[PATCH] fix Apple Silicon JIT compilation

["Aleix Conchillo Flaqué" <aconchillo@gmail.com>]

* configure.ac: check for pthread_jit_write_protect_np.

* libguile/jit.c: add support for Apple Silicon JIT compilation.

Fixes https://debbugs.gnu.org/cgi/bugreport.cgi?bug=44505
---
 configure.ac   |  3 +++
 libguile/jit.c | 25 ++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index b3879df1f..f8c12f0d7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1187,6 +1187,9 @@ case "$with_threads" in
       pthread_get_stackaddr_np pthread_attr_get_np pthread_sigmask	\
       pthread_cancel])
 
+    # Apple Silicon JIT code arena needs to be unprotected before writing.
+    AC_CHECK_FUNCS([pthread_jit_write_protect_np])
+
     # On past versions of Solaris, believe 8 through 10 at least, you
     # had to write "pthread_once_t foo = { PTHREAD_ONCE_INIT };".
     # This is contrary to POSIX:
diff --git a/libguile/jit.c b/libguile/jit.c
index 8420829b4..5cef8fae3 100644
--- a/libguile/jit.c
+++ b/libguile/jit.c
@@ -47,6 +47,10 @@
 #include <sys/mman.h>
 #endif
 
+#if defined __APPLE__ && HAVE_PTHREAD_JIT_WRITE_PROTECT_NP
+#include <libkern/OSCacheControl.h>
+#endif
+
 #include "jit.h"
 
 
@@ -1349,9 +1353,13 @@ allocate_code_arena (size_t size, struct code_arena *prev)
   ret->size = size;
   ret->prev = prev;
 #ifndef __MINGW32__
+  int flags = MAP_PRIVATE | MAP_ANONYMOUS;
+#if defined __APPLE__ && HAVE_PTHREAD_JIT_WRITE_PROTECT_NP
+  flags |= MAP_JIT;
+#endif
   ret->base = mmap (NULL, ret->size,
                     PROT_EXEC | PROT_READ | PROT_WRITE,
-                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+                    flags, -1, 0);
   if (ret->base == MAP_FAILED)
     {
       perror ("allocating JIT code buffer failed");
@@ -1406,11 +1414,21 @@ emit_code (scm_jit_state *j, void (*emit) (scm_jit_state *))
 
       uint8_t *ret = jit_address (j->jit);
 
+#if defined __APPLE__ && HAVE_PTHREAD_JIT_WRITE_PROTECT_NP
+      pthread_jit_write_protect_np(0);
+#endif
+
       emit (j);
 
       size_t size;
       if (!jit_has_overflow (j->jit) && jit_end (j->jit, &size))
         {
+#if defined __APPLE__ && HAVE_PTHREAD_JIT_WRITE_PROTECT_NP
+          /* protect previous code arena. leave unprotected after emit()
+             since jit_end() also writes to code arena. */
+          pthread_jit_write_protect_np(1);
+          sys_icache_invalidate(arena->base, arena->size);
+#endif
           ASSERT (size <= (arena->size - arena->used));
           DEBUG ("mcode: %p,+%zu\n", ret, size);
           arena->used += size;
@@ -1424,6 +1442,11 @@ emit_code (scm_jit_state *j, void (*emit) (scm_jit_state *))
         }
       else
         {
+#if defined __APPLE__ && HAVE_PTHREAD_JIT_WRITE_PROTECT_NP
+          /* protect previous code arena */
+          pthread_jit_write_protect_np(1);
+          sys_icache_invalidate(arena->base, arena->size);
+#endif
           jit_reset (j->jit);
           if (arena->used == 0)
             {
-- 
2.37.1 (Apple Git-137.1)