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Cleanup and enable external unwinding for more platforms.

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This commit is contained in:
Mike Pall
2021-03-23 00:22:34 +01:00
parent ce9faf2e0d
commit e131936133
4 changed files with 197 additions and 190 deletions
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321
src/lj_err.c
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@@ -29,12 +29,18 @@
** Pros and Cons:
**
** - EXT requires unwind tables for *all* functions on the C stack between
** the pcall/catch and the error/throw. This is the default on x64,
** but needs to be manually enabled on x86/PPC for non-C++ code.
** 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).
** - 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
@@ -46,27 +52,33 @@
** the wrapper function feature. Lua errors thrown through C++ frames
** cannot be caught by C++ code and C++ destructors are not run.
**
** EXT is the default on x64 systems and on Windows, INT is the default on all
** other systems.
** 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
**
** EXT can be manually enabled on POSIX systems using GCC and DWARF2 stack
** unwinding with -DLUAJIT_UNWIND_EXTERNAL. *All* C code must be compiled
** with -funwind-tables (or -fexceptions). This includes LuaJIT itself (set
** TARGET_CFLAGS), all of your C/Lua binding code, all loadable C modules
** and all C libraries that have callbacks which may be used to call back
** into Lua. C++ code must *not* be compiled with -fno-exceptions.
** INT is the default on all other systems.
**
** EXT is mandatory on WIN64 since the calling convention has an abundance
** of callee-saved registers (rbx, rbp, rsi, rdi, r12-r15, xmm6-xmm15).
** The POSIX/x64 interpreter only saves r12/r13 for INT (e.g. PS4).
** 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.
*/
#if (defined(__GNUC__) || defined(__clang__)) && (LJ_TARGET_X64 || defined(LUAJIT_UNWIND_EXTERNAL)) && !LJ_NO_UNWIND
#define LJ_UNWIND_EXT 1
#elif LJ_TARGET_WINDOWS
#define LJ_UNWIND_EXT 1
#endif
/* -- Error messages ------------------------------------------------------ */
/* Error message strings. */
@@ -184,7 +196,125 @@ static void *err_unwind(lua_State *L, void *stopcf, int errcode)
/* -- External frame unwinding -------------------------------------------- */
#if (defined(__GNUC__) || defined(__clang__)) && !LJ_NO_UNWIND && !LJ_ABI_WIN
#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 */
}
/* Raise Windows exception. */
static void err_raise_ext(global_State *g, int errcode)
{
#if LJ_HASJIT
setmref(g->jit_base, NULL);
#endif
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,
@@ -233,7 +363,6 @@ LJ_FUNCA int lj_err_unwind_dwarf(int version, int actions,
lua_State *L;
if (version != 1)
return _URC_FATAL_PHASE1_ERROR;
UNUSED(uexclass);
cf = (void *)_Unwind_GetCFA(ctx);
L = cframe_L(cf);
if ((actions & _UA_SEARCH_PHASE)) {
@@ -281,6 +410,9 @@ LJ_FUNCA int lj_err_unwind_dwarf(int version, int actions,
** 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;
@@ -288,14 +420,6 @@ LJ_FUNCA int lj_err_unwind_dwarf(int version, int actions,
#if LJ_UNWIND_EXT
static __thread _Unwind_Exception static_uex;
/* Raise DWARF2 exception. */
static void err_raise_ext(int errcode)
{
static_uex.exclass = LJ_UEXCLASS_MAKE(errcode);
static_uex.excleanup = NULL;
_Unwind_RaiseException(&static_uex);
}
#endif
#else /* LJ_TARGET_ARM */
@@ -369,132 +493,22 @@ LJ_FUNCA int lj_err_unwind_arm(int state, _Unwind_Control_Block *ucb,
#if LJ_UNWIND_EXT
static __thread _Unwind_Control_Block static_uex;
#endif
#endif /* LJ_TARGET_ARM */
static void err_raise_ext(int errcode)
#if LJ_UNWIND_EXT
/* Raise external exception. */
static void err_raise_ext(global_State *g, int errcode)
{
#if LJ_HASJIT
setmref(g->jit_base, NULL);
#endif
memset(&static_uex, 0, sizeof(static_uex));
static_uex.exclass = LJ_UEXCLASS_MAKE(errcode);
_Unwind_RaiseException(&static_uex);
}
#endif
#endif /* LJ_TARGET_ARM */
#elif 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_X64
/* 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;
#else
typedef void *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_X64
void *cf = f;
#else
void *cf = (char *)f - CFRAME_OFS_SEH;
#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_WINDOWS
__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_X64
/* Unwind the stack and call all handlers for all lower C frames
** (including ourselves) again with EH_UNWINDING set. Then set
** rsp = cf, rax = 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. */
#else
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. */
#endif
}
}
return 1; /* ExceptionContinueSearch */
}
/* Raise Windows exception. */
static void err_raise_ext(int errcode)
{
RaiseException(LJ_EXCODE_MAKE(errcode), 1 /* EH_NONCONTINUABLE */, 0, NULL);
}
#endif
/* -- Error handling ------------------------------------------------------ */
@@ -504,22 +518,23 @@ LJ_NOINLINE void LJ_FASTCALL lj_err_throw(lua_State *L, int errcode)
{
global_State *g = G(L);
lj_trace_abort(g);
setmref(g->jit_base, NULL);
L->status = LUA_OK;
#if LJ_UNWIND_EXT
err_raise_ext(errcode);
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 should never happen on x64, but may happen if you've manually
** enabled LUAJIT_UNWIND_EXTERNAL and forgot to recompile *every*
** non-C++ file with -funwind-tables.
** 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))