NetBSD: Use PROT_MPROTECT() and disable getentropy().

Note: this is not an officially supported target.
Contributed by David Carlier.

src/lj_ccallback.c

@@ -256,6 +256,11 @@ static void *callback_mcode_init(global_State *g, uint32_t *page)
 #ifndef MAP_ANONYMOUS
 #define MAP_ANONYMOUS   MAP_ANON
 #endif
+#ifdef PROT_MPROTECT
+#define CCPROT_CREATE	(PROT_MPROTECT(PROT_EXEC))
+#else
+#define CCPROT_CREATE	0
+#endif
 
 #endif
 
@@ -271,7 +276,7 @@ static void callback_mcode_new(CTState *cts)
   if (!p)
     lj_err_caller(cts->L, LJ_ERR_FFI_CBACKOV);
 #elif LJ_TARGET_POSIX
-  p = mmap(NULL, sz, (PROT_READ|PROT_WRITE), MAP_PRIVATE|MAP_ANONYMOUS,
+  p = mmap(NULL, sz, (PROT_READ|PROT_WRITE|CCPROT_CREATE), MAP_PRIVATE|MAP_ANONYMOUS,
 	   -1, 0);
   if (p == MAP_FAILED)
     lj_err_caller(cts->L, LJ_ERR_FFI_CBACKOV);

src/lj_mcode.c

@@ -97,10 +97,15 @@ static int mcode_setprot(void *p, size_t sz, DWORD prot)
 #define MCPROT_RW	(PROT_READ|PROT_WRITE)
 #define MCPROT_RX	(PROT_READ|PROT_EXEC)
 #define MCPROT_RWX	(PROT_READ|PROT_WRITE|PROT_EXEC)
+#ifdef PROT_MPROTECT
+#define MCPROT_CREATE	(PROT_MPROTECT(MCPROT_RWX))
+#else
+#define MCPROT_CREATE	0
+#endif
 
 static void *mcode_alloc_at(jit_State *J, uintptr_t hint, size_t sz, int prot)
 {
-  void *p = mmap((void *)hint, sz, prot, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+  void *p = mmap((void *)hint, sz, prot|MCPROT_CREATE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
   if (p == MAP_FAILED) {
     if (!hint) lj_trace_err(J, LJ_TRERR_MCODEAL);
     p = NULL;
@@ -238,7 +243,7 @@ static void *mcode_alloc(jit_State *J, size_t sz)
 /* All memory addresses are reachable by relative jumps. */
 static void *mcode_alloc(jit_State *J, size_t sz)
 {
-#if defined(__OpenBSD__) || LJ_TARGET_UWP
+#if defined(__OpenBSD__) || defined(__NetBSD__) || LJ_TARGET_UWP
   /* Allow better executable memory allocation for OpenBSD W^X mode. */
   void *p = mcode_alloc_at(J, 0, sz, MCPROT_RUN);
   if (p && mcode_setprot(p, sz, MCPROT_GEN)) {

src/lj_prng.c

@@ -121,7 +121,7 @@ static PRGR libfunc_rgr;
 #if __MAC_OS_X_VERSION_MIN_REQUIRED >= 101200
 #define LJ_TARGET_HAS_GETENTROPY	1
 #endif
-#elif LJ_TARGET_BSD || LJ_TARGET_SOLARIS || LJ_TARGET_CYGWIN
+#elif (LJ_TARGET_BSD && !defined(__NetBSD__)) || LJ_TARGET_SOLARIS || LJ_TARGET_CYGWIN
 #define LJ_TARGET_HAS_GETENTROPY	1
 #endif