1/*
2** State and stack handling.
3** Copyright (C) 2005-2021 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. */
57static 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. */
84void 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). */
91void 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. */
103void LJ_FASTCALL lj_state_growstack(lua_State *L, MSize need)
104{
105 MSize n;
106 if (L->stacksize > LJ_STACK_MAXEX) /* Overflow while handling overflow? */
107 lj_err_throw(L, LUA_ERRERR);
108 n = L->stacksize + need;
109 if (n > LJ_STACK_MAX) {
110 n += 2*LUA_MINSTACK;
111 } else if (n < 2*L->stacksize) {
112 n = 2*L->stacksize;
113 if (n >= LJ_STACK_MAX)
114 n = LJ_STACK_MAX;
115 }
116 resizestack(L, n);
117 if (L->stacksize > LJ_STACK_MAXEX)
118 lj_err_msg(L, LJ_ERR_STKOV);
119}
120
121void LJ_FASTCALL lj_state_growstack1(lua_State *L)
122{
123 lj_state_growstack(L, 1);
124}
125
126/* Allocate basic stack for new state. */
127static void stack_init(lua_State *L1, lua_State *L)
128{
129 TValue *stend, *st = lj_mem_newvec(L, LJ_STACK_START+LJ_STACK_EXTRA, TValue);
130 setmref(L1->stack, st);
131 L1->stacksize = LJ_STACK_START + LJ_STACK_EXTRA;
132 stend = st + L1->stacksize;
133 setmref(L1->maxstack, stend - LJ_STACK_EXTRA - 1);
134 setthreadV(L1, st++, L1); /* Needed for curr_funcisL() on empty stack. */
135 if (LJ_FR2) setnilV(st++);
136 L1->base = L1->top = st;
137 while (st < stend) /* Clear new slots. */
138 setnilV(st++);
139}
140
141/* -- State handling ------------------------------------------------------ */
142
143/* Open parts that may cause memory-allocation errors. */
144static TValue *cpluaopen(lua_State *L, lua_CFunction dummy, void *ud)
145{
146 global_State *g = G(L);
147 UNUSED(dummy);
148 UNUSED(ud);
149 stack_init(L, L);
150 /* NOBARRIER: State initialization, all objects are white. */
151 setgcref(L->env, obj2gco(lj_tab_new(L, 0, LJ_MIN_GLOBAL)));
152 settabV(L, registry(L), lj_tab_new(L, 0, LJ_MIN_REGISTRY));
153 lj_str_init(L);
154 lj_meta_init(L);
155 lj_lex_init(L);
156 fixstring(lj_err_str(L, LJ_ERR_ERRMEM)); /* Preallocate memory error msg. */
157 g->gc.threshold = 4*g->gc.total;
158 lj_trace_initstate(g);
159 lj_err_verify();
160 return NULL;
161}
162
163static void close_state(lua_State *L)
164{
165 global_State *g = G(L);
166 lj_func_closeuv(L, tvref(L->stack));
167 lj_gc_freeall(g);
168 lj_assertG(gcref(g->gc.root) == obj2gco(L),
169 "main thread is not first GC object");
170 lj_assertG(g->str.num == 0, "leaked %d strings", g->str.num);
171 lj_trace_freestate(g);
172#if LJ_HASFFI
173 lj_ctype_freestate(g);
174#endif
175 lj_str_freetab(g);
176 lj_buf_free(g, &g->tmpbuf);
177 lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
178#if LJ_64
179 if (mref(g->gc.lightudseg, uint32_t)) {
180 MSize segnum = g->gc.lightudnum ? (2 << lj_fls(g->gc.lightudnum)) : 2;
181 lj_mem_freevec(g, mref(g->gc.lightudseg, uint32_t), segnum, uint32_t);
182 }
183#endif
184 lj_assertG(g->gc.total == sizeof(GG_State),
185 "memory leak of %lld bytes",
186 (long long)(g->gc.total - sizeof(GG_State)));
187#ifndef LUAJIT_USE_SYSMALLOC
188 if (g->allocf == lj_alloc_f)
189 lj_alloc_destroy(g->allocd);
190 else
191#endif
192 g->allocf(g->allocd, G2GG(g), sizeof(GG_State), 0);
193}
194
195#if LJ_64 && !LJ_GC64 && !(defined(LUAJIT_USE_VALGRIND) && defined(LUAJIT_USE_SYSMALLOC))
196lua_State *lj_state_newstate(lua_Alloc allocf, void *allocd)
197#else
198LUA_API lua_State *lua_newstate(lua_Alloc allocf, void *allocd)
199#endif
200{
201 PRNGState prng;
202 GG_State *GG;
203 lua_State *L;
204 global_State *g;
205 /* We need the PRNG for the memory allocator, so initialize this first. */
206 if (!lj_prng_seed_secure(&prng)) {
207 lj_assertX(0, "secure PRNG seeding failed");
208 /* Can only return NULL here, so this errors with "not enough memory". */
209 return NULL;
210 }
211#ifndef LUAJIT_USE_SYSMALLOC
212 if (allocf == LJ_ALLOCF_INTERNAL) {
213 allocd = lj_alloc_create(&prng);
214 if (!allocd) return NULL;
215 allocf = lj_alloc_f;
216 }
217#endif
218 GG = (GG_State *)allocf(allocd, NULL, 0, sizeof(GG_State));
219 if (GG == NULL || !checkptrGC(GG)) return NULL;
220 memset(GG, 0, sizeof(GG_State));
221 L = &GG->L;
222 g = &GG->g;
223 L->gct = ~LJ_TTHREAD;
224 L->marked = LJ_GC_WHITE0 | LJ_GC_FIXED | LJ_GC_SFIXED; /* Prevent free. */
225 L->dummy_ffid = FF_C;
226 setmref(L->glref, g);
227 g->gc.currentwhite = LJ_GC_WHITE0 | LJ_GC_FIXED;
228 g->strempty.marked = LJ_GC_WHITE0;
229 g->strempty.gct = ~LJ_TSTR;
230 g->allocf = allocf;
231 g->allocd = allocd;
232 g->prng = prng;
233#ifndef LUAJIT_USE_SYSMALLOC
234 if (allocf == lj_alloc_f) {
235 lj_alloc_setprng(allocd, &g->prng);
236 }
237#endif
238 setgcref(g->mainthref, obj2gco(L));
239 setgcref(g->uvhead.prev, obj2gco(&g->uvhead));
240 setgcref(g->uvhead.next, obj2gco(&g->uvhead));
241 g->str.mask = ~(MSize)0;
242 setnilV(registry(L));
243 setnilV(&g->nilnode.val);
244 setnilV(&g->nilnode.key);
245#if !LJ_GC64
246 setmref(g->nilnode.freetop, &g->nilnode);
247#endif
248 lj_buf_init(NULL, &g->tmpbuf);
249 g->gc.state = GCSpause;
250 setgcref(g->gc.root, obj2gco(L));
251 setmref(g->gc.sweep, &g->gc.root);
252 g->gc.total = sizeof(GG_State);
253 g->gc.pause = LUAI_GCPAUSE;
254 g->gc.stepmul = LUAI_GCMUL;
255 lj_dispatch_init((GG_State *)L);
256 L->status = LUA_ERRERR+1; /* Avoid touching the stack upon memory error. */
257 if (lj_vm_cpcall(L, NULL, NULL, cpluaopen) != 0) {
258 /* Memory allocation error: free partial state. */
259 close_state(L);
260 return NULL;
261 }
262 L->status = LUA_OK;
263 return L;
264}
265
266static TValue *cpfinalize(lua_State *L, lua_CFunction dummy, void *ud)
267{
268 UNUSED(dummy);
269 UNUSED(ud);
270 lj_gc_finalize_cdata(L);
271 lj_gc_finalize_udata(L);
272 /* Frame pop omitted. */
273 return NULL;
274}
275
276LUA_API void lua_close(lua_State *L)
277{
278 global_State *g = G(L);
279 int i;
280 L = mainthread(g); /* Only the main thread can be closed. */
281#if LJ_HASPROFILE
282 luaJIT_profile_stop(L);
283#endif
284 setgcrefnull(g->cur_L);
285 lj_func_closeuv(L, tvref(L->stack));
286 lj_gc_separateudata(g, 1); /* Separate udata which have GC metamethods. */
287#if LJ_HASJIT
288 G2J(g)->flags &= ~JIT_F_ON;
289 G2J(g)->state = LJ_TRACE_IDLE;
290 lj_dispatch_update(g);
291#endif
292 for (i = 0;;) {
293 hook_enter(g);
294 L->status = LUA_OK;
295 L->base = L->top = tvref(L->stack) + 1 + LJ_FR2;
296 L->cframe = NULL;
297 if (lj_vm_cpcall(L, NULL, NULL, cpfinalize) == LUA_OK) {
298 if (++i >= 10) break;
299 lj_gc_separateudata(g, 1); /* Separate udata again. */
300 if (gcref(g->gc.mmudata) == NULL) /* Until nothing is left to do. */
301 break;
302 }
303 }
304 close_state(L);
305}
306
307lua_State *lj_state_new(lua_State *L)
308{
309 lua_State *L1 = lj_mem_newobj(L, lua_State);
310 L1->gct = ~LJ_TTHREAD;
311 L1->dummy_ffid = FF_C;
312 L1->status = LUA_OK;
313 L1->stacksize = 0;
314 setmref(L1->stack, NULL);
315 L1->cframe = NULL;
316 /* NOBARRIER: The lua_State is new (marked white). */
317 setgcrefnull(L1->openupval);
318 setmrefr(L1->glref, L->glref);
319 setgcrefr(L1->env, L->env);
320 stack_init(L1, L); /* init stack */
321 lj_assertL(iswhite(obj2gco(L1)), "new thread object is not white");
322 return L1;
323}
324
325void LJ_FASTCALL lj_state_free(global_State *g, lua_State *L)
326{
327 lj_assertG(L != mainthread(g), "free of main thread");
328 if (obj2gco(L) == gcref(g->cur_L))
329 setgcrefnull(g->cur_L);
330 lj_func_closeuv(L, tvref(L->stack));
331 lj_assertG(gcref(L->openupval) == NULL, "stale open upvalues");
332 lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
333 lj_mem_freet(g, L);
334}
335
336