9d1e3afb54
The actual stack unwind code is still in C, but the rest of the code,
notably all the memory allocation, is now in Go. The names are changed
to the names used in the Go 1.7 runtime, but the code is necessarily
somewhat different.
The __go_makefunc_can_recover function is dropped, as the uses of it
were removed in https://golang.org/cl/198770044.
Reviewed-on: https://go-review.googlesource.com/33414
From-SVN: r242715
372 lines
9.9 KiB
C
372 lines
9.9 KiB
C
/* go-unwind.c -- unwind the stack for panic/recover.
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Copyright 2010 The Go Authors. All rights reserved.
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Use of this source code is governed by a BSD-style
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license that can be found in the LICENSE file. */
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#include "config.h"
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#include <stdlib.h>
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#include <unistd.h>
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#include "unwind.h"
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#define NO_SIZE_OF_ENCODED_VALUE
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#include "unwind-pe.h"
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#include "runtime.h"
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#include "go-alloc.h"
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/* The code for a Go exception. */
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#ifdef __ARM_EABI_UNWINDER__
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static const _Unwind_Exception_Class __go_exception_class =
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{ 'G', 'N', 'U', 'C', 'G', 'O', '\0', '\0' };
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#else
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static const _Unwind_Exception_Class __go_exception_class =
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((((((((_Unwind_Exception_Class) 'G'
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<< 8 | (_Unwind_Exception_Class) 'N')
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<< 8 | (_Unwind_Exception_Class) 'U')
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<< 8 | (_Unwind_Exception_Class) 'C')
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<< 8 | (_Unwind_Exception_Class) 'G')
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<< 8 | (_Unwind_Exception_Class) 'O')
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<< 8 | (_Unwind_Exception_Class) '\0')
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<< 8 | (_Unwind_Exception_Class) '\0');
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#endif
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/* Rethrow an exception. */
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void rethrowException (void) __asm__(GOSYM_PREFIX "runtime.rethrowException");
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void
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rethrowException ()
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{
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struct _Unwind_Exception *hdr;
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hdr = (struct _Unwind_Exception *) runtime_g()->exception;
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#ifdef __USING_SJLJ_EXCEPTIONS__
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_Unwind_SjLj_Resume_or_Rethrow (hdr);
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#else
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#if defined(_LIBUNWIND_STD_ABI)
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_Unwind_RaiseException (hdr);
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#else
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_Unwind_Resume_or_Rethrow (hdr);
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#endif
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#endif
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/* Rethrowing the exception should not return. */
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abort();
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}
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/* Return the size of the type that holds an exception header, so that
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it can be allocated by Go code. */
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uintptr unwindExceptionSize(void)
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__asm__ (GOSYM_PREFIX "runtime.unwindExceptionSize");
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uintptr
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unwindExceptionSize ()
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{
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uintptr ret, align;
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ret = sizeof (struct _Unwind_Exception);
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/* Adjust the size fo make sure that we can get an aligned value. */
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align = __alignof__ (struct _Unwind_Exception);
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if (align > __alignof__ (uintptr))
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ret += align - __alignof__ (uintptr);
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return ret;
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}
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/* Throw an exception. This is called with g->exception pointing to
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an uninitialized _Unwind_Exception instance. */
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void throwException (void) __asm__(GOSYM_PREFIX "runtime.throwException");
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void
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throwException ()
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{
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struct _Unwind_Exception *hdr;
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uintptr align;
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hdr = (struct _Unwind_Exception *)runtime_g ()->exception;
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/* Make sure the value is correctly aligned. It will be large
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enough, because of unwindExceptionSize. */
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align = __alignof__ (struct _Unwind_Exception);
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hdr = ((struct _Unwind_Exception *)
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(((uintptr) hdr + align - 1) &~ (align - 1)));
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__builtin_memcpy (&hdr->exception_class, &__go_exception_class,
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sizeof hdr->exception_class);
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hdr->exception_cleanup = NULL;
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#ifdef __USING_SJLJ_EXCEPTIONS__
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_Unwind_SjLj_RaiseException (hdr);
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#else
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_Unwind_RaiseException (hdr);
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#endif
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/* Raising an exception should not return. */
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abort ();
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}
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/* The rest of this code is really similar to gcc/unwind-c.c and
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libjava/exception.cc. */
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typedef struct
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{
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_Unwind_Ptr Start;
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_Unwind_Ptr LPStart;
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_Unwind_Ptr ttype_base;
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const unsigned char *TType;
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const unsigned char *action_table;
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unsigned char ttype_encoding;
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unsigned char call_site_encoding;
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} lsda_header_info;
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static const unsigned char *
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parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p,
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lsda_header_info *info)
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{
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_uleb128_t tmp;
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unsigned char lpstart_encoding;
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info->Start = (context ? _Unwind_GetRegionStart (context) : 0);
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/* Find @LPStart, the base to which landing pad offsets are relative. */
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lpstart_encoding = *p++;
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if (lpstart_encoding != DW_EH_PE_omit)
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p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart);
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else
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info->LPStart = info->Start;
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/* Find @TType, the base of the handler and exception spec type data. */
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info->ttype_encoding = *p++;
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if (info->ttype_encoding != DW_EH_PE_omit)
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{
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p = read_uleb128 (p, &tmp);
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info->TType = p + tmp;
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}
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else
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info->TType = 0;
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/* The encoding and length of the call-site table; the action table
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immediately follows. */
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info->call_site_encoding = *p++;
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p = read_uleb128 (p, &tmp);
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info->action_table = p + tmp;
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return p;
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}
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/* The personality function is invoked when unwinding the stack due to
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a panic. Its job is to find the cleanup and exception handlers to
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run. We can't split the stack here, because we won't be able to
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unwind from that split. */
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#ifdef __ARM_EABI_UNWINDER__
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/* ARM EABI personality routines must also unwind the stack. */
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#define CONTINUE_UNWINDING \
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do \
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{ \
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if (__gnu_unwind_frame (ue_header, context) != _URC_OK) \
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return _URC_FAILURE; \
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return _URC_CONTINUE_UNWIND; \
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} \
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while (0)
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#else
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#define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND
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#endif
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#ifdef __USING_SJLJ_EXCEPTIONS__
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#define PERSONALITY_FUNCTION __gccgo_personality_sj0
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#define __builtin_eh_return_data_regno(x) x
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#else
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#define PERSONALITY_FUNCTION __gccgo_personality_v0
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#endif
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#ifdef __ARM_EABI_UNWINDER__
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_Unwind_Reason_Code
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PERSONALITY_FUNCTION (_Unwind_State, struct _Unwind_Exception *,
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struct _Unwind_Context *)
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__attribute__ ((no_split_stack, flatten));
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_Unwind_Reason_Code
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PERSONALITY_FUNCTION (_Unwind_State state,
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struct _Unwind_Exception * ue_header,
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struct _Unwind_Context * context)
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#else
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_Unwind_Reason_Code
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PERSONALITY_FUNCTION (int, _Unwind_Action, _Unwind_Exception_Class,
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struct _Unwind_Exception *, struct _Unwind_Context *)
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__attribute__ ((no_split_stack, flatten));
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_Unwind_Reason_Code
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PERSONALITY_FUNCTION (int version,
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_Unwind_Action actions,
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_Unwind_Exception_Class exception_class,
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struct _Unwind_Exception *ue_header,
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struct _Unwind_Context *context)
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#endif
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{
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lsda_header_info info;
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const unsigned char *language_specific_data, *p, *action_record;
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_Unwind_Ptr landing_pad, ip;
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int ip_before_insn = 0;
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_Bool is_foreign;
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G *g;
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#ifdef __ARM_EABI_UNWINDER__
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_Unwind_Action actions;
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switch (state & _US_ACTION_MASK)
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{
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case _US_VIRTUAL_UNWIND_FRAME:
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actions = _UA_SEARCH_PHASE;
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break;
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case _US_UNWIND_FRAME_STARTING:
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actions = _UA_CLEANUP_PHASE;
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if (!(state & _US_FORCE_UNWIND)
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&& ue_header->barrier_cache.sp == _Unwind_GetGR(context, 13))
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actions |= _UA_HANDLER_FRAME;
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break;
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case _US_UNWIND_FRAME_RESUME:
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CONTINUE_UNWINDING;
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break;
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default:
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abort();
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}
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actions |= state & _US_FORCE_UNWIND;
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is_foreign = 0;
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/* The dwarf unwinder assumes the context structure holds things like the
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function and LSDA pointers. The ARM implementation caches these in
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the exception header (UCB). To avoid rewriting everything we make the
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virtual IP register point at the UCB. */
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ip = (_Unwind_Ptr) ue_header;
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_Unwind_SetGR (context, 12, ip);
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#else
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if (version != 1)
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return _URC_FATAL_PHASE1_ERROR;
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is_foreign = exception_class != __go_exception_class;
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#endif
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language_specific_data = (const unsigned char *)
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_Unwind_GetLanguageSpecificData (context);
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/* If no LSDA, then there are no handlers or cleanups. */
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if (! language_specific_data)
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CONTINUE_UNWINDING;
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/* Parse the LSDA header. */
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p = parse_lsda_header (context, language_specific_data, &info);
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#ifdef HAVE_GETIPINFO
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ip = _Unwind_GetIPInfo (context, &ip_before_insn);
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#else
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ip = _Unwind_GetIP (context);
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#endif
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if (! ip_before_insn)
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--ip;
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landing_pad = 0;
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action_record = NULL;
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#ifdef __USING_SJLJ_EXCEPTIONS__
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/* The given "IP" is an index into the call-site table, with two
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exceptions -- -1 means no-action, and 0 means terminate. But
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since we're using uleb128 values, we've not got random access
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to the array. */
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if ((int) ip <= 0)
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return _URC_CONTINUE_UNWIND;
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else
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{
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_uleb128_t cs_lp, cs_action;
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do
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{
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p = read_uleb128 (p, &cs_lp);
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p = read_uleb128 (p, &cs_action);
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}
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while (--ip);
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/* Can never have null landing pad for sjlj -- that would have
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been indicated by a -1 call site index. */
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landing_pad = (_Unwind_Ptr)cs_lp + 1;
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if (cs_action)
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action_record = info.action_table + cs_action - 1;
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goto found_something;
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}
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#else
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/* Search the call-site table for the action associated with this IP. */
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while (p < info.action_table)
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{
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_Unwind_Ptr cs_start, cs_len, cs_lp;
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_uleb128_t cs_action;
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/* Note that all call-site encodings are "absolute" displacements. */
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p = read_encoded_value (0, info.call_site_encoding, p, &cs_start);
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p = read_encoded_value (0, info.call_site_encoding, p, &cs_len);
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p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp);
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p = read_uleb128 (p, &cs_action);
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/* The table is sorted, so if we've passed the ip, stop. */
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if (ip < info.Start + cs_start)
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p = info.action_table;
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else if (ip < info.Start + cs_start + cs_len)
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{
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if (cs_lp)
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landing_pad = info.LPStart + cs_lp;
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if (cs_action)
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action_record = info.action_table + cs_action - 1;
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goto found_something;
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}
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}
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#endif
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/* IP is not in table. No associated cleanups. */
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CONTINUE_UNWINDING;
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found_something:
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if (landing_pad == 0)
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{
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/* IP is present, but has a null landing pad.
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No handler to be run. */
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CONTINUE_UNWINDING;
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}
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if (actions & _UA_SEARCH_PHASE)
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{
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if (action_record == 0)
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{
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/* This indicates a cleanup rather than an exception
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handler. */
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CONTINUE_UNWINDING;
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}
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return _URC_HANDLER_FOUND;
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}
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/* It's possible for g to be NULL here for an exception thrown by a
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language other than Go. */
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g = runtime_g ();
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if (g == NULL)
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{
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if (!is_foreign)
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abort ();
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}
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else
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{
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g->exception = ue_header;
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g->isforeign = is_foreign;
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}
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_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
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(_Unwind_Ptr) ue_header);
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_Unwind_SetGR (context, __builtin_eh_return_data_regno (1), 0);
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_Unwind_SetIP (context, landing_pad);
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return _URC_INSTALL_CONTEXT;
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}
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