src/lj_state.c

   1 /*
   2 ** State and stack handling.
   3 ** Copyright (C) 2005-2017 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_str.h"
  16 #include "lj_tab.h"
  17 #include "lj_func.h"
  18 #include "lj_meta.h"
  19 #include "lj_state.h"
  20 #include "lj_frame.h"
  21 #if LJ_HASFFI
  22 #include "lj_ctype.h"
  23 #endif
  24 #include "lj_trace.h"
  25 #include "lj_dispatch.h"
  26 #include "lj_vm.h"
  27 #include "lj_lex.h"
  28 #include "lj_alloc.h"
  29
  30 /* -- Stack handling ------------------------------------------------------ */
  31
  32 /* Stack sizes. */
  33 #define LJ_STACK_MIN    LUA_MINSTACK    /* Min. stack size. */
  34 #define LJ_STACK_MAX    LUAI_MAXSTACK   /* Max. stack size. */
  35 #define LJ_STACK_START  (2*LJ_STACK_MIN)        /* Starting stack size. */
  36 #define LJ_STACK_MAXEX  (LJ_STACK_MAX + 1 + LJ_STACK_EXTRA)
  37
  38 /* Explanation of LJ_STACK_EXTRA:
  39 **
  40 ** Calls to metamethods store their arguments beyond the current top
  41 ** without checking for the stack limit. This avoids stack resizes which
  42 ** would invalidate passed TValue pointers. The stack check is performed
  43 ** later by the function header. This can safely resize the stack or raise
  44 ** an error. Thus we need some extra slots beyond the current stack limit.
  45 **
  46 ** Most metamethods need 4 slots above top (cont, mobj, arg1, arg2) plus
  47 ** one extra slot if mobj is not a function. Only lj_meta_tset needs 5
  48 ** slots above top, but then mobj is always a function. So we can get by
  49 ** with 5 extra slots.
  50 */
  51
  52 /* Resize stack slots and adjust pointers in state. */
  53 static void resizestack(lua_State *L, MSize n)
  54 {
  55   TValue *st, *oldst = tvref(L->stack);
  56   ptrdiff_t delta;
  57   MSize oldsize = L->stacksize;
  58   MSize realsize = n + 1 + LJ_STACK_EXTRA;
  59   GCobj *up;
  60   lua_assert((MSize)(tvref(L->maxstack)-oldst)==L->stacksize-LJ_STACK_EXTRA-1);
  61   st = (TValue *)lj_mem_realloc(L, tvref(L->stack),
  62                                 (MSize)(L->stacksize*sizeof(TValue)),
  63                                 (MSize)(realsize*sizeof(TValue)));
  64   setmref(L->stack, st);
  65   delta = (char *)st - (char *)oldst;
  66   setmref(L->maxstack, st + n);
  67   while (oldsize < realsize)  /* Clear new slots. */
  68     setnilV(st + oldsize++);
  69   L->stacksize = realsize;
  70   L->base = (TValue *)((char *)L->base + delta);
  71   L->top = (TValue *)((char *)L->top + delta);
  72   for (up = gcref(L->openupval); up != NULL; up = gcnext(up))
  73     setmref(gco2uv(up)->v, (TValue *)((char *)uvval(gco2uv(up)) + delta));
  74   if (obj2gco(L) == gcref(G(L)->jit_L))
  75     setmref(G(L)->jit_base, mref(G(L)->jit_base, char) + delta);
  76 }
  77
  78 /* Relimit stack after error, in case the limit was overdrawn. */
  79 void lj_state_relimitstack(lua_State *L)
  80 {
  81   if (L->stacksize > LJ_STACK_MAXEX && L->top-tvref(L->stack) < LJ_STACK_MAX-1)
  82     resizestack(L, LJ_STACK_MAX);
  83 }
  84
  85 /* Try to shrink the stack (called from GC). */
  86 void lj_state_shrinkstack(lua_State *L, MSize used)
  87 {
  88   if (L->stacksize > LJ_STACK_MAXEX)
  89     return;  /* Avoid stack shrinking while handling stack overflow. */
  90   if (4*used < L->stacksize &&
  91       2*(LJ_STACK_START+LJ_STACK_EXTRA) < L->stacksize &&
  92       obj2gco(L) != gcref(G(L)->jit_L))  /* Don't shrink stack of live trace. */
  93     resizestack(L, L->stacksize >> 1);
  94 }
  95
  96 /* Try to grow stack. */
  97 void LJ_FASTCALL lj_state_growstack(lua_State *L, MSize need)
  98 {
  99   MSize n;
 100   if (L->stacksize > LJ_STACK_MAXEX)  /* Overflow while handling overflow? */
 101     lj_err_throw(L, LUA_ERRERR);
 102   n = L->stacksize + need;
 103   if (n > LJ_STACK_MAX) {
 104     n += 2*LUA_MINSTACK;
 105   } else if (n < 2*L->stacksize) {
 106     n = 2*L->stacksize;
 107     if (n >= LJ_STACK_MAX)
 108       n = LJ_STACK_MAX;
 109   }
 110   resizestack(L, n);
 111   if (L->stacksize > LJ_STACK_MAXEX)
 112     lj_err_msg(L, LJ_ERR_STKOV);
 113 }
 114
 115 void LJ_FASTCALL lj_state_growstack1(lua_State *L)
 116 {
 117   lj_state_growstack(L, 1);
 118 }
 119
 120 /* Allocate basic stack for new state. */
 121 static void stack_init(lua_State *L1, lua_State *L)
 122 {
 123   TValue *stend, *st = lj_mem_newvec(L, LJ_STACK_START+LJ_STACK_EXTRA, TValue);
 124   setmref(L1->stack, st);
 125   L1->stacksize = LJ_STACK_START + LJ_STACK_EXTRA;
 126   stend = st + L1->stacksize;
 127   setmref(L1->maxstack, stend - LJ_STACK_EXTRA - 1);
 128   L1->base = L1->top = st+1;
 129   setthreadV(L1, st, L1);  /* Needed for curr_funcisL() on empty stack. */
 130   while (st < stend)  /* Clear new slots. */
 131     setnilV(st++);
 132 }
 133
 134 /* -- State handling ------------------------------------------------------ */
 135
 136 /* Open parts that may cause memory-allocation errors. */
 137 static TValue *cpluaopen(lua_State *L, lua_CFunction dummy, void *ud)
 138 {
 139   global_State *g = G(L);
 140   UNUSED(dummy);
 141   UNUSED(ud);
 142   stack_init(L, L);
 143   /* NOBARRIER: State initialization, all objects are white. */
 144   setgcref(L->env, obj2gco(lj_tab_new(L, 0, LJ_MIN_GLOBAL)));
 145   settabV(L, registry(L), lj_tab_new(L, 0, LJ_MIN_REGISTRY));
 146   lj_str_resize(L, LJ_MIN_STRTAB-1);
 147   lj_meta_init(L);
 148   lj_lex_init(L);
 149   fixstring(lj_err_str(L, LJ_ERR_ERRMEM));  /* Preallocate memory error msg. */
 150   g->gc.threshold = 4*g->gc.total;
 151   lj_trace_initstate(g);
 152   return NULL;
 153 }
 154
 155 static void close_state(lua_State *L)
 156 {
 157   global_State *g = G(L);
 158   lj_func_closeuv(L, tvref(L->stack));
 159   lj_gc_freeall(g);
 160   lua_assert(gcref(g->gc.root) == obj2gco(L));
 161   lua_assert(g->strnum == 0);
 162   lj_trace_freestate(g);
 163 #if LJ_HASFFI
 164   lj_ctype_freestate(g);
 165 #endif
 166   lj_mem_freevec(g, g->strhash, g->strmask+1, GCRef);
 167   lj_str_freebuf(g, &g->tmpbuf);
 168   lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
 169   lua_assert(g->gc.total == sizeof(GG_State));
 170 #ifndef LUAJIT_USE_SYSMALLOC
 171   if (g->allocf == lj_alloc_f)
 172     lj_alloc_destroy(g->allocd);
 173   else
 174 #endif
 175     g->allocf(g->allocd, G2GG(g), sizeof(GG_State), 0);
 176 }
 177
 178 #if LJ_64 && !(defined(LUAJIT_USE_VALGRIND) && defined(LUAJIT_USE_SYSMALLOC))
 179 lua_State *lj_state_newstate(lua_Alloc f, void *ud)
 180 #else
 181 LUA_API lua_State *lua_newstate(lua_Alloc f, void *ud)
 182 #endif
 183 {
 184   GG_State *GG = (GG_State *)f(ud, NULL, 0, sizeof(GG_State));
 185   lua_State *L = &GG->L;
 186   global_State *g = &GG->g;
 187   if (GG == NULL || !checkptr32(GG)) return NULL;
 188   memset(GG, 0, sizeof(GG_State));
 189   L->gct = ~LJ_TTHREAD;
 190   L->marked = LJ_GC_WHITE0 | LJ_GC_FIXED | LJ_GC_SFIXED;  /* Prevent free. */
 191   L->dummy_ffid = FF_C;
 192   setmref(L->glref, g);
 193   g->gc.currentwhite = LJ_GC_WHITE0 | LJ_GC_FIXED;
 194   g->strempty.marked = LJ_GC_WHITE0;
 195   g->strempty.gct = ~LJ_TSTR;
 196   g->allocf = f;
 197   g->allocd = ud;
 198   setgcref(g->mainthref, obj2gco(L));
 199   setgcref(g->uvhead.prev, obj2gco(&g->uvhead));
 200   setgcref(g->uvhead.next, obj2gco(&g->uvhead));
 201   g->strmask = ~(MSize)0;
 202   setnilV(registry(L));
 203   setnilV(&g->nilnode.val);
 204   setnilV(&g->nilnode.key);
 205   setmref(g->nilnode.freetop, &g->nilnode);
 206   lj_str_initbuf(&g->tmpbuf);
 207   g->gc.state = GCSpause;
 208   setgcref(g->gc.root, obj2gco(L));
 209   setmref(g->gc.sweep, &g->gc.root);
 210   g->gc.total = sizeof(GG_State);
 211   g->gc.pause = LUAI_GCPAUSE;
 212   g->gc.stepmul = LUAI_GCMUL;
 213   lj_dispatch_init((GG_State *)L);
 214   L->status = LUA_ERRERR+1;  /* Avoid touching the stack upon memory error. */
 215   if (lj_vm_cpcall(L, NULL, NULL, cpluaopen) != 0) {
 216     /* Memory allocation error: free partial state. */
 217     close_state(L);
 218     return NULL;
 219   }
 220   L->status = 0;
 221   return L;
 222 }
 223
 224 static TValue *cpfinalize(lua_State *L, lua_CFunction dummy, void *ud)
 225 {
 226   UNUSED(dummy);
 227   UNUSED(ud);
 228   lj_gc_finalize_cdata(L);
 229   lj_gc_finalize_udata(L);
 230   /* Frame pop omitted. */
 231   return NULL;
 232 }
 233
 234 LUA_API void lua_close(lua_State *L)
 235 {
 236   global_State *g = G(L);
 237   int i;
 238   L = mainthread(g);  /* Only the main thread can be closed. */
 239   lj_func_closeuv(L, tvref(L->stack));
 240   lj_gc_separateudata(g, 1);  /* Separate udata which have GC metamethods. */
 241 #if LJ_HASJIT
 242   G2J(g)->flags &= ~JIT_F_ON;
 243   G2J(g)->state = LJ_TRACE_IDLE;
 244   lj_dispatch_update(g);
 245 #endif
 246   for (i = 0;;) {
 247     hook_enter(g);
 248     L->status = 0;
 249     L->cframe = NULL;
 250     L->base = L->top = tvref(L->stack) + 1;
 251     if (lj_vm_cpcall(L, NULL, NULL, cpfinalize) == 0) {
 252       if (++i >= 10) break;
 253       lj_gc_separateudata(g, 1);  /* Separate udata again. */
 254       if (gcref(g->gc.mmudata) == NULL)  /* Until nothing is left to do. */
 255         break;
 256     }
 257   }
 258   close_state(L);
 259 }
 260
 261 lua_State *lj_state_new(lua_State *L)
 262 {
 263   lua_State *L1 = lj_mem_newobj(L, lua_State);
 264   L1->gct = ~LJ_TTHREAD;
 265   L1->dummy_ffid = FF_C;
 266   L1->status = 0;
 267   L1->stacksize = 0;
 268   setmref(L1->stack, NULL);
 269   L1->cframe = NULL;
 270   /* NOBARRIER: The lua_State is new (marked white). */
 271   setgcrefnull(L1->openupval);
 272   setmrefr(L1->glref, L->glref);
 273   setgcrefr(L1->env, L->env);
 274   stack_init(L1, L);  /* init stack */
 275   lua_assert(iswhite(obj2gco(L1)));
 276   return L1;
 277 }
 278
 279 void LJ_FASTCALL lj_state_free(global_State *g, lua_State *L)
 280 {
 281   lua_assert(L != mainthread(g));
 282   lj_func_closeuv(L, tvref(L->stack));
 283   lua_assert(gcref(L->openupval) == NULL);
 284   lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
 285   lj_mem_freet(g, L);
 286 }
 287