gh-103295: expose API for writing perf map files (#103546)

Co-authored-by: Aniket Panse <aniketpanse@fb.com>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
Co-authored-by: Carl Meyer <carl@oddbird.net>

1 files changed, 16 insertions, 68 deletions

diff --git a/Python/perf_trampoline.c b/Python/perf_trampoline.c
index 3b18328..6a6f223 100644
--- a/Python/perf_trampoline.c
+++ b/Python/perf_trampoline.c
@@ -193,75 +193,33 @@ typedef struct trampoline_api_st trampoline_api_t;
 #define trampoline_api _PyRuntime.ceval.perf.trampoline_api
 #define perf_map_file _PyRuntime.ceval.perf.map_file
 
-static void *
-perf_map_get_file(void)
-{
-    if (perf_map_file) {
-        return perf_map_file;
-    }
-    char filename[100];
-    pid_t pid = getpid();
-    // Location and file name of perf map is hard-coded in perf tool.
-    // Use exclusive create flag wit nofollow to prevent symlink attacks.
-    int flags = O_WRONLY | O_CREAT | O_EXCL | O_NOFOLLOW | O_CLOEXEC;
-    snprintf(filename, sizeof(filename) - 1, "/tmp/perf-%jd.map",
-             (intmax_t)pid);
-    int fd = open(filename, flags, 0600);
-    if (fd == -1) {
-        perf_status = PERF_STATUS_FAILED;
-        PyErr_SetFromErrnoWithFilename(PyExc_OSError, filename);
-        return NULL;
-    }
-    perf_map_file = fdopen(fd, "w");
-    if (!perf_map_file) {
-        perf_status = PERF_STATUS_FAILED;
-        PyErr_SetFromErrnoWithFilename(PyExc_OSError, filename);
-        close(fd);
-        return NULL;
-    }
-    return perf_map_file;
-}
-
-static int
-perf_map_close(void *state)
-{
-    FILE *fp = (FILE *)state;
-    int ret = 0;
-    if (fp) {
-        ret = fclose(fp);
-    }
-    perf_map_file = NULL;
-    perf_status = PERF_STATUS_NO_INIT;
-    return ret;
-}
 
 static void
 perf_map_write_entry(void *state, const void *code_addr,
                          unsigned int code_size, PyCodeObject *co)
 {
-    assert(state != NULL);
-    FILE *method_file = (FILE *)state;
-    const char *entry = PyUnicode_AsUTF8(co->co_qualname);
-    if (entry == NULL) {
-        _PyErr_WriteUnraisableMsg("Failed to get qualname from code object",
-                                  NULL);
-        return;
+    const char *entry = "";
+    if (co->co_qualname != NULL) {
+        entry = PyUnicode_AsUTF8(co->co_qualname);
     }
-    const char *filename = PyUnicode_AsUTF8(co->co_filename);
-    if (filename == NULL) {
-        _PyErr_WriteUnraisableMsg("Failed to get filename from code object",
-                                  NULL);
+    const char *filename = "";
+    if (co->co_filename != NULL) {
+        filename = PyUnicode_AsUTF8(co->co_filename);
+    }
+    size_t perf_map_entry_size = snprintf(NULL, 0, "py::%s:%s", entry, filename) + 1;
+    char* perf_map_entry = (char*) PyMem_RawMalloc(perf_map_entry_size);
+    if (perf_map_entry == NULL) {
         return;
     }
-    fprintf(method_file, "%" PRIxPTR " %x py::%s:%s\n", (uintptr_t) code_addr, code_size, entry,
-            filename);
-    fflush(method_file);
+    snprintf(perf_map_entry, perf_map_entry_size, "py::%s:%s", entry, filename);
+    PyUnstable_WritePerfMapEntry(code_addr, code_size, perf_map_entry);
+    PyMem_RawFree(perf_map_entry);
 }
 
 _PyPerf_Callbacks _Py_perfmap_callbacks = {
-    &perf_map_get_file,
+    NULL,
     &perf_map_write_entry,
-    &perf_map_close
+    NULL,
 };
 
 static int
@@ -465,13 +423,6 @@ _PyPerfTrampoline_Init(int activate)
         if (new_code_arena() < 0) {
             return -1;
         }
-        if (trampoline_api.state == NULL) {
-            void *state = trampoline_api.init_state();
-            if (state == NULL) {
-                return -1;
-            }
-            trampoline_api.state = state;
-        }
         extra_code_index = _PyEval_RequestCodeExtraIndex(NULL);
         if (extra_code_index == -1) {
             return -1;
@@ -491,10 +442,6 @@ _PyPerfTrampoline_Fini(void)
         tstate->interp->eval_frame = NULL;
     }
     free_code_arenas();
-    if (trampoline_api.state != NULL) {
-        trampoline_api.free_state(trampoline_api.state);
-        trampoline_api.state = NULL;
-    }
     extra_code_index = -1;
 #endif
     return 0;
@@ -507,6 +454,7 @@ _PyPerfTrampoline_AfterFork_Child(void)
     // Restart trampoline in file in child.
     int was_active = _PyIsPerfTrampolineActive();
     _PyPerfTrampoline_Fini();
+    PyUnstable_PerfMapState_Fini();
     if (was_active) {
         _PyPerfTrampoline_Init(1);
     }