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Subject[PATCH 5/5] perf record: Put a copy of kcore into the perf.data directory
Date
Add a new 'perf record' option '--kcore' which will put a copy of
/proc/kcore, kallsyms and modules into a perf.data directory. Note, that
without the --kcore option, output goes to a file as previously.
The tools' -o and -i options work with either a file name or directory
name.

Example:

$ sudo perf record --kcore uname

$ sudo tree perf.data
perf.data
├── kcore_dir
│   ├── kallsyms
│   ├── kcore
│   └── modules
└── data

$ sudo perf script -v
build id event received for vmlinux: 1eaa285996affce2d74d8e66dcea09a80c9941de
build id event received for [vdso]: 8bbaf5dc62a9b644b4d4e4539737e104e4a84541
Samples for 'cycles' event do not have CPU attribute set. Skipping 'cpu' field.
Using CPUID GenuineIntel-6-8E-A
Using perf.data/kcore_dir/kcore for kernel data
Using perf.data/kcore_dir/kallsyms for symbols
perf 19058 506778.423729: 1 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
perf 19058 506778.423733: 1 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
perf 19058 506778.423734: 7 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
perf 19058 506778.423736: 117 cycles: ffffffffa2caa54a native_write_msr+0xa (vmlinux)
perf 19058 506778.423738: 2092 cycles: ffffffffa2c9b7b0 native_apic_msr_write+0x0 (vmlinux)
perf 19058 506778.423740: 37380 cycles: ffffffffa2f121d0 perf_event_addr_filters_exec+0x0 (vmlinux)
uname 19058 506778.423751: 582673 cycles: ffffffffa303a407 propagate_protected_usage+0x147 (vmlinux)
uname 19058 506778.423892: 2241841 cycles: ffffffffa2cae0c9 unwind_next_frame.part.5+0x79 (vmlinux)
uname 19058 506778.424430: 2457397 cycles: ffffffffa3019232 check_memory_region+0x52 (vmlinux)

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/Documentation/perf-record.txt | 3 ++
.../perf.data-directory-format.txt | 35 +++++++++++++
tools/perf/builtin-record.c | 52 +++++++++++++++++++
tools/perf/util/data.c | 33 ++++++++++++
tools/perf/util/data.h | 2 +
tools/perf/util/record.h | 1 +
tools/perf/util/session.c | 4 ++
tools/perf/util/util.c | 17 ++++++
8 files changed, 147 insertions(+)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index c6f9f31b6039..8a4506113d9f 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -571,6 +571,9 @@ config terms. For example: 'cycles/overwrite/' and 'instructions/no-overwrite/'.

Implies --tail-synthesize.

+--kcore::
+Make a copy of /proc/kcore and place it into a directory with the perf data file.
+
SEE ALSO
--------
linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/Documentation/perf.data-directory-format.txt b/tools/perf/Documentation/perf.data-directory-format.txt
index 4bf08908178d..f37fbd29112e 100644
--- a/tools/perf/Documentation/perf.data-directory-format.txt
+++ b/tools/perf/Documentation/perf.data-directory-format.txt
@@ -26,3 +26,38 @@ The current only version value 0 means that:

Future versions are expected to describe different data files
layout according to special needs.
+
+Currently the only 'perf record' option to output to a directory is
+the --kcore option which puts a copy of /proc/kcore into the directory.
+e.g.
+
+ $ sudo perf record --kcore uname
+ Linux
+ [ perf record: Woken up 1 times to write data ]
+ [ perf record: Captured and wrote 0.015 MB perf.data (9 samples) ]
+ $ sudo tree -ps perf.data
+ perf.data
+ ├── [-rw------- 23744] data
+ └── [drwx------ 4096] kcore_dir
+ ├── [-r-------- 6731125] kallsyms
+ ├── [-r-------- 40230912] kcore
+ └── [-r-------- 5419] modules
+
+ 1 directory, 4 files
+ $ sudo perf script -v
+ build id event received for vmlinux: 1eaa285996affce2d74d8e66dcea09a80c9941de
+ build id event received for [vdso]: 8bbaf5dc62a9b644b4d4e4539737e104e4a84541
+ build id event received for /lib/x86_64-linux-gnu/libc-2.28.so: 5b157f49586a3ca84d55837f97ff466767dd3445
+ Samples for 'cycles' event do not have CPU attribute set. Skipping 'cpu' field.
+ Using CPUID GenuineIntel-6-8E-A
+ Using perf.data/kcore_dir/kcore for kernel data
+ Using perf.data/kcore_dir/kallsyms for symbols
+ perf 15316 2060795.480902: 1 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
+ perf 15316 2060795.480906: 1 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
+ perf 15316 2060795.480908: 7 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
+ perf 15316 2060795.480910: 119 cycles: ffffffffa2caa54a native_write_msr+0xa (vmlinux)
+ perf 15316 2060795.480912: 2109 cycles: ffffffffa2c9b7b0 native_apic_msr_write+0x0 (vmlinux)
+ perf 15316 2060795.480914: 37606 cycles: ffffffffa2f121fe perf_event_addr_filters_exec+0x2e (vmlinux)
+ uname 15316 2060795.480924: 588287 cycles: ffffffffa303a56d page_counter_try_charge+0x6d (vmlinux)
+ uname 15316 2060795.481067: 2261945 cycles: ffffffffa301438f kmem_cache_free+0x4f (vmlinux)
+ uname 15316 2060795.481643: 2172167 cycles: 7f1a48c393c0 _IO_un_link+0x0 (/lib/x86_64-linux-gnu/libc-2.28.so)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index fceac9d42b4e..ca9bf249cfb2 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -55,6 +55,9 @@
#include <signal.h>
#include <sys/mman.h>
#include <sys/wait.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/time64.h>
@@ -699,6 +702,37 @@ static int record__auxtrace_init(struct record *rec __maybe_unused)

#endif

+static bool record__kcore_readable(struct machine *machine)
+{
+ char kcore[PATH_MAX];
+ int fd;
+
+ scnprintf(kcore, sizeof(kcore), "%s/proc/kcore", machine->root_dir);
+
+ fd = open(kcore, O_RDONLY);
+ if (fd < 0)
+ return false;
+
+ close(fd);
+
+ return true;
+}
+
+static int record__kcore_copy(struct machine *machine, struct perf_data *data)
+{
+ char from_dir[PATH_MAX];
+ char kcore_dir[PATH_MAX];
+ int ret;
+
+ snprintf(from_dir, sizeof(from_dir), "%s/proc", machine->root_dir);
+
+ ret = perf_data__make_kcore_dir(data, kcore_dir, sizeof(kcore_dir));
+ if (ret)
+ return ret;
+
+ return kcore_copy(from_dir, kcore_dir);
+}
+
static int record__mmap_evlist(struct record *rec,
struct evlist *evlist)
{
@@ -1383,6 +1417,12 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
session->header.env.comp_type = PERF_COMP_ZSTD;
session->header.env.comp_level = rec->opts.comp_level;

+ if (rec->opts.kcore &&
+ !record__kcore_readable(&session->machines.host)) {
+ pr_err("ERROR: kcore is not readable.\n");
+ return -1;
+ }
+
record__init_features(rec);

if (rec->opts.use_clockid && rec->opts.clockid_res_ns)
@@ -1414,6 +1454,14 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
}
session->header.env.comp_mmap_len = session->evlist->core.mmap_len;

+ if (rec->opts.kcore) {
+ err = record__kcore_copy(&session->machines.host, data);
+ if (err) {
+ pr_err("ERROR: Failed to copy kcore\n");
+ goto out_child;
+ }
+ }
+
err = bpf__apply_obj_config();
if (err) {
char errbuf[BUFSIZ];
@@ -2184,6 +2232,7 @@ static struct option __record_options[] = {
parse_cgroups),
OPT_UINTEGER('D', "delay", &record.opts.initial_delay,
"ms to wait before starting measurement after program start"),
+ OPT_BOOLEAN(0, "kcore", &record.opts.kcore, "copy /proc/kcore"),
OPT_STRING('u', "uid", &record.opts.target.uid_str, "user",
"user to profile"),

@@ -2322,6 +2371,9 @@ int cmd_record(int argc, const char **argv)

}

+ if (rec->opts.kcore)
+ rec->data.is_dir = true;
+
if (rec->opts.comp_level != 0) {
pr_debug("Compression enabled, disabling build id collection at the end of the session.\n");
rec->no_buildid = true;
diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
index 964ea101dba6..c47aa34fdc0a 100644
--- a/tools/perf/util/data.c
+++ b/tools/perf/util/data.c
@@ -424,3 +424,36 @@ unsigned long perf_data__size(struct perf_data *data)

return size;
}
+
+int perf_data__make_kcore_dir(struct perf_data *data, char *buf, size_t buf_sz)
+{
+ int ret;
+
+ if (!data->is_dir)
+ return -1;
+
+ ret = snprintf(buf, buf_sz, "%s/kcore_dir", data->path);
+ if (ret < 0 || (size_t)ret >= buf_sz)
+ return -1;
+
+ return mkdir(buf, S_IRWXU);
+}
+
+char *perf_data__kallsyms_name(struct perf_data *data)
+{
+ char *kallsyms_name;
+ struct stat st;
+
+ if (!data->is_dir)
+ return NULL;
+
+ if (asprintf(&kallsyms_name, "%s/kcore_dir/kallsyms", data->path) < 0)
+ return NULL;
+
+ if (stat(kallsyms_name, &st)) {
+ free(kallsyms_name);
+ return NULL;
+ }
+
+ return kallsyms_name;
+}
diff --git a/tools/perf/util/data.h b/tools/perf/util/data.h
index f68815f7e428..75947ef6bc17 100644
--- a/tools/perf/util/data.h
+++ b/tools/perf/util/data.h
@@ -87,4 +87,6 @@ int perf_data__open_dir(struct perf_data *data);
void perf_data__close_dir(struct perf_data *data);
int perf_data__update_dir(struct perf_data *data);
unsigned long perf_data__size(struct perf_data *data);
+int perf_data__make_kcore_dir(struct perf_data *data, char *buf, size_t buf_sz);
+char *perf_data__kallsyms_name(struct perf_data *data);
#endif /* __PERF_DATA_H */
diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index 00275afc524d..948bbcf9aef3 100644
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -44,6 +44,7 @@ struct record_opts {
bool strict_freq;
bool sample_id;
bool no_bpf_event;
+ bool kcore;
unsigned int freq;
unsigned int mmap_pages;
unsigned int auxtrace_mmap_pages;
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 061bb4d6a3f5..bfa80fe8d369 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -230,6 +230,10 @@ struct perf_session *perf_session__new(struct perf_data *data,
if (ret)
goto out_delete;
}
+
+ if (!symbol_conf.kallsyms_name &&
+ !symbol_conf.vmlinux_name)
+ symbol_conf.kallsyms_name = perf_data__kallsyms_name(data);
}
} else {
session->machines.host.env = &perf_env;
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 56f30ad29ca7..16f81a0a9208 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -180,6 +180,21 @@ static int rm_rf_depth_pat(const char *path, int depth, const char **pat)
return rmdir(path);
}

+static int rm_rf_kcore_dir(const char *path)
+{
+ char kcore_dir_path[PATH_MAX];
+ const char *pat[] = {
+ "kcore",
+ "kallsyms",
+ "modules",
+ NULL,
+ };
+
+ snprintf(kcore_dir_path, sizeof(kcore_dir_path), "%s/kcore_dir", path);
+
+ return rm_rf_depth_pat(kcore_dir_path, 0, pat);
+}
+
int rm_rf_perf_data(const char *path)
{
const char *pat[] = {
@@ -188,6 +203,8 @@ int rm_rf_perf_data(const char *path)
NULL,
};

+ rm_rf_kcore_dir(path);
+
return rm_rf_depth_pat(path, 0, pat);
}

--
2.17.1
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