src/lj_state.c

   1 /*
   2 ** State and stack handling.
   3 ** Copyright (C) 2005-2023 Mike Pall. See Copyright Notice in luajit.h
   4 **
   5 ** Portions taken verbatim or adapted from the Lua interpreter.
   6 ** Copyright (C) 1994-2008 Lua.org, PUC-Rio. See Copyright Notice in lua.h
   7 */
   8
   9 #define lj_state_c
  10 #define LUA_CORE
  11
  12 #include "lj_obj.h"
  13 #include "lj_gc.h"
  14 #include "lj_err.h"
  15 #include "lj_buf.h"
  16 #include "lj_str.h"
  17 #include "lj_tab.h"
  18 #include "lj_func.h"
  19 #include "lj_meta.h"
  20 #include "lj_state.h"
  21 #include "lj_frame.h"
  22 #if LJ_HASFFI
  23 #include "lj_ctype.h"
  24 #endif
  25 #include "lj_trace.h"
  26 #include "lj_dispatch.h"
  27 #include "lj_vm.h"
  28 #include "lj_prng.h"
  29 #include "lj_lex.h"
  30 #include "lj_alloc.h"
  31 #include "luajit.h"
  32
  33 /* -- Stack handling ------------------------------------------------------ */
  34
  35 /* Stack sizes. */
  36 #define LJ_STACK_MIN    LUA_MINSTACK    /* Min. stack size. */
  37 #define LJ_STACK_MAX    LUAI_MAXSTACK   /* Max. stack size. */
  38 #define LJ_STACK_START  (2*LJ_STACK_MIN)        /* Starting stack size. */
  39 #define LJ_STACK_MAXEX  (LJ_STACK_MAX + 1 + LJ_STACK_EXTRA)
  40
  41 /* Explanation of LJ_STACK_EXTRA:
  42 **
  43 ** Calls to metamethods store their arguments beyond the current top
  44 ** without checking for the stack limit. This avoids stack resizes which
  45 ** would invalidate passed TValue pointers. The stack check is performed
  46 ** later by the function header. This can safely resize the stack or raise
  47 ** an error. Thus we need some extra slots beyond the current stack limit.
  48 **
  49 ** Most metamethods need 4 slots above top (cont, mobj, arg1, arg2) plus
  50 ** one extra slot if mobj is not a function. Only lj_meta_tset needs 5
  51 ** slots above top, but then mobj is always a function. So we can get by
  52 ** with 5 extra slots.
  53 ** LJ_FR2: We need 2 more slots for the frame PC and the continuation PC.
  54 */
  55
  56 /* Resize stack slots and adjust pointers in state. */
  57 static void resizestack(lua_State *L, MSize n)
  58 {
  59   TValue *st, *oldst = tvref(L->stack);
  60   ptrdiff_t delta;
  61   MSize oldsize = L->stacksize;
  62   MSize realsize = n + 1 + LJ_STACK_EXTRA;
  63   GCobj *up;
  64   lj_assertL((MSize)(tvref(L->maxstack)-oldst) == L->stacksize-LJ_STACK_EXTRA-1,
  65              "inconsistent stack size");
  66   st = (TValue *)lj_mem_realloc(L, tvref(L->stack),
  67                                 (MSize)(oldsize*sizeof(TValue)),
  68                                 (MSize)(realsize*sizeof(TValue)));
  69   setmref(L->stack, st);
  70   delta = (char *)st - (char *)oldst;
  71   setmref(L->maxstack, st + n);
  72   while (oldsize < realsize)  /* Clear new slots. */
  73     setnilV(st + oldsize++);
  74   L->stacksize = realsize;
  75   if ((size_t)(mref(G(L)->jit_base, char) - (char *)oldst) < oldsize)
  76     setmref(G(L)->jit_base, mref(G(L)->jit_base, char) + delta);
  77   L->base = (TValue *)((char *)L->base + delta);
  78   L->top = (TValue *)((char *)L->top + delta);
  79   for (up = gcref(L->openupval); up != NULL; up = gcnext(up))
  80     setmref(gco2uv(up)->v, (TValue *)((char *)uvval(gco2uv(up)) + delta));
  81 }
  82
  83 /* Relimit stack after error, in case the limit was overdrawn. */
  84 void lj_state_relimitstack(lua_State *L)
  85 {
  86   if (L->stacksize > LJ_STACK_MAXEX && L->top-tvref(L->stack) < LJ_STACK_MAX-1)
  87     resizestack(L, LJ_STACK_MAX);
  88 }
  89
  90 /* Try to shrink the stack (called from GC). */
  91 void lj_state_shrinkstack(lua_State *L, MSize used)
  92 {
  93   if (L->stacksize > LJ_STACK_MAXEX)
  94     return;  /* Avoid stack shrinking while handling stack overflow. */
  95   if (4*used < L->stacksize &&
  96       2*(LJ_STACK_START+LJ_STACK_EXTRA) < L->stacksize &&
  97       /* Don't shrink stack of live trace. */
  98       (tvref(G(L)->jit_base) == NULL || obj2gco(L) != gcref(G(L)->cur_L)))
  99     resizestack(L, L->stacksize >> 1);
 100 }
 101
 102 /* Try to grow stack. */
 103 void LJ_FASTCALL lj_state_growstack(lua_State *L, MSize need)
 104 {
 105   MSize n;
 106   if (L->stacksize >= LJ_STACK_MAXEX) {
 107     /* 4. Throw 'error in error handling' when we are _over_ the limit. */
 108     if (L->stacksize > LJ_STACK_MAXEX)
 109       lj_err_throw(L, LUA_ERRERR);  /* Does not invoke an error handler. */
 110     /* 1. We are _at_ the limit after the last growth. */
 111     if (L->status < LUA_ERRRUN) {  /* 2. Throw 'stack overflow'. */
 112       L->status = LUA_ERRRUN;  /* Prevent ending here again for pushed msg. */
 113       lj_err_msg(L, LJ_ERR_STKOV);  /* May invoke an error handler. */
 114     }
 115     /* 3. Add space (over the limit) for pushed message and error handler. */
 116   }
 117   n = L->stacksize + need;
 118   if (n > LJ_STACK_MAX) {
 119     n += 2*LUA_MINSTACK;
 120   } else if (n < 2*L->stacksize) {
 121     n = 2*L->stacksize;
 122     if (n >= LJ_STACK_MAX)
 123       n = LJ_STACK_MAX;
 124   }
 125   resizestack(L, n);
 126 }
 127
 128 void LJ_FASTCALL lj_state_growstack1(lua_State *L)
 129 {
 130   lj_state_growstack(L, 1);
 131 }
 132
 133 static TValue *cpgrowstack(lua_State *co, lua_CFunction dummy, void *ud)
 134 {
 135   UNUSED(dummy);
 136   lj_state_growstack(co, *(MSize *)ud);
 137   return NULL;
 138 }
 139
 140 int LJ_FASTCALL lj_state_cpgrowstack(lua_State *L, MSize need)
 141 {
 142   return lj_vm_cpcall(L, NULL, &need, cpgrowstack);
 143 }
 144
 145 /* Allocate basic stack for new state. */
 146 static void stack_init(lua_State *L1, lua_State *L)
 147 {
 148   TValue *stend, *st = lj_mem_newvec(L, LJ_STACK_START+LJ_STACK_EXTRA, TValue);
 149   setmref(L1->stack, st);
 150   L1->stacksize = LJ_STACK_START + LJ_STACK_EXTRA;
 151   stend = st + L1->stacksize;
 152   setmref(L1->maxstack, stend - LJ_STACK_EXTRA - 1);
 153   setthreadV(L1, st++, L1);  /* Needed for curr_funcisL() on empty stack. */
 154   if (LJ_FR2) setnilV(st++);
 155   L1->base = L1->top = st;
 156   while (st < stend)  /* Clear new slots. */
 157     setnilV(st++);
 158 }
 159
 160 /* -- State handling ------------------------------------------------------ */
 161
 162 /* Open parts that may cause memory-allocation errors. */
 163 static TValue *cpluaopen(lua_State *L, lua_CFunction dummy, void *ud)
 164 {
 165   global_State *g = G(L);
 166   UNUSED(dummy);
 167   UNUSED(ud);
 168   stack_init(L, L);
 169   /* NOBARRIER: State initialization, all objects are white. */
 170   setgcref(L->env, obj2gco(lj_tab_new(L, 0, LJ_MIN_GLOBAL)));
 171   settabV(L, registry(L), lj_tab_new(L, 0, LJ_MIN_REGISTRY));
 172   lj_str_init(L);
 173   lj_meta_init(L);
 174   lj_lex_init(L);
 175   fixstring(lj_err_str(L, LJ_ERR_ERRMEM));  /* Preallocate memory error msg. */
 176   g->gc.threshold = 4*g->gc.total;
 177   lj_trace_initstate(g);
 178   lj_err_verify();
 179   return NULL;
 180 }
 181
 182 static void close_state(lua_State *L)
 183 {
 184   global_State *g = G(L);
 185   lj_func_closeuv(L, tvref(L->stack));
 186   lj_gc_freeall(g);
 187   lj_assertG(gcref(g->gc.root) == obj2gco(L),
 188              "main thread is not first GC object");
 189   lj_assertG(g->str.num == 0, "leaked %d strings", g->str.num);
 190   lj_trace_freestate(g);
 191 #if LJ_HASFFI
 192   lj_ctype_freestate(g);
 193 #endif
 194   lj_str_freetab(g);
 195   lj_buf_free(g, &g->tmpbuf);
 196   lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
 197 #if LJ_64
 198   if (mref(g->gc.lightudseg, uint32_t)) {
 199     MSize segnum = g->gc.lightudnum ? (2 << lj_fls(g->gc.lightudnum)) : 2;
 200     lj_mem_freevec(g, mref(g->gc.lightudseg, uint32_t), segnum, uint32_t);
 201   }
 202 #endif
 203   lj_assertG(g->gc.total == sizeof(GG_State),
 204              "memory leak of %lld bytes",
 205              (long long)(g->gc.total - sizeof(GG_State)));
 206 #ifndef LUAJIT_USE_SYSMALLOC
 207   if (g->allocf == lj_alloc_f)
 208     lj_alloc_destroy(g->allocd);
 209   else
 210 #endif
 211     g->allocf(g->allocd, G2GG(g), sizeof(GG_State), 0);
 212 }
 213
 214 #if LJ_64 && !LJ_GC64 && !(defined(LUAJIT_USE_VALGRIND) && defined(LUAJIT_USE_SYSMALLOC))
 215 lua_State *lj_state_newstate(lua_Alloc allocf, void *allocd)
 216 #else
 217 LUA_API lua_State *lua_newstate(lua_Alloc allocf, void *allocd)
 218 #endif
 219 {
 220   PRNGState prng;
 221   GG_State *GG;
 222   lua_State *L;
 223   global_State *g;
 224   /* We need the PRNG for the memory allocator, so initialize this first. */
 225   if (!lj_prng_seed_secure(&prng)) {
 226     lj_assertX(0, "secure PRNG seeding failed");
 227     /* Can only return NULL here, so this errors with "not enough memory". */
 228     return NULL;
 229   }
 230 #ifndef LUAJIT_USE_SYSMALLOC
 231   if (allocf == LJ_ALLOCF_INTERNAL) {
 232     allocd = lj_alloc_create(&prng);
 233     if (!allocd) return NULL;
 234     allocf = lj_alloc_f;
 235   }
 236 #endif
 237   GG = (GG_State *)allocf(allocd, NULL, 0, sizeof(GG_State));
 238   if (GG == NULL || !checkptrGC(GG)) return NULL;
 239   memset(GG, 0, sizeof(GG_State));
 240   L = &GG->L;
 241   g = &GG->g;
 242   L->gct = ~LJ_TTHREAD;
 243   L->marked = LJ_GC_WHITE0 | LJ_GC_FIXED | LJ_GC_SFIXED;  /* Prevent free. */
 244   L->dummy_ffid = FF_C;
 245   setmref(L->glref, g);
 246   g->gc.currentwhite = LJ_GC_WHITE0 | LJ_GC_FIXED;
 247   g->strempty.marked = LJ_GC_WHITE0;
 248   g->strempty.gct = ~LJ_TSTR;
 249   g->allocf = allocf;
 250   g->allocd = allocd;
 251   g->prng = prng;
 252 #ifndef LUAJIT_USE_SYSMALLOC
 253   if (allocf == lj_alloc_f) {
 254     lj_alloc_setprng(allocd, &g->prng);
 255   }
 256 #endif
 257   setgcref(g->mainthref, obj2gco(L));
 258   setgcref(g->uvhead.prev, obj2gco(&g->uvhead));
 259   setgcref(g->uvhead.next, obj2gco(&g->uvhead));
 260   g->str.mask = ~(MSize)0;
 261   setnilV(registry(L));
 262   setnilV(&g->nilnode.val);
 263   setnilV(&g->nilnode.key);
 264 #if !LJ_GC64
 265   setmref(g->nilnode.freetop, &g->nilnode);
 266 #endif
 267   lj_buf_init(NULL, &g->tmpbuf);
 268   g->gc.state = GCSpause;
 269   setgcref(g->gc.root, obj2gco(L));
 270   setmref(g->gc.sweep, &g->gc.root);
 271   g->gc.total = sizeof(GG_State);
 272   g->gc.pause = LUAI_GCPAUSE;
 273   g->gc.stepmul = LUAI_GCMUL;
 274   lj_dispatch_init((GG_State *)L);
 275   L->status = LUA_ERRERR+1;  /* Avoid touching the stack upon memory error. */
 276   if (lj_vm_cpcall(L, NULL, NULL, cpluaopen) != 0) {
 277     /* Memory allocation error: free partial state. */
 278     close_state(L);
 279     return NULL;
 280   }
 281   L->status = LUA_OK;
 282   return L;
 283 }
 284
 285 static TValue *cpfinalize(lua_State *L, lua_CFunction dummy, void *ud)
 286 {
 287   UNUSED(dummy);
 288   UNUSED(ud);
 289   lj_gc_finalize_cdata(L);
 290   lj_gc_finalize_udata(L);
 291   /* Frame pop omitted. */
 292   return NULL;
 293 }
 294
 295 LUA_API void lua_close(lua_State *L)
 296 {
 297   global_State *g = G(L);
 298   int i;
 299   L = mainthread(g);  /* Only the main thread can be closed. */
 300 #if LJ_HASPROFILE
 301   luaJIT_profile_stop(L);
 302 #endif
 303   setgcrefnull(g->cur_L);
 304   lj_func_closeuv(L, tvref(L->stack));
 305   lj_gc_separateudata(g, 1);  /* Separate udata which have GC metamethods. */
 306 #if LJ_HASJIT
 307   G2J(g)->flags &= ~JIT_F_ON;
 308   G2J(g)->state = LJ_TRACE_IDLE;
 309   lj_dispatch_update(g);
 310 #endif
 311   for (i = 0;;) {
 312     hook_enter(g);
 313     L->status = LUA_OK;
 314     L->base = L->top = tvref(L->stack) + 1 + LJ_FR2;
 315     L->cframe = NULL;
 316     if (lj_vm_cpcall(L, NULL, NULL, cpfinalize) == LUA_OK) {
 317       if (++i >= 10) break;
 318       lj_gc_separateudata(g, 1);  /* Separate udata again. */
 319       if (gcref(g->gc.mmudata) == NULL)  /* Until nothing is left to do. */
 320         break;
 321     }
 322   }
 323   close_state(L);
 324 }
 325
 326 lua_State *lj_state_new(lua_State *L)
 327 {
 328   lua_State *L1 = lj_mem_newobj(L, lua_State);
 329   L1->gct = ~LJ_TTHREAD;
 330   L1->dummy_ffid = FF_C;
 331   L1->status = LUA_OK;
 332   L1->stacksize = 0;
 333   setmref(L1->stack, NULL);
 334   L1->cframe = NULL;
 335   /* NOBARRIER: The lua_State is new (marked white). */
 336   setgcrefnull(L1->openupval);
 337   setmrefr(L1->glref, L->glref);
 338   setgcrefr(L1->env, L->env);
 339   stack_init(L1, L);  /* init stack */
 340   lj_assertL(iswhite(obj2gco(L1)), "new thread object is not white");
 341   return L1;
 342 }
 343
 344 void LJ_FASTCALL lj_state_free(global_State *g, lua_State *L)
 345 {
 346   lj_assertG(L != mainthread(g), "free of main thread");
 347   if (obj2gco(L) == gcref(g->cur_L))
 348     setgcrefnull(g->cur_L);
 349   lj_func_closeuv(L, tvref(L->stack));
 350   lj_assertG(gcref(L->openupval) == NULL, "stale open upvalues");
 351   lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
 352   lj_mem_freet(g, L);
 353 }
 354