[PATCH V2 11/13] perf tools: Add support for PERF_RECORD_TEXT_POKE

From: Adrian Hunter
Date: Wed Feb 12 2020 - 07:51:30 EST

Add processing for PERF_RECORD_TEXT_POKE events. When a text poke event is
processed, then the kernel dso data cache is updated with the poked bytes.

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
tools/include/uapi/linux/perf_event.h | 21 ++++++++++-
tools/lib/perf/include/perf/event.h | 9 +++++
tools/perf/builtin-record.c | 45 +++++++++++++++++++++++
tools/perf/util/event.c | 40 ++++++++++++++++++++
tools/perf/util/event.h | 5 +++
tools/perf/util/evlist.h | 1 +
tools/perf/util/evsel.c | 7 +++-
tools/perf/util/machine.c | 43 ++++++++++++++++++++++
tools/perf/util/machine.h | 3 ++
tools/perf/util/perf_event_attr_fprintf.c | 1 +
tools/perf/util/record.c | 10 +++++
tools/perf/util/record.h | 1 +
tools/perf/util/session.c | 23 ++++++++++++
tools/perf/util/tool.h | 3 +-
14 files changed, 209 insertions(+), 3 deletions(-)

diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index 377d794d3105..bae9e9d2d897 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -377,7 +377,8 @@ struct perf_event_attr {
ksymbol : 1, /* include ksymbol events */
bpf_event : 1, /* include bpf events */
aux_output : 1, /* generate AUX records instead of events */
- __reserved_1 : 32;
+ text_poke : 1, /* include text poke events */
+ __reserved_1 : 31;

union {
__u32 wakeup_events; /* wakeup every n events */
@@ -1006,6 +1007,24 @@ enum perf_event_type {
*/
PERF_RECORD_BPF_EVENT = 18,

+ /*
+ * Records changes to kernel text i.e. self-modified code. 'old_len' is
+ * the number of old bytes, 'new_len' is the number of new bytes. Either
+ * 'old_len' or 'new_len' may be zero to indicate, for example, the
+ * addition or removal of a trampoline. 'bytes' contains the old bytes
+ * followed immediately by the new bytes.
+ *
+ * struct {
+ * struct perf_event_header header;
+ * u64 addr;
+ * u16 old_len;
+ * u16 new_len;
+ * u8 bytes[];
+ * struct sample_id sample_id;
+ * };
+ */
+ PERF_RECORD_TEXT_POKE = 19,
+
PERF_RECORD_MAX, /* non-ABI */
};

diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h
index 18106899cb4e..e3bc9afff150 100644
--- a/tools/lib/perf/include/perf/event.h
+++ b/tools/lib/perf/include/perf/event.h
@@ -105,6 +105,14 @@ struct perf_record_bpf_event {
__u8 tag[BPF_TAG_SIZE]; // prog tag
};

+struct perf_record_text_poke_event {
+ struct perf_event_header header;
+ __u64 addr;
+ __u16 old_len;
+ __u16 new_len;
+ __u8 bytes[];
+};
+
struct perf_record_sample {
struct perf_event_header header;
__u64 array[];
@@ -360,6 +368,7 @@ union perf_event {
struct perf_record_sample sample;
struct perf_record_bpf_event bpf;
struct perf_record_ksymbol ksymbol;
+ struct perf_record_text_poke_event text_poke;
struct perf_record_header_attr attr;
struct perf_record_event_update event_update;
struct perf_record_header_event_type event_type;
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 4c301466101b..538e3622547e 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -723,6 +723,43 @@ static int record__auxtrace_init(struct record *rec __maybe_unused)

#endif

+static int record__config_text_poke(struct evlist *evlist)
+{
+ struct evsel *evsel;
+ int err;
+
+ /* Nothing to do if text poke is already configured */
+ evlist__for_each_entry(evlist, evsel) {
+ if (evsel->core.attr.text_poke)
+ return 0;
+ }
+
+ err = parse_events(evlist, "dummy:u", NULL);
+ if (err)
+ return err;
+
+ evsel = evlist__last(evlist);
+
+ evsel->core.attr.freq = 0;
+ evsel->core.attr.sample_period = 1;
+ evsel->core.attr.text_poke = 1;
+ evsel->core.attr.ksymbol = 1;
+
+ evsel->core.system_wide = true;
+ evsel->no_aux_samples = true;
+ evsel->immediate = true;
+
+ /* Text poke must be collected on all CPUs */
+ perf_cpu_map__put(evsel->core.own_cpus);
+ evsel->core.own_cpus = perf_cpu_map__new(NULL);
+ perf_cpu_map__put(evsel->core.cpus);
+ evsel->core.cpus = perf_cpu_map__get(evsel->core.own_cpus);
+
+ perf_evsel__set_sample_bit(evsel, TIME);
+
+ return 0;
+}
+
static bool record__kcore_readable(struct machine *machine)
{
char kcore[PATH_MAX];
@@ -2610,6 +2647,14 @@ int cmd_record(int argc, const char **argv)
if (rec->opts.full_auxtrace)
rec->buildid_all = true;

+ if (rec->opts.text_poke) {
+ err = record__config_text_poke(rec->evlist);
+ if (err) {
+ pr_err("record__config_text_poke failed, error %d\n", err);
+ goto out;
+ }
+ }
+
if (record_opts__config(&rec->opts)) {
err = -EINVAL;
goto out;
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index c5447ff516a2..5a5baa4edde5 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -31,6 +31,7 @@
#include "stat.h"
#include "session.h"
#include "bpf-event.h"
+#include "print_binary.h"
#include "tool.h"
#include "../perf.h"

@@ -54,6 +55,7 @@ static const char *perf_event__names[] = {
[PERF_RECORD_NAMESPACES] = "NAMESPACES",
[PERF_RECORD_KSYMBOL] = "KSYMBOL",
[PERF_RECORD_BPF_EVENT] = "BPF_EVENT",
+ [PERF_RECORD_TEXT_POKE] = "TEXT_POKE",
[PERF_RECORD_HEADER_ATTR] = "ATTR",
[PERF_RECORD_HEADER_EVENT_TYPE] = "EVENT_TYPE",
[PERF_RECORD_HEADER_TRACING_DATA] = "TRACING_DATA",
@@ -252,6 +254,14 @@ int perf_event__process_bpf(struct perf_tool *tool __maybe_unused,
return machine__process_bpf(machine, event, sample);
}

+int perf_event__process_text_poke(struct perf_tool *tool __maybe_unused,
+ union perf_event *event,
+ struct perf_sample *sample,
+ struct machine *machine)
+{
+ return machine__process_text_poke(machine, event, sample);
+}
+
size_t perf_event__fprintf_mmap(union perf_event *event, FILE *fp)
{
return fprintf(fp, " %d/%d: [%#" PRI_lx64 "(%#" PRI_lx64 ") @ %#" PRI_lx64 "]: %c %s\n",
@@ -398,6 +408,33 @@ size_t perf_event__fprintf_bpf(union perf_event *event, FILE *fp)
event->bpf.type, event->bpf.flags, event->bpf.id);
}

+static int text_poke_printer(enum binary_printer_ops op, unsigned int val,
+ void *extra __maybe_unused, FILE *fp)
+{
+ if (op == BINARY_PRINT_NUM_DATA)
+ return fprintf(fp, " %02x", val);
+ if (op == BINARY_PRINT_LINE_END)
+ return fprintf(fp, "\n");
+ return 0;
+}
+
+size_t perf_event__fprintf_text_poke(union perf_event *event, FILE *fp)
+{
+ size_t ret = fprintf(fp, " addr %#" PRI_lx64 " old len %u new len %u\n",
+ event->text_poke.addr,
+ event->text_poke.old_len,
+ event->text_poke.new_len);
+
+ ret += fprintf(fp, " old bytes:");
+ ret += binary__fprintf(event->text_poke.bytes, event->text_poke.old_len,
+ 16, text_poke_printer, NULL, fp);
+ ret += fprintf(fp, " new bytes:");
+ ret += binary__fprintf(event->text_poke.bytes + event->text_poke.old_len,
+ event->text_poke.new_len, 16, text_poke_printer,
+ NULL, fp);
+ return ret;
+}
+
size_t perf_event__fprintf(union perf_event *event, FILE *fp)
{
size_t ret = fprintf(fp, "PERF_RECORD_%s",
@@ -439,6 +476,9 @@ size_t perf_event__fprintf(union perf_event *event, FILE *fp)
case PERF_RECORD_BPF_EVENT:
ret += perf_event__fprintf_bpf(event, fp);
break;
+ case PERF_RECORD_TEXT_POKE:
+ ret += perf_event__fprintf_text_poke(event, fp);
+ break;
default:
ret += fprintf(fp, "\n");
}
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 85223159737c..cbe98e22527f 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -345,6 +345,10 @@ int perf_event__process_bpf(struct perf_tool *tool,
union perf_event *event,
struct perf_sample *sample,
struct machine *machine);
+int perf_event__process_text_poke(struct perf_tool *tool,
+ union perf_event *event,
+ struct perf_sample *sample,
+ struct machine *machine);
int perf_event__process(struct perf_tool *tool,
union perf_event *event,
struct perf_sample *sample,
@@ -378,6 +382,7 @@ size_t perf_event__fprintf_cpu_map(union perf_event *event, FILE *fp);
size_t perf_event__fprintf_namespaces(union perf_event *event, FILE *fp);
size_t perf_event__fprintf_ksymbol(union perf_event *event, FILE *fp);
size_t perf_event__fprintf_bpf(union perf_event *event, FILE *fp);
+size_t perf_event__fprintf_text_poke(union perf_event *event, FILE *fp);
size_t perf_event__fprintf(union perf_event *event, FILE *fp);

int kallsyms__get_function_start(const char *kallsyms_filename,
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index f5bd5c386df1..93e9b35e53b0 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -175,6 +175,7 @@ struct callchain_param;
void perf_evlist__set_id_pos(struct evlist *evlist);
bool perf_can_sample_identifier(void);
bool perf_can_record_switch_events(void);
+bool perf_can_record_text_poke_events(void);
bool perf_can_record_cpu_wide(void);
bool perf_can_aux_sample(void);
void perf_evlist__config(struct evlist *evlist, struct record_opts *opts,
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index c8dc4450884c..acaa82a0787d 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1096,7 +1096,12 @@ void perf_evsel__config(struct evsel *evsel, struct record_opts *opts,
attr->mmap = track;
attr->mmap2 = track && !perf_missing_features.mmap2;
attr->comm = track;
- attr->ksymbol = track && !perf_missing_features.ksymbol;
+ /*
+ * ksymbol is tracked separately with text poke because it needs to be
+ * system wide and enabled immediately.
+ */
+ if (!opts->text_poke)
+ attr->ksymbol = track && !perf_missing_features.ksymbol;
attr->bpf_event = track && !opts->no_bpf_event && !perf_missing_features.bpf;

if (opts->record_namespaces)
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index c8c5410315e8..c2825aaf3927 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -770,6 +770,47 @@ int machine__process_ksymbol(struct machine *machine __maybe_unused,
return machine__process_ksymbol_register(machine, event, sample);
}

+int machine__process_text_poke(struct machine *machine, union perf_event *event,
+ struct perf_sample *sample __maybe_unused)
+{
+ struct map *map = maps__find(&machine->kmaps, event->text_poke.addr);
+ u8 cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;
+
+ if (dump_trace)
+ perf_event__fprintf_text_poke(event, stdout);
+
+ if (!event->text_poke.new_len)
+ return 0;
+
+ if (cpumode != PERF_RECORD_MISC_KERNEL) {
+ pr_debug("%s: unsupported cpumode - ignoring\n", __func__);
+ return 0;
+ }
+
+ if (map && map->dso) {
+ u8 *new_bytes = event->text_poke.bytes + event->text_poke.old_len;
+ int ret;
+
+ /*
+ * Kernel maps might be changed when loading symbols so loading
+ * must be done prior to using kernel maps.
+ */
+ map__load(map);
+ ret = dso__data_write_cache_addr(map->dso, map, machine,
+ event->text_poke.addr,
+ new_bytes,
+ event->text_poke.new_len);
+ if (ret != event->text_poke.new_len)
+ pr_debug("Failed to write kernel text poke at %#" PRI_lx64 "\n",
+ event->text_poke.addr);
+ } else {
+ pr_debug("Failed to find kernel text poke address map for %#" PRI_lx64 "\n",
+ event->text_poke.addr);
+ }
+
+ return 0;
+}
+
static struct map *machine__addnew_module_map(struct machine *machine, u64 start,
const char *filename)
{
@@ -1901,6 +1942,8 @@ int machine__process_event(struct machine *machine, union perf_event *event,
ret = machine__process_ksymbol(machine, event, sample); break;
case PERF_RECORD_BPF_EVENT:
ret = machine__process_bpf(machine, event, sample); break;
+ case PERF_RECORD_TEXT_POKE:
+ ret = machine__process_text_poke(machine, event, sample); break;
default:
ret = -1;
break;
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index be0a930eca89..0bb086acb7ed 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -135,6 +135,9 @@ int machine__process_mmap2_event(struct machine *machine, union perf_event *even
int machine__process_ksymbol(struct machine *machine,
union perf_event *event,
struct perf_sample *sample);
+int machine__process_text_poke(struct machine *machine,
+ union perf_event *event,
+ struct perf_sample *sample);
int machine__process_event(struct machine *machine, union perf_event *event,
struct perf_sample *sample);

diff --git a/tools/perf/util/perf_event_attr_fprintf.c b/tools/perf/util/perf_event_attr_fprintf.c
index 651203126c71..4c6c700335a6 100644
--- a/tools/perf/util/perf_event_attr_fprintf.c
+++ b/tools/perf/util/perf_event_attr_fprintf.c
@@ -144,6 +144,7 @@ int perf_event_attr__fprintf(FILE *fp, struct perf_event_attr *attr,
PRINT_ATTRf(aux_watermark, p_unsigned);
PRINT_ATTRf(sample_max_stack, p_unsigned);
PRINT_ATTRf(aux_sample_size, p_unsigned);
+ PRINT_ATTRf(text_poke, p_unsigned);

return ret;
}
diff --git a/tools/perf/util/record.c b/tools/perf/util/record.c
index 7def66168503..207ba2a65008 100644
--- a/tools/perf/util/record.c
+++ b/tools/perf/util/record.c
@@ -97,6 +97,11 @@ static void perf_probe_context_switch(struct evsel *evsel)
evsel->core.attr.context_switch = 1;
}

+static void perf_probe_text_poke(struct evsel *evsel)
+{
+ evsel->core.attr.text_poke = 1;
+}
+
bool perf_can_sample_identifier(void)
{
return perf_probe_api(perf_probe_sample_identifier);
@@ -112,6 +117,11 @@ bool perf_can_record_switch_events(void)
return perf_probe_api(perf_probe_context_switch);
}

+bool perf_can_record_text_poke_events(void)
+{
+ return perf_probe_api(perf_probe_text_poke);
+}
+
bool perf_can_record_cpu_wide(void)
{
struct perf_event_attr attr = {
diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index 5421fd2ad383..127b4ca11fd3 100644
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -46,6 +46,7 @@ struct record_opts {
bool sample_id;
bool no_bpf_event;
bool kcore;
+ bool text_poke;
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 d0d7d25b23e3..20bfdb08264f 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -489,6 +489,8 @@ void perf_tool__fill_defaults(struct perf_tool *tool)
tool->ksymbol = perf_event__process_ksymbol;
if (tool->bpf == NULL)
tool->bpf = perf_event__process_bpf;
+ if (tool->text_poke == NULL)
+ tool->text_poke = perf_event__process_text_poke;
if (tool->read == NULL)
tool->read = process_event_sample_stub;
if (tool->throttle == NULL)
@@ -658,6 +660,24 @@ static void perf_event__switch_swap(union perf_event *event, bool sample_id_all)
swap_sample_id_all(event, &event->context_switch + 1);
}

+static void perf_event__text_poke_swap(union perf_event *event, bool sample_id_all)
+{
+ event->text_poke.addr = bswap_64(event->text_poke.addr);
+ event->text_poke.old_len = bswap_16(event->text_poke.old_len);
+ event->text_poke.new_len = bswap_16(event->text_poke.new_len);
+
+ if (sample_id_all) {
+ size_t len = sizeof(event->text_poke.old_len) +
+ sizeof(event->text_poke.new_len) +
+ event->text_poke.old_len +
+ event->text_poke.new_len;
+ void *data = &event->text_poke.old_len;
+
+ data += PERF_ALIGN(len, sizeof(u64));
+ swap_sample_id_all(event, data);
+ }
+}
+
static void perf_event__throttle_swap(union perf_event *event,
bool sample_id_all)
{
@@ -931,6 +951,7 @@ static perf_event__swap_op perf_event__swap_ops[] = {
[PERF_RECORD_SWITCH] = perf_event__switch_swap,
[PERF_RECORD_SWITCH_CPU_WIDE] = perf_event__switch_swap,
[PERF_RECORD_NAMESPACES] = perf_event__namespaces_swap,
+ [PERF_RECORD_TEXT_POKE] = perf_event__text_poke_swap,
[PERF_RECORD_HEADER_ATTR] = perf_event__hdr_attr_swap,
[PERF_RECORD_HEADER_EVENT_TYPE] = perf_event__event_type_swap,
[PERF_RECORD_HEADER_TRACING_DATA] = perf_event__tracing_data_swap,
@@ -1470,6 +1491,8 @@ static int machines__deliver_event(struct machines *machines,
return tool->ksymbol(tool, event, sample, machine);
case PERF_RECORD_BPF_EVENT:
return tool->bpf(tool, event, sample, machine);
+ case PERF_RECORD_TEXT_POKE:
+ return tool->text_poke(tool, event, sample, machine);
default:
++evlist->stats.nr_unknown_events;
return -1;
diff --git a/tools/perf/util/tool.h b/tools/perf/util/tool.h
index 2abbf668b8de..006182923bbe 100644
--- a/tools/perf/util/tool.h
+++ b/tools/perf/util/tool.h
@@ -56,7 +56,8 @@ struct perf_tool {
throttle,
unthrottle,
ksymbol,
- bpf;
+ bpf,
+ text_poke;

event_attr_op attr;
event_attr_op event_update;
--
2.17.1