Use mach_vm_remap in Tachyon on macOS

Lib/test/test_external_inspection.py

@@ -3772,6 +3772,13 @@ def test_get_stats(self):
             "batched_read_misses",
             "batched_read_segments_requested",
             "batched_read_segments_completed",
+            "alias_hits",
+            "alias_misses",
+            "alias_remap_failures",
+            "alias_validation_fails",
+            "alias_evictions",
+            "alias_probe_checks",
+            "alias_probe_recycles",
             "batched_read_success_rate",
             "batched_read_segment_completion_rate",
         ]

Modules/Setup.stdlib.in

@@ -41,7 +41,7 @@
 @MODULE__PICKLE_TRUE@_pickle _pickle.c
 @MODULE__QUEUE_TRUE@_queue _queuemodule.c
 @MODULE__RANDOM_TRUE@_random _randommodule.c
-@MODULE__REMOTE_DEBUGGING_TRUE@_remote_debugging _remote_debugging/module.c _remote_debugging/gc_stats.c _remote_debugging/object_reading.c _remote_debugging/code_objects.c _remote_debugging/frames.c _remote_debugging/frame_cache.c _remote_debugging/threads.c _remote_debugging/asyncio.c _remote_debugging/binary_io_writer.c _remote_debugging/binary_io_reader.c _remote_debugging/subprocess.c _remote_debugging/interpreters.c
+@MODULE__REMOTE_DEBUGGING_TRUE@_remote_debugging _remote_debugging/module.c _remote_debugging/gc_stats.c _remote_debugging/object_reading.c _remote_debugging/code_objects.c _remote_debugging/frames.c _remote_debugging/frame_cache.c _remote_debugging/threads.c _remote_debugging/asyncio.c _remote_debugging/alias_read.c _remote_debugging/binary_io_writer.c _remote_debugging/binary_io_reader.c _remote_debugging/subprocess.c _remote_debugging/interpreters.c
 @MODULE__STRUCT_TRUE@_struct _struct.c
 
 # build supports subinterpreters

Modules/_remote_debugging/_remote_debugging.h

@@ -262,6 +262,31 @@ typedef struct {
     uintptr_t frame_addr;
 } RemoteReadPrefetch;
 
+#if defined(__APPLE__) && TARGET_OS_OSX
+#define MAX_ALIAS_PAGES 256
+#define ALIAS_PROBE_DEFAULT_MASK 0x3ff
+#define ALIAS_PROBE_MIN_MASK 0x3f
+#define ALIAS_PROBE_MAX_MASK 0x3fff
+
+typedef struct {
+    uintptr_t remote_page_base;
+    mach_vm_address_t local_page_base;
+    uint64_t access_seq;
+    int valid;
+    uint64_t map_objid;
+    uint64_t map_offset;
+} AliasPageEntry;
+
+typedef struct {
+    AliasPageEntry pages[MAX_ALIAS_PAGES];
+    mach_vm_address_t region_base;
+    uint64_t access_seq;
+    uint32_t probe_counter;
+    uint32_t probe_mask;
+    int disabled;
+} AliasReadCache;
+#endif
+
 /* Statistics for profiling performance analysis */
 typedef struct {
     uint64_t total_samples;                  // Total number of get_stack_trace calls
@@ -280,6 +305,13 @@ typedef struct {
     uint64_t batched_read_misses;            // Attempts that fell back or partially read
     uint64_t batched_read_segments_requested; // Segments requested by batched reads
     uint64_t batched_read_segments_completed; // Segments completed by batched reads
+    uint64_t alias_hits;                     // macOS alias-cache hits
+    uint64_t alias_misses;                   // macOS alias-cache misses
+    uint64_t alias_remap_failures;           // macOS remap/protect failures
+    uint64_t alias_validation_fails;         // macOS alias snapshot validation failures
+    uint64_t alias_evictions;                // macOS alias-cache LRU evictions
+    uint64_t alias_probe_checks;             // macOS alias object identity probes
+    uint64_t alias_probe_recycles;           // macOS alias recycled-page detections
 } UnwinderStats;
 
 #if defined(__GNUC__) || defined(__clang__)
@@ -349,6 +381,9 @@ typedef struct {
     proc_handle_t handle;
     uintptr_t runtime_start_address;
     struct _Py_DebugOffsets debug_offsets;
+    size_t interp_window_start;
+    size_t interp_window_size;
+    uintptr_t vm_max_address;
     int async_debug_offsets_available;
     struct _Py_AsyncioModuleDebugOffsets async_debug_offsets;
     uintptr_t interpreter_addr;
@@ -382,6 +417,9 @@ typedef struct {
 #ifdef __APPLE__
     uint64_t thread_id_offset;
     int thread_id_offset_initialized;
+#  if TARGET_OS_OSX
+    AliasReadCache alias_cache;
+#  endif
 #endif
 #ifdef MS_WINDOWS
     PVOID win_process_buffer;
@@ -648,6 +686,27 @@ extern int collect_frames_with_cache(
     FrameWalkContext *ctx,
     uint64_t thread_id);
 
+#if defined(__APPLE__) && TARGET_OS_OSX
+
+extern int _Py_RemoteDebug_ValidateThreadStateSnapshot(
+    RemoteUnwinderObject *unwinder,
+    const char *tstate_buffer,
+    uintptr_t tstate_addr,
+    uintptr_t current_interpreter
+);
+/* Returns 0 if bytes were served from an aliased page snapshot (callers
+ * should validate), 1 if no snapshot was involved (live syscall read or
+ * zero-length no-op; skip validation), -1 on error with an exception
+ * set. */
+extern int _Py_RemoteDebug_AliasedRead(
+    RemoteUnwinderObject *unwinder,
+    uintptr_t remote_addr,
+    size_t len,
+    void *dst);
+extern void _Py_RemoteDebug_AliasCacheInit(RemoteUnwinderObject *unwinder);
+extern void _Py_RemoteDebug_AliasCacheClear(RemoteUnwinderObject *unwinder);
+#endif
+
 /* ============================================================================
  * THREAD FUNCTION DECLARATIONS
  * ============================================================================ */
@@ -676,6 +735,7 @@ extern int get_thread_status(RemoteUnwinderObject *unwinder, uint64_t tid, uint6
 
 extern PyObject* unwind_stack_for_thread(
     RemoteUnwinderObject *unwinder,
+    uintptr_t current_interpreter,
     uintptr_t *current_tstate,
     uintptr_t gil_holder_tstate,
     uintptr_t gc_frame,