read4(pevent);
-	if (!size)
-		return 0;
 	/*
 	 * Just skip it, now that we configure libtraceevent to use the
 	 * tools/perf/ symbol resolver.
@@ -160,11 +160,56 @@ static int read_proc_kallsyms(struct tep_handle *pevent)
 	 * payload", so that older tools can continue reading it and interpret
 	 * it as "no kallsyms payload is present".
 	 */
-	lseek(input_fd, size, SEEK_CUR);
+	/* Write kallsyms section with empty payload if no data */
+	if (!size) {
+		if (trace_dat_fp) {
+			unsigned short section_id = TRACE_DAT_SECTION_KALLSYMS;
+			unsigned short flags = 0;
+			unsigned long long section_size = sizeof(unsigned int);
+			unsigned int kallsyms_data = 0;
+			unsigned int string_id = STRID_KALLSYMS;
+
+			trace_dat_kallsyms_offset = ftell(trace_dat_fp);
+			if (!fwrite(&section_id, sizeof(unsigned short), 1, trace_dat_fp) ||
+			    !fwrite(&flags, sizeof(unsigned short), 1, trace_dat_fp) ||
+			    !fwrite(&string_id, sizeof(unsigned int), 1, trace_dat_fp) ||
+			    !fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+			    !fwrite(&kallsyms_data, sizeof(unsigned int), 1, trace_dat_fp))
+				return -EIO;
+		}
+		return 0;
+	}
+	buf = malloc(size);
+	if (buf == NULL)
+		return -1;
+	if (read(input_fd, buf, size) < 0) {
+		free(buf);
+		return -1;
+	}
 	trace_data_size += size;
+	/* Write kallsyms section with data */
+	if (trace_dat_fp) {
+		unsigned short section_id = TRACE_DAT_SECTION_KALLSYMS;
+		unsigned int string_id = STRID_KALLSYMS;
+		unsigned long long section_size = sizeof(unsigned int) + size;
+		unsigned short flags = 0;
+
+		trace_dat_kallsyms_offset = ftell(trace_dat_fp);
+		if (!fwrite(&section_id, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&flags, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&string_id, sizeof(unsigned int), 1, trace_dat_fp) ||
+		    !fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+		    !fwrite(&size, sizeof(unsigned int), 1, trace_dat_fp) ||
+		    !fwrite(buf, 1, size, trace_dat_fp)) {
+			free(buf);
+			return -EIO;
+		}
+	}
+	free(buf);
 	return 0;
 }
 
+
 static int read_ftrace_printk(struct tep_handle *pevent)
 {
 	unsigned int size;
@@ -195,6 +240,13 @@ static int read_ftrace_printk(struct tep_handle *pevent)
 static int read_header_files(struct tep_handle *pevent)
 {
 	unsigned long long size;
+	unsigned long long header_page_size;
+	unsigned long long header_event_size;
+	char *header_event;
+	unsigned short section_id;
+	unsigned short flags;
+	unsigned int string_id;
+	unsigned long long section_size;
 	char *header_page;
 	char buf[BUFSIZ];
 	int ret = 0;
@@ -209,6 +261,7 @@ static int read_header_files(struct tep_handle *pevent)
 
 	size = read8(pevent);
 
+	header_page_size = size;
 	header_page = malloc(size);
 	if (header_page == NULL)
 		return -1;
@@ -227,19 +280,59 @@ static int read_header_files(struct tep_handle *pevent)
 		 */
 		tep_set_long_size(pevent, tep_get_header_page_size(pevent));
 	}
-	free(header_page);
 
-	if (do_read(buf, 13) < 0)
+	if (do_read(buf, 13) < 0) {
+		free(header_page);
 		return -1;
+	}
 
 	if (memcmp(buf, "header_event", 13) != 0) {
 		pr_debug("did not read header event");
+		free(header_page);
 		return -1;
 	}
 
 	size = read8(pevent);
-	skip(size);
+	if (trace_dat_fp) {
+		header_event_size = size;
+		header_event = malloc(size);
+		if (header_event == NULL) {
+			free(header_page);
+			return -1;
+		}
+		if (do_read(header_event, size) < 0) {
+			free(header_page);
+			free(header_event);
+			return -1;
+		}
+		/* Write header_page and header_event to trace.dat */
+		section_id = TRACE_DAT_SECTION_HEADER;
+		flags = 0;
+		string_id = STRID_HEADERS;
+		section_size = 12 + 8 + header_page_size + 13 + 8 +
+				header_event_size;
+
+		trace_dat_header_info_offset = ftell(trace_dat_fp);
+		if (!fwrite(&section_id, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&flags, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&string_id, sizeof(unsigned int), 1, trace_dat_fp) ||
+		    !fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+		    !fwrite("header_page\0", 1, 12, trace_dat_fp) ||
+		    !fwrite(&header_page_size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+		    !fwrite(header_page, 1, header_page_size, trace_dat_fp) ||
+		    !fwrite("header_event\0", 1, 13, trace_dat_fp) ||
+		    !fwrite(&header_event_size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+		    !fwrite(header_event, 1, header_event_size, trace_dat_fp)) {
+			free(header_page);
+			free(header_event);
+			return -EIO;
+		}
+		free(header_event);
+	} else {
+		skip(size);
+	}
 
+	free(header_page);
 	return ret;
 }
 
@@ -259,6 +352,13 @@ static int read_ftrace_file(struct tep_handle *pevent, unsigned long long size)
 		pr_debug("error reading ftrace file.\n");
 		goto out;
 	}
+	if (trace_dat_fp) {
+		if (!fwrite(&size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+		    !fwrite(buf, 1, size, trace_dat_fp)) {
+			free(buf);
+			return -EIO;
+		}
+	}
 
 	ret = parse_ftrace_file(pevent, buf, size);
 	if (ret < 0)
@@ -283,6 +383,13 @@ static int read_event_file(struct tep_handle *pevent, char *sys,
 	ret = do_read(buf, size);
 	if (ret < 0)
 		goto out;
+	if (trace_dat_fp) {
+		if (!fwrite(&size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+		    !fwrite(buf, 1, size, trace_dat_fp)) {
+			free(buf);
+			return -EIO;
+		}
+	}
 
 	ret = parse_event_file(pevent, buf, size, sys);
 	if (ret < 0)
@@ -298,8 +405,31 @@ static int read_ftrace_files(struct tep_handle *pevent)
 	int count;
 	int i;
 	int ret;
+	long section_size_pos = 0;
+	long count_pos = 0;
+	unsigned long long section_size = 0;
+	long end_pos;
 
 	count = read4(pevent);
+	/* Write ftrace formats section to trace.dat output file */
+	if (trace_dat_fp) {
+		unsigned short section_id = TRACE_DAT_SECTION_FTRACE;
+		unsigned short flags = 0;
+		unsigned int string_id = STRID_FTRACE_FORMATS;
+
+		trace_dat_ftrace_format_offset = ftell(trace_dat_fp);
+
+		if (!fwrite(&section_id, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&flags, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&string_id, sizeof(unsigned int), 1, trace_dat_fp))
+			return -EIO;
+		section_size_pos = ftell(trace_dat_fp);
+		if (!fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp))
+			return -EIO;
+		count_pos = ftell(trace_dat_fp);
+		if (!fwrite(&count, sizeof(unsigned int), 1, trace_dat_fp))
+			return -EIO;
+	}
 
 	for (i = 0; i < count; i++) {
 		size = read8(pevent);
@@ -307,6 +437,16 @@ static int read_ftrace_files(struct tep_handle *pevent)
 		if (ret)
 			return ret;
 	}
+	/* Fill in section size after writing all ftrace files */
+	if (trace_dat_fp) {
+		end_pos = ftell(trace_dat_fp);
+		section_size = end_pos - count_pos;
+		fseek(trace_dat_fp, section_size_pos, SEEK_SET);
+		if (!fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp))
+			return -EIO;
+		fseek(trace_dat_fp, end_pos, SEEK_SET);
+	}
+
 	return 0;
 }
 
@@ -318,8 +458,30 @@ static int read_event_files(struct tep_handle *pevent)
 	int count;
 	int i,x;
 	int ret;
+	long section_size_pos = 0;
+	long sys_count_pos = 0;
+	unsigned long long section_size = 0;
+	long end_pos;
 
 	systems = read4(pevent);
+	/* Write event formats section to trace.dat output file */
+	if (trace_dat_fp) {
+		unsigned short section_id = TRACE_DAT_SECTION_EVENTS;
+		unsigned short flags = 0;
+		unsigned int string_id = STRID_EVENT_FORMATS;
+
+		trace_dat_events_format_offset = ftell(trace_dat_fp);
+		if (!fwrite(&section_id, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&flags, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&string_id, sizeof(unsigned int), 1, trace_dat_fp))
+			return -EIO;
+		section_size_pos = ftell(trace_dat_fp);
+		if (!fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp))
+			return -EIO;
+		sys_count_pos = ftell(trace_dat_fp);
+		if (!fwrite(&systems, sizeof(unsigned int), 1, trace_dat_fp))
+			return -EIO;
+	}
 
 	for (i = 0; i < systems; i++) {
 		sys = read_string();
@@ -327,6 +489,11 @@ static int read_event_files(struct tep_handle *pevent)
 			return -1;
 
 		count = read4(pevent);
+		if (trace_dat_fp) {
+			if (!fwrite(sys, 1, strlen(sys) + 1, trace_dat_fp) ||
+			   !fwrite(&count, sizeof(unsigned int), 1, trace_dat_fp))
+				return -EIO;
+		}
 
 		for (x=0; x < count; x++) {
 			size = read8(pevent);
@@ -338,6 +505,16 @@ static int read_event_files(struct tep_handle *pevent)
 		}
 		free(sys);
 	}
+	/* Fill in section size after writing all event files */
+	if (trace_dat_fp) {
+		end_pos = ftell(trace_dat_fp);
+		section_size = end_pos - sys_count_pos;
+		fseek(trace_dat_fp, section_size_pos, SEEK_SET);
+		if (!fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp))
+			return -EIO;
+		fseek(trace_dat_fp, end_pos, SEEK_SET);
+	}
+
 	return 0;
 }
 
@@ -349,8 +526,25 @@ static int read_saved_cmdline(struct tep_handle *pevent)
 
 	/* it can have 0 size */
 	size = read8(pevent);
-	if (!size)
+	/* Write cmdlines section with empty payload if no data */
+	if (!size) {
+		if (trace_dat_fp) {
+			unsigned short section_id = TRACE_DAT_SECTION_CMDLINE;
+			unsigned short flags = 0;
+			unsigned int string_id = STRID_CMDLINES;
+			unsigned long long section_size = sizeof(unsigned long long);
+			unsigned long long section_data = 0;
+
+			trace_dat_cmdline_offset = ftell(trace_dat_fp);
+			if (!fwrite(&section_id, sizeof(unsigned short), 1, trace_dat_fp) ||
+			    !fwrite(&flags, sizeof(unsigned short), 1, trace_dat_fp) ||
+			    !fwrite(&string_id, sizeof(unsigned int), 1, trace_dat_fp) ||
+			    !fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+			    !fwrite(&section_data, sizeof(unsigned long long), 1, trace_dat_fp))
+				return -EIO;
+		}
 		return 0;
+	}
 
 	buf = malloc(size + 1);
 	if (buf == NULL) {
@@ -363,6 +557,23 @@ static int read_saved_cmdline(struct tep_handle *pevent)
 		pr_debug("error reading saved cmdlines\n");
 		goto out;
 	}
+	/* Write cmdlines section with data */
+	if (trace_dat_fp) {
+		unsigned short section_id = TRACE_DAT_SECTION_CMDLINE;
+		unsigned short flags = 0;
+		unsigned int string_id = STRID_CMDLINES;
+		unsigned long long section_size = sizeof(unsigned long long) + size;
+
+		trace_dat_cmdline_offset = ftell(trace_dat_fp);
+		if (!fwrite(&section_id, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&flags, sizeof(unsigned short), 1, trace_dat_fp) ||
+		    !fwrite(&string_id, sizeof(unsigned int), 1, trace_dat_fp) ||
+		    !fwrite(&section_size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+		    !fwrite(&size, sizeof(unsigned long long), 1, trace_dat_fp) ||
+		    !fwrite(buf, 1, size, trace_dat_fp))
+			return -EIO;
+	}
+
 	buf[ret] = '\0';
 
 	parse_saved_cmdline(pevent, buf, size);
@@ -387,6 +598,7 @@ ssize_t trace_report(int fd, struct trace_event *tevent, bool __repipe)
 	int file_page_size;
 	struct tep_handle *pevent = NULL;
 	int err;
+	char magic_buf[10];
 
 	repipe = __repipe;
 	input_fd = fd;
@@ -398,12 +610,17 @@ ssize_t trace_report(int fd, struct trace_event *tevent, bool __repipe)
 		return -1;
 	}
 
+	if (trace_dat_fp)
+		memcpy(magic_buf, buf, 3);
+
 	if (do_read(buf, 7) < 0)
 		return -1;
 	if (memcmp(buf, "tracing", 7) != 0) {
 		pr_debug("not a trace file (missing 'tracing' tag)");
 		return -1;
 	}
+	if (trace_dat_fp)
+		memcpy(magic_buf + 3, buf, 7);
 
 	version = read_string();
 	if (version == NULL)
@@ -440,6 +657,28 @@ ssize_t trace_report(int fd, struct trace_event *tevent, bool __repipe)
 	tep_set_long_size(pevent, file_long_size);
 	tep_set_page_size(pevent, file_page_size);
 
+	/* Write initial file header to trace.dat */
+	if (trace_dat_fp) {
+		unsigned char endian = file_bigendian;
+		unsigned char long_size = file_long_size;
+		unsigned int page_size = file_page_size;
+		unsigned long long placeholder = 0;
+		char trace_dat_version = TRACE_DAT_VERSION;
+
+		if (!fwrite(magic_buf, 1, 10, trace_dat_fp) ||    /* magic + "tracing" */
+		    !fwrite(&trace_dat_version, 1, 2, trace_dat_fp) ||
+		    !fwrite(&endian, 1, 1, trace_dat_fp) ||
+		    !fwrite(&long_size, 1, 1, trace_dat_fp) ||
+		    !fwrite(&page_size, sizeof(unsigned int), 1, trace_dat_fp) ||
+		    !fwrite("none", 1, 4, trace_dat_fp) ||
+		    !fwrite("\0", 1, 1, trace_dat_fp) ||
+		    !fwrite("\0", 1, 1, trace_dat_fp))
+			return -EIO;
+		trace_dat_options_offset = ftell(trace_dat_fp);
+		if (!fwrite(&placeholder, sizeof(unsigned long long), 1, trace_dat_fp))
+			return -EIO;
+	}
+
 	err = read_header_files(pevent);
 	if (err)
 		goto out;
@@ -460,6 +699,12 @@ ssize_t trace_report(int fd, struct trace_event *tevent, bool __repipe)
 		if (err)
 			goto out;
 	}
+	/* Write strings section to trace.dat output file */
+	if (trace_dat_fp) {
+		err = trace_dat__write_strings_section();
+		if (err)
+			goto out;
+	}
 
 	size = trace_data_size;
 	repipe = false;
-- 
2.53.0