6406081177

Committed 04 Oct 2023 12:37PM UTC coverage: 88.14% (-0.1%) from 88.236%

Build # 6406081177

Build Type

push

github

Committed by

fckxorg

Commit Message

Fix snapshot PC when linking to BC_JLOOP that was a BC_RET*.

Reported by Arseny Vakhrushev.
Fix contributed by Peter Cawley.

(cherry-picked from commit 5c46f4773)

As specified in the comment in `lj_record_stop`, all loops must
set `J->pc` to the next instruction. However, the chunk of logic
in `lj_trace_exit` expects it to be set to `BC_JLOOP` itself if
it used to be a `BC_RET`. This wrong pc results in the execution
of random data that goes after `BC_JLOOP` in the case of
restoration from the snapshot.

This patch fixes that behavior by adapting the loop recording
logic to this specific case.

NOTICE: This patch is only a part of the original commit,
and the other part is backported in the previous commit. The
patch was split into two, so the test case becomes easier to
implement since it can now depend on this assertion instead
of memory layout.

Maxim Kokryashkin:
* added the description and the test for the problem

Part of tarantool/tarantool#9145

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89.3

/src/lj_err.c

/*
** Error handling.
** Copyright (C) 2005-2017 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)
{
#if !LJ_TARGET_OSX
  /* Check disabled on MacOS due to brilliant software engineering at Apple. */
  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");
#endif
  /* 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);
  if (LJ_HASJIT) {
    TValue *base = tvref(G(L)->jit_base);
    if (base) L->base = base;
  }
  if (curr_funcisL(L)) L->top = curr_topL(L);
  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 (LJ_HASJIT) {
    TValue *base = tvref(G(L)->jit_base);
    if (base) L->base = base;
  }
  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 = L->base-1;
  TValue *pframe = NULL;
  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);
}

/* Formatted argument error. */
LJ_NOINLINE void lj_err_argv(lua_State *L, int narg, ErrMsg em, ...)
{
  const char *msg;
  va_list argp;
  va_start(argp, em);
  msg = lj_strfmt_pushvf(L, err2msg(em), argp);
  va_end(argp);
  err_argmsg(L, narg, msg);
}

/* Argument error. */
LJ_NOINLINE void lj_err_arg(lua_State *L, int narg, ErrMsg em)
{
  err_argmsg(L, narg, err2msg(em));
}

/* Typecheck error for arguments. */
LJ_NOINLINE void lj_err_argtype(lua_State *L, int narg, const char *xname)
{
  const char *tname, *msg;
  if (narg <= LUA_REGISTRYINDEX) {
    if (narg >= LUA_GLOBALSINDEX) {
      tname = lj_obj_itypename[~LJ_TTAB];
    } else {
      GCfunc *fn = curr_func(L);
      int idx = LUA_GLOBALSINDEX - narg;
      if (idx <= fn->c.nupvalues)
        tname = lj_typename(&fn->c.upvalue[idx-1]);
      else
        tname = lj_obj_typename[0];
    }
  } else {
    TValue *o = narg < 0 ? L->top + narg : L->base + narg-1;
    tname = o < L->top ? lj_typename(o) : lj_obj_typename[0];
  }
  msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADTYPE), xname, tname);
  err_argmsg(L, narg, msg);
}

/* Typecheck error for arguments. */
LJ_NOINLINE void lj_err_argt(lua_State *L, int narg, int tt)
{
  lj_err_argtype(L, narg, lj_obj_typename[tt+1]);
}

/* -- Public error handling API ------------------------------------------- */

LUA_API lua_CFunction lua_atpanic(lua_State *L, lua_CFunction panicf)
{
  lua_CFunction old = G(L)->panic;
  G(L)->panic = panicf;
  return old;
}

/* Forwarders for the public API (C calling convention and no LJ_NORET). */
LUA_API int lua_error(lua_State *L)
{
  lj_err_run(L);
  return 0;  /* unreachable */
}

LUALIB_API int luaL_argerror(lua_State *L, int narg, const char *msg)
{
  err_argmsg(L, narg, msg);
  return 0;  /* unreachable */
}

LUALIB_API int luaL_typerror(lua_State *L, int narg, const char *xname)
{
  lj_err_argtype(L, narg, xname);
  return 0;  /* unreachable */
}

LUALIB_API void luaL_where(lua_State *L, int level)
{
  int size;
  cTValue *frame = lj_debug_frame(L, level, &size);
  lj_debug_addloc(L, "", frame, size ? frame+size : NULL);
}

LUALIB_API int luaL_error(lua_State *L, const char *fmt, ...)
{
  const char *msg;
  va_list argp;
  va_start(argp, fmt);
  msg = lj_strfmt_pushvf(L, fmt, argp);
  va_end(argp);
  lj_err_callermsg(L, msg);
  return 0;  /* unreachable */
}


tarantool / luajit / 6406081177

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