perf tool: add meta-data header support for pipe-mode

index 948b2c5efb65..2415d41282d8 100644
@@ -72,6 +72,7 @@ bool perf_header__has_feat(const struct perf_header *header, int feat)
 	return test_bit(feat, header->adds_features);
 }
 
+/* Return: 0 if succeded, -ERR if failed. */
 static int do_write(int fd, const void *buf, size_t size)
 {
 	while (size) {

@@ -87,6 +88,7 @@ static int do_write(int fd, const void *buf, size_t size)
 	return 0;
 }
 
+/* Return: 0 if succeded, -ERR if failed. */
 int write_padded(int fd, const void *bf, size_t count, size_t count_aligned)
 {
 	static const char zero_buf[NAME_ALIGN];

@@ -101,6 +103,7 @@ int write_padded(int fd, const void *bf, size_t count, size_t count_aligned)
 #define string_size(str)						\
 	(PERF_ALIGN((strlen(str) + 1), NAME_ALIGN) + sizeof(u32))
 
+/* Return: 0 if succeded, -ERR if failed. */
 static int do_write_string(int fd, const char *str)
 {
 	u32 len, olen;

@@ -3277,7 +3280,8 @@ int perf_event__synthesize_tracing_data(struct perf_tool *tool, int fd,
 	 */
 	tracing_data_put(tdata);
 
-	write_padded(fd, NULL, 0, padding);
+	if (write_padded(fd, NULL, 0, padding))
+		return -1;
 
 	return aligned_size;
 }

index ce44edc30c71..ffe28002dc4f 100644
@@ -398,6 +398,7 @@ int cmd_annotate(int argc, const char **argv)
 			.attr	= perf_event__process_attr,
 			.build_id = perf_event__process_build_id,
 			.tracing_data   = perf_event__process_tracing_data,
+			.feature	= perf_event__process_feature,
 			.ordered_events = true,
 			.ordering_requires_timestamps = true,
 		},

index ea8db38eedd1..2b8032908fb2 100644
@@ -770,6 +770,7 @@ int cmd_inject(int argc, const char **argv)
 			.finished_round	= perf_event__repipe_oe_synth,
 			.build_id	= perf_event__repipe_op2_synth,
 			.id_index	= perf_event__repipe_op2_synth,
+			.feature	= perf_event__repipe_op2_synth,
 		},
 		.input_name  = "-",
 		.samples = LIST_HEAD_INIT(inject.samples),

index ee7d0a82ccd0..a1bcb72b4195 100644
@@ -799,6 +799,13 @@ static int record__synthesize(struct record *rec, bool tail)
 		return 0;
 
 	if (file->is_pipe) {
+		err = perf_event__synthesize_features(
+			tool, session, rec->evlist, process_synthesized_event);
+		if (err < 0) {
+			pr_err("Couldn't synthesize features.\n");
+			return err;
+		}
+
 		err = perf_event__synthesize_attrs(tool, session,
 						   process_synthesized_event);
 		if (err < 0) {

index 08c90d65a252..5a6917410469 100644
@@ -717,6 +717,7 @@ int cmd_report(int argc, const char **argv)
 			.id_index	 = perf_event__process_id_index,
 			.auxtrace_info	 = perf_event__process_auxtrace_info,
 			.auxtrace	 = perf_event__process_auxtrace,
+			.feature	 = perf_event__process_feature,
 			.ordered_events	 = true,
 			.ordering_requires_timestamps = true,
 		},

index 142835c0ca0a..cef1322d2993 100644
@@ -56,6 +56,19 @@ static const char *perf_event__names[] = {
 	[PERF_RECORD_STAT_ROUND]		= "STAT_ROUND",
 	[PERF_RECORD_EVENT_UPDATE]		= "EVENT_UPDATE",
 	[PERF_RECORD_TIME_CONV]			= "TIME_CONV",
+	[PERF_RECORD_HEADER_HOSTNAME]		= "HOSTNAME",
+	[PERF_RECORD_HEADER_OSRELEASE]		= "OSRELEASE",
+	[PERF_RECORD_HEADER_VERSION]		= "VERSION",
+	[PERF_RECORD_HEADER_ARCH]		= "ARCH",
+	[PERF_RECORD_HEADER_NRCPUS]		= "NRCPUS",
+	[PERF_RECORD_HEADER_CPUDESC]		= "CPUDESC",
+	[PERF_RECORD_HEADER_CPUID]		= "CPUID",
+	[PERF_RECORD_HEADER_TOTAL_MEM]		= "TOTAL_MEM",
+	[PERF_RECORD_HEADER_CMDLINE]		= "CMDLINE",
+	[PERF_RECORD_HEADER_EVENT_DESC]		= "EVENT_DESC",
+	[PERF_RECORD_HEADER_CPU_TOPOLOGY]	= "CPU_TOPOLOGY",
+	[PERF_RECORD_HEADER_NUMA_TOPOLOGY]	= "NUMA_TOPOLOGY",
+	[PERF_RECORD_HEADER_PMU_MAPPINGS]	= "PMU_MAPPINGS",
 };
 
 static const char *perf_ns__names[] = {

index db2de6413518..d404f50260f8 100644
@@ -244,6 +244,19 @@ enum perf_user_event_type { /* above any possible kernel type */
 	PERF_RECORD_STAT_ROUND			= 77,
 	PERF_RECORD_EVENT_UPDATE		= 78,
 	PERF_RECORD_TIME_CONV			= 79,
+	PERF_RECORD_HEADER_HOSTNAME		= 80,
+	PERF_RECORD_HEADER_OSRELEASE		= 81,
+	PERF_RECORD_HEADER_VERSION		= 82,
+	PERF_RECORD_HEADER_ARCH			= 83,
+	PERF_RECORD_HEADER_NRCPUS		= 84,
+	PERF_RECORD_HEADER_CPUDESC		= 85,
+	PERF_RECORD_HEADER_CPUID		= 86,
+	PERF_RECORD_HEADER_TOTAL_MEM		= 87,
+	PERF_RECORD_HEADER_CMDLINE		= 88,
+	PERF_RECORD_HEADER_EVENT_DESC		= 89,
+	PERF_RECORD_HEADER_CPU_TOPOLOGY		= 90,
+	PERF_RECORD_HEADER_NUMA_TOPOLOGY	= 91,
+	PERF_RECORD_HEADER_PMU_MAPPINGS		= 92,
 	PERF_RECORD_HEADER_MAX
 };
 

@@ -488,6 +501,11 @@ struct time_conv_event {
 	u64 time_zero;
 };
 
+struct feature_event {
+	struct perf_event_header header;
+	char data[]; /* size bytes of raw data specific to the feature */
+};
+
 union perf_event {
 	struct perf_event_header	header;
 	struct mmap_event		mmap;

@@ -518,6 +536,7 @@ union perf_event {
 	struct stat_event		stat;
 	struct stat_round_event		stat_round;
 	struct time_conv_event		time_conv;
+	struct feature_event		feat;
 };
 
 void perf_event__print_totals(void);

293 lines not on this page · raw message

index 86ab723cbee4..fbe1a4690627 100644
@@ -102,6 +102,15 @@ int perf_header__process_sections(struct perf_header *header, int fd,
 
 int perf_header__fprintf_info(struct perf_session *s, FILE *fp, bool full);
 
+int perf_event__synthesize_features(struct perf_tool *tool,
+				    struct perf_session *session,
+				    struct perf_evlist *evlist,
+				    perf_event__handler_t process);
+
+int perf_event__process_feature(struct perf_tool *tool,
+				union perf_event *event,
+				struct perf_session *session);
+
 int perf_event__synthesize_attr(struct perf_tool *tool,
 				struct perf_event_attr *attr, u32 ids, u64 *id,
 				perf_event__handler_t process);

index 3041c6b98191..ef788b91239e 100644
@@ -256,6 +256,14 @@ static int process_event_stub(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
+static int process_feature_stub(struct perf_tool *tool __maybe_unused,
+				union perf_event *event __maybe_unused,
+				struct perf_session *session __maybe_unused)
+{
+	dump_printf(": unhandled!\n");
+	return 0;
+}
+
 static int process_finished_round_stub(struct perf_tool *tool __maybe_unused,
 				       union perf_event *event __maybe_unused,
 				       struct ordered_events *oe __maybe_unused)

@@ -427,6 +435,8 @@ void perf_tool__fill_defaults(struct perf_tool *tool)
 		tool->stat_round = process_stat_round_stub;
 	if (tool->time_conv == NULL)
 		tool->time_conv = process_event_op2_stub;
+	if (tool->feature == NULL)
+		tool->feature = process_feature_stub;
 }
 
 static void swap_sample_id_all(union perf_event *event, void *data)

@@ -1370,6 +1380,8 @@ static s64 perf_session__process_user_event(struct perf_session *session,
 	case PERF_RECORD_TIME_CONV:
 		session->time_conv = event->time_conv;
 		return tool->time_conv(tool, event, session);
+	case PERF_RECORD_HEADER_HOSTNAME ... PERF_RECORD_HEADER_PMU_MAPPINGS:
+		return tool->feature(tool, event, session);
 	default:
 		return -EINVAL;
 	}

index 795b2be7b51f..70cb36e6b098 100644
@@ -63,7 +63,8 @@ struct perf_tool {
 			cpu_map,
 			stat_config,
 			stat,
-			stat_round;
+			stat_round,
+			feature;
 	event_op3	auxtrace;
 	bool		ordered_events;
 	bool		ordering_requires_timestamps;

index 5ca603b7a7a3..e28770d12c1c 100644
@@ -1117,62 +1117,56 @@ static int write_stat(struct feat_fd *fd __maybe_unused,
 	return 0;
 }
 
-static void print_hostname(struct perf_header *ph, int fd __maybe_unused,
-			   FILE *fp)
+static void print_hostname(struct feat_fd *fd, FILE *fp)
 {
-	fprintf(fp, "# hostname : %s\n", ph->env.hostname);
+	fprintf(fp, "# hostname : %s\n", fd->ph->env.hostname);
 }
 
-static void print_osrelease(struct perf_header *ph, int fd __maybe_unused,
-			    FILE *fp)
+static void print_osrelease(struct feat_fd *fd, FILE *fp)
 {
-	fprintf(fp, "# os release : %s\n", ph->env.os_release);
+	fprintf(fp, "# os release : %s\n", fd->ph->env.os_release);
 }
 
-static void print_arch(struct perf_header *ph, int fd __maybe_unused, FILE *fp)
+static void print_arch(struct feat_fd *fd, FILE *fp)
 {
-	fprintf(fp, "# arch : %s\n", ph->env.arch);
+	fprintf(fp, "# arch : %s\n", fd->ph->env.arch);
 }
 
-static void print_cpudesc(struct perf_header *ph, int fd __maybe_unused,
-			  FILE *fp)
+static void print_cpudesc(struct feat_fd *fd, FILE *fp)
 {
-	fprintf(fp, "# cpudesc : %s\n", ph->env.cpu_desc);
+	fprintf(fp, "# cpudesc : %s\n", fd->ph->env.cpu_desc);
 }
 
-static void print_nrcpus(struct perf_header *ph, int fd __maybe_unused,
-			 FILE *fp)
+static void print_nrcpus(struct feat_fd *fd, FILE *fp)
 {
-	fprintf(fp, "# nrcpus online : %u\n", ph->env.nr_cpus_online);
-	fprintf(fp, "# nrcpus avail : %u\n", ph->env.nr_cpus_avail);
+	fprintf(fp, "# nrcpus online : %u\n", fd->ph->env.nr_cpus_online);
+	fprintf(fp, "# nrcpus avail : %u\n", fd->ph->env.nr_cpus_avail);
 }
 
-static void print_version(struct perf_header *ph, int fd __maybe_unused,
-			  FILE *fp)
+static void print_version(struct feat_fd *fd, FILE *fp)
 {
-	fprintf(fp, "# perf version : %s\n", ph->env.version);
+	fprintf(fp, "# perf version : %s\n", fd->ph->env.version);
 }
 
-static void print_cmdline(struct perf_header *ph, int fd __maybe_unused,
-			  FILE *fp)
+static void print_cmdline(struct feat_fd *fd, FILE *fp)
 {
 	int nr, i;
 
-	nr = ph->env.nr_cmdline;
+	nr = fd->ph->env.nr_cmdline;
 
 	fprintf(fp, "# cmdline : ");
 
 	for (i = 0; i < nr; i++)
-		fprintf(fp, "%s ", ph->env.cmdline_argv[i]);
+		fprintf(fp, "%s ", fd->ph->env.cmdline_argv[i]);
 	fputc('\n', fp);
 }
 
-static void print_cpu_topology(struct perf_header *ph, int fd __maybe_unused,
-			       FILE *fp)
+static void print_cpu_topology(struct feat_fd *fd, FILE *fp)
 {
+	struct perf_header *ph = fd->ph;
+	int cpu_nr = ph->env.nr_cpus_avail;
 	int nr, i;
 	char *str;
-	int cpu_nr = ph->env.nr_cpus_avail;
 
 	nr = ph->env.nr_sibling_cores;
 	str = ph->env.sibling_cores;

@@ -1312,9 +1306,9 @@ static int __desc_attr__fprintf(FILE *fp, const char *name, const char *val,
 	return fprintf(fp, ", %s = %s", name, val);
 }
 
-static void print_event_desc(struct perf_header *ph, int fd, FILE *fp)
+static void print_event_desc(struct feat_fd *fd, FILE *fp)
 {
-	struct perf_evsel *evsel, *events = read_event_desc(ph, fd);
+	struct perf_evsel *evsel, *events = read_event_desc(fd->ph, fd->fd);
 	u32 j;
 	u64 *id;
 

@@ -1344,20 +1338,18 @@ static void print_event_desc(struct perf_header *ph, int fd, FILE *fp)
 	free_event_desc(events);
 }
 
-static void print_total_mem(struct perf_header *ph, int fd __maybe_unused,
-			    FILE *fp)
+static void print_total_mem(struct feat_fd *fd, FILE *fp)
 {
-	fprintf(fp, "# total memory : %Lu kB\n", ph->env.total_mem);
+	fprintf(fp, "# total memory : %llu kB\n", fd->ph->env.total_mem);
 }
 
-static void print_numa_topology(struct perf_header *ph, int fd __maybe_unused,
-				FILE *fp)
+static void print_numa_topology(struct feat_fd *fd, FILE *fp)
 {
 	int i;
 	struct numa_node *n;
 
-	for (i = 0; i < ph->env.nr_numa_nodes; i++) {
-		n = &ph->env.numa_nodes[i];
+	for (i = 0; i < fd->ph->env.nr_numa_nodes; i++) {
+		n = &fd->ph->env.numa_nodes[i];
 
 		fprintf(fp, "# node%u meminfo  : total = %"PRIu64" kB,"
 			    " free = %"PRIu64" kB\n",

@@ -1368,56 +1360,51 @@ static void print_numa_topology(struct perf_header *ph, int fd __maybe_unused,
 	}
 }
 
-static void print_cpuid(struct perf_header *ph, int fd __maybe_unused, FILE *fp)
+static void print_cpuid(struct feat_fd *fd, FILE *fp)
 {
-	fprintf(fp, "# cpuid : %s\n", ph->env.cpuid);
+	fprintf(fp, "# cpuid : %s\n", fd->ph->env.cpuid);
 }
 
-static void print_branch_stack(struct perf_header *ph __maybe_unused,
-			       int fd __maybe_unused, FILE *fp)
+static void print_branch_stack(struct feat_fd *fd __maybe_unused, FILE *fp)
 {
 	fprintf(fp, "# contains samples with branch stack\n");
 }
 
-static void print_auxtrace(struct perf_header *ph __maybe_unused,
-			   int fd __maybe_unused, FILE *fp)
+static void print_auxtrace(struct feat_fd *fd __maybe_unused, FILE *fp)
 {
 	fprintf(fp, "# contains AUX area data (e.g. instruction trace)\n");
 }
 
-static void print_stat(struct perf_header *ph __maybe_unused,
-		       int fd __maybe_unused, FILE *fp)
+static void print_stat(struct feat_fd *fd __maybe_unused, FILE *fp)
 {
 	fprintf(fp, "# contains stat data\n");
 }
 
-static void print_cache(struct perf_header *ph __maybe_unused,
-			int fd __maybe_unused, FILE *fp __maybe_unused)
+static void print_cache(struct feat_fd *fd, FILE *fp __maybe_unused)
 {
 	int i;
 
 	fprintf(fp, "# CPU cache info:\n");
-	for (i = 0; i < ph->env.caches_cnt; i++) {
+	for (i = 0; i < fd->ph->env.caches_cnt; i++) {
 		fprintf(fp, "#  ");
-		cpu_cache_level__fprintf(fp, &ph->env.caches[i]);
+		cpu_cache_level__fprintf(fp, &fd->ph->env.caches[i]);
 	}
 }
 
-static void print_pmu_mappings(struct perf_header *ph, int fd __maybe_unused,
-			       FILE *fp)
+static void print_pmu_mappings(struct feat_fd *fd, FILE *fp)
 {
 	const char *delimiter = "# pmu mappings: ";
 	char *str, *tmp;
 	u32 pmu_num;
 	u32 type;
 
-	pmu_num = ph->env.nr_pmu_mappings;
+	pmu_num = fd->ph->env.nr_pmu_mappings;
 	if (!pmu_num) {
 		fprintf(fp, "# pmu mappings: not available\n");
 		return;
 	}
 
-	str = ph->env.pmu_mappings;
+	str = fd->ph->env.pmu_mappings;
 
 	while (pmu_num) {
 		type = strtoul(str, &tmp, 0);

@@ -1440,14 +1427,13 @@ static void print_pmu_mappings(struct perf_header *ph, int fd __maybe_unused,
 	fprintf(fp, "# pmu mappings: unable to read\n");
 }
 
-static void print_group_desc(struct perf_header *ph, int fd __maybe_unused,
-			     FILE *fp)
+static void print_group_desc(struct feat_fd *fd, FILE *fp)
 {
 	struct perf_session *session;
 	struct perf_evsel *evsel;
 	u32 nr = 0;
 
-	session = container_of(ph, struct perf_session, header);
+	session = container_of(fd->ph, struct perf_session, header);
 
 	evlist__for_each_entry(session->evlist, evsel) {
 		if (perf_evsel__is_group_leader(evsel) &&

@@ -2218,7 +2204,7 @@ static int process_cache(struct perf_file_section *section __maybe_unused,
 
 struct feature_ops {
 	int (*write)(struct feat_fd *fd, struct perf_evlist *evlist);
-	void (*print)(struct perf_header *h, int fd, FILE *fp);
+	void (*print)(struct feat_fd *fd, FILE *fp);
 	int (*process)(struct perf_file_section *section,
 		       struct perf_header *h, int fd, void *data);
 	const char *name;

@@ -2271,6 +2257,7 @@ static int perf_file_section__fprintf_info(struct perf_file_section *section,
 					   int feat, int fd, void *data)
 {
 	struct header_print_data *hd = data;
+	struct feat_fd fdd;
 
 	if (lseek(fd, section->offset, SEEK_SET) == (off_t)-1) {
 		pr_debug("Failed to lseek to %" PRIu64 " offset for feature "

@@ -2284,8 +2271,15 @@ static int perf_file_section__fprintf_info(struct perf_file_section *section,
 	if (!feat_ops[feat].print)
 		return 0;
 
+	fdd = (struct  feat_fd) {
+		.fd = fd,
+		.ph = ph,
+		.size = section->size,
+		.offset = section->offset,
+	};
+
 	if (!feat_ops[feat].full_only || hd->full)
-		feat_ops[feat].print(ph, fd, hd->fp);
+		feat_ops[feat].print(&fdd, hd->fp);
 	else
 		fprintf(hd->fp, "# %s info available, use -I to display\n",
 			feat_ops[feat].name);

index 22478ff2b706..08c90d65a252 100644
@@ -54,7 +54,6 @@ struct report {
 	struct perf_tool	tool;
 	struct perf_session	*session;
 	bool			use_tui, use_gtk, use_stdio;
-	bool			show_full_info;
 	bool			show_threads;
 	bool			inverted_callchain;
 	bool			mem_mode;

@@ -806,7 +805,7 @@ int cmd_report(int argc, const char **argv)
 		     symbol__config_symfs),
 	OPT_STRING('C', "cpu", &report.cpu_list, "cpu",
 		   "list of cpus to profile"),
-	OPT_BOOLEAN('I', "show-info", &report.show_full_info,
+	OPT_BOOLEAN('I', "show-info", &report.tool.show_full_info,
 		    "Display extended information about perf.data file"),
 	OPT_BOOLEAN(0, "source", &symbol_conf.annotate_src,
 		    "Interleave source code with assembly code (default)"),

@@ -1005,7 +1004,7 @@ int cmd_report(int argc, const char **argv)
 
 	if ((report.header || report.header_only) && !quiet) {
 		perf_session__fprintf_info(session, stdout,
-					   report.show_full_info);
+					   report.tool.show_full_info);
 		if (report.header_only) {
 			ret = 0;
 			goto error;

index d05aec491cff..1edfa0da0a6c 100644
@@ -2374,7 +2374,6 @@ int process_cpu_map_event(struct perf_tool *tool __maybe_unused,
 
 int cmd_script(int argc, const char **argv)
 {
-	bool show_full_info = false;
 	bool header = false;
 	bool header_only = false;
 	bool script_started = false;

@@ -2466,7 +2465,7 @@ int cmd_script(int argc, const char **argv)
 		     "Set the maximum stack depth when parsing the callchain, "
 		     "anything beyond the specified depth will be ignored. "
 		     "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
-	OPT_BOOLEAN('I', "show-info", &show_full_info,
+	OPT_BOOLEAN('I', "show-info", &script.tool.show_full_info,
 		    "display extended information from perf.data file"),
 	OPT_BOOLEAN('\0', "show-kernel-path", &symbol_conf.show_kernel_path,
 		    "Show the path of [kernel.kallsyms]"),

@@ -2684,7 +2683,8 @@ int cmd_script(int argc, const char **argv)
 		return -1;
 
 	if (header || header_only) {
-		perf_session__fprintf_info(session, stdout, show_full_info);
+		perf_session__fprintf_info(session, stdout,
+					   script.tool.show_full_info);
 		if (header_only)
 			goto out_delete;
 	}

index 829471a1c6d7..795b2be7b51f 100644
@@ -68,6 +68,7 @@ struct perf_tool {
 	bool		ordered_events;
 	bool		ordering_requires_timestamps;
 	bool		namespace_events;
+	bool		show_full_info;
 };
 
 #endif /* __PERF_TOOL_H */

index e28770d12c1c..981f5e9685e2 100644
@@ -141,27 +141,67 @@ static int do_write_string(struct feat_fd *fd, const char *str)
 	return write_padded(fd, str, olen, len);
 }
 
-static char *do_read_string(int fd, struct perf_header *ph)
+static int __do_read(struct feat_fd *fd, void *addr, ssize_t size)
+{
+	if (!fd->buf) {
+		ssize_t ret = readn(fd->fd, addr, size);
+
+		if (ret != (ssize_t)size)
+			return ret < 0 ? (int)ret : -1;
+		return 0;
+	}
+
+	assert((ssize_t)fd->size > fd->offset);
+	if (size > (ssize_t)fd->size - fd->offset)
+		return -1;
+
+	memcpy(addr, fd->buf + fd->offset, size);
+	fd->offset += size;
+
+	return 0;
+}
+
+static int do_read_u32(struct feat_fd *fd, u32 *addr)
+{
+	int ret;
+
+	ret = __do_read(fd, addr, sizeof(*addr));
+	if (ret)
+		return ret;
+
+	if (fd->ph->needs_swap)
+		*addr = bswap_32(*addr);
+	return 0;
+}
+
+static int do_read_u64(struct feat_fd *fd, u64 *addr)
+{
+	int ret;
+
+	ret = __do_read(fd, addr, sizeof(*addr));
+	if (ret)
+		return ret;
+
+	if (fd->ph->needs_swap)
+		*addr = bswap_64(*addr);
+	return 0;
+}
+
+static char *do_read_string(struct feat_fd *fd)
 {
-	ssize_t sz, ret;
 	u32 len;
 	char *buf;
 
-	sz = readn(fd, &len, sizeof(len));
-	if (sz < (ssize_t)sizeof(len))
+	if (do_read_u32(fd, &len))
 		return NULL;
 
-	if (ph->needs_swap)
-		len = bswap_32(len);
-
 	buf = malloc(len);
 	if (!buf)
 		return NULL;
 
-	ret = readn(fd, buf, len);
-	if (ret == (ssize_t)len) {
+	if (!__do_read(fd, buf, len)) {
 		/*
-		 * strings are padded by zeroes
+		 * note that strings are padded by zeroes
 		 * thus the actual strlen of buf
 		 * may be less than len
 		 */

@@ -1207,8 +1247,7 @@ static void free_event_desc(struct perf_evsel *events)
 	free(events);
 }
 
-static struct perf_evsel *
-read_event_desc(struct perf_header *ph, int fd)
+static struct perf_evsel *read_event_desc(struct feat_fd *fd)
 {
 	struct perf_evsel *evsel, *events = NULL;
 	u64 *id;

@@ -1218,20 +1257,12 @@ read_event_desc(struct perf_header *ph, int fd)
 	size_t msz;
 
 	/* number of events */
-	ret = readn(fd, &nre, sizeof(nre));
-	if (ret != (ssize_t)sizeof(nre))
+	if (do_read_u32(fd, &nre))
 		goto error;
 
-	if (ph->needs_swap)
-		nre = bswap_32(nre);
-
-	ret = readn(fd, &sz, sizeof(sz));
-	if (ret != (ssize_t)sizeof(sz))
+	if (do_read_u32(fd, &sz))
 		goto error;
 
-	if (ph->needs_swap)
-		sz = bswap_32(sz);
-
 	/* buffer to hold on file attr struct */
 	buf = malloc(sz);
 	if (!buf)

@@ -1253,25 +1284,22 @@ read_event_desc(struct perf_header *ph, int fd)
 		 * must read entire on-file attr struct to
 		 * sync up with layout.
 		 */
-		ret = readn(fd, buf, sz);
+		ret = __do_read(fd, buf, sz);
 		if (ret != (ssize_t)sz)
 			goto error;
 
-		if (ph->needs_swap)
+		if (fd->ph->needs_swap)
 			perf_event__attr_swap(buf);
 
 		memcpy(&evsel->attr, buf, msz);
 
-		ret = readn(fd, &nr, sizeof(nr));
-		if (ret != (ssize_t)sizeof(nr))
+		if (do_read_u32(fd, &nr))
 			goto error;
 
-		if (ph->needs_swap) {
-			nr = bswap_32(nr);
+		if (fd->ph->needs_swap)
 			evsel->needs_swap = true;
-		}
 
-		evsel->name = do_read_string(fd, ph);
+		evsel->name = do_read_string(fd);
 
 		if (!nr)
 			continue;

@@ -1283,11 +1311,8 @@ read_event_desc(struct perf_header *ph, int fd)
 		evsel->id = id;
 
 		for (j = 0 ; j < nr; j++) {
-			ret = readn(fd, id, sizeof(*id));
-			if (ret != (ssize_t)sizeof(*id))
+			if (do_read_u64(fd, id))
 				goto error;
-			if (ph->needs_swap)
-				*id = bswap_64(*id);
 			id++;
 		}
 	}

@@ -1308,7 +1333,7 @@ static int __desc_attr__fprintf(FILE *fp, const char *name, const char *val,
 
 static void print_event_desc(struct feat_fd *fd, FILE *fp)
 {
-	struct perf_evsel *evsel, *events = read_event_desc(fd->ph, fd->fd);
+	struct perf_evsel *evsel, *events = read_event_desc(fd);
 	u32 j;
 	u64 *id;
 

@@ -1598,113 +1623,61 @@ static int perf_header__read_build_ids(struct perf_header *header,
 	return err;
 }
 
-static int process_tracing_data(struct perf_file_section *section __maybe_unused,
-				struct perf_header *ph __maybe_unused,
-				int fd, void *data)
-{
-	ssize_t ret = trace_report(fd, data, false);
-	return ret < 0 ? -1 : 0;
+/* Macro for features that simply need to read and store a string. */
+#define FEAT_PROCESS_STR_FUN(__feat, __feat_env) \
+static int process_##__feat(struct feat_fd *fd, void *data __maybe_unused) \
+{\
+	fd->ph->env.__feat_env = do_read_string(fd); \
+	return fd->ph->env.__feat_env ? 0 : -ENOMEM; \
 }
 
-static int process_build_id(struct perf_file_section *section,
-			    struct perf_header *ph, int fd,
-			    void *data __maybe_unused)
+FEAT_PROCESS_STR_FUN(hostname, hostname);
+FEAT_PROCESS_STR_FUN(osrelease, os_release);
+FEAT_PROCESS_STR_FUN(version, version);
+FEAT_PROCESS_STR_FUN(arch, arch);
+FEAT_PROCESS_STR_FUN(cpudesc, cpu_desc);
+FEAT_PROCESS_STR_FUN(cpuid, cpuid);
+
+static int process_build_id(struct feat_fd *fd, void *data __maybe_unused)
 {
-	if (perf_header__read_build_ids(ph, fd, section->offset, section->size))
+	if (perf_header__read_build_ids(fd->ph, fd->fd, fd->offset, fd->size))
 		pr_debug("Failed to read buildids, continuing...\n");
 	return 0;
 }
 
-static int process_hostname(struct perf_file_section *section __maybe_unused,
-			    struct perf_header *ph, int fd,
-			    void *data __maybe_unused)
-{
-	ph->env.hostname = do_read_string(fd, ph);
-	return ph->env.hostname ? 0 : -ENOMEM;
-}
-
-static int process_osrelease(struct perf_file_section *section __maybe_unused,
-			     struct perf_header *ph, int fd,
-			     void *data __maybe_unused)
-{
-	ph->env.os_release = do_read_string(fd, ph);
-	return ph->env.os_release ? 0 : -ENOMEM;
-}
-
-static int process_version(struct perf_file_section *section __maybe_unused,
-			   struct perf_header *ph, int fd,
-			   void *data __maybe_unused)
+static int process_tracing_data(struct feat_fd *fd, void *data)
 {
-	ph->env.version = do_read_string(fd, ph);
-	return ph->env.version ? 0 : -ENOMEM;
-}
+	ssize_t ret = trace_report(fd->fd, data, false);
 
-static int process_arch(struct perf_file_section *section __maybe_unused,
-			struct perf_header *ph,	int fd,
-			void *data __maybe_unused)
-{
-	ph->env.arch = do_read_string(fd, ph);
-	return ph->env.arch ? 0 : -ENOMEM;
+	return ret < 0 ? -1 : 0;
 }
 
-static int process_nrcpus(struct perf_file_section *section __maybe_unused,
-			  struct perf_header *ph, int fd,
-			  void *data __maybe_unused)
+static int process_nrcpus(struct feat_fd *fd, void *data __maybe_unused)
 {
-	ssize_t ret;
-	u32 nr;
-
-	ret = readn(fd, &nr, sizeof(nr));
-	if (ret != sizeof(nr))
-		return -1;
-
-	if (ph->needs_swap)
-		nr = bswap_32(nr);
-
-	ph->env.nr_cpus_avail = nr;
-
-	ret = readn(fd, &nr, sizeof(nr));
-	if (ret != sizeof(nr))
-		return -1;
+	int ret;
+	u32 nr_cpus_avail, nr_cpus_online;
 
-	if (ph->needs_swap)
-		nr = bswap_32(nr);
+	ret = do_read_u32(fd, &nr_cpus_avail);
+	if (ret)
+		return ret;
 
-	ph->env.nr_cpus_online = nr;
+	ret = do_read_u32(fd, &nr_cpus_online);
+	if (ret)
+		return ret;
+	fd->ph->env.nr_cpus_avail = (int)nr_cpus_avail;
+	fd->ph->env.nr_cpus_online = (int)nr_cpus_online;
 	return 0;
 }
 
-static int process_cpudesc(struct perf_file_section *section __maybe_unused,
-			   struct perf_header *ph, int fd,
-			   void *data __maybe_unused)
-{
-	ph->env.cpu_desc = do_read_string(fd, ph);
-	return ph->env.cpu_desc ? 0 : -ENOMEM;
-}
-
-static int process_cpuid(struct perf_file_section *section __maybe_unused,
-			 struct perf_header *ph,  int fd,
-			 void *data __maybe_unused)
-{
-	ph->env.cpuid = do_read_string(fd, ph);
-	return ph->env.cpuid ? 0 : -ENOMEM;
-}
-
-static int process_total_mem(struct perf_file_section *section __maybe_unused,
-			     struct perf_header *ph, int fd,
-			     void *data __maybe_unused)
+static int process_total_mem(struct feat_fd *fd, void *data __maybe_unused)
 {
-	uint64_t mem;
-	ssize_t ret;
+	u64 total_mem;
+	int ret;
 
-	ret = readn(fd, &mem, sizeof(mem));
-	if (ret != sizeof(mem))
+	ret = do_read_u64(fd, &total_mem);
+	if (ret)
 		return -1;
-
-	if (ph->needs_swap)
-		mem = bswap_64(mem);
-
-	ph->env.total_mem = mem;
+	fd->ph->env.total_mem = (unsigned long long)total_mem;
 	return 0;
 }
 

@@ -1741,17 +1714,15 @@ perf_evlist__set_event_name(struct perf_evlist *evlist,
 }
 
 static int
-process_event_desc(struct perf_file_section *section __maybe_unused,
-		   struct perf_header *header, int fd,
-		   void *data __maybe_unused)
+process_event_desc(struct feat_fd *fd, void *data __maybe_unused)
 {
 	struct perf_session *session;
-	struct perf_evsel *evsel, *events = read_event_desc(header, fd);
+	struct perf_evsel *evsel, *events = read_event_desc(fd);
 
 	if (!events)
 		return 0;
 
-	session = container_of(header, struct perf_session, header);
+	session = container_of(fd->ph, struct perf_session, header);
 	for (evsel = events; evsel->attr.size; evsel++)
 		perf_evlist__set_event_name(session->evlist, evsel);
 

@@ -1760,24 +1731,17 @@ process_event_desc(struct perf_file_section *section __maybe_unused,
 	return 0;
 }
 
-static int process_cmdline(struct perf_file_section *section,
-			   struct perf_header *ph, int fd,
-			   void *data __maybe_unused)
+static int process_cmdline(struct feat_fd *fd, void *data __maybe_unused)
 {
-	ssize_t ret;
 	char *str, *cmdline = NULL, **argv = NULL;
 	u32 nr, i, len = 0;
 
-	ret = readn(fd, &nr, sizeof(nr));
-	if (ret != sizeof(nr))
+	if (do_read_u32(fd, &nr))
 		return -1;
 
-	if (ph->needs_swap)
-		nr = bswap_32(nr);
-
-	ph->env.nr_cmdline = nr;
+	fd->ph->env.nr_cmdline = nr;
 
-	cmdline = zalloc(section->size + nr + 1);
+	cmdline = zalloc(fd->size + nr + 1);
 	if (!cmdline)
 		return -1;
 

@@ -1786,7 +1750,7 @@ static int process_cmdline(struct perf_file_section *section,
 		goto error;
 
 	for (i = 0; i < nr; i++) {
-		str = do_read_string(fd, ph);
+		str = do_read_string(fd);
 		if (!str)
 			goto error;
 

@@ -1795,8 +1759,8 @@ static int process_cmdline(struct perf_file_section *section,
 		len += strlen(str) + 1;
 		free(str);
 	}
-	ph->env.cmdline = cmdline;
-	ph->env.cmdline_argv = (const char **) argv;
+	fd->ph->env.cmdline = cmdline;
+	fd->ph->env.cmdline_argv = (const char **) argv;
 	return 0;
 
 error:

@@ -1805,65 +1769,51 @@ static int process_cmdline(struct perf_file_section *section,
 	return -1;
 }
 
-static int process_cpu_topology(struct perf_file_section *section,
-				struct perf_header *ph, int fd,
-				void *data __maybe_unused)
+static int process_cpu_topology(struct feat_fd *fd, void *data __maybe_unused)
 {
-	ssize_t ret;
 	u32 nr, i;
 	char *str;
 	struct strbuf sb;
-	int cpu_nr = ph->env.nr_cpus_avail;
-	u64 size = 0;
+	int cpu_nr = fd->ph->env.nr_cpus_avail;
+	struct perf_header *ph = fd->ph;
+	u64 start_offset = fd->offset;
 
 	ph->env.cpu = calloc(cpu_nr, sizeof(*ph->env.cpu));
 	if (!ph->env.cpu)
 		return -1;
 
-	ret = readn(fd, &nr, sizeof(nr));
-	if (ret != sizeof(nr))
+	if (do_read_u32(fd, &nr))
 		goto free_cpu;
 
-	if (ph->needs_swap)
-		nr = bswap_32(nr);
-
 	ph->env.nr_sibling_cores = nr;
-	size += sizeof(u32);
 	if (strbuf_init(&sb, 128) < 0)
 		goto free_cpu;
 
 	for (i = 0; i < nr; i++) {
-		str = do_read_string(fd, ph);
+		str = do_read_string(fd);
 		if (!str)
 			goto error;
 
 		/* include a NULL character at the end */
 		if (strbuf_add(&sb, str, strlen(str) + 1) < 0)
 			goto error;
-		size += string_size(str);
 		free(str);
 	}
 	ph->env.sibling_cores = strbuf_detach(&sb, NULL);
 
-	ret = readn(fd, &nr, sizeof(nr));
-	if (ret != sizeof(nr))
+	if (do_read_u32(fd, &nr))
 		return -1;
 
-	if (ph->needs_swap)
-		nr = bswap_32(nr);
-
 	ph->env.nr_sibling_threads = nr;
-	size += sizeof(u32);
 
 	for (i = 0; i < nr; i++) {
-		str = do_read_string(fd, ph);
+		str = do_read_string(fd);
 		if (!str)
 			goto error;
 
 		/* include a NULL character at the end */
 		if (strbuf_add(&sb, str, strlen(str) + 1) < 0)
 			goto error;
-		size += string_size(str);
 		free(str);
 	}
 	ph->env.sibling_threads = strbuf_detach(&sb, NULL);

@@ -1872,28 +1822,20 @@ static int process_cpu_topology(struct perf_file_section *section,
 	 * The header may be from old perf,
 	 * which doesn't include core id and socket id information.
 	 */
-	if (section->size <= size) {
+	if (fd->size <= fd->offset - start_offset) {
 		zfree(&ph->env.cpu);
 		return 0;
 	}
 
 	for (i = 0; i < (u32)cpu_nr; i++) {
-		ret = readn(fd, &nr, sizeof(nr));
-		if (ret != sizeof(nr))
+		if (do_read_u32(fd, &nr))
 			goto free_cpu;
 
-		if (ph->needs_swap)
-			nr = bswap_32(nr);
-
 		ph->env.cpu[i].core_id = nr;
 
-		ret = readn(fd, &nr, sizeof(nr));
-		if (ret != sizeof(nr))
+		if (do_read_u32(fd, &nr))
 			goto free_cpu;
 
-		if (ph->needs_swap)
-			nr = bswap_32(nr);
-
 		if (nr != (u32)-1 && nr > (u32)cpu_nr) {
 			pr_debug("socket_id number is too big."
 				 "You may need to upgrade the perf tool.\n");

@@ -1912,23 +1854,17 @@ static int process_cpu_topology(struct perf_file_section *section,
 	return -1;
 }
 
-static int process_numa_topology(struct perf_file_section *section __maybe_unused,
-				 struct perf_header *ph, int fd,
-				 void *data __maybe_unused)
+static int process_numa_topology(struct feat_fd *fd, void *data __maybe_unused)
 {
+	struct perf_header *ph = fd->ph;
 	struct numa_node *nodes, *n;
-	ssize_t ret;
 	u32 nr, i;
 	char *str;
 
 	/* nr nodes */
-	ret = readn(fd, &nr, sizeof(nr));
-	if (ret != sizeof(nr))
+	if (do_read_u32(fd, &nr))
 		return -1;
 
-	if (ph->needs_swap)
-		nr = bswap_32(nr);
-
 	nodes = zalloc(sizeof(*nodes) * nr);
 	if (!nodes)
 		return -ENOMEM;

@@ -1937,25 +1873,16 @@ static int process_numa_topology(struct perf_file_section *section __maybe_unuse
 		n = &nodes[i];
 
 		/* node number */
-		ret = readn(fd, &n->node, sizeof(u32));
-		if (ret != sizeof(n->node))
+		if (do_read_u32(fd, &n->node))
 			goto error;
 
-		ret = readn(fd, &n->mem_total, sizeof(u64));
-		if (ret != sizeof(u64))
+		if (do_read_u64(fd, &n->mem_total))
 			goto error;
 
-		ret = readn(fd, &n->mem_free, sizeof(u64));
-		if (ret != sizeof(u64))
+		if (do_read_u64(fd, &n->mem_free))
 			goto error;
 
-		if (ph->needs_swap) {
-			n->node      = bswap_32(n->node);
-			n->mem_total = bswap_64(n->mem_total);
-			n->mem_free  = bswap_64(n->mem_free);
-		}
-
-		str = do_read_string(fd, ph);
+		str = do_read_string(fd);
 		if (!str)
 			goto error;
 

@@ -1974,23 +1901,17 @@ static int process_numa_topology(struct perf_file_section *section __maybe_unuse
 	return -1;
 }
 
-static int process_pmu_mappings(struct perf_file_section *section __maybe_unused,
-				struct perf_header *ph, int fd,
-				void *data __maybe_unused)
+static int process_pmu_mappings(struct feat_fd *fd, void *data __maybe_unused)
 {
-	ssize_t ret;
+	struct perf_header *ph = fd->ph;
 	char *name;
 	u32 pmu_num;
 	u32 type;
 	struct strbuf sb;
 
-	ret = readn(fd, &pmu_num, sizeof(pmu_num));
-	if (ret != sizeof(pmu_num))
+	if (do_read_u32(fd, &pmu_num))
 		return -1;
 
-	if (ph->needs_swap)
-		pmu_num = bswap_32(pmu_num);
-
 	if (!pmu_num) {
 		pr_debug("pmu mappings not available\n");
 		return 0;

@@ -2001,12 +1922,10 @@ static int process_pmu_mappings(struct perf_file_section *section __maybe_unused
 		return -1;
 
 	while (pmu_num) {
-		if (readn(fd, &type, sizeof(type)) != sizeof(type))
+		if (do_read_u32(fd, &type))
 			goto error;
-		if (ph->needs_swap)
-			type = bswap_32(type);
 
-		name = do_read_string(fd, ph);
+		name = do_read_string(fd);
 		if (!name)
 			goto error;
 

@@ -2030,10 +1949,9 @@ static int process_pmu_mappings(struct perf_file_section *section __maybe_unused
 	return -1;
 }
 
-static int process_group_desc(struct perf_file_section *section __maybe_unused,
-			      struct perf_header *ph, int fd,
-			      void *data __maybe_unused)
+static int process_group_desc(struct feat_fd *fd, void *data __maybe_unused)
 {
+	struct perf_header *ph = fd->ph;
 	size_t ret = -1;
 	u32 i, nr, nr_groups;
 	struct perf_session *session;

@@ -2044,12 +1962,9 @@ static int process_group_desc(struct perf_file_section *section __maybe_unused,
 		u32 nr_members;
 	} *desc;
 
-	if (readn(fd, &nr_groups, sizeof(nr_groups)) != sizeof(nr_groups))
+	if (do_read_u32(fd, &nr_groups))
 		return -1;
 
-	if (ph->needs_swap)
-		nr_groups = bswap_32(nr_groups);
-
 	ph->env.nr_groups = nr_groups;
 	if (!nr_groups) {
 		pr_debug("group desc not available\n");

@@ -2061,20 +1976,15 @@ static int process_group_desc(struct perf_file_section *section __maybe_unused,
 		return -1;
 
 	for (i = 0; i < nr_groups; i++) {
-		desc[i].name = do_read_string(fd, ph);
+		desc[i].name = do_read_string(fd);
 		if (!desc[i].name)
 			goto out_free;
 
-		if (readn(fd, &desc[i].leader_idx, sizeof(u32)) != sizeof(u32))
+		if (do_read_u32(fd, &desc[i].leader_idx))
 			goto out_free;
 
-		if (readn(fd, &desc[i].nr_members, sizeof(u32)) != sizeof(u32))
+		if (do_read_u32(fd, &desc[i].nr_members))
 			goto out_free;
-
-		if (ph->needs_swap) {
-			desc[i].leader_idx = bswap_32(desc[i].leader_idx);
-			desc[i].nr_members = bswap_32(desc[i].nr_members);
-		}
 	}
 
 	/*

@@ -2124,44 +2034,35 @@ static int process_group_desc(struct perf_file_section *section __maybe_unused,
 	return ret;
 }
 
-static int process_auxtrace(struct perf_file_section *section,
-			    struct perf_header *ph, int fd,
-			    void *data __maybe_unused)
+static int process_auxtrace(struct feat_fd *fd, void *data __maybe_unused)
 {
 	struct perf_session *session;
 	int err;
 
-	session = container_of(ph, struct perf_session, header);
+	session = container_of(fd->ph, struct perf_session, header);
 
-	err = auxtrace_index__process(fd, section->size, session,
-				      ph->needs_swap);
+	err = auxtrace_index__process(fd->fd, fd->size, session,
+				      fd->ph->needs_swap);
 	if (err < 0)
 		pr_err("Failed to process auxtrace index\n");
 	return err;
 }
 
-static int process_cache(struct perf_file_section *section __maybe_unused,
-			 struct perf_header *ph __maybe_unused, int fd __maybe_unused,
-			 void *data __maybe_unused)
+static int process_cache(struct feat_fd *fd, void *data __maybe_unused)
 {
 	struct cpu_cache_level *caches;
 	u32 cnt, i, version;
 
-	if (readn(fd, &version, sizeof(version)) != sizeof(version))
+	pr_err("process_cache\n");
+	if (do_read_u32(fd, &version))
 		return -1;
 
-	if (ph->needs_swap)
-		version = bswap_32(version);
-
 	if (version != 1)
 		return -1;
 
-	if (readn(fd, &cnt, sizeof(cnt)) != sizeof(cnt))
+	if (do_read_u32(fd, &cnt))
 		return -1;
 
-	if (ph->needs_swap)
-		cnt = bswap_32(cnt);
-
 	caches = zalloc(sizeof(*caches) * cnt);
 	if (!caches)
 		return -1;

@@ -2170,10 +2071,8 @@ static int process_cache(struct perf_file_section *section __maybe_unused,
 		struct cpu_cache_level c;
 
 		#define _R(v)						\
-			if (readn(fd, &c.v, sizeof(u32)) != sizeof(u32))\
+			if (do_read_u32(fd, &c.v))\
 				goto out_free_caches;			\
-			if (ph->needs_swap)				\
-				c.v = bswap_32(c.v);			\
 
 		_R(level)
 		_R(line_size)

@@ -2182,7 +2081,7 @@ static int process_cache(struct perf_file_section *section __maybe_unused,
 		#undef _R
 
 		#define _R(v)				\
-			c.v = do_read_string(fd, ph);	\
+			c.v = do_read_string(fd);	\
 			if (!c.v)			\
 				goto out_free_caches;
 

@@ -2194,8 +2093,8 @@ static int process_cache(struct perf_file_section *section __maybe_unused,
 		caches[i] = c;
 	}
 
-	ph->env.caches = caches;
-	ph->env.caches_cnt = cnt;
+	fd->ph->env.caches = caches;
+	fd->ph->env.caches_cnt = cnt;
 	return 0;
 out_free_caches:
 	free(caches);

@@ -2205,8 +2104,7 @@ static int process_cache(struct perf_file_section *section __maybe_unused,
 struct feature_ops {
 	int (*write)(struct feat_fd *fd, struct perf_evlist *evlist);
 	void (*print)(struct feat_fd *fd, FILE *fp);
-	int (*process)(struct perf_file_section *section,
-		       struct perf_header *h, int fd, void *data);
+	int (*process)(struct feat_fd *fd, void *data);
 	const char *name;
 	bool full_only;
 };

@@ -2747,6 +2645,13 @@ static int perf_file_section__process(struct perf_file_section *section,
 				      struct perf_header *ph,
 				      int feat, int fd, void *data)
 {
+	struct feat_fd fdd = {
+		.fd = fd,
+		.ph = ph,
+		.size = section->size,
+		.offset = section->offset,
+	};
+
 	if (lseek(fd, section->offset, SEEK_SET) == (off_t)-1) {
 		pr_debug("Failed to lseek to %" PRIu64 " offset for feature "
 			  "%d, continuing...\n", section->offset, feat);

@@ -2761,7 +2666,7 @@ static int perf_file_section__process(struct perf_file_section *section,
 	if (!feat_ops[feat].process)
 		return 0;
 
-	return feat_ops[feat].process(section, ph, fd, data);
+	return feat_ops[feat].process(&fdd, data);
 }
 
 static int perf_file_header__read_pipe(struct perf_pipe_file_header *header,

index 9d8dcd5eb727..86ab723cbee4 100644
@@ -78,6 +78,7 @@ struct perf_header {
 	struct perf_env 	env;
 };
 
+struct feat_fd;
 struct perf_evlist;
 struct perf_session;
 

index 168cc49654e7..292e90db3924 100644
@@ -330,7 +330,7 @@ bool dso__build_id_is_kmod(const struct dso *dso, char *bf, size_t size)
 		else
 
 static int write_buildid(const char *name, size_t name_len, u8 *build_id,
-			 pid_t pid, u16 misc, int fd)
+			 pid_t pid, u16 misc, struct feat_fd *fd)
 {
 	int err;
 	struct build_id_event b;

@@ -345,14 +345,15 @@ static int write_buildid(const char *name, size_t name_len, u8 *build_id,
 	b.header.misc = misc;
 	b.header.size = sizeof(b) + len;
 
-	err = writen(fd, &b, sizeof(b));
+	err = do_write(fd, &b, sizeof(b));
 	if (err < 0)
 		return err;
 
 	return write_padded(fd, name, name_len + 1, len);
 }
 
-static int machine__write_buildid_table(struct machine *machine, int fd)
+static int machine__write_buildid_table(struct machine *machine,
+					struct feat_fd *fd)
 {
 	int err = 0;
 	char nm[PATH_MAX];

@@ -397,7 +398,8 @@ static int machine__write_buildid_table(struct machine *machine, int fd)
 	return err;
 }
 
-int perf_session__write_buildid_table(struct perf_session *session, int fd)
+int perf_session__write_buildid_table(struct perf_session *session,
+				      struct feat_fd *fd)
 {
 	struct rb_node *nd;
 	int err = machine__write_buildid_table(&session->machines.host, fd);

index a96081121179..84e5e8a52970 100644
@@ -9,6 +9,7 @@
 
 extern struct perf_tool build_id__mark_dso_hit_ops;
 struct dso;
+struct feat_fd;
 
 int build_id__sprintf(const u8 *build_id, int len, char *bf);
 int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id);

@@ -26,7 +27,8 @@ int build_id__mark_dso_hit(struct perf_tool *tool, union perf_event *event,
 int dsos__hit_all(struct perf_session *session);
 
 bool perf_session__read_build_ids(struct perf_session *session, bool with_hits);
-int perf_session__write_buildid_table(struct perf_session *session, int fd);
+int perf_session__write_buildid_table(struct perf_session *session,
+				      struct feat_fd *fd);
 int perf_session__cache_build_ids(struct perf_session *session);
 
 char *build_id_cache__origname(const char *sbuild_id);

497 lines not on this page · raw message

index d30109b421ee..9d8dcd5eb727 100644
@@ -144,7 +144,12 @@ bool is_perf_magic(u64 magic);
 
 #define NAME_ALIGN 64
 
-int write_padded(int fd, const void *bf, size_t count, size_t count_aligned);
+struct feat_fd;
+
+int do_write(struct feat_fd *fd, const void *buf, size_t size);
+
+int write_padded(struct feat_fd *fd, const void *bf,
+		 size_t count, size_t count_aligned);
 
 /*
  * arch specific callback

index 6450c75a6f5b..31ca7661e5fb 100644
@@ -260,6 +260,7 @@ static ssize_t ion(bool is_read, int fd, void *buf, size_t n)
 	size_t left = n;
 
 	while (left) {
+		/* buf must be treated as const if !is_read. */
 		ssize_t ret = is_read ? read(fd, buf, left) :
 					write(fd, buf, left);
 

@@ -287,9 +288,10 @@ ssize_t readn(int fd, void *buf, size_t n)
 /*
  * Write exactly 'n' bytes or return an error.
  */
-ssize_t writen(int fd, void *buf, size_t n)
+ssize_t writen(int fd, const void *buf, size_t n)
 {
-	return ion(false, fd, buf, n);
+	/* ion does not modify buf. */
+	return ion(false, fd, (void *)buf, n);
 }
 
 size_t hex_width(u64 v)

index 3852b6d3270a..e0881bf67fc9 100644
@@ -57,7 +57,7 @@ int copyfile_mode(const char *from, const char *to, mode_t mode);
 int copyfile_offset(int fromfd, loff_t from_ofs, int tofd, loff_t to_ofs, u64 size);
 
 ssize_t readn(int fd, void *buf, size_t n);
-ssize_t writen(int fd, void *buf, size_t n);
+ssize_t writen(int fd, const void *buf, size_t n);
 
 struct perf_event_attr;