--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/luajit/src/lj_mcode.c	Thu Jan 22 20:10:30 2026 -0800
@@ -0,0 +1,374 @@
+/*
+** Machine code management.
+** Copyright (C) 2005-2023 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+#define lj_mcode_c
+#define LUA_CORE
+
+#include "lj_obj.h"
+#if LJ_HASJIT
+#include "lj_gc.h"
+#include "lj_err.h"
+#include "lj_jit.h"
+#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"
+#endif
+
+/* -- OS-specific functions ----------------------------------------------- */
+
+#if LJ_HASJIT || LJ_HASFFI
+
+/* Define this if you want to run LuaJIT with Valgrind. */
+#ifdef LUAJIT_USE_VALGRIND
+#include <valgrind/valgrind.h>
+#endif
+
+#if LJ_TARGET_IOS
+void sys_icache_invalidate(void *start, size_t len);
+#endif
+
+/* Synchronize data/instruction cache. */
+void lj_mcode_sync(void *start, void *end)
+{
+#ifdef LUAJIT_USE_VALGRIND
+  VALGRIND_DISCARD_TRANSLATIONS(start, (char *)end-(char *)start);
+#endif
+#if LJ_TARGET_X86ORX64
+  UNUSED(start); UNUSED(end);
+#elif LJ_TARGET_IOS
+  sys_icache_invalidate(start, (char *)end-(char *)start);
+#elif LJ_TARGET_PPC
+  lj_vm_cachesync(start, end);
+#elif defined(__GNUC__) || defined(__clang__)
+  __clear_cache(start, end);
+#else
+#error "Missing builtin to flush instruction cache"
+#endif
+}
+
+#endif
+
+#if LJ_HASJIT
+
+#if LJ_TARGET_WINDOWS
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#define MCPROT_RW	PAGE_READWRITE
+#define MCPROT_RX	PAGE_EXECUTE_READ
+#define MCPROT_RWX	PAGE_EXECUTE_READWRITE
+
+static void *mcode_alloc_at(jit_State *J, uintptr_t hint, size_t sz, DWORD prot)
+{
+  void *p = LJ_WIN_VALLOC((void *)hint, sz,
+			  MEM_RESERVE|MEM_COMMIT|MEM_TOP_DOWN, prot);
+  if (!p && !hint)
+    lj_trace_err(J, LJ_TRERR_MCODEAL);
+  return p;
+}
+
+static void mcode_free(jit_State *J, void *p, size_t sz)
+{
+  UNUSED(J); UNUSED(sz);
+  VirtualFree(p, 0, MEM_RELEASE);
+}
+
+static int mcode_setprot(void *p, size_t sz, DWORD prot)
+{
+  DWORD oprot;
+  return !LJ_WIN_VPROTECT(p, sz, prot, &oprot);
+}
+
+#elif LJ_TARGET_POSIX
+
+#include <sys/mman.h>
+
+#ifndef MAP_ANONYMOUS
+#define MAP_ANONYMOUS	MAP_ANON
+#endif
+
+#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|MCPROT_CREATE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+  if (p == MAP_FAILED) {
+    if (!hint) lj_trace_err(J, LJ_TRERR_MCODEAL);
+    p = NULL;
+  }
+  return p;
+}
+
+static void mcode_free(jit_State *J, void *p, size_t sz)
+{
+  UNUSED(J);
+  munmap(p, sz);
+}
+
+static int mcode_setprot(void *p, size_t sz, int prot)
+{
+  return mprotect(p, sz, prot);
+}
+
+#else
+
+#error "Missing OS support for explicit placement of executable memory"
+
+#endif
+
+/* -- MCode area protection ----------------------------------------------- */
+
+#if LUAJIT_SECURITY_MCODE == 0
+
+/* 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.
+**
+** 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 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(mcode_setprot);
+}
+
+#else
+
+/* This is the default behaviour and much safer:
+**
+** Most of the time the memory pages holding machine code are executable,
+** but NONE of them is writable.
+**
+** The current memory area is marked read-write (but NOT executable) only
+** during the short time window while the assembler generates machine code.
+*/
+#define MCPROT_GEN	MCPROT_RW
+#define MCPROT_RUN	MCPROT_RX
+
+/* Protection twiddling failed. Probably due to kernel security. */
+static LJ_NORET LJ_NOINLINE void mcode_protfail(jit_State *J)
+{
+  lua_CFunction panic = J2G(J)->panic;
+  if (panic) {
+    lua_State *L = J->L;
+    setstrV(L, L->top++, lj_err_str(L, LJ_ERR_JITPROT));
+    panic(L);
+  }
+  exit(EXIT_FAILURE);
+}
+
+/* Change protection of MCode area. */
+static void mcode_protect(jit_State *J, int prot)
+{
+  if (J->mcprot != prot) {
+    if (LJ_UNLIKELY(mcode_setprot(J->mcarea, J->szmcarea, prot)))
+      mcode_protfail(J);
+    J->mcprot = prot;
+  }
+}
+
+#endif
+
+/* -- MCode area allocation ----------------------------------------------- */
+
+#if LJ_64
+#define mcode_validptr(p)	(p)
+#else
+#define mcode_validptr(p)	((p) && (uintptr_t)(p) < 0xffff0000)
+#endif
+
+#ifdef LJ_TARGET_JUMPRANGE
+
+/* Get memory within relative jump distance of our code in 64 bit mode. */
+static void *mcode_alloc(jit_State *J, size_t sz)
+{
+  /* Target an address in the static assembler code (64K aligned).
+  ** Try addresses within a distance of target-range/2+1MB..target+range/2-1MB.
+  ** Use half the jump range so every address in the range can reach any other.
+  */
+#if LJ_TARGET_MIPS
+  /* Use the middle of the 256MB-aligned region. */
+  uintptr_t target = ((uintptr_t)(void *)lj_vm_exit_handler &
+		      ~(uintptr_t)0x0fffffffu) + 0x08000000u;
+#else
+  uintptr_t target = (uintptr_t)(void *)lj_vm_exit_handler & ~(uintptr_t)0xffff;
+#endif
+  const uintptr_t range = (1u << (LJ_TARGET_JUMPRANGE-1)) - (1u << 21);
+  /* First try a contiguous area below the last one. */
+  uintptr_t hint = J->mcarea ? (uintptr_t)J->mcarea - sz : 0;
+  int i;
+  /* Limit probing iterations, depending on the available pool size. */
+  for (i = 0; i < LJ_TARGET_JUMPRANGE; i++) {
+    if (mcode_validptr(hint)) {
+      void *p = mcode_alloc_at(J, hint, sz, MCPROT_GEN);
+
+      if (mcode_validptr(p) &&
+	  ((uintptr_t)p + sz - target < range || target - (uintptr_t)p < range))
+	return p;
+      if (p) mcode_free(J, p, sz);  /* Free badly placed area. */
+    }
+    /* Next try probing 64K-aligned pseudo-random addresses. */
+    do {
+      hint = lj_prng_u64(&J2G(J)->prng) & ((1u<<LJ_TARGET_JUMPRANGE)-0x10000);
+    } while (!(hint + sz < range+range));
+    hint = target + hint - range;
+  }
+  lj_trace_err(J, LJ_TRERR_MCODEAL);  /* Give up. OS probably ignores hints? */
+  return NULL;
+}
+
+#else
+
+/* All memory addresses are reachable by relative jumps. */
+static void *mcode_alloc(jit_State *J, size_t sz)
+{
+#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)) {
+    mcode_free(J, p, sz);
+    return NULL;
+  }
+  return p;
+#else
+  return mcode_alloc_at(J, 0, sz, MCPROT_GEN);
+#endif
+}
+
+#endif
+
+/* -- MCode area management ----------------------------------------------- */
+
+/* Allocate a new MCode area. */
+static void mcode_allocarea(jit_State *J)
+{
+  MCode *oldarea = J->mcarea;
+  size_t sz = (size_t)J->param[JIT_P_sizemcode] << 10;
+  sz = (sz + LJ_PAGESIZE-1) & ~(size_t)(LJ_PAGESIZE - 1);
+  J->mcarea = (MCode *)mcode_alloc(J, sz);
+  J->szmcarea = sz;
+  J->mcprot = MCPROT_GEN;
+  J->mctop = (MCode *)((char *)J->mcarea + J->szmcarea);
+  J->mcbot = (MCode *)((char *)J->mcarea + sizeof(MCLink));
+  ((MCLink *)J->mcarea)->next = oldarea;
+  ((MCLink *)J->mcarea)->size = sz;
+  J->szallmcarea += sz;
+  J->mcbot = (MCode *)lj_err_register_mcode(J->mcarea, sz, (uint8_t *)J->mcbot);
+}
+
+/* Free all MCode areas. */
+void lj_mcode_free(jit_State *J)
+{
+  MCode *mc = J->mcarea;
+  J->mcarea = NULL;
+  J->szallmcarea = 0;
+  while (mc) {
+    MCode *next = ((MCLink *)mc)->next;
+    size_t sz = ((MCLink *)mc)->size;
+    lj_err_deregister_mcode(mc, sz, (uint8_t *)mc + sizeof(MCLink));
+    mcode_free(J, mc, sz);
+    mc = next;
+  }
+}
+
+/* -- MCode transactions -------------------------------------------------- */
+
+/* Reserve the remainder of the current MCode area. */
+MCode *lj_mcode_reserve(jit_State *J, MCode **lim)
+{
+  if (!J->mcarea)
+    mcode_allocarea(J);
+  else
+    mcode_protect(J, MCPROT_GEN);
+  *lim = J->mcbot;
+  return J->mctop;
+}
+
+/* Commit the top part of the current MCode area. */
+void lj_mcode_commit(jit_State *J, MCode *top)
+{
+  J->mctop = top;
+  mcode_protect(J, MCPROT_RUN);
+}
+
+/* Abort the reservation. */
+void lj_mcode_abort(jit_State *J)
+{
+  if (J->mcarea)
+    mcode_protect(J, MCPROT_RUN);
+}
+
+/* Set/reset protection to allow patching of MCode areas. */
+MCode *lj_mcode_patch(jit_State *J, MCode *ptr, int finish)
+{
+  if (finish) {
+#if LUAJIT_SECURITY_MCODE
+    if (J->mcarea == ptr)
+      mcode_protect(J, MCPROT_RUN);
+    else if (LJ_UNLIKELY(mcode_setprot(ptr, ((MCLink *)ptr)->size, MCPROT_RUN)))
+      mcode_protfail(J);
+#endif
+    return NULL;
+  } else {
+    MCode *mc = J->mcarea;
+    /* Try current area first to use the protection cache. */
+    if (ptr >= mc && ptr < (MCode *)((char *)mc + J->szmcarea)) {
+#if LUAJIT_SECURITY_MCODE
+      mcode_protect(J, MCPROT_GEN);
+#endif
+      return mc;
+    }
+    /* Otherwise search through the list of MCode areas. */
+    for (;;) {
+      mc = ((MCLink *)mc)->next;
+      lj_assertJ(mc != NULL, "broken MCode area chain");
+      if (ptr >= mc && ptr < (MCode *)((char *)mc + ((MCLink *)mc)->size)) {
+#if LUAJIT_SECURITY_MCODE
+	if (LJ_UNLIKELY(mcode_setprot(mc, ((MCLink *)mc)->size, MCPROT_GEN)))
+	  mcode_protfail(J);
+#endif
+	return mc;
+      }
+    }
+  }
+}
+
+/* Limit of MCode reservation reached. */
+void lj_mcode_limiterr(jit_State *J, size_t need)
+{
+  size_t sizemcode, maxmcode;
+  lj_mcode_abort(J);
+  sizemcode = (size_t)J->param[JIT_P_sizemcode] << 10;
+  sizemcode = (sizemcode + LJ_PAGESIZE-1) & ~(size_t)(LJ_PAGESIZE - 1);
+  maxmcode = (size_t)J->param[JIT_P_maxmcode] << 10;
+  if ((size_t)need > sizemcode)
+    lj_trace_err(J, LJ_TRERR_MCODEOV);  /* Too long for any area. */
+  if (J->szallmcarea + sizemcode > maxmcode)
+    lj_trace_err(J, LJ_TRERR_MCODEAL);
+  mcode_allocarea(J);
+  lj_trace_err(J, LJ_TRERR_MCODELM);  /* Retry with new area. */
+}
+
+#endif