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/* Exception handling and frame unwind runtime interface routines.
Copyright (C) 2001-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* @@@ Really this should be out of line, but this also causes link
compatibility problems with the base ABI. This is slightly better
than duplicating code, however. */
/* If using C++, references to abort have to be qualified with std::. */
#if __cplusplus
#define __gxx_abort std::abort
#else
#define __gxx_abort abort
#endif
/* Pointer encodings, from dwarf2.h. */
#define DW_EH_PE_absptr 0x00
#define DW_EH_PE_omit 0xff
#define DW_EH_PE_uleb128 0x01
#define DW_EH_PE_udata2 0x02
#define DW_EH_PE_udata4 0x03
#define DW_EH_PE_udata8 0x04
#define DW_EH_PE_sleb128 0x09
#define DW_EH_PE_sdata2 0x0A
#define DW_EH_PE_sdata4 0x0B
#define DW_EH_PE_sdata8 0x0C
#define DW_EH_PE_signed 0x08
#define DW_EH_PE_pcrel 0x10
#define DW_EH_PE_textrel 0x20
#define DW_EH_PE_datarel 0x30
#define DW_EH_PE_funcrel 0x40
#define DW_EH_PE_aligned 0x50
#define DW_EH_PE_indirect 0x80
#if defined(_LIBC)
/* Prototypes. */
extern unsigned int size_of_encoded_value (unsigned char encoding)
attribute_hidden;
extern const unsigned char *read_encoded_value_with_base
(unsigned char encoding, _Unwind_Ptr base,
const unsigned char *p, _Unwind_Ptr *val)
attribute_hidden;
extern const unsigned char * read_encoded_value
(struct _Unwind_Context *context, unsigned char encoding,
const unsigned char *p, _Unwind_Ptr *val)
attribute_hidden;
extern const unsigned char * read_uleb128 (const unsigned char *p,
_Unwind_Word *val)
attribute_hidden;
extern const unsigned char * read_sleb128 (const unsigned char *p,
_Unwind_Sword *val)
attribute_hidden;
#endif
#if defined(_LIBC) && defined(_LIBC_DEFINITIONS)
#ifdef _LIBC
#define STATIC
#else
#define STATIC static
#endif
/* Given an encoding, return the number of bytes the format occupies.
This is only defined for fixed-size encodings, and so does not
include leb128. */
STATIC unsigned int
size_of_encoded_value (unsigned char encoding)
{
if (encoding == DW_EH_PE_omit)
return 0;
switch (encoding & 0x07)
{
case DW_EH_PE_absptr:
return sizeof (void *);
case DW_EH_PE_udata2:
return 2;
case DW_EH_PE_udata4:
return 4;
case DW_EH_PE_udata8:
return 8;
}
__gxx_abort ();
}
#ifndef NO_BASE_OF_ENCODED_VALUE
/* Given an encoding and an _Unwind_Context, return the base to which
the encoding is relative. This base may then be passed to
read_encoded_value_with_base for use when the _Unwind_Context is
not available. */
STATIC _Unwind_Ptr
base_of_encoded_value (unsigned char encoding, struct _Unwind_Context *context)
{
if (encoding == DW_EH_PE_omit)
return 0;
switch (encoding & 0x70)
{
case DW_EH_PE_absptr:
case DW_EH_PE_pcrel:
case DW_EH_PE_aligned:
return 0;
case DW_EH_PE_textrel:
return _Unwind_GetTextRelBase (context);
case DW_EH_PE_datarel:
return _Unwind_GetDataRelBase (context);
case DW_EH_PE_funcrel:
return _Unwind_GetRegionStart (context);
}
__gxx_abort ();
}
#endif
/* Read an unsigned leb128 value from P, store the value in VAL, return
P incremented past the value. We assume that a word is large enough to
hold any value so encoded; if it is smaller than a pointer on some target,
pointers should not be leb128 encoded on that target. */
STATIC const unsigned char *
read_uleb128 (const unsigned char *p, _Unwind_Word *val)
{
unsigned int shift = 0;
unsigned char byte;
_Unwind_Word result;
result = 0;
do
{
byte = *p++;
result |= (byte & 0x7f) << shift;
shift += 7;
}
while (byte & 0x80);
*val = result;
return p;
}
/* Similar, but read a signed leb128 value. */
STATIC const unsigned char *
read_sleb128 (const unsigned char *p, _Unwind_Sword *val)
{
unsigned int shift = 0;
unsigned char byte;
_Unwind_Word result;
result = 0;
do
{
byte = *p++;
result |= (byte & 0x7f) << shift;
shift += 7;
}
while (byte & 0x80);
/* Sign-extend a negative value. */
if (shift < 8 * sizeof(result) && (byte & 0x40) != 0)
result |= -(1L << shift);
*val = (_Unwind_Sword) result;
return p;
}
/* Load an encoded value from memory at P. The value is returned in VAL;
The function returns P incremented past the value. BASE is as given
by base_of_encoded_value for this encoding in the appropriate context. */
STATIC const unsigned char *
read_encoded_value_with_base (unsigned char encoding, _Unwind_Ptr base,
const unsigned char *p, _Unwind_Ptr *val)
{
union unaligned
{
void *ptr;
unsigned u2 __attribute__ ((mode (HI)));
unsigned u4 __attribute__ ((mode (SI)));
unsigned u8 __attribute__ ((mode (DI)));
signed s2 __attribute__ ((mode (HI)));
signed s4 __attribute__ ((mode (SI)));
signed s8 __attribute__ ((mode (DI)));
} __attribute__((__packed__));
union unaligned *u = (union unaligned *) p;
_Unwind_Internal_Ptr result;
if (encoding == DW_EH_PE_aligned)
{
_Unwind_Internal_Ptr a = (_Unwind_Internal_Ptr) p;
a = (a + sizeof (void *) - 1) & - sizeof(void *);
result = *(_Unwind_Internal_Ptr *) a;
p = (const unsigned char *) (a + sizeof (void *));
}
else
{
switch (encoding & 0x0f)
{
case DW_EH_PE_absptr:
result = (_Unwind_Internal_Ptr) u->ptr;
p += sizeof (void *);
break;
case DW_EH_PE_uleb128:
{
_Unwind_Word tmp;
p = read_uleb128 (p, &tmp);
result = (_Unwind_Internal_Ptr) tmp;
}
break;
case DW_EH_PE_sleb128:
{
_Unwind_Sword tmp;
p = read_sleb128 (p, &tmp);
result = (_Unwind_Internal_Ptr) tmp;
}
break;
case DW_EH_PE_udata2:
result = u->u2;
p += 2;
break;
case DW_EH_PE_udata4:
result = u->u4;
p += 4;
break;
case DW_EH_PE_udata8:
result = u->u8;
p += 8;
break;
case DW_EH_PE_sdata2:
result = u->s2;
p += 2;
break;
case DW_EH_PE_sdata4:
result = u->s4;
p += 4;
break;
case DW_EH_PE_sdata8:
result = u->s8;
p += 8;
break;
default:
__gxx_abort ();
}
if (result != 0)
{
result += ((encoding & 0x70) == DW_EH_PE_pcrel
? (_Unwind_Internal_Ptr) u : base);
if (encoding & DW_EH_PE_indirect)
result = *(_Unwind_Internal_Ptr *) result;
}
}
*val = result;
return p;
}
#ifndef NO_BASE_OF_ENCODED_VALUE
/* Like read_encoded_value_with_base, but get the base from the context
rather than providing it directly. */
STATIC const unsigned char *
read_encoded_value (struct _Unwind_Context *context, unsigned char encoding,
const unsigned char *p, _Unwind_Ptr *val)
{
return read_encoded_value_with_base (encoding,
base_of_encoded_value (encoding, context),
p, val);
}
#endif
#endif /* _LIBC */
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