gh-140421: Fix perf trampoline on older macOS

* Use mach_absolute_time() when clock_gettime() is not available.
* Define MAP_ANONYMOUS to MAP_ANON if the latter is defined and the
  former is not. This matches what is done elsewhere in the code base
  in this situation, e.g. mmapmodule.c.
* Don't build perf trampoline on ppc systems, where getting this to
  work would be a lot more effort.

Author: jmroot

Python/perf_jit_trampoline.c

@@ -80,6 +80,17 @@
 #  include <sys/syscall.h>        // System call interface
 #endif
 
+#if defined(__APPLE__)
+#include <AvailabilityMacros.h>
+#if defined(MAC_OS_X_VERSION_MIN_REQUIRED) \
+        && (!defined(MAC_OS_X_VERSION_10_12) || \
+        MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_12)
+#define PY_PERF_JIT_USE_MACH_TIME
+#include <inttypes.h>
+#include <mach/mach_time.h>       // mach_absolute_time
+#endif
+#endif
+
 // =============================================================================
 //                           CONSTANTS AND CONFIGURATION
 // =============================================================================
@@ -284,6 +295,12 @@ static const intptr_t nanoseconds_per_second = 1000000000;
  * Returns: Current monotonic time in nanoseconds since an arbitrary epoch
  */
 static int64_t get_current_monotonic_ticks(void) {
+#if defined(__APPLE__) && defined(PY_PERF_JIT_USE_MACH_TIME)
+    /* clock_gettime() is not available before macOS 10.12.
+     * mach_absolute_time() should always return a value in
+     * nanoseconds on x86. */
+    return (int64_t)mach_absolute_time();
+#else
     struct timespec ts;
     if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0) {
         Py_UNREACHABLE();  // Should never fail on supported systems
@@ -295,6 +312,7 @@ static int64_t get_current_monotonic_ticks(void) {
     result *= nanoseconds_per_second;
     result += ts.tv_nsec;
     return result;
+#endif
 }
 
 /*

Python/perf_trampoline.c

@@ -145,6 +145,9 @@ any DWARF information available for them).
 #include <unistd.h>               // sysconf()
 #include <sys/time.h>           // gettimeofday()
 
+#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
+#  define MAP_ANONYMOUS MAP_ANON
+#endif
 
 #if defined(__arm__) || defined(__arm64__) || defined(__aarch64__)
 #define PY_HAVE_INVALIDATE_ICACHE

configure

@@ -3704,7 +3704,10 @@ AC_MSG_CHECKING([perf trampoline])
 AS_CASE([$PLATFORM_TRIPLET],
   [x86_64-linux-gnu], [perf_trampoline=yes],
   [aarch64-linux-gnu], [perf_trampoline=yes],
-  [darwin], [perf_trampoline=yes],
+  [darwin], AS_CASE([$host_cpu],
+                [p*pc*], [perf_trampoline=no],
+                [*], [perf_trampoline=yes]
+                ),
   [perf_trampoline=no]
 )
 AC_MSG_RESULT([$perf_trampoline])