1/*
2** Error handling.
3** Copyright (C) 2005-2021 Mike Pall. See Copyright Notice in luajit.h
4*/
5
6#define lj_err_c
7#define LUA_CORE
8
9#include "lj_obj.h"
10#include "lj_err.h"
11#include "lj_debug.h"
12#include "lj_str.h"
13#include "lj_func.h"
14#include "lj_state.h"
15#include "lj_frame.h"
16#include "lj_ff.h"
17#include "lj_trace.h"
18#include "lj_vm.h"
19#include "lj_strfmt.h"
20
21/*
22** LuaJIT can either use internal or external frame unwinding:
23**
24** - Internal frame unwinding (INT) is free-standing and doesn't require
25** any OS or library support.
26**
27** - External frame unwinding (EXT) uses the system-provided unwind handler.
28**
29** Pros and Cons:
30**
31** - EXT requires unwind tables for *all* functions on the C stack between
32** the pcall/catch and the error/throw. C modules used by Lua code can
33** throw errors, so these need to have unwind tables, too. Transitively
34** this applies to all system libraries used by C modules -- at least
35** when they have callbacks which may throw an error.
36**
37** - INT is faster when actually throwing errors, but this happens rarely.
38** Setting up error handlers is zero-cost in any case.
39**
40** - INT needs to save *all* callee-saved registers when entering the
41** interpreter. EXT only needs to save those actually used inside the
42** interpreter. JIT-compiled code may need to save some more.
43**
44** - EXT provides full interoperability with C++ exceptions. You can throw
45** Lua errors or C++ exceptions through a mix of Lua frames and C++ frames.
46** C++ destructors are called as needed. C++ exceptions caught by pcall
47** are converted to the string "C++ exception". Lua errors can be caught
48** with catch (...) in C++.
49**
50** - INT has only limited support for automatically catching C++ exceptions
51** on POSIX systems using DWARF2 stack unwinding. Other systems may use
52** the wrapper function feature. Lua errors thrown through C++ frames
53** cannot be caught by C++ code and C++ destructors are not run.
54**
55** - EXT can handle errors from internal helper functions that are called
56** from JIT-compiled code (except for Windows/x86 and 32 bit ARM).
57** INT has no choice but to call the panic handler, if this happens.
58** Note: this is mainly relevant for out-of-memory errors.
59**
60** EXT is the default on all systems where the toolchain produces unwind
61** tables by default (*). This is hard-coded and/or detected in src/Makefile.
62** You can thwart the detection with: TARGET_XCFLAGS=-DLUAJIT_UNWIND_INTERNAL
63**
64** INT is the default on all other systems.
65**
66** EXT can be manually enabled for toolchains that are able to produce
67** conforming unwind tables:
68** "TARGET_XCFLAGS=-funwind-tables -DLUAJIT_UNWIND_EXTERNAL"
69** As explained above, *all* C code used directly or indirectly by LuaJIT
70** must be compiled with -funwind-tables (or -fexceptions). C++ code must
71** *not* be compiled with -fno-exceptions.
72**
73** If you're unsure whether error handling inside the VM works correctly,
74** try running this and check whether it prints "OK":
75**
76** luajit -e "print(select(2, load('OK')):match('OK'))"
77**
78** (*) Originally, toolchains only generated unwind tables for C++ code. For
79** interoperability reasons, this can be manually enabled for plain C code,
80** too (with -funwind-tables). With the introduction of the x64 architecture,
81** the corresponding POSIX and Windows ABIs mandated unwind tables for all
82** code. Over the following years most desktop and server platforms have
83** enabled unwind tables by default on all architectures. OTOH mobile and
84** embedded platforms do not consistently mandate unwind tables.
85*/
86
87/* -- Error messages ------------------------------------------------------ */
88
89/* Error message strings. */
90LJ_DATADEF const char *lj_err_allmsg =
91#define ERRDEF(name, msg) msg "\0"
92#include "lj_errmsg.h"
93;
94
95/* -- Internal frame unwinding -------------------------------------------- */
96
97/* Unwind Lua stack and move error message to new top. */
98LJ_NOINLINE static void unwindstack(lua_State *L, TValue *top)
99{
100 lj_func_closeuv(L, top);
101 if (top < L->top-1) {
102 copyTV(L, top, L->top-1);
103 L->top = top+1;
104 }
105 lj_state_relimitstack(L);
106}
107
108/* Unwind until stop frame. Optionally cleanup frames. */
109static void *err_unwind(lua_State *L, void *stopcf, int errcode)
110{
111 TValue *frame = L->base-1;
112 void *cf = L->cframe;
113 while (cf) {
114 int32_t nres = cframe_nres(cframe_raw(cf));
115 if (nres < 0) { /* C frame without Lua frame? */
116 TValue *top = restorestack(L, -nres);
117 if (frame < top) { /* Frame reached? */
118 if (errcode) {
119 L->base = frame+1;
120 L->cframe = cframe_prev(cf);
121 unwindstack(L, top);
122 }
123 return cf;
124 }
125 }
126 if (frame <= tvref(L->stack)+LJ_FR2)
127 break;
128 switch (frame_typep(frame)) {
129 case FRAME_LUA: /* Lua frame. */
130 case FRAME_LUAP:
131 frame = frame_prevl(frame);
132 break;
133 case FRAME_C: /* C frame. */
134 unwind_c:
135#if LJ_UNWIND_EXT
136 if (errcode) {
137 L->base = frame_prevd(frame) + 1;
138 L->cframe = cframe_prev(cf);
139 unwindstack(L, frame - LJ_FR2);
140 } else if (cf != stopcf) {
141 cf = cframe_prev(cf);
142 frame = frame_prevd(frame);
143 break;
144 }
145 return NULL; /* Continue unwinding. */
146#else
147 UNUSED(stopcf);
148 cf = cframe_prev(cf);
149 frame = frame_prevd(frame);
150 break;
151#endif
152 case FRAME_CP: /* Protected C frame. */
153 if (cframe_canyield(cf)) { /* Resume? */
154 if (errcode) {
155 hook_leave(G(L)); /* Assumes nobody uses coroutines inside hooks. */
156 L->cframe = NULL;
157 L->status = (uint8_t)errcode;
158 }
159 return cf;
160 }
161 if (errcode) {
162 L->base = frame_prevd(frame) + 1;
163 L->cframe = cframe_prev(cf);
164 unwindstack(L, frame - LJ_FR2);
165 }
166 return cf;
167 case FRAME_CONT: /* Continuation frame. */
168 if (frame_iscont_fficb(frame))
169 goto unwind_c;
170 /* fallthrough */
171 case FRAME_VARG: /* Vararg frame. */
172 frame = frame_prevd(frame);
173 break;
174 case FRAME_PCALL: /* FF pcall() frame. */
175 case FRAME_PCALLH: /* FF pcall() frame inside hook. */
176 if (errcode) {
177 if (errcode == LUA_YIELD) {
178 frame = frame_prevd(frame);
179 break;
180 }
181 if (frame_typep(frame) == FRAME_PCALL)
182 hook_leave(G(L));
183 L->base = frame_prevd(frame) + 1;
184 L->cframe = cf;
185 unwindstack(L, L->base);
186 }
187 return (void *)((intptr_t)cf | CFRAME_UNWIND_FF);
188 }
189 }
190 /* No C frame. */
191 if (errcode) {
192 L->base = tvref(L->stack)+1+LJ_FR2;
193 L->cframe = NULL;
194 unwindstack(L, L->base);
195 if (G(L)->panic)
196 G(L)->panic(L);
197 exit(EXIT_FAILURE);
198 }
199 return L; /* Anything non-NULL will do. */
200}
201
202/* -- External frame unwinding -------------------------------------------- */
203
204#if LJ_ABI_WIN
205
206/*
207** Someone in Redmond owes me several days of my life. A lot of this is
208** undocumented or just plain wrong on MSDN. Some of it can be gathered
209** from 3rd party docs or must be found by trial-and-error. They really
210** don't want you to write your own language-specific exception handler
211** or to interact gracefully with MSVC. :-(
212**
213** Apparently MSVC doesn't call C++ destructors for foreign exceptions
214** unless you compile your C++ code with /EHa. Unfortunately this means
215** catch (...) also catches things like access violations. The use of
216** _set_se_translator doesn't really help, because it requires /EHa, too.
217*/
218
219#define WIN32_LEAN_AND_MEAN
220#include <windows.h>
221
222#if LJ_TARGET_X86
223typedef void *UndocumentedDispatcherContext; /* Unused on x86. */
224#else
225/* Taken from: http://www.nynaeve.net/?p=99 */
226typedef struct UndocumentedDispatcherContext {
227 ULONG64 ControlPc;
228 ULONG64 ImageBase;
229 PRUNTIME_FUNCTION FunctionEntry;
230 ULONG64 EstablisherFrame;
231 ULONG64 TargetIp;
232 PCONTEXT ContextRecord;
233 void (*LanguageHandler)(void);
234 PVOID HandlerData;
235 PUNWIND_HISTORY_TABLE HistoryTable;
236 ULONG ScopeIndex;
237 ULONG Fill0;
238} UndocumentedDispatcherContext;
239#endif
240
241/* Another wild guess. */
242extern void __DestructExceptionObject(EXCEPTION_RECORD *rec, int nothrow);
243
244#if LJ_TARGET_X64 && defined(MINGW_SDK_INIT)
245/* Workaround for broken MinGW64 declaration. */
246VOID RtlUnwindEx_FIXED(PVOID,PVOID,PVOID,PVOID,PVOID,PVOID) asm("RtlUnwindEx");
247#define RtlUnwindEx RtlUnwindEx_FIXED
248#endif
249
250#define LJ_MSVC_EXCODE ((DWORD)0xe06d7363)
251#define LJ_GCC_EXCODE ((DWORD)0x20474343)
252
253#define LJ_EXCODE ((DWORD)0xe24c4a00)
254#define LJ_EXCODE_MAKE(c) (LJ_EXCODE | (DWORD)(c))
255#define LJ_EXCODE_CHECK(cl) (((cl) ^ LJ_EXCODE) <= 0xff)
256#define LJ_EXCODE_ERRCODE(cl) ((int)((cl) & 0xff))
257
258/* Windows exception handler for interpreter frame. */
259LJ_FUNCA int lj_err_unwind_win(EXCEPTION_RECORD *rec,
260 void *f, CONTEXT *ctx, UndocumentedDispatcherContext *dispatch)
261{
262#if LJ_TARGET_X86
263 void *cf = (char *)f - CFRAME_OFS_SEH;
264#else
265 void *cf = f;
266#endif
267 lua_State *L = cframe_L(cf);
268 int errcode = LJ_EXCODE_CHECK(rec->ExceptionCode) ?
269 LJ_EXCODE_ERRCODE(rec->ExceptionCode) : LUA_ERRRUN;
270 if ((rec->ExceptionFlags & 6)) { /* EH_UNWINDING|EH_EXIT_UNWIND */
271 /* Unwind internal frames. */
272 err_unwind(L, cf, errcode);
273 } else {
274 void *cf2 = err_unwind(L, cf, 0);
275 if (cf2) { /* We catch it, so start unwinding the upper frames. */
276 if (rec->ExceptionCode == LJ_MSVC_EXCODE ||
277 rec->ExceptionCode == LJ_GCC_EXCODE) {
278#if !LJ_TARGET_CYGWIN
279 __DestructExceptionObject(rec, 1);
280#endif
281 setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
282 } else if (!LJ_EXCODE_CHECK(rec->ExceptionCode)) {
283 /* Don't catch access violations etc. */
284 return 1; /* ExceptionContinueSearch */
285 }
286#if LJ_TARGET_X86
287 UNUSED(ctx);
288 UNUSED(dispatch);
289 /* Call all handlers for all lower C frames (including ourselves) again
290 ** with EH_UNWINDING set. Then call the specified function, passing cf
291 ** and errcode.
292 */
293 lj_vm_rtlunwind(cf, (void *)rec,
294 (cframe_unwind_ff(cf2) && errcode != LUA_YIELD) ?
295 (void *)lj_vm_unwind_ff : (void *)lj_vm_unwind_c, errcode);
296 /* lj_vm_rtlunwind does not return. */
297#else
298 /* Unwind the stack and call all handlers for all lower C frames
299 ** (including ourselves) again with EH_UNWINDING set. Then set
300 ** stack pointer = cf, result = errcode and jump to the specified target.
301 */
302 RtlUnwindEx(cf, (void *)((cframe_unwind_ff(cf2) && errcode != LUA_YIELD) ?
303 lj_vm_unwind_ff_eh :
304 lj_vm_unwind_c_eh),
305 rec, (void *)(uintptr_t)errcode, ctx, dispatch->HistoryTable);
306 /* RtlUnwindEx should never return. */
307#endif
308 }
309 }
310 return 1; /* ExceptionContinueSearch */
311}
312
313#if LJ_UNWIND_JIT
314
315#if LJ_TARGET_X64
316#define CONTEXT_REG_PC Rip
317#elif LJ_TARGET_ARM64
318#define CONTEXT_REG_PC Pc
319#else
320#error "NYI: Windows arch-specific unwinder for JIT-compiled code"
321#endif
322
323/* Windows unwinder for JIT-compiled code. */
324static void err_unwind_win_jit(global_State *g, int errcode)
325{
326 CONTEXT ctx;
327 UNWIND_HISTORY_TABLE hist;
328
329 memset(&hist, 0, sizeof(hist));
330 RtlCaptureContext(&ctx);
331 while (1) {
332 uintptr_t frame, base, addr = ctx.CONTEXT_REG_PC;
333 void *hdata;
334 PRUNTIME_FUNCTION func = RtlLookupFunctionEntry(addr, &base, &hist);
335 if (!func) { /* Found frame without .pdata: must be JIT-compiled code. */
336 ExitNo exitno;
337 uintptr_t stub = lj_trace_unwind(G2J(g), addr - sizeof(MCode), &exitno);
338 if (stub) { /* Jump to side exit to unwind the trace. */
339 ctx.CONTEXT_REG_PC = stub;
340 G2J(g)->exitcode = errcode;
341 RtlRestoreContext(&ctx, NULL); /* Does not return. */
342 }
343 break;
344 }
345 RtlVirtualUnwind(UNW_FLAG_NHANDLER, base, addr, func,
346 &ctx, &hdata, &frame, NULL);
347 if (!addr) break;
348 }
349 /* Unwinding failed, if we end up here. */
350}
351#endif
352
353/* Raise Windows exception. */
354static void err_raise_ext(global_State *g, int errcode)
355{
356#if LJ_UNWIND_JIT
357 if (tvref(g->jit_base)) {
358 err_unwind_win_jit(g, errcode);
359 return; /* Unwinding failed. */
360 }
361#elif LJ_HASJIT
362 /* Cannot catch on-trace errors for Windows/x86 SEH. Unwind to interpreter. */
363 setmref(g->jit_base, NULL);
364#endif
365 UNUSED(g);
366 RaiseException(LJ_EXCODE_MAKE(errcode), 1 /* EH_NONCONTINUABLE */, 0, NULL);
367}
368
369#elif !LJ_NO_UNWIND && (defined(__GNUC__) || defined(__clang__))
370
371/*
372** We have to use our own definitions instead of the mandatory (!) unwind.h,
373** since various OS, distros and compilers mess up the header installation.
374*/
375
376typedef struct _Unwind_Context _Unwind_Context;
377
378#define _URC_OK 0
379#define _URC_FATAL_PHASE2_ERROR 2
380#define _URC_FATAL_PHASE1_ERROR 3
381#define _URC_HANDLER_FOUND 6
382#define _URC_INSTALL_CONTEXT 7
383#define _URC_CONTINUE_UNWIND 8
384#define _URC_FAILURE 9
385
386#define LJ_UEXCLASS 0x4c55414a49543200ULL /* LUAJIT2\0 */
387#define LJ_UEXCLASS_MAKE(c) (LJ_UEXCLASS | (uint64_t)(c))
388#define LJ_UEXCLASS_CHECK(cl) (((cl) ^ LJ_UEXCLASS) <= 0xff)
389#define LJ_UEXCLASS_ERRCODE(cl) ((int)((cl) & 0xff))
390
391#if !LJ_TARGET_ARM
392
393typedef struct _Unwind_Exception
394{
395 uint64_t exclass;
396 void (*excleanup)(int, struct _Unwind_Exception *);
397 uintptr_t p1, p2;
398} __attribute__((__aligned__)) _Unwind_Exception;
399#define UNWIND_EXCEPTION_TYPE _Unwind_Exception
400
401extern uintptr_t _Unwind_GetCFA(_Unwind_Context *);
402extern void _Unwind_SetGR(_Unwind_Context *, int, uintptr_t);
403extern uintptr_t _Unwind_GetIP(_Unwind_Context *);
404extern void _Unwind_SetIP(_Unwind_Context *, uintptr_t);
405extern void _Unwind_DeleteException(_Unwind_Exception *);
406extern int _Unwind_RaiseException(_Unwind_Exception *);
407
408#define _UA_SEARCH_PHASE 1
409#define _UA_CLEANUP_PHASE 2
410#define _UA_HANDLER_FRAME 4
411#define _UA_FORCE_UNWIND 8
412
413/* DWARF2 personality handler referenced from interpreter .eh_frame. */
414LJ_FUNCA int lj_err_unwind_dwarf(int version, int actions,
415 uint64_t uexclass, _Unwind_Exception *uex, _Unwind_Context *ctx)
416{
417 void *cf;
418 lua_State *L;
419 if (version != 1)
420 return _URC_FATAL_PHASE1_ERROR;
421 cf = (void *)_Unwind_GetCFA(ctx);
422 L = cframe_L(cf);
423 if ((actions & _UA_SEARCH_PHASE)) {
424#if LJ_UNWIND_EXT
425 if (err_unwind(L, cf, 0) == NULL)
426 return _URC_CONTINUE_UNWIND;
427#endif
428 if (!LJ_UEXCLASS_CHECK(uexclass)) {
429 setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
430 }
431 return _URC_HANDLER_FOUND;
432 }
433 if ((actions & _UA_CLEANUP_PHASE)) {
434 int errcode;
435 if (LJ_UEXCLASS_CHECK(uexclass)) {
436 errcode = LJ_UEXCLASS_ERRCODE(uexclass);
437 } else {
438 if ((actions & _UA_HANDLER_FRAME))
439 _Unwind_DeleteException(uex);
440 errcode = LUA_ERRRUN;
441 }
442#if LJ_UNWIND_EXT
443 cf = err_unwind(L, cf, errcode);
444 if ((actions & _UA_FORCE_UNWIND)) {
445 return _URC_CONTINUE_UNWIND;
446 } else if (cf) {
447 _Unwind_SetGR(ctx, LJ_TARGET_EHRETREG, errcode);
448 _Unwind_SetIP(ctx, (uintptr_t)(cframe_unwind_ff(cf) ?
449 lj_vm_unwind_ff_eh :
450 lj_vm_unwind_c_eh));
451 return _URC_INSTALL_CONTEXT;
452 }
453#if LJ_TARGET_X86ORX64
454 else if ((actions & _UA_HANDLER_FRAME)) {
455 /* Workaround for ancient libgcc bug. Still present in RHEL 5.5. :-/
456 ** Real fix: http://gcc.gnu.org/viewcvs/trunk/gcc/unwind-dw2.c?r1=121165&r2=124837&pathrev=153877&diff_format=h
457 */
458 _Unwind_SetGR(ctx, LJ_TARGET_EHRETREG, errcode);
459 _Unwind_SetIP(ctx, (uintptr_t)lj_vm_unwind_rethrow);
460 return _URC_INSTALL_CONTEXT;
461 }
462#endif
463#else
464 /* This is not the proper way to escape from the unwinder. We get away with
465 ** it on non-x64 because the interpreter restores all callee-saved regs.
466 */
467 lj_err_throw(L, errcode);
468#if LJ_TARGET_X64
469#error "Broken build system -- only use the provided Makefiles!"
470#endif
471#endif
472 }
473 return _URC_CONTINUE_UNWIND;
474}
475
476#if LJ_UNWIND_EXT && defined(LUA_USE_ASSERT)
477struct dwarf_eh_bases { void *tbase, *dbase, *func; };
478extern const void *_Unwind_Find_FDE(void *pc, struct dwarf_eh_bases *bases);
479
480/* Verify that external error handling actually has a chance to work. */
481void lj_err_verify(void)
482{
483 struct dwarf_eh_bases ehb;
484 lj_assertX(_Unwind_Find_FDE((void *)lj_err_throw, &ehb), "broken build: external frame unwinding enabled, but missing -funwind-tables");
485 lj_assertX(_Unwind_Find_FDE((void *)_Unwind_RaiseException, &ehb), "broken build: external frame unwinding enabled, but system libraries have no unwind tables");
486}
487#endif
488
489#if LJ_UNWIND_JIT
490/* DWARF2 personality handler for JIT-compiled code. */
491static int err_unwind_jit(int version, int actions,
492 uint64_t uexclass, _Unwind_Exception *uex, _Unwind_Context *ctx)
493{
494 /* NYI: FFI C++ exception interoperability. */
495 if (version != 1 || !LJ_UEXCLASS_CHECK(uexclass))
496 return _URC_FATAL_PHASE1_ERROR;
497 if ((actions & _UA_SEARCH_PHASE)) {
498 return _URC_HANDLER_FOUND;
499 }
500 if ((actions & _UA_CLEANUP_PHASE)) {
501 global_State *g = *(global_State **)(uex+1);
502 ExitNo exitno;
503 uintptr_t addr = _Unwind_GetIP(ctx); /* Return address _after_ call. */
504 uintptr_t stub = lj_trace_unwind(G2J(g), addr - sizeof(MCode), &exitno);
505 lj_assertG(tvref(g->jit_base), "unexpected throw across mcode frame");
506 if (stub) { /* Jump to side exit to unwind the trace. */
507 G2J(g)->exitcode = LJ_UEXCLASS_ERRCODE(uexclass);
508#ifdef LJ_TARGET_MIPS
509 _Unwind_SetGR(ctx, 4, stub);
510 _Unwind_SetGR(ctx, 5, exitno);
511 _Unwind_SetIP(ctx, (uintptr_t)(void *)lj_vm_unwind_stub);
512#else
513 _Unwind_SetIP(ctx, stub);
514#endif
515 return _URC_INSTALL_CONTEXT;
516 }
517 return _URC_FATAL_PHASE2_ERROR;
518 }
519 return _URC_FATAL_PHASE1_ERROR;
520}
521
522/* DWARF2 template frame info for JIT-compiled code.
523**
524** After copying the template to the start of the mcode segment,
525** the frame handler function and the code size is patched.
526** The frame handler always installs a new context to jump to the exit,
527** so don't bother to add any unwind opcodes.
528*/
529static const uint8_t err_frame_jit_template[] = {
530#if LJ_BE
531 0,0,0,
532#endif
533 LJ_64 ? 0x1c : 0x14, /* CIE length. */
534#if LJ_LE
535 0,0,0,
536#endif
537 0,0,0,0, 1, 'z','P','R',0, /* CIE mark, CIE version, augmentation. */
538 1, LJ_64 ? 0x78 : 0x7c, LJ_TARGET_EHRAREG, /* Code/data align, RA. */
539#if LJ_64
540 10, 0, 0,0,0,0,0,0,0,0, 0x1b, /* Aug. data ABS handler, PCREL|SDATA4 code. */
541 0,0,0,0,0, /* Alignment. */
542#else
543 6, 0, 0,0,0,0, 0x1b, /* Aug. data ABS handler, PCREL|SDATA4 code. */
544 0, /* Alignment. */
545#endif
546#if LJ_BE
547 0,0,0,
548#endif
549 LJ_64 ? 0x14 : 0x10, /* FDE length. */
550 0,0,0,
551 LJ_64 ? 0x24 : 0x1c, /* CIE offset. */
552 0,0,0,
553 LJ_64 ? 0x14 : 0x10, /* Code offset. After Final FDE. */
554#if LJ_LE
555 0,0,0,
556#endif
557 0,0,0,0, 0, 0,0,0, /* Code size, augmentation length, alignment. */
558#if LJ_64
559 0,0,0,0, /* Alignment. */
560#endif
561 0,0,0,0 /* Final FDE. */
562};
563
564#define ERR_FRAME_JIT_OFS_HANDLER 0x12
565#define ERR_FRAME_JIT_OFS_FDE (LJ_64 ? 0x20 : 0x18)
566#define ERR_FRAME_JIT_OFS_CODE_SIZE (LJ_64 ? 0x2c : 0x24)
567#if LJ_TARGET_OSX
568#define ERR_FRAME_JIT_OFS_REGISTER ERR_FRAME_JIT_OFS_FDE
569#else
570#define ERR_FRAME_JIT_OFS_REGISTER 0
571#endif
572
573extern void __register_frame(const void *);
574extern void __deregister_frame(const void *);
575
576uint8_t *lj_err_register_mcode(void *base, size_t sz, uint8_t *info)
577{
578 void **handler;
579 memcpy(info, err_frame_jit_template, sizeof(err_frame_jit_template));
580 handler = (void *)err_unwind_jit;
581 memcpy(info + ERR_FRAME_JIT_OFS_HANDLER, &handler, sizeof(handler));
582 *(uint32_t *)(info + ERR_FRAME_JIT_OFS_CODE_SIZE) =
583 (uint32_t)(sz - sizeof(err_frame_jit_template) - (info - (uint8_t *)base));
584 __register_frame(info + ERR_FRAME_JIT_OFS_REGISTER);
585#ifdef LUA_USE_ASSERT
586 {
587 struct dwarf_eh_bases ehb;
588 lj_assertX(_Unwind_Find_FDE(info + sizeof(err_frame_jit_template)+1, &ehb),
589 "bad JIT unwind table registration");
590 }
591#endif
592 return info + sizeof(err_frame_jit_template);
593}
594
595void lj_err_deregister_mcode(void *base, size_t sz, uint8_t *info)
596{
597 UNUSED(base); UNUSED(sz);
598 __deregister_frame(info + ERR_FRAME_JIT_OFS_REGISTER);
599}
600#endif
601
602#else /* LJ_TARGET_ARM */
603
604#define _US_VIRTUAL_UNWIND_FRAME 0
605#define _US_UNWIND_FRAME_STARTING 1
606#define _US_ACTION_MASK 3
607#define _US_FORCE_UNWIND 8
608
609typedef struct _Unwind_Control_Block _Unwind_Control_Block;
610#define UNWIND_EXCEPTION_TYPE _Unwind_Control_Block
611
612struct _Unwind_Control_Block {
613 uint64_t exclass;
614 uint32_t misc[20];
615};
616
617extern int _Unwind_RaiseException(_Unwind_Control_Block *);
618extern int __gnu_unwind_frame(_Unwind_Control_Block *, _Unwind_Context *);
619extern int _Unwind_VRS_Set(_Unwind_Context *, int, uint32_t, int, void *);
620extern int _Unwind_VRS_Get(_Unwind_Context *, int, uint32_t, int, void *);
621
622static inline uint32_t _Unwind_GetGR(_Unwind_Context *ctx, int r)
623{
624 uint32_t v;
625 _Unwind_VRS_Get(ctx, 0, r, 0, &v);
626 return v;
627}
628
629static inline void _Unwind_SetGR(_Unwind_Context *ctx, int r, uint32_t v)
630{
631 _Unwind_VRS_Set(ctx, 0, r, 0, &v);
632}
633
634extern void lj_vm_unwind_ext(void);
635
636/* ARM unwinder personality handler referenced from interpreter .ARM.extab. */
637LJ_FUNCA int lj_err_unwind_arm(int state, _Unwind_Control_Block *ucb,
638 _Unwind_Context *ctx)
639{
640 void *cf = (void *)_Unwind_GetGR(ctx, 13);
641 lua_State *L = cframe_L(cf);
642 int errcode;
643
644 switch ((state & _US_ACTION_MASK)) {
645 case _US_VIRTUAL_UNWIND_FRAME:
646 if ((state & _US_FORCE_UNWIND)) break;
647 return _URC_HANDLER_FOUND;
648 case _US_UNWIND_FRAME_STARTING:
649 if (LJ_UEXCLASS_CHECK(ucb->exclass)) {
650 errcode = LJ_UEXCLASS_ERRCODE(ucb->exclass);
651 } else {
652 errcode = LUA_ERRRUN;
653 setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
654 }
655 cf = err_unwind(L, cf, errcode);
656 if ((state & _US_FORCE_UNWIND) || cf == NULL) break;
657 _Unwind_SetGR(ctx, 15, (uint32_t)lj_vm_unwind_ext);
658 _Unwind_SetGR(ctx, 0, (uint32_t)ucb);
659 _Unwind_SetGR(ctx, 1, (uint32_t)errcode);
660 _Unwind_SetGR(ctx, 2, cframe_unwind_ff(cf) ?
661 (uint32_t)lj_vm_unwind_ff_eh :
662 (uint32_t)lj_vm_unwind_c_eh);
663 return _URC_INSTALL_CONTEXT;
664 default:
665 return _URC_FAILURE;
666 }
667 if (__gnu_unwind_frame(ucb, ctx) != _URC_OK)
668 return _URC_FAILURE;
669#ifdef LUA_USE_ASSERT
670 /* We should never get here unless this is a forced unwind aka backtrace. */
671 if (_Unwind_GetGR(ctx, 0) == 0xff33aa77) {
672 _Unwind_SetGR(ctx, 0, 0xff33aa88);
673 }
674#endif
675 return _URC_CONTINUE_UNWIND;
676}
677
678#if LJ_UNWIND_EXT && defined(LUA_USE_ASSERT)
679typedef int (*_Unwind_Trace_Fn)(_Unwind_Context *, void *);
680extern int _Unwind_Backtrace(_Unwind_Trace_Fn, void *);
681
682static int err_verify_bt(_Unwind_Context *ctx, int *got)
683{
684 if (_Unwind_GetGR(ctx, 0) == 0xff33aa88) { *got = 2; }
685 else if (*got == 0) { *got = 1; _Unwind_SetGR(ctx, 0, 0xff33aa77); }
686 return _URC_OK;
687}
688
689/* Verify that external error handling actually has a chance to work. */
690void lj_err_verify(void)
691{
692 int got = 0;
693 _Unwind_Backtrace((_Unwind_Trace_Fn)err_verify_bt, &got);
694 lj_assertX(got == 2, "broken build: external frame unwinding enabled, but missing -funwind-tables");
695}
696#endif
697
698/*
699** Note: LJ_UNWIND_JIT is not implemented for 32 bit ARM.
700**
701** The quirky ARM unwind API doesn't have __register_frame().
702** A potential workaround might involve _Unwind_Backtrace.
703** But most 32 bit ARM targets don't qualify for LJ_UNWIND_EXT, anyway,
704** since they are built without unwind tables by default.
705*/
706
707#endif /* LJ_TARGET_ARM */
708
709
710#if LJ_UNWIND_EXT
711static __thread struct {
712 UNWIND_EXCEPTION_TYPE ex;
713 global_State *g;
714} static_uex;
715
716/* Raise external exception. */
717static void err_raise_ext(global_State *g, int errcode)
718{
719 memset(&static_uex, 0, sizeof(static_uex));
720 static_uex.ex.exclass = LJ_UEXCLASS_MAKE(errcode);
721 static_uex.g = g;
722 _Unwind_RaiseException(&static_uex.ex);
723}
724
725#endif
726
727#endif
728
729/* -- Error handling ------------------------------------------------------ */
730
731/* Throw error. Find catch frame, unwind stack and continue. */
732LJ_NOINLINE void LJ_FASTCALL lj_err_throw(lua_State *L, int errcode)
733{
734 global_State *g = G(L);
735 lj_trace_abort(g);
736 L->status = LUA_OK;
737#if LJ_UNWIND_EXT
738 err_raise_ext(g, errcode);
739 /*
740 ** A return from this function signals a corrupt C stack that cannot be
741 ** unwound. We have no choice but to call the panic function and exit.
742 **
743 ** Usually this is caused by a C function without unwind information.
744 ** This may happen if you've manually enabled LUAJIT_UNWIND_EXTERNAL
745 ** and forgot to recompile *every* non-C++ file with -funwind-tables.
746 */
747 if (G(L)->panic)
748 G(L)->panic(L);
749#else
750#if LJ_HASJIT
751 setmref(g->jit_base, NULL);
752#endif
753 {
754 void *cf = err_unwind(L, NULL, errcode);
755 if (cframe_unwind_ff(cf))
756 lj_vm_unwind_ff(cframe_raw(cf));
757 else
758 lj_vm_unwind_c(cframe_raw(cf), errcode);
759 }
760#endif
761 exit(EXIT_FAILURE);
762}
763
764/* Return string object for error message. */
765LJ_NOINLINE GCstr *lj_err_str(lua_State *L, ErrMsg em)
766{
767 return lj_str_newz(L, err2msg(em));
768}
769
770/* Out-of-memory error. */
771LJ_NOINLINE void lj_err_mem(lua_State *L)
772{
773 if (L->status == LUA_ERRERR+1) /* Don't touch the stack during lua_open. */
774 lj_vm_unwind_c(L->cframe, LUA_ERRMEM);
775 setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRMEM));
776 lj_err_throw(L, LUA_ERRMEM);
777}
778
779/* Find error function for runtime errors. Requires an extra stack traversal. */
780static ptrdiff_t finderrfunc(lua_State *L)
781{
782 cTValue *frame = L->base-1, *bot = tvref(L->stack)+LJ_FR2;
783 void *cf = L->cframe;
784 while (frame > bot && cf) {
785 while (cframe_nres(cframe_raw(cf)) < 0) { /* cframe without frame? */
786 if (frame >= restorestack(L, -cframe_nres(cf)))
787 break;
788 if (cframe_errfunc(cf) >= 0) /* Error handler not inherited (-1)? */
789 return cframe_errfunc(cf);
790 cf = cframe_prev(cf); /* Else unwind cframe and continue searching. */
791 if (cf == NULL)
792 return 0;
793 }
794 switch (frame_typep(frame)) {
795 case FRAME_LUA:
796 case FRAME_LUAP:
797 frame = frame_prevl(frame);
798 break;
799 case FRAME_C:
800 cf = cframe_prev(cf);
801 /* fallthrough */
802 case FRAME_VARG:
803 frame = frame_prevd(frame);
804 break;
805 case FRAME_CONT:
806 if (frame_iscont_fficb(frame))
807 cf = cframe_prev(cf);
808 frame = frame_prevd(frame);
809 break;
810 case FRAME_CP:
811 if (cframe_canyield(cf)) return 0;
812 if (cframe_errfunc(cf) >= 0)
813 return cframe_errfunc(cf);
814 cf = cframe_prev(cf);
815 frame = frame_prevd(frame);
816 break;
817 case FRAME_PCALL:
818 case FRAME_PCALLH:
819 if (frame_func(frame_prevd(frame))->c.ffid == FF_xpcall)
820 return savestack(L, frame_prevd(frame)+1); /* xpcall's errorfunc. */
821 return 0;
822 default:
823 lj_assertL(0, "bad frame type");
824 return 0;
825 }
826 }
827 return 0;
828}
829
830/* Runtime error. */
831LJ_NOINLINE void LJ_FASTCALL lj_err_run(lua_State *L)
832{
833 ptrdiff_t ef = (LJ_HASJIT && tvref(G(L)->jit_base)) ? 0 : finderrfunc(L);
834 if (ef) {
835 TValue *errfunc = restorestack(L, ef);
836 TValue *top = L->top;
837 lj_trace_abort(G(L));
838 if (!tvisfunc(errfunc) || L->status == LUA_ERRERR) {
839 setstrV(L, top-1, lj_err_str(L, LJ_ERR_ERRERR));
840 lj_err_throw(L, LUA_ERRERR);
841 }
842 L->status = LUA_ERRERR;
843 copyTV(L, top+LJ_FR2, top-1);
844 copyTV(L, top-1, errfunc);
845 if (LJ_FR2) setnilV(top++);
846 L->top = top+1;
847 lj_vm_call(L, top, 1+1); /* Stack: |errfunc|msg| -> |msg| */
848 }
849 lj_err_throw(L, LUA_ERRRUN);
850}
851
852#if LJ_HASJIT
853LJ_NOINLINE void LJ_FASTCALL lj_err_trace(lua_State *L, int errcode)
854{
855 if (errcode == LUA_ERRRUN)
856 lj_err_run(L);
857 else
858 lj_err_throw(L, errcode);
859}
860#endif
861
862/* Formatted runtime error message. */
863LJ_NORET LJ_NOINLINE static void err_msgv(lua_State *L, ErrMsg em, ...)
864{
865 const char *msg;
866 va_list argp;
867 va_start(argp, em);
868 if (curr_funcisL(L)) L->top = curr_topL(L);
869 msg = lj_strfmt_pushvf(L, err2msg(em), argp);
870 va_end(argp);
871 lj_debug_addloc(L, msg, L->base-1, NULL);
872 lj_err_run(L);
873}
874
875/* Non-vararg variant for better calling conventions. */
876LJ_NOINLINE void lj_err_msg(lua_State *L, ErrMsg em)
877{
878 err_msgv(L, em);
879}
880
881/* Lexer error. */
882LJ_NOINLINE void lj_err_lex(lua_State *L, GCstr *src, const char *tok,
883 BCLine line, ErrMsg em, va_list argp)
884{
885 char buff[LUA_IDSIZE];
886 const char *msg;
887 lj_debug_shortname(buff, src, line);
888 msg = lj_strfmt_pushvf(L, err2msg(em), argp);
889 msg = lj_strfmt_pushf(L, "%s:%d: %s", buff, line, msg);
890 if (tok)
891 lj_strfmt_pushf(L, err2msg(LJ_ERR_XNEAR), msg, tok);
892 lj_err_throw(L, LUA_ERRSYNTAX);
893}
894
895/* Typecheck error for operands. */
896LJ_NOINLINE void lj_err_optype(lua_State *L, cTValue *o, ErrMsg opm)
897{
898 const char *tname = lj_typename(o);
899 const char *opname = err2msg(opm);
900 if (curr_funcisL(L)) {
901 GCproto *pt = curr_proto(L);
902 const BCIns *pc = cframe_Lpc(L) - 1;
903 const char *oname = NULL;
904 const char *kind = lj_debug_slotname(pt, pc, (BCReg)(o-L->base), &oname);
905 if (kind)
906 err_msgv(L, LJ_ERR_BADOPRT, opname, kind, oname, tname);
907 }
908 err_msgv(L, LJ_ERR_BADOPRV, opname, tname);
909}
910
911/* Typecheck error for ordered comparisons. */
912LJ_NOINLINE void lj_err_comp(lua_State *L, cTValue *o1, cTValue *o2)
913{
914 const char *t1 = lj_typename(o1);
915 const char *t2 = lj_typename(o2);
916 err_msgv(L, t1 == t2 ? LJ_ERR_BADCMPV : LJ_ERR_BADCMPT, t1, t2);
917 /* This assumes the two "boolean" entries are commoned by the C compiler. */
918}
919
920/* Typecheck error for __call. */
921LJ_NOINLINE void lj_err_optype_call(lua_State *L, TValue *o)
922{
923 /* Gross hack if lua_[p]call or pcall/xpcall fail for a non-callable object:
924 ** L->base still points to the caller. So add a dummy frame with L instead
925 ** of a function. See lua_getstack().
926 */
927 const BCIns *pc = cframe_Lpc(L);
928 if (((ptrdiff_t)pc & FRAME_TYPE) != FRAME_LUA) {
929 const char *tname = lj_typename(o);
930 setframe_gc(o, obj2gco(L), LJ_TTHREAD);
931 if (LJ_FR2) o++;
932 setframe_pc(o, pc);
933 L->top = L->base = o+1;
934 err_msgv(L, LJ_ERR_BADCALL, tname);
935 }
936 lj_err_optype(L, o, LJ_ERR_OPCALL);
937}
938
939/* Error in context of caller. */
940LJ_NOINLINE void lj_err_callermsg(lua_State *L, const char *msg)
941{
942 TValue *frame = L->base-1;
943 TValue *pframe = NULL;
944 if (frame_islua(frame)) {
945 pframe = frame_prevl(frame);
946 } else if (frame_iscont(frame)) {
947 if (frame_iscont_fficb(frame)) {
948 pframe = frame;
949 frame = NULL;
950 } else {
951 pframe = frame_prevd(frame);
952#if LJ_HASFFI
953 /* Remove frame for FFI metamethods. */
954 if (frame_func(frame)->c.ffid >= FF_ffi_meta___index &&
955 frame_func(frame)->c.ffid <= FF_ffi_meta___tostring) {
956 L->base = pframe+1;
957 L->top = frame;
958 setcframe_pc(cframe_raw(L->cframe), frame_contpc(frame));
959 }
960#endif
961 }
962 }
963 lj_debug_addloc(L, msg, pframe, frame);
964 lj_err_run(L);
965}
966
967/* Formatted error in context of caller. */
968LJ_NOINLINE void lj_err_callerv(lua_State *L, ErrMsg em, ...)
969{
970 const char *msg;
971 va_list argp;
972 va_start(argp, em);
973 msg = lj_strfmt_pushvf(L, err2msg(em), argp);
974 va_end(argp);
975 lj_err_callermsg(L, msg);
976}
977
978/* Error in context of caller. */
979LJ_NOINLINE void lj_err_caller(lua_State *L, ErrMsg em)
980{
981 lj_err_callermsg(L, err2msg(em));
982}
983
984/* Argument error message. */
985LJ_NORET LJ_NOINLINE static void err_argmsg(lua_State *L, int narg,
986 const char *msg)
987{
988 const char *fname = "?";
989 const char *ftype = lj_debug_funcname(L, L->base - 1, &fname);
990 if (narg < 0 && narg > LUA_REGISTRYINDEX)
991 narg = (int)(L->top - L->base) + narg + 1;
992 if (ftype && ftype[3] == 'h' && --narg == 0) /* Check for "method". */
993 msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADSELF), fname, msg);
994 else
995 msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADARG), narg, fname, msg);
996 lj_err_callermsg(L, msg);
997}
998
999/* Formatted argument error. */
1000LJ_NOINLINE void lj_err_argv(lua_State *L, int narg, ErrMsg em, ...)
1001{
1002 const char *msg;
1003 va_list argp;
1004 va_start(argp, em);
1005 msg = lj_strfmt_pushvf(L, err2msg(em), argp);
1006 va_end(argp);
1007 err_argmsg(L, narg, msg);
1008}
1009
1010/* Argument error. */
1011LJ_NOINLINE void lj_err_arg(lua_State *L, int narg, ErrMsg em)
1012{
1013 err_argmsg(L, narg, err2msg(em));
1014}
1015
1016/* Typecheck error for arguments. */
1017LJ_NOINLINE void lj_err_argtype(lua_State *L, int narg, const char *xname)
1018{
1019 const char *tname, *msg;
1020 if (narg <= LUA_REGISTRYINDEX) {
1021 if (narg >= LUA_GLOBALSINDEX) {
1022 tname = lj_obj_itypename[~LJ_TTAB];
1023 } else {
1024 GCfunc *fn = curr_func(L);
1025 int idx = LUA_GLOBALSINDEX - narg;
1026 if (idx <= fn->c.nupvalues)
1027 tname = lj_typename(&fn->c.upvalue[idx-1]);
1028 else
1029 tname = lj_obj_typename[0];
1030 }
1031 } else {
1032 TValue *o = narg < 0 ? L->top + narg : L->base + narg-1;
1033 tname = o < L->top ? lj_typename(o) : lj_obj_typename[0];
1034 }
1035 msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADTYPE), xname, tname);
1036 err_argmsg(L, narg, msg);
1037}
1038
1039/* Typecheck error for arguments. */
1040LJ_NOINLINE void lj_err_argt(lua_State *L, int narg, int tt)
1041{
1042 lj_err_argtype(L, narg, lj_obj_typename[tt+1]);
1043}
1044
1045/* -- Public error handling API ------------------------------------------- */
1046
1047LUA_API lua_CFunction lua_atpanic(lua_State *L, lua_CFunction panicf)
1048{
1049 lua_CFunction old = G(L)->panic;
1050 G(L)->panic = panicf;
1051 return old;
1052}
1053
1054/* Forwarders for the public API (C calling convention and no LJ_NORET). */
1055LUA_API int lua_error(lua_State *L)
1056{
1057 lj_err_run(L);
1058 return 0; /* unreachable */
1059}
1060
1061LUALIB_API int luaL_argerror(lua_State *L, int narg, const char *msg)
1062{
1063 err_argmsg(L, narg, msg);
1064 return 0; /* unreachable */
1065}
1066
1067LUALIB_API int luaL_typerror(lua_State *L, int narg, const char *xname)
1068{
1069 lj_err_argtype(L, narg, xname);
1070 return 0; /* unreachable */
1071}
1072
1073LUALIB_API void luaL_where(lua_State *L, int level)
1074{
1075 int size;
1076 cTValue *frame = lj_debug_frame(L, level, &size);
1077 lj_debug_addloc(L, "", frame, size ? frame+size : NULL);
1078}
1079
1080LUALIB_API int luaL_error(lua_State *L, const char *fmt, ...)
1081{
1082 const char *msg;
1083 va_list argp;
1084 va_start(argp, fmt);
1085 msg = lj_strfmt_pushvf(L, fmt, argp);
1086 va_end(argp);
1087 lj_err_callermsg(L, msg);
1088 return 0; /* unreachable */
1089}
1090
1091