[PATCH v1 1/2] perf machine: Factor creating a "live" machine out of dwarf-unwind

From: Ian Rogers
Date: Thu Mar 13 2025 - 01:30:11 EST


Factor out for use in places other than the dwarf unwinding tests for
libunwind.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
tools/perf/tests/dwarf-unwind.c | 35 ++++------------------
tools/perf/util/machine.c | 53 +++++++++++++++++++++++++++------
tools/perf/util/machine.h | 1 +
3 files changed, 51 insertions(+), 38 deletions(-)

diff --git a/tools/perf/tests/dwarf-unwind.c b/tools/perf/tests/dwarf-unwind.c
index 4803ab2d97ba..525c46b7971a 100644
--- a/tools/perf/tests/dwarf-unwind.c
+++ b/tools/perf/tests/dwarf-unwind.c
@@ -15,7 +15,6 @@
#include "symbol.h"
#include "thread.h"
#include "callchain.h"
-#include "util/synthetic-events.h"

/* For bsearch. We try to unwind functions in shared object. */
#include <stdlib.h>
@@ -37,24 +36,6 @@
#define NO_TAIL_CALL_BARRIER __asm__ __volatile__("" : : : "memory");
#endif

-static int mmap_handler(const struct perf_tool *tool __maybe_unused,
- union perf_event *event,
- struct perf_sample *sample,
- struct machine *machine)
-{
- return machine__process_mmap2_event(machine, event, sample);
-}
-
-static int init_live_machine(struct machine *machine)
-{
- union perf_event event;
- pid_t pid = getpid();
-
- memset(&event, 0, sizeof(event));
- return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
- mmap_handler, machine, true);
-}
-
/*
* We need to keep these functions global, despite the
* fact that they are used only locally in this object,
@@ -202,8 +183,12 @@ noinline int test__dwarf_unwind(struct test_suite *test __maybe_unused,
struct machine *machine;
struct thread *thread;
int err = -1;
+ pid_t pid = getpid();

- machine = machine__new_host();
+ callchain_param.record_mode = CALLCHAIN_DWARF;
+ dwarf_callchain_users = true;
+
+ machine = machine__new_live(/*kernel_maps=*/true, pid);
if (!machine) {
pr_err("Could not get machine\n");
return -1;
@@ -214,18 +199,10 @@ noinline int test__dwarf_unwind(struct test_suite *test __maybe_unused,
return -1;
}

- callchain_param.record_mode = CALLCHAIN_DWARF;
- dwarf_callchain_users = true;
-
- if (init_live_machine(machine)) {
- pr_err("Could not init machine\n");
- goto out;
- }
-
if (verbose > 1)
machine__fprintf(machine, stderr);

- thread = machine__find_thread(machine, getpid(), getpid());
+ thread = machine__find_thread(machine, pid, pid);
if (!thread) {
pr_err("Could not get thread\n");
goto out;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 2531b373f2cf..c5e28d15323f 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -20,6 +20,7 @@
#include "path.h"
#include "srcline.h"
#include "symbol.h"
+#include "synthetic-events.h"
#include "sort.h"
#include "strlist.h"
#include "target.h"
@@ -128,23 +129,57 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
return 0;
}

-struct machine *machine__new_host(void)
+static struct machine *__machine__new_host(bool kernel_maps)
{
struct machine *machine = malloc(sizeof(*machine));

- if (machine != NULL) {
- machine__init(machine, "", HOST_KERNEL_ID);
+ if (!machine)
+ return NULL;

- if (machine__create_kernel_maps(machine) < 0)
- goto out_delete;
+ machine__init(machine, "", HOST_KERNEL_ID);

- machine->env = &perf_env;
+ if (kernel_maps && machine__create_kernel_maps(machine) < 0) {
+ free(machine);
+ return NULL;
}
+ machine->env = &perf_env;
+ return machine;
+}
+
+struct machine *machine__new_host(void)
+{
+ return __machine__new_host(/*kernel_maps=*/true);
+}
+
+static int mmap_handler(const struct perf_tool *tool __maybe_unused,
+ union perf_event *event,
+ struct perf_sample *sample,
+ struct machine *machine)
+{
+ return machine__process_mmap2_event(machine, event, sample);
+}

+static int machine__init_live(struct machine *machine, pid_t pid)
+{
+ union perf_event event;
+
+ memset(&event, 0, sizeof(event));
+ return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
+ mmap_handler, machine, true);
+}
+
+struct machine *machine__new_live(bool kernel_maps, pid_t pid)
+{
+ struct machine *machine = __machine__new_host(kernel_maps);
+
+ if (!machine)
+ return NULL;
+
+ if (machine__init_live(machine, pid)) {
+ machine__delete(machine);
+ return NULL;
+ }
return machine;
-out_delete:
- free(machine);
- return NULL;
}

struct machine *machine__new_kallsyms(void)
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index b56abec84fed..180b369c366c 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -171,6 +171,7 @@ void machines__set_comm_exec(struct machines *machines, bool comm_exec);

struct machine *machine__new_host(void);
struct machine *machine__new_kallsyms(void);
+struct machine *machine__new_live(bool kernel_maps, pid_t pid);
int machine__init(struct machine *machine, const char *root_dir, pid_t pid);
void machine__exit(struct machine *machine);
void machine__delete_threads(struct machine *machine);
--
2.49.0.rc0.332.g42c0ae87b1-goog