600 lines
16 KiB
C++
600 lines
16 KiB
C++
// -*- C++ -*- The GNU C++ exception personality routine.
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// Copyright (C) 2001 Free Software Foundation, Inc.
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//
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// This file is part of GNU CC.
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//
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// GNU CC is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2, or (at your option)
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// any later version.
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//
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// GNU CC is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with GNU CC; see the file COPYING. If not, write to
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// the Free Software Foundation, 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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#include <bits/c++config.h>
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#include <cstdlib>
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#include "unwind-cxx.h"
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using namespace __cxxabiv1;
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// ??? These ought to go somewhere else dwarf2 or dwarf2eh related.
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// Pointer encodings.
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#define DW_EH_PE_absptr 0x00
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#define DW_EH_PE_omit 0xff
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#define DW_EH_PE_uleb128 0x01
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#define DW_EH_PE_udata2 0x02
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#define DW_EH_PE_udata4 0x03
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#define DW_EH_PE_udata8 0x04
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#define DW_EH_PE_sleb128 0x09
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#define DW_EH_PE_sdata2 0x0A
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#define DW_EH_PE_sdata4 0x0B
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#define DW_EH_PE_sdata8 0x0C
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#define DW_EH_PE_signed 0x08
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#define DW_EH_PE_pcrel 0x10
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#define DW_EH_PE_textrel 0x20
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#define DW_EH_PE_datarel 0x30
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#define DW_EH_PE_funcrel 0x40
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static unsigned int
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size_of_encoded_value (unsigned char encoding)
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{
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switch (encoding & 0x07)
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{
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case DW_EH_PE_absptr:
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return sizeof (void *);
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case DW_EH_PE_udata2:
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return 2;
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case DW_EH_PE_udata4:
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return 4;
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case DW_EH_PE_udata8:
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return 8;
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}
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abort ();
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}
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static const unsigned char *
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read_encoded_value (_Unwind_Context *context, unsigned char encoding,
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const unsigned char *p, _Unwind_Ptr *val)
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{
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union unaligned
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{
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void *ptr;
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unsigned u2 __attribute__ ((mode (HI)));
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unsigned u4 __attribute__ ((mode (SI)));
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unsigned u8 __attribute__ ((mode (DI)));
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signed s2 __attribute__ ((mode (HI)));
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signed s4 __attribute__ ((mode (SI)));
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signed s8 __attribute__ ((mode (DI)));
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} __attribute__((__packed__));
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union unaligned *u = (union unaligned *) p;
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_Unwind_Ptr result;
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switch (encoding & 0x0f)
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{
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case DW_EH_PE_absptr:
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result = (_Unwind_Ptr) u->ptr;
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p += sizeof (void *);
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break;
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case DW_EH_PE_uleb128:
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{
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unsigned int shift = 0;
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unsigned char byte;
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result = 0;
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do
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{
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byte = *p++;
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result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
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shift += 7;
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}
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while (byte & 0x80);
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}
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break;
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case DW_EH_PE_sleb128:
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{
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unsigned int shift = 0;
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unsigned char byte;
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result = 0;
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do
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{
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byte = *p++;
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result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
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shift += 7;
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}
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while (byte & 0x80);
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if (shift < 8 * sizeof(result) && (byte & 0x40) != 0)
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result |= -(1L << shift);
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}
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break;
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case DW_EH_PE_udata2:
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result = u->u2;
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p += 2;
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break;
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case DW_EH_PE_udata4:
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result = u->u4;
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p += 4;
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break;
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case DW_EH_PE_udata8:
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result = u->u8;
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p += 8;
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break;
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case DW_EH_PE_sdata2:
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result = u->s2;
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p += 2;
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break;
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case DW_EH_PE_sdata4:
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result = u->s4;
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p += 4;
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break;
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case DW_EH_PE_sdata8:
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result = u->s8;
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p += 8;
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break;
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default:
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abort ();
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}
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if (result != 0)
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switch (encoding & 0xf0)
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{
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case DW_EH_PE_absptr:
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break;
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case DW_EH_PE_pcrel:
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// Define as relative to the beginning of the pointer.
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result += (_Unwind_Ptr) u;
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break;
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case DW_EH_PE_textrel:
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case DW_EH_PE_datarel:
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// FIXME.
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abort ();
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case DW_EH_PE_funcrel:
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result += _Unwind_GetRegionStart (context);
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break;
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default:
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abort ();
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}
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*val = result;
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return p;
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}
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static inline const unsigned char *
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read_uleb128 (const unsigned char *p, _Unwind_Ptr *val)
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{
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return read_encoded_value (0, DW_EH_PE_uleb128, p, val);
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}
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static inline const unsigned char *
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read_sleb128 (const unsigned char *p, _Unwind_Ptr *val)
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{
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return read_encoded_value (0, DW_EH_PE_sleb128, p, val);
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}
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struct lsda_header_info
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{
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_Unwind_Ptr Start;
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_Unwind_Ptr LPStart;
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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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};
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static const unsigned char *
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parse_lsda_header (_Unwind_Context *context, const unsigned char *p,
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lsda_header_info *info)
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{
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_Unwind_Ptr 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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static const std::type_info *
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get_ttype_entry (_Unwind_Context *context, lsda_header_info *info, long i)
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{
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_Unwind_Ptr ptr;
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i *= size_of_encoded_value (info->ttype_encoding);
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read_encoded_value (context, info->ttype_encoding, info->TType - i, &ptr);
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return reinterpret_cast<const std::type_info *>(ptr);
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}
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static bool
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check_exception_spec (_Unwind_Context *context, lsda_header_info *info,
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const std::type_info *throw_type, long filter_value)
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{
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const unsigned char *e = info->TType - filter_value - 1;
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while (1)
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{
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const std::type_info *catch_type;
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_Unwind_Ptr tmp;
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void *dummy;
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e = read_uleb128 (e, &tmp);
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// Zero signals the end of the list. If we've not found
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// a match by now, then we've failed the specification.
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if (tmp == 0)
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return false;
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// Match a ttype entry.
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catch_type = get_ttype_entry (context, info, tmp);
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if (catch_type->__do_catch (throw_type, &dummy, 1))
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return true;
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}
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}
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// Using a different personality function name causes link failures
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// when trying to mix code using different exception handling models.
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#ifdef _GLIBCPP_SJLJ_EXCEPTIONS
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#define PERSONALITY_FUNCTION __gxx_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 __gxx_personality_v0
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#endif
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extern "C" _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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{
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__cxa_exception *xh = __get_exception_header_from_ue (ue_header);
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enum found_handler_type
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{
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found_nothing,
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found_terminate,
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found_cleanup,
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found_handler
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} found_type;
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lsda_header_info info;
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const unsigned char *language_specific_data;
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const unsigned char *action_record;
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const unsigned char *p;
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_Unwind_Ptr landing_pad, ip;
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int handler_switch_value;
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void *adjusted_ptr = xh + 1;
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// Interface version check.
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if (version != 1)
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return _URC_FATAL_PHASE1_ERROR;
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// Shortcut for phase 2 found handler for domestic exception.
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if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME)
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&& exception_class == __gxx_exception_class)
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{
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handler_switch_value = xh->handlerSwitchValue;
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landing_pad = (_Unwind_Ptr) xh->catchTemp;
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found_type = (landing_pad == 0 ? found_terminate : found_handler);
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goto install_context;
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}
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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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return _URC_CONTINUE_UNWIND;
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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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ip = _Unwind_GetIP (context) - 1;
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landing_pad = 0;
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action_record = 0;
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handler_switch_value = 0;
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#ifdef _GLIBCPP_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 if (ip == 0)
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{
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// Fall through to set found_terminate.
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}
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else
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{
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_Unwind_Ptr 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 = 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, 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 // _GLIBCPP_SJLJ_EXCEPTIONS
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// If ip is not present in the table, call terminate. This is for
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// a destructor inside a cleanup, or a library routine the compiler
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// was not expecting to throw.
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found_type = (actions & _UA_FORCE_UNWIND ? found_nothing : found_terminate);
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goto do_something;
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found_something:
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if (landing_pad == 0)
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{
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// If ip is present, and has a null landing pad, there are
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// no cleanups or handlers to be run.
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found_type = found_nothing;
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}
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else if (action_record == 0)
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{
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// If ip is present, has a non-null landing pad, and a null
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// action table offset, then there are only cleanups present.
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// Cleanups use a zero switch value, as set above.
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found_type = found_cleanup;
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}
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else
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{
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// Otherwise we have a catch handler or exception specification.
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signed long ar_filter, ar_disp;
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const std::type_info *throw_type, *catch_type;
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bool saw_cleanup = false;
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bool saw_handler = false;
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// During forced unwinding, we only run cleanups. With a foreign
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// exception class, there's no exception type.
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// ??? What to do about GNU Java and GNU Ada exceptions.
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if ((actions & _UA_FORCE_UNWIND)
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|| exception_class != __gxx_exception_class)
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throw_type = 0;
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else
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throw_type = xh->exceptionType;
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while (1)
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{
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_Unwind_Ptr tmp;
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p = action_record;
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p = read_sleb128 (p, &tmp); ar_filter = tmp;
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read_sleb128 (p, &tmp); ar_disp = tmp;
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if (ar_filter == 0)
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{
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// Zero filter values are cleanups.
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saw_cleanup = true;
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}
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else if (ar_filter > 0)
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{
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// Positive filter values are handlers.
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catch_type = get_ttype_entry (context, &info, ar_filter);
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adjusted_ptr = xh + 1;
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// Null catch type is a catch-all handler. We can catch
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// foreign exceptions with this.
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if (! catch_type)
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{
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if (!(actions & _UA_FORCE_UNWIND))
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{
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saw_handler = true;
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break;
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}
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}
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else if (throw_type)
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{
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// Pointer types need to adjust the actual pointer, not
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// the pointer to pointer that is the exception object.
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// This also has the effect of passing pointer types
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// "by value" through the __cxa_begin_catch return value.
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if (throw_type->__is_pointer_p ())
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adjusted_ptr = *(void **) adjusted_ptr;
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if (catch_type->__do_catch (throw_type, &adjusted_ptr, 1))
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{
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saw_handler = true;
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break;
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}
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}
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}
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else
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{
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// Negative filter values are exception specifications.
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// ??? How do foreign exceptions fit in? As far as I can
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// see we can't match because there's no __cxa_exception
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// object to stuff bits in for __cxa_call_unexpected to use.
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if (throw_type
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&& ! check_exception_spec (context, &info, throw_type,
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ar_filter))
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{
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saw_handler = true;
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break;
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}
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}
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if (ar_disp == 0)
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break;
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action_record = p + ar_disp;
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}
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if (saw_handler)
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{
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handler_switch_value = ar_filter;
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found_type = found_handler;
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}
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else
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found_type = (saw_cleanup ? found_cleanup : found_nothing);
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}
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do_something:
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if (found_type == found_nothing)
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return _URC_CONTINUE_UNWIND;
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if (actions & _UA_SEARCH_PHASE)
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{
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if (found_type == found_cleanup)
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return _URC_CONTINUE_UNWIND;
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// For domestic exceptions, we cache data from phase 1 for phase 2.
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if (exception_class == __gxx_exception_class)
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{
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xh->handlerSwitchValue = handler_switch_value;
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xh->actionRecord = action_record;
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xh->languageSpecificData = language_specific_data;
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xh->adjustedPtr = adjusted_ptr;
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// ??? Completely unknown what this field is supposed to be for.
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// ??? Need to cache TType encoding base for call_unexpected.
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xh->catchTemp = (void *) (_Unwind_Ptr) landing_pad;
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}
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return _URC_HANDLER_FOUND;
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}
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|
||
install_context:
|
||
if (found_type == found_terminate)
|
||
{
|
||
__cxa_begin_catch (&xh->unwindHeader);
|
||
__terminate (xh->terminateHandler);
|
||
}
|
||
|
||
_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
|
||
(_Unwind_Ptr) &xh->unwindHeader);
|
||
_Unwind_SetGR (context, __builtin_eh_return_data_regno (1),
|
||
handler_switch_value);
|
||
_Unwind_SetIP (context, landing_pad);
|
||
return _URC_INSTALL_CONTEXT;
|
||
}
|
||
|
||
extern "C" void
|
||
__cxa_call_unexpected (_Unwind_Exception *exc_obj)
|
||
{
|
||
__cxa_begin_catch (exc_obj);
|
||
|
||
// This function is a handler for our exception argument. If we exit
|
||
// by throwing a different exception, we'll need the original cleaned up.
|
||
struct end_catch_protect
|
||
{
|
||
end_catch_protect() { }
|
||
~end_catch_protect() { __cxa_end_catch(); }
|
||
} end_catch_protect_obj;
|
||
|
||
__cxa_exception *xh = __get_exception_header_from_ue (exc_obj);
|
||
|
||
try {
|
||
__unexpected (xh->unexpectedHandler);
|
||
} catch (...) {
|
||
// Get the exception thrown from unexpected.
|
||
// ??? Foreign exceptions can't be stacked this way.
|
||
|
||
__cxa_eh_globals *globals = __cxa_get_globals_fast ();
|
||
__cxa_exception *new_xh = globals->caughtExceptions;
|
||
|
||
// We don't quite have enough stuff cached; re-parse the LSDA.
|
||
lsda_header_info info;
|
||
parse_lsda_header (0, xh->languageSpecificData, &info);
|
||
|
||
// If this new exception meets the exception spec, allow it.
|
||
if (check_exception_spec (0, &info, new_xh->exceptionType,
|
||
xh->handlerSwitchValue))
|
||
throw;
|
||
|
||
// If the exception spec allows std::bad_exception, throw that.
|
||
const std::type_info &bad_exc = typeid (std::bad_exception);
|
||
if (check_exception_spec (0, &info, &bad_exc, xh->handlerSwitchValue))
|
||
throw std::bad_exception ();
|
||
|
||
// Otherwise, die.
|
||
__terminate(xh->terminateHandler);
|
||
}
|
||
}
|