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lj_err.c
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/*
** Error handling.
** Copyright (C) 2005-2021 Mike Pall. See Copyright Notice in luajit.h
*/
#define lj_err_c
#define LUA_CORE
#include "lj_obj.h"
#include "lj_err.h"
#include "lj_debug.h"
#include "lj_str.h"
#include "lj_func.h"
#include "lj_state.h"
#include "lj_frame.h"
#include "lj_ff.h"
#include "lj_trace.h"
#include "lj_vm.h"
#include "lj_strfmt.h"
/*
** LuaJIT can either use internal or external frame unwinding:
**
** - Internal frame unwinding (INT) is free-standing and doesn't require
** any OS or library support.
**
** - External frame unwinding (EXT) uses the system-provided unwind handler.
**
** Pros and Cons:
**
** - EXT requires unwind tables for *all* functions on the C stack between
** the pcall/catch and the error/throw. C modules used by Lua code can
** throw errors, so these need to have unwind tables, too. Transitively
** this applies to all system libraries used by C modules -- at least
** when they have callbacks which may throw an error.
**
** - INT is faster when actually throwing errors, but this happens rarely.
** Setting up error handlers is zero-cost in any case.
**
** - INT needs to save *all* callee-saved registers when entering the
** interpreter. EXT only needs to save those actually used inside the
** interpreter. JIT-compiled code may need to save some more.
**
** - EXT provides full interoperability with C++ exceptions. You can throw
** Lua errors or C++ exceptions through a mix of Lua frames and C++ frames.
** C++ destructors are called as needed. C++ exceptions caught by pcall
** are converted to the string "C++ exception". Lua errors can be caught
** with catch (...) in C++.
**
** - INT has only limited support for automatically catching C++ exceptions
** on POSIX systems using DWARF2 stack unwinding. Other systems may use
** the wrapper function feature. Lua errors thrown through C++ frames
** cannot be caught by C++ code and C++ destructors are not run.
**
** - EXT can handle errors from internal helper functions that are called
** from JIT-compiled code (except for Windows/x86 and 32 bit ARM).
** INT has no choice but to call the panic handler, if this happens.
** Note: this is mainly relevant for out-of-memory errors.
**
** EXT is the default on all systems where the toolchain produces unwind
** tables by default (*). This is hard-coded and/or detected in src/Makefile.
** You can thwart the detection with: TARGET_XCFLAGS=-DLUAJIT_UNWIND_INTERNAL
**
** INT is the default on all other systems.
**
** EXT can be manually enabled for toolchains that are able to produce
** conforming unwind tables:
** "TARGET_XCFLAGS=-funwind-tables -DLUAJIT_UNWIND_EXTERNAL"
** As explained above, *all* C code used directly or indirectly by LuaJIT
** must be compiled with -funwind-tables (or -fexceptions). C++ code must
** *not* be compiled with -fno-exceptions.
**
** If you're unsure whether error handling inside the VM works correctly,
** try running this and check whether it prints "OK":
**
** luajit -e "print(select(2, load('OK')):match('OK'))"
**
** (*) Originally, toolchains only generated unwind tables for C++ code. For
** interoperability reasons, this can be manually enabled for plain C code,
** too (with -funwind-tables). With the introduction of the x64 architecture,
** the corresponding POSIX and Windows ABIs mandated unwind tables for all
** code. Over the following years most desktop and server platforms have
** enabled unwind tables by default on all architectures. OTOH mobile and
** embedded platforms do not consistently mandate unwind tables.
*/
/* -- Error messages ------------------------------------------------------ */
/* Error message strings. */
LJ_DATADEF const char *lj_err_allmsg =
#define ERRDEF(name, msg) msg "\0"
#include "lj_errmsg.h"
;
/* -- Internal frame unwinding -------------------------------------------- */
/* Unwind Lua stack and move error message to new top. */
LJ_NOINLINE static void unwindstack(lua_State *L, TValue *top)
{
lj_func_closeuv(L, top);
if (top < L->top-1) {
copyTV(L, top, L->top-1);
L->top = top+1;
}
lj_state_relimitstack(L);
}
/* Unwind until stop frame. Optionally cleanup frames. */
static void *err_unwind(lua_State *L, void *stopcf, int errcode)
{
TValue *frame = L->base-1;
void *cf = L->cframe;
while (cf) {
int32_t nres = cframe_nres(cframe_raw(cf));
if (nres < 0) { /* C frame without Lua frame? */
TValue *top = restorestack(L, -nres);
if (frame < top) { /* Frame reached? */
if (errcode) {
L->base = frame+1;
L->cframe = cframe_prev(cf);
unwindstack(L, top);
}
return cf;
}
}
if (frame <= tvref(L->stack)+LJ_FR2)
break;
switch (frame_typep(frame)) {
case FRAME_LUA: /* Lua frame. */
case FRAME_LUAP:
frame = frame_prevl(frame);
break;
case FRAME_C: /* C frame. */
unwind_c:
#if LJ_UNWIND_EXT
if (errcode) {
L->base = frame_prevd(frame) + 1;
L->cframe = cframe_prev(cf);
unwindstack(L, frame - LJ_FR2);
} else if (cf != stopcf) {
cf = cframe_prev(cf);
frame = frame_prevd(frame);
break;
}
return NULL; /* Continue unwinding. */
#else
UNUSED(stopcf);
cf = cframe_prev(cf);
frame = frame_prevd(frame);
break;
#endif
case FRAME_CP: /* Protected C frame. */
if (cframe_canyield(cf)) { /* Resume? */
if (errcode) {
hook_leave(G(L)); /* Assumes nobody uses coroutines inside hooks. */
L->cframe = NULL;
L->status = (uint8_t)errcode;
}
return cf;
}
if (errcode) {
L->base = frame_prevd(frame) + 1;
L->cframe = cframe_prev(cf);
unwindstack(L, frame - LJ_FR2);
}
return cf;
case FRAME_CONT: /* Continuation frame. */
if (frame_iscont_fficb(frame))
goto unwind_c;
/* fallthrough */
case FRAME_VARG: /* Vararg frame. */
frame = frame_prevd(frame);
break;
case FRAME_PCALL: /* FF pcall() frame. */
case FRAME_PCALLH: /* FF pcall() frame inside hook. */
if (errcode) {
if (errcode == LUA_YIELD) {
frame = frame_prevd(frame);
break;
}
if (frame_typep(frame) == FRAME_PCALL)
hook_leave(G(L));
L->base = frame_prevd(frame) + 1;
L->cframe = cf;
unwindstack(L, L->base);
}
return (void *)((intptr_t)cf | CFRAME_UNWIND_FF);
}
}
/* No C frame. */
if (errcode) {
L->base = tvref(L->stack)+1+LJ_FR2;
L->cframe = NULL;
unwindstack(L, L->base);
if (G(L)->panic)
G(L)->panic(L);
exit(EXIT_FAILURE);
}
return L; /* Anything non-NULL will do. */
}
/* -- External frame unwinding -------------------------------------------- */
#if LJ_ABI_WIN
/*
** Someone in Redmond owes me several days of my life. A lot of this is
** undocumented or just plain wrong on MSDN. Some of it can be gathered
** from 3rd party docs or must be found by trial-and-error. They really
** don't want you to write your own language-specific exception handler
** or to interact gracefully with MSVC. :-(
**
** Apparently MSVC doesn't call C++ destructors for foreign exceptions
** unless you compile your C++ code with /EHa. Unfortunately this means
** catch (...) also catches things like access violations. The use of
** _set_se_translator doesn't really help, because it requires /EHa, too.
*/
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#if LJ_TARGET_X86
typedef void *UndocumentedDispatcherContext; /* Unused on x86. */
#else
/* Taken from: http://www.nynaeve.net/?p=99 */
typedef struct UndocumentedDispatcherContext {
ULONG64 ControlPc;
ULONG64 ImageBase;
PRUNTIME_FUNCTION FunctionEntry;
ULONG64 EstablisherFrame;
ULONG64 TargetIp;
PCONTEXT ContextRecord;
void (*LanguageHandler)(void);
PVOID HandlerData;
PUNWIND_HISTORY_TABLE HistoryTable;
ULONG ScopeIndex;
ULONG Fill0;
} UndocumentedDispatcherContext;
#endif
/* Another wild guess. */
extern void __DestructExceptionObject(EXCEPTION_RECORD *rec, int nothrow);
#if LJ_TARGET_X64 && defined(MINGW_SDK_INIT)
/* Workaround for broken MinGW64 declaration. */
VOID RtlUnwindEx_FIXED(PVOID,PVOID,PVOID,PVOID,PVOID,PVOID) asm("RtlUnwindEx");
#define RtlUnwindEx RtlUnwindEx_FIXED
#endif
#define LJ_MSVC_EXCODE ((DWORD)0xe06d7363)
#define LJ_GCC_EXCODE ((DWORD)0x20474343)
#define LJ_EXCODE ((DWORD)0xe24c4a00)
#define LJ_EXCODE_MAKE(c) (LJ_EXCODE | (DWORD)(c))
#define LJ_EXCODE_CHECK(cl) (((cl) ^ LJ_EXCODE) <= 0xff)
#define LJ_EXCODE_ERRCODE(cl) ((int)((cl) & 0xff))
/* Windows exception handler for interpreter frame. */
LJ_FUNCA int lj_err_unwind_win(EXCEPTION_RECORD *rec,
void *f, CONTEXT *ctx, UndocumentedDispatcherContext *dispatch)
{
#if LJ_TARGET_X86
void *cf = (char *)f - CFRAME_OFS_SEH;
#else
void *cf = f;
#endif
lua_State *L = cframe_L(cf);
int errcode = LJ_EXCODE_CHECK(rec->ExceptionCode) ?
LJ_EXCODE_ERRCODE(rec->ExceptionCode) : LUA_ERRRUN;
if ((rec->ExceptionFlags & 6)) { /* EH_UNWINDING|EH_EXIT_UNWIND */
/* Unwind internal frames. */
err_unwind(L, cf, errcode);
} else {
void *cf2 = err_unwind(L, cf, 0);
if (cf2) { /* We catch it, so start unwinding the upper frames. */
if (rec->ExceptionCode == LJ_MSVC_EXCODE ||
rec->ExceptionCode == LJ_GCC_EXCODE) {
#if !LJ_TARGET_CYGWIN
__DestructExceptionObject(rec, 1);
#endif
setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
} else if (!LJ_EXCODE_CHECK(rec->ExceptionCode)) {
/* Don't catch access violations etc. */
return 1; /* ExceptionContinueSearch */
}
#if LJ_TARGET_X86
UNUSED(ctx);
UNUSED(dispatch);
/* Call all handlers for all lower C frames (including ourselves) again
** with EH_UNWINDING set. Then call the specified function, passing cf
** and errcode.
*/
lj_vm_rtlunwind(cf, (void *)rec,
(cframe_unwind_ff(cf2) && errcode != LUA_YIELD) ?
(void *)lj_vm_unwind_ff : (void *)lj_vm_unwind_c, errcode);
/* lj_vm_rtlunwind does not return. */
#else
/* Unwind the stack and call all handlers for all lower C frames
** (including ourselves) again with EH_UNWINDING set. Then set
** stack pointer = cf, result = errcode and jump to the specified target.
*/
RtlUnwindEx(cf, (void *)((cframe_unwind_ff(cf2) && errcode != LUA_YIELD) ?
lj_vm_unwind_ff_eh :
lj_vm_unwind_c_eh),
rec, (void *)(uintptr_t)errcode, ctx, dispatch->HistoryTable);
/* RtlUnwindEx should never return. */
#endif
}
}
return 1; /* ExceptionContinueSearch */
}
#if LJ_UNWIND_JIT
#if LJ_TARGET_X64
#define CONTEXT_REG_PC Rip
#elif LJ_TARGET_ARM64
#define CONTEXT_REG_PC Pc
#else
#error "NYI: Windows arch-specific unwinder for JIT-compiled code"
#endif
/* Windows unwinder for JIT-compiled code. */
static void err_unwind_win_jit(global_State *g, int errcode)
{
CONTEXT ctx;
UNWIND_HISTORY_TABLE hist;
memset(&hist, 0, sizeof(hist));
RtlCaptureContext(&ctx);
while (1) {
uintptr_t frame, base, addr = ctx.CONTEXT_REG_PC;
void *hdata;
PRUNTIME_FUNCTION func = RtlLookupFunctionEntry(addr, &base, &hist);
if (!func) { /* Found frame without .pdata: must be JIT-compiled code. */
ExitNo exitno;
uintptr_t stub = lj_trace_unwind(G2J(g), addr - sizeof(MCode), &exitno);
if (stub) { /* Jump to side exit to unwind the trace. */
ctx.CONTEXT_REG_PC = stub;
G2J(g)->exitcode = errcode;
RtlRestoreContext(&ctx, NULL); /* Does not return. */
}
break;
}
RtlVirtualUnwind(UNW_FLAG_NHANDLER, base, addr, func,
&ctx, &hdata, &frame, NULL);
if (!addr) break;
}
/* Unwinding failed, if we end up here. */
}
#endif
/* Raise Windows exception. */
static void err_raise_ext(global_State *g, int errcode)
{
#if LJ_UNWIND_JIT
if (tvref(g->jit_base)) {
err_unwind_win_jit(g, errcode);
return; /* Unwinding failed. */
}
#elif LJ_HASJIT
/* Cannot catch on-trace errors for Windows/x86 SEH. Unwind to interpreter. */
setmref(g->jit_base, NULL);
#endif
UNUSED(g);
RaiseException(LJ_EXCODE_MAKE(errcode), 1 /* EH_NONCONTINUABLE */, 0, NULL);
}
#elif !LJ_NO_UNWIND && (defined(__GNUC__) || defined(__clang__))
/*
** We have to use our own definitions instead of the mandatory (!) unwind.h,
** since various OS, distros and compilers mess up the header installation.
*/
typedef struct _Unwind_Context _Unwind_Context;
#define _URC_OK 0
#define _URC_FATAL_PHASE2_ERROR 2
#define _URC_FATAL_PHASE1_ERROR 3
#define _URC_HANDLER_FOUND 6
#define _URC_INSTALL_CONTEXT 7
#define _URC_CONTINUE_UNWIND 8
#define _URC_FAILURE 9
#define LJ_UEXCLASS 0x4c55414a49543200ULL /* LUAJIT2\0 */
#define LJ_UEXCLASS_MAKE(c) (LJ_UEXCLASS | (uint64_t)(c))
#define LJ_UEXCLASS_CHECK(cl) (((cl) ^ LJ_UEXCLASS) <= 0xff)
#define LJ_UEXCLASS_ERRCODE(cl) ((int)((cl) & 0xff))
#if !LJ_TARGET_ARM
typedef struct _Unwind_Exception
{
uint64_t exclass;
void (*excleanup)(int, struct _Unwind_Exception *);
uintptr_t p1, p2;
} __attribute__((__aligned__)) _Unwind_Exception;
#define UNWIND_EXCEPTION_TYPE _Unwind_Exception
extern uintptr_t _Unwind_GetCFA(_Unwind_Context *);
extern void _Unwind_SetGR(_Unwind_Context *, int, uintptr_t);
extern uintptr_t _Unwind_GetIP(_Unwind_Context *);
extern void _Unwind_SetIP(_Unwind_Context *, uintptr_t);
extern void _Unwind_DeleteException(_Unwind_Exception *);
extern int _Unwind_RaiseException(_Unwind_Exception *);
#define _UA_SEARCH_PHASE 1
#define _UA_CLEANUP_PHASE 2
#define _UA_HANDLER_FRAME 4
#define _UA_FORCE_UNWIND 8
/* DWARF2 personality handler referenced from interpreter .eh_frame. */
LJ_FUNCA int lj_err_unwind_dwarf(int version, int actions,
uint64_t uexclass, _Unwind_Exception *uex, _Unwind_Context *ctx)
{
void *cf;
lua_State *L;
if (version != 1)
return _URC_FATAL_PHASE1_ERROR;
cf = (void *)_Unwind_GetCFA(ctx);
L = cframe_L(cf);
if ((actions & _UA_SEARCH_PHASE)) {
#if LJ_UNWIND_EXT
if (err_unwind(L, cf, 0) == NULL)
return _URC_CONTINUE_UNWIND;
#endif
if (!LJ_UEXCLASS_CHECK(uexclass)) {
setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
}
return _URC_HANDLER_FOUND;
}
if ((actions & _UA_CLEANUP_PHASE)) {
int errcode;
if (LJ_UEXCLASS_CHECK(uexclass)) {
errcode = LJ_UEXCLASS_ERRCODE(uexclass);
} else {
if ((actions & _UA_HANDLER_FRAME))
_Unwind_DeleteException(uex);
errcode = LUA_ERRRUN;
}
#if LJ_UNWIND_EXT
cf = err_unwind(L, cf, errcode);
if ((actions & _UA_FORCE_UNWIND)) {
return _URC_CONTINUE_UNWIND;
} else if (cf) {
_Unwind_SetGR(ctx, LJ_TARGET_EHRETREG, errcode);
_Unwind_SetIP(ctx, (uintptr_t)(cframe_unwind_ff(cf) ?
lj_vm_unwind_ff_eh :
lj_vm_unwind_c_eh));
return _URC_INSTALL_CONTEXT;
}
#if LJ_TARGET_X86ORX64
else if ((actions & _UA_HANDLER_FRAME)) {
/* Workaround for ancient libgcc bug. Still present in RHEL 5.5. :-/
** Real fix: http://gcc.gnu.org/viewcvs/trunk/gcc/unwind-dw2.c?r1=121165&r2=124837&pathrev=153877&diff_format=h
*/
_Unwind_SetGR(ctx, LJ_TARGET_EHRETREG, errcode);
_Unwind_SetIP(ctx, (uintptr_t)lj_vm_unwind_rethrow);
return _URC_INSTALL_CONTEXT;
}
#endif
#else
/* This is not the proper way to escape from the unwinder. We get away with
** it on non-x64 because the interpreter restores all callee-saved regs.
*/
lj_err_throw(L, errcode);
#if LJ_TARGET_X64
#error "Broken build system -- only use the provided Makefiles!"
#endif
#endif
}
return _URC_CONTINUE_UNWIND;
}
#if LJ_UNWIND_EXT && defined(LUA_USE_ASSERT)
struct dwarf_eh_bases { void *tbase, *dbase, *func; };
extern const void *_Unwind_Find_FDE(void *pc, struct dwarf_eh_bases *bases);
/* Verify that external error handling actually has a chance to work. */
void lj_err_verify(void)
{
struct dwarf_eh_bases ehb;
lj_assertX(_Unwind_Find_FDE((void *)lj_err_throw, &ehb), "broken build: external frame unwinding enabled, but missing -funwind-tables");
/* Check disabled, because of broken Fedora/ARM64. See #722.
lj_assertX(_Unwind_Find_FDE((void *)_Unwind_RaiseException, &ehb), "broken build: external frame unwinding enabled, but system libraries have no unwind tables");
*/
}
#endif
#if LJ_UNWIND_JIT
/* DWARF2 personality handler for JIT-compiled code. */
static int err_unwind_jit(int version, int actions,
uint64_t uexclass, _Unwind_Exception *uex, _Unwind_Context *ctx)
{
/* NYI: FFI C++ exception interoperability. */
if (version != 1 || !LJ_UEXCLASS_CHECK(uexclass))
return _URC_FATAL_PHASE1_ERROR;
if ((actions & _UA_SEARCH_PHASE)) {
return _URC_HANDLER_FOUND;
}
if ((actions & _UA_CLEANUP_PHASE)) {
global_State *g = *(global_State **)(uex+1);
ExitNo exitno;
uintptr_t addr = _Unwind_GetIP(ctx); /* Return address _after_ call. */
uintptr_t stub = lj_trace_unwind(G2J(g), addr - sizeof(MCode), &exitno);
lj_assertG(tvref(g->jit_base), "unexpected throw across mcode frame");
if (stub) { /* Jump to side exit to unwind the trace. */
G2J(g)->exitcode = LJ_UEXCLASS_ERRCODE(uexclass);
#ifdef LJ_TARGET_MIPS
_Unwind_SetGR(ctx, 4, stub);
_Unwind_SetGR(ctx, 5, exitno);
_Unwind_SetIP(ctx, (uintptr_t)(void *)lj_vm_unwind_stub);
#else
_Unwind_SetIP(ctx, stub);
#endif
return _URC_INSTALL_CONTEXT;
}
return _URC_FATAL_PHASE2_ERROR;
}
return _URC_FATAL_PHASE1_ERROR;
}
/* DWARF2 template frame info for JIT-compiled code.
**
** After copying the template to the start of the mcode segment,
** the frame handler function and the code size is patched.
** The frame handler always installs a new context to jump to the exit,
** so don't bother to add any unwind opcodes.
*/
static const uint8_t err_frame_jit_template[] = {
#if LJ_BE
0,0,0,
#endif
LJ_64 ? 0x1c : 0x14, /* CIE length. */
#if LJ_LE
0,0,0,
#endif
0,0,0,0, 1, 'z','P','R',0, /* CIE mark, CIE version, augmentation. */
1, LJ_64 ? 0x78 : 0x7c, LJ_TARGET_EHRAREG, /* Code/data align, RA. */
#if LJ_64
10, 0, 0,0,0,0,0,0,0,0, 0x1b, /* Aug. data ABS handler, PCREL|SDATA4 code. */
0,0,0,0,0, /* Alignment. */
#else
6, 0, 0,0,0,0, 0x1b, /* Aug. data ABS handler, PCREL|SDATA4 code. */
0, /* Alignment. */
#endif
#if LJ_BE
0,0,0,
#endif
LJ_64 ? 0x14 : 0x10, /* FDE length. */
0,0,0,
LJ_64 ? 0x24 : 0x1c, /* CIE offset. */
0,0,0,
LJ_64 ? 0x14 : 0x10, /* Code offset. After Final FDE. */
#if LJ_LE
0,0,0,
#endif
0,0,0,0, 0, 0,0,0, /* Code size, augmentation length, alignment. */
#if LJ_64
0,0,0,0, /* Alignment. */
#endif
0,0,0,0 /* Final FDE. */
};
#define ERR_FRAME_JIT_OFS_HANDLER 0x12
#define ERR_FRAME_JIT_OFS_FDE (LJ_64 ? 0x20 : 0x18)
#define ERR_FRAME_JIT_OFS_CODE_SIZE (LJ_64 ? 0x2c : 0x24)
#if LJ_TARGET_OSX
#define ERR_FRAME_JIT_OFS_REGISTER ERR_FRAME_JIT_OFS_FDE
#else
#define ERR_FRAME_JIT_OFS_REGISTER 0
#endif
extern void __register_frame(const void *);
extern void __deregister_frame(const void *);
uint8_t *lj_err_register_mcode(void *base, size_t sz, uint8_t *info)
{
void **handler;
memcpy(info, err_frame_jit_template, sizeof(err_frame_jit_template));
handler = (void *)err_unwind_jit;
memcpy(info + ERR_FRAME_JIT_OFS_HANDLER, &handler, sizeof(handler));
*(uint32_t *)(info + ERR_FRAME_JIT_OFS_CODE_SIZE) =
(uint32_t)(sz - sizeof(err_frame_jit_template) - (info - (uint8_t *)base));
__register_frame(info + ERR_FRAME_JIT_OFS_REGISTER);
#ifdef LUA_USE_ASSERT
{
struct dwarf_eh_bases ehb;
lj_assertX(_Unwind_Find_FDE(info + sizeof(err_frame_jit_template)+1, &ehb),
"bad JIT unwind table registration");
}
#endif
return info + sizeof(err_frame_jit_template);
}
void lj_err_deregister_mcode(void *base, size_t sz, uint8_t *info)
{
UNUSED(base); UNUSED(sz);
__deregister_frame(info + ERR_FRAME_JIT_OFS_REGISTER);
}
#endif
#else /* LJ_TARGET_ARM */
#define _US_VIRTUAL_UNWIND_FRAME 0
#define _US_UNWIND_FRAME_STARTING 1
#define _US_ACTION_MASK 3
#define _US_FORCE_UNWIND 8
typedef struct _Unwind_Control_Block _Unwind_Control_Block;
#define UNWIND_EXCEPTION_TYPE _Unwind_Control_Block
struct _Unwind_Control_Block {
uint64_t exclass;
uint32_t misc[20];
};
extern int _Unwind_RaiseException(_Unwind_Control_Block *);
extern int __gnu_unwind_frame(_Unwind_Control_Block *, _Unwind_Context *);
extern int _Unwind_VRS_Set(_Unwind_Context *, int, uint32_t, int, void *);
extern int _Unwind_VRS_Get(_Unwind_Context *, int, uint32_t, int, void *);
static inline uint32_t _Unwind_GetGR(_Unwind_Context *ctx, int r)
{
uint32_t v;
_Unwind_VRS_Get(ctx, 0, r, 0, &v);
return v;
}
static inline void _Unwind_SetGR(_Unwind_Context *ctx, int r, uint32_t v)
{
_Unwind_VRS_Set(ctx, 0, r, 0, &v);
}
extern void lj_vm_unwind_ext(void);
/* ARM unwinder personality handler referenced from interpreter .ARM.extab. */
LJ_FUNCA int lj_err_unwind_arm(int state, _Unwind_Control_Block *ucb,
_Unwind_Context *ctx)
{
void *cf = (void *)_Unwind_GetGR(ctx, 13);
lua_State *L = cframe_L(cf);
int errcode;
switch ((state & _US_ACTION_MASK)) {
case _US_VIRTUAL_UNWIND_FRAME:
if ((state & _US_FORCE_UNWIND)) break;
return _URC_HANDLER_FOUND;
case _US_UNWIND_FRAME_STARTING:
if (LJ_UEXCLASS_CHECK(ucb->exclass)) {
errcode = LJ_UEXCLASS_ERRCODE(ucb->exclass);
} else {
errcode = LUA_ERRRUN;
setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
}
cf = err_unwind(L, cf, errcode);
if ((state & _US_FORCE_UNWIND) || cf == NULL) break;
_Unwind_SetGR(ctx, 15, (uint32_t)lj_vm_unwind_ext);
_Unwind_SetGR(ctx, 0, (uint32_t)ucb);
_Unwind_SetGR(ctx, 1, (uint32_t)errcode);
_Unwind_SetGR(ctx, 2, cframe_unwind_ff(cf) ?
(uint32_t)lj_vm_unwind_ff_eh :
(uint32_t)lj_vm_unwind_c_eh);
return _URC_INSTALL_CONTEXT;
default:
return _URC_FAILURE;
}
if (__gnu_unwind_frame(ucb, ctx) != _URC_OK)
return _URC_FAILURE;
#ifdef LUA_USE_ASSERT
/* We should never get here unless this is a forced unwind aka backtrace. */
if (_Unwind_GetGR(ctx, 0) == 0xff33aa77) {
_Unwind_SetGR(ctx, 0, 0xff33aa88);
}
#endif
return _URC_CONTINUE_UNWIND;
}
#if LJ_UNWIND_EXT && defined(LUA_USE_ASSERT)
typedef int (*_Unwind_Trace_Fn)(_Unwind_Context *, void *);
extern int _Unwind_Backtrace(_Unwind_Trace_Fn, void *);
static int err_verify_bt(_Unwind_Context *ctx, int *got)
{
if (_Unwind_GetGR(ctx, 0) == 0xff33aa88) { *got = 2; }
else if (*got == 0) { *got = 1; _Unwind_SetGR(ctx, 0, 0xff33aa77); }
return _URC_OK;
}
/* Verify that external error handling actually has a chance to work. */
void lj_err_verify(void)
{
int got = 0;
_Unwind_Backtrace((_Unwind_Trace_Fn)err_verify_bt, &got);
lj_assertX(got == 2, "broken build: external frame unwinding enabled, but missing -funwind-tables");
}
#endif
/*
** Note: LJ_UNWIND_JIT is not implemented for 32 bit ARM.
**
** The quirky ARM unwind API doesn't have __register_frame().
** A potential workaround might involve _Unwind_Backtrace.
** But most 32 bit ARM targets don't qualify for LJ_UNWIND_EXT, anyway,
** since they are built without unwind tables by default.
*/
#endif /* LJ_TARGET_ARM */
#if LJ_UNWIND_EXT
static __thread struct {
UNWIND_EXCEPTION_TYPE ex;
global_State *g;
} static_uex;
/* Raise external exception. */
static void err_raise_ext(global_State *g, int errcode)
{
memset(&static_uex, 0, sizeof(static_uex));
static_uex.ex.exclass = LJ_UEXCLASS_MAKE(errcode);
static_uex.g = g;
_Unwind_RaiseException(&static_uex.ex);
}
#endif
#endif
/* -- Error handling ------------------------------------------------------ */
/* Throw error. Find catch frame, unwind stack and continue. */
LJ_NOINLINE void LJ_FASTCALL lj_err_throw(lua_State *L, int errcode)
{
global_State *g = G(L);
lj_trace_abort(g);
L->status = LUA_OK;
#if LJ_UNWIND_EXT
err_raise_ext(g, errcode);
/*
** A return from this function signals a corrupt C stack that cannot be
** unwound. We have no choice but to call the panic function and exit.
**
** Usually this is caused by a C function without unwind information.
** This may happen if you've manually enabled LUAJIT_UNWIND_EXTERNAL
** and forgot to recompile *every* non-C++ file with -funwind-tables.
*/
if (G(L)->panic)
G(L)->panic(L);
#else
#if LJ_HASJIT
setmref(g->jit_base, NULL);
#endif
{
void *cf = err_unwind(L, NULL, errcode);
if (cframe_unwind_ff(cf))
lj_vm_unwind_ff(cframe_raw(cf));
else
lj_vm_unwind_c(cframe_raw(cf), errcode);
}
#endif
exit(EXIT_FAILURE);
}
/* Return string object for error message. */
LJ_NOINLINE GCstr *lj_err_str(lua_State *L, ErrMsg em)
{
return lj_str_newz(L, err2msg(em));
}
/* Out-of-memory error. */
LJ_NOINLINE void lj_err_mem(lua_State *L)
{
if (L->status == LUA_ERRERR+1) /* Don't touch the stack during lua_open. */
lj_vm_unwind_c(L->cframe, LUA_ERRMEM);
setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRMEM));
lj_err_throw(L, LUA_ERRMEM);
}
/* Find error function for runtime errors. Requires an extra stack traversal. */
static ptrdiff_t finderrfunc(lua_State *L)
{
cTValue *frame = L->base-1, *bot = tvref(L->stack)+LJ_FR2;
void *cf = L->cframe;
while (frame > bot && cf) {
while (cframe_nres(cframe_raw(cf)) < 0) { /* cframe without frame? */
if (frame >= restorestack(L, -cframe_nres(cf)))
break;
if (cframe_errfunc(cf) >= 0) /* Error handler not inherited (-1)? */
return cframe_errfunc(cf);
cf = cframe_prev(cf); /* Else unwind cframe and continue searching. */
if (cf == NULL)
return 0;
}
switch (frame_typep(frame)) {
case FRAME_LUA:
case FRAME_LUAP:
frame = frame_prevl(frame);
break;
case FRAME_C:
cf = cframe_prev(cf);
/* fallthrough */
case FRAME_VARG:
frame = frame_prevd(frame);
break;
case FRAME_CONT:
if (frame_iscont_fficb(frame))
cf = cframe_prev(cf);
frame = frame_prevd(frame);
break;
case FRAME_CP:
if (cframe_canyield(cf)) return 0;
if (cframe_errfunc(cf) >= 0)
return cframe_errfunc(cf);
cf = cframe_prev(cf);
frame = frame_prevd(frame);
break;
case FRAME_PCALL:
case FRAME_PCALLH:
if (frame_func(frame_prevd(frame))->c.ffid == FF_xpcall)
return savestack(L, frame_prevd(frame)+1); /* xpcall's errorfunc. */
return 0;
default:
lj_assertL(0, "bad frame type");
return 0;
}
}
return 0;
}
/* Runtime error. */
LJ_NOINLINE void LJ_FASTCALL lj_err_run(lua_State *L)
{
ptrdiff_t ef = (LJ_HASJIT && tvref(G(L)->jit_base)) ? 0 : finderrfunc(L);
if (ef) {
TValue *errfunc = restorestack(L, ef);
TValue *top = L->top;
lj_trace_abort(G(L));
if (!tvisfunc(errfunc) || L->status == LUA_ERRERR) {
setstrV(L, top-1, lj_err_str(L, LJ_ERR_ERRERR));
lj_err_throw(L, LUA_ERRERR);
}
L->status = LUA_ERRERR;
copyTV(L, top+LJ_FR2, top-1);
copyTV(L, top-1, errfunc);
if (LJ_FR2) setnilV(top++);
L->top = top+1;
lj_vm_call(L, top, 1+1); /* Stack: |errfunc|msg| -> |msg| */
}
lj_err_throw(L, LUA_ERRRUN);
}
#if LJ_HASJIT
LJ_NOINLINE void LJ_FASTCALL lj_err_trace(lua_State *L, int errcode)
{
if (errcode == LUA_ERRRUN)
lj_err_run(L);
else
lj_err_throw(L, errcode);
}
#endif
/* Formatted runtime error message. */
LJ_NORET LJ_NOINLINE static void err_msgv(lua_State *L, ErrMsg em, ...)
{
const char *msg;
va_list argp;
va_start(argp, em);
if (curr_funcisL(L)) L->top = curr_topL(L);
msg = lj_strfmt_pushvf(L, err2msg(em), argp);
va_end(argp);
lj_debug_addloc(L, msg, L->base-1, NULL);
lj_err_run(L);
}
/* Non-vararg variant for better calling conventions. */
LJ_NOINLINE void lj_err_msg(lua_State *L, ErrMsg em)
{
err_msgv(L, em);
}
/* Lexer error. */
LJ_NOINLINE void lj_err_lex(lua_State *L, GCstr *src, const char *tok,
BCLine line, ErrMsg em, va_list argp)
{
char buff[LUA_IDSIZE];
const char *msg;
lj_debug_shortname(buff, src, line);
msg = lj_strfmt_pushvf(L, err2msg(em), argp);
msg = lj_strfmt_pushf(L, "%s:%d: %s", buff, line, msg);
if (tok)
lj_strfmt_pushf(L, err2msg(LJ_ERR_XNEAR), msg, tok);
lj_err_throw(L, LUA_ERRSYNTAX);
}
/* Typecheck error for operands. */
LJ_NOINLINE void lj_err_optype(lua_State *L, cTValue *o, ErrMsg opm)
{
const char *tname = lj_typename(o);
const char *opname = err2msg(opm);
if (curr_funcisL(L)) {
GCproto *pt = curr_proto(L);
const BCIns *pc = cframe_Lpc(L) - 1;
const char *oname = NULL;
const char *kind = lj_debug_slotname(pt, pc, (BCReg)(o-L->base), &oname);
if (kind)
err_msgv(L, LJ_ERR_BADOPRT, opname, kind, oname, tname);
}
err_msgv(L, LJ_ERR_BADOPRV, opname, tname);
}
/* Typecheck error for ordered comparisons. */
LJ_NOINLINE void lj_err_comp(lua_State *L, cTValue *o1, cTValue *o2)
{
const char *t1 = lj_typename(o1);
const char *t2 = lj_typename(o2);
err_msgv(L, t1 == t2 ? LJ_ERR_BADCMPV : LJ_ERR_BADCMPT, t1, t2);
/* This assumes the two "boolean" entries are commoned by the C compiler. */
}
/* Typecheck error for __call. */
LJ_NOINLINE void lj_err_optype_call(lua_State *L, TValue *o)
{
/* Gross hack if lua_[p]call or pcall/xpcall fail for a non-callable object:
** L->base still points to the caller. So add a dummy frame with L instead
** of a function. See lua_getstack().
*/
const BCIns *pc = cframe_Lpc(L);
if (((ptrdiff_t)pc & FRAME_TYPE) != FRAME_LUA) {
const char *tname = lj_typename(o);
setframe_gc(o, obj2gco(L), LJ_TTHREAD);
if (LJ_FR2) o++;
setframe_pc(o, pc);
L->top = L->base = o+1;
err_msgv(L, LJ_ERR_BADCALL, tname);
}
lj_err_optype(L, o, LJ_ERR_OPCALL);
}
/* Error in context of caller. */
LJ_NOINLINE void lj_err_callermsg(lua_State *L, const char *msg)
{
TValue *frame = NULL, *pframe = NULL;
if (!(LJ_HASJIT && tvref(G(L)->jit_base))) {
frame = L->base-1;
if (frame_islua(frame)) {
pframe = frame_prevl(frame);
} else if (frame_iscont(frame)) {
if (frame_iscont_fficb(frame)) {
pframe = frame;
frame = NULL;
} else {
pframe = frame_prevd(frame);
#if LJ_HASFFI
/* Remove frame for FFI metamethods. */
if (frame_func(frame)->c.ffid >= FF_ffi_meta___index &&
frame_func(frame)->c.ffid <= FF_ffi_meta___tostring) {
L->base = pframe+1;
L->top = frame;
setcframe_pc(cframe_raw(L->cframe), frame_contpc(frame));
}
#endif
}
}
}
lj_debug_addloc(L, msg, pframe, frame);
lj_err_run(L);
}
/* Formatted error in context of caller. */
LJ_NOINLINE void lj_err_callerv(lua_State *L, ErrMsg em, ...)
{
const char *msg;
va_list argp;
va_start(argp, em);
msg = lj_strfmt_pushvf(L, err2msg(em), argp);
va_end(argp);
lj_err_callermsg(L, msg);
}
/* Error in context of caller. */
LJ_NOINLINE void lj_err_caller(lua_State *L, ErrMsg em)
{
lj_err_callermsg(L, err2msg(em));
}
/* Argument error message. */
LJ_NORET LJ_NOINLINE static void err_argmsg(lua_State *L, int narg,
const char *msg)
{
const char *fname = "?";
const char *ftype = lj_debug_funcname(L, L->base - 1, &fname);
if (narg < 0 && narg > LUA_REGISTRYINDEX)
narg = (int)(L->top - L->base) + narg + 1;
if (ftype && ftype[3] == 'h' && --narg == 0) /* Check for "method". */
msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADSELF), fname, msg);
else
msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADARG), narg, fname, msg);
lj_err_callermsg(L, msg);