1 files changed, 12 insertions, 29 deletions

diff --git a/src/lj_mcode.c b/src/lj_mcode.c
index e64c5878..b2d12118 100644
--- a/src/lj_mcode.c
+++ b/src/lj_mcode.c
@@ -14,6 +14,7 @@
 #include "lj_mcode.h"
 #include "lj_trace.h"
 #include "lj_dispatch.h"
+#include "lj_prng.h"
 #endif
 #if LJ_HASJIT || LJ_HASFFI
 #include "lj_vm.h"
@@ -118,52 +119,34 @@ static int mcode_setprot(void *p, size_t sz, int prot)
   return mprotect(p, sz, prot);
 }
 
-#elif LJ_64
-
-#error "Missing OS support for explicit placement of executable memory"
-
 #else
 
-/* Fallback allocator. This will fail if memory is not executable by default. */
-#define LUAJIT_UNPROTECT_MCODE
-#define MCPROT_RW       0
-#define MCPROT_RX       0
-#define MCPROT_RWX      0
-
-static void *mcode_alloc_at(jit_State *J, uintptr_t hint, size_t sz, int prot)
-{
-  UNUSED(hint); UNUSED(prot);
-  return lj_mem_new(J->L, sz);
-}
-
-static void mcode_free(jit_State *J, void *p, size_t sz)
-{
-  lj_mem_free(J2G(J), p, sz);
-}
+#error "Missing OS support for explicit placement of executable memory"
 
 #endif
 
 /* -- MCode area protection ----------------------------------------------- */
 
-/* Define this ONLY if page protection twiddling becomes a bottleneck. */
-#ifdef LUAJIT_UNPROTECT_MCODE
+#if LUAJIT_SECURITY_MCODE == 0
 
-/* It's generally considered to be a potential security risk to have
+/* Define this ONLY if page protection twiddling becomes a bottleneck.
+**
+** It's generally considered to be a potential security risk to have
 ** pages with simultaneous write *and* execute access in a process.
 **
 ** Do not even think about using this mode for server processes or
-** apps handling untrusted external data (such as a browser).
+** apps handling untrusted external data.
 **
 ** The security risk is not in LuaJIT itself -- but if an adversary finds
-** any *other* flaw in your C application logic, then any RWX memory page
-** simplifies writing an exploit considerably.
+** any *other* flaw in your C application logic, then any RWX memory pages
+** simplify writing an exploit considerably.
 */
 #define MCPROT_GEN      MCPROT_RWX
 #define MCPROT_RUN      MCPROT_RWX
 
 static void mcode_protect(jit_State *J, int prot)
 {
-  UNUSED(J); UNUSED(prot);
+  UNUSED(J); UNUSED(prot); UNUSED(mcode_setprot);
 }
 
 #else
@@ -242,7 +225,7 @@ static void *mcode_alloc(jit_State *J, size_t sz)
     }
     /* Next try probing 64K-aligned pseudo-random addresses. */
     do {
-      hint = LJ_PRNG_BITS(J, LJ_TARGET_JUMPRANGE-16) << 16;
+      hint = lj_prng_u64(&J2G(J)->prng) & ((1u<<LJ_TARGET_JUMPRANGE)-0x10000);
     } while (!(hint + sz < range+range));
     hint = target + hint - range;
   }
@@ -331,7 +314,7 @@ void lj_mcode_abort(jit_State *J)
 /* Set/reset protection to allow patching of MCode areas. */
 MCode *lj_mcode_patch(jit_State *J, MCode *ptr, int finish)
 {
-#ifdef LUAJIT_UNPROTECT_MCODE
+#if LUAJIT_SECURITY_MCODE == 0
   UNUSED(J); UNUSED(ptr); UNUSED(finish);
   return NULL;
 #else