perf dlfilter: Add object_code() to perf_dlfilter_fns

Add a function, for use by dlfilters, to read object code.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210627131818.810-11-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-dlfilter.txt

@@ -127,7 +127,8 @@ struct perf_dlfilter_fns {
 	const __u8 *(*insn)(void *ctx, __u32 *length);
 	const char *(*srcline)(void *ctx, __u32 *line_number);
 	struct perf_event_attr *(*attr)(void *ctx);
-	void *(*reserved[121])(void *);
+	__s32 (*object_code)(void *ctx, __u64 ip, void *buf, __u32 len);
+	void *(*reserved[120])(void *);
 };
 ----
 
@@ -146,6 +147,8 @@ before calling. Returns 0 on success, -1 otherwise.
 
 'attr' returns perf_event_attr, refer <linux/perf_event.h>.
 
+'object_code' reads object code and returns the number of bytes read.
+
 The perf_dlfilter_al structure
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

tools/perf/util/dlfilter.c

@@ -245,6 +245,39 @@ static struct perf_event_attr *dlfilter__attr(void *ctx)
 	return &d->evsel->core.attr;
 }
 
+static __s32 dlfilter__object_code(void *ctx, __u64 ip, void *buf, __u32 len)
+{
+	struct dlfilter *d = (struct dlfilter *)ctx;
+	struct addr_location *al;
+	struct addr_location a;
+	struct map *map;
+	u64 offset;
+
+	if (!d->ctx_valid)
+		return -1;
+
+	al = get_al(d);
+	if (!al)
+		return -1;
+
+	map = al->map;
+
+	if (map && ip >= map->start && ip < map->end &&
+	    machine__kernel_ip(d->machine, ip) == machine__kernel_ip(d->machine, d->sample->ip))
+		goto have_map;
+
+	thread__find_map_fb(al->thread, d->sample->cpumode, ip, &a);
+	if (!a.map)
+		return -1;
+
+	map = a.map;
+have_map:
+	offset = map->map_ip(map, ip);
+	if (ip + len >= map->end)
+		len = map->end - ip;
+	return dso__data_read_offset(map->dso, d->machine, offset, buf, len);
+}
+
 static const struct perf_dlfilter_fns perf_dlfilter_fns = {
 	.resolve_ip      = dlfilter__resolve_ip,
 	.resolve_addr    = dlfilter__resolve_addr,
@@ -253,6 +286,7 @@ static const struct perf_dlfilter_fns perf_dlfilter_fns = {
 	.insn            = dlfilter__insn,
 	.srcline         = dlfilter__srcline,
 	.attr            = dlfilter__attr,
+	.object_code     = dlfilter__object_code,
 };
 
 static char *find_dlfilter(const char *file)

tools/perf/util/perf_dlfilter.h

@@ -103,8 +103,10 @@ struct perf_dlfilter_fns {
 	const char *(*srcline)(void *ctx, __u32 *line_number);
 	/* Return perf_event_attr, refer <linux/perf_event.h> */
 	struct perf_event_attr *(*attr)(void *ctx);
+	/* Read object code, return numbers of bytes read */
+	__s32 (*object_code)(void *ctx, __u64 ip, void *buf, __u32 len);
 	/* Reserved */
-	void *(*reserved[121])(void *);
+	void *(*reserved[120])(void *);
 };
 
 /*