binutils-gdb/elfcpp/elfcpp_swap.h
Nick Alcock e755667f94 libctf, elfcpp, gold: do not assume that <byteswap.h> contains bswap_*
At least one C library (uclibc-ng) defines some of these only when
the compiler is GCC.  We might as well test for all three cases and
handle any of them being missing.

Very similar code exists in libctf and split between elfcpp and gold:
fix both.

(Also sync up elfcpp with a change made to libctf swap.h a few months
ago: since there is no out-of-line definition of the bswap replacements,
they should be declared static inline, not just inline, to prevent the
linker generating out-of-line references to them.)

	PR libctf/25120
libctf/
	* configure.ac: Check for bswap_16, bswap_32, and bswap_64 decls.
	* swap.h (bswap_16): Do not assume that presence of <byteswap.h>
	means this is declared.
	(bswap_32): Likewise.
	(bswap_64): Likewise.
	(bswap_identity_64): Remove, unused.
	* configure: Regenerated.
	* config.h.in: Likewise.
gold/
	* configure.ac: Check for bswap_16, bswap_32, and bswap_64 decls.
	* configure: Regenerated.
	* config.h.in: Likewise.
elfcpp/
	* elfcpp_swap.h (bswap_16): Do not assume that presence of
	<byteswap.h> means this is declared.  Make static inline, matching
	recent change to libctf, since there is no non-inline definition
	of these functions.
	(bswap_32): Likewise.
	(bswap_64): Likewise.
2020-06-26 15:56:39 +01:00

507 lines
12 KiB
C++

// elfcpp_swap.h -- Handle swapping for elfcpp -*- C++ -*-
// Copyright (C) 2006-2020 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of elfcpp.
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public License
// as published by the Free Software Foundation; either version 2, or
// (at your option) any later version.
// In addition to the permissions in the GNU Library General Public
// License, the Free Software Foundation gives you unlimited
// permission to link the compiled version of this file into
// combinations with other programs, and to distribute those
// combinations without any restriction coming from the use of this
// file. (The Library Public License restrictions do apply in other
// respects; for example, they cover modification of the file, and
/// distribution when not linked into a combined executable.)
// This program 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
// Library General Public License for more details.
// You should have received a copy of the GNU Library General Public
// License along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
// 02110-1301, USA.
// This header file defines basic template classes to efficiently swap
// numbers between host form and target form. When the host and
// target have the same endianness, these turn into no-ops.
#ifndef ELFCPP_SWAP_H
#define ELFCPP_SWAP_H
#include <stdint.h>
// We need an autoconf-generated config.h file for endianness and
// swapping. We check two macros: WORDS_BIGENDIAN and
// HAVE_BYTESWAP_H.
#include "config.h"
#ifdef HAVE_BYTESWAP_H
#include <byteswap.h>
#endif // defined(HAVE_BYTESWAP_H)
// Provide our own versions of the byteswap functions.
#if !HAVE_DECL_BSWAP_16
static inline uint16_t
bswap_16(uint16_t v)
{
return ((v >> 8) & 0xff) | ((v & 0xff) << 8);
}
#endif // !HAVE_DECL_BSWAP16
#if !HAVE_DECL_BSWAP_32
static inline uint32_t
bswap_32(uint32_t v)
{
return ( ((v & 0xff000000) >> 24)
| ((v & 0x00ff0000) >> 8)
| ((v & 0x0000ff00) << 8)
| ((v & 0x000000ff) << 24));
}
#endif // !HAVE_DECL_BSWAP32
#if !HAVE_DECL_BSWAP_64
static inline uint64_t
bswap_64(uint64_t v)
{
return ( ((v & 0xff00000000000000ULL) >> 56)
| ((v & 0x00ff000000000000ULL) >> 40)
| ((v & 0x0000ff0000000000ULL) >> 24)
| ((v & 0x000000ff00000000ULL) >> 8)
| ((v & 0x00000000ff000000ULL) << 8)
| ((v & 0x0000000000ff0000ULL) << 24)
| ((v & 0x000000000000ff00ULL) << 40)
| ((v & 0x00000000000000ffULL) << 56));
}
#endif // !HAVE_DECL_BSWAP64
// gcc 4.3 and later provides __builtin_bswap32 and __builtin_bswap64.
#if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))
#undef bswap_32
#define bswap_32 __builtin_bswap32
#undef bswap_64
#define bswap_64 __builtin_bswap64
#endif
namespace elfcpp
{
// Endian simply indicates whether the host is big endian or not.
struct Endian
{
public:
// Used for template specializations.
static const bool host_big_endian =
#ifdef WORDS_BIGENDIAN
true
#else
false
#endif
;
};
// Valtype_base is a template based on size (8, 16, 32, 64) which
// defines the type Valtype as the unsigned integer, and
// Signed_valtype as the signed integer, of the specified size.
template<int size>
struct Valtype_base;
template<>
struct Valtype_base<8>
{
typedef uint8_t Valtype;
typedef int8_t Signed_valtype;
};
template<>
struct Valtype_base<16>
{
typedef uint16_t Valtype;
typedef int16_t Signed_valtype;
};
template<>
struct Valtype_base<32>
{
typedef uint32_t Valtype;
typedef int32_t Signed_valtype;
};
template<>
struct Valtype_base<64>
{
typedef uint64_t Valtype;
typedef int64_t Signed_valtype;
};
// Convert_endian is a template based on size and on whether the host
// and target have the same endianness. It defines the type Valtype
// as Valtype_base does, and also defines a function convert_host
// which takes an argument of type Valtype and returns the same value,
// but swapped if the host and target have different endianness.
template<int size, bool same_endian>
struct Convert_endian;
template<int size>
struct Convert_endian<size, true>
{
typedef typename Valtype_base<size>::Valtype Valtype;
static inline Valtype
convert_host(Valtype v)
{ return v; }
};
template<>
struct Convert_endian<8, false>
{
typedef Valtype_base<8>::Valtype Valtype;
static inline Valtype
convert_host(Valtype v)
{ return v; }
};
template<>
struct Convert_endian<16, false>
{
typedef Valtype_base<16>::Valtype Valtype;
static inline Valtype
convert_host(Valtype v)
{ return bswap_16(v); }
};
template<>
struct Convert_endian<32, false>
{
typedef Valtype_base<32>::Valtype Valtype;
static inline Valtype
convert_host(Valtype v)
{ return bswap_32(v); }
};
template<>
struct Convert_endian<64, false>
{
typedef Valtype_base<64>::Valtype Valtype;
static inline Valtype
convert_host(Valtype v)
{ return bswap_64(v); }
};
// Convert is a template based on size and on whether the target is
// big endian. It defines Valtype and convert_host like
// Convert_endian. That is, it is just like Convert_endian except in
// the meaning of the second template parameter.
template<int size, bool big_endian>
struct Convert
{
typedef typename Valtype_base<size>::Valtype Valtype;
static inline Valtype
convert_host(Valtype v)
{
return Convert_endian<size, big_endian == Endian::host_big_endian>
::convert_host(v);
}
};
// Swap is a template based on size and on whether the target is big
// endian. It defines the type Valtype and the functions readval and
// writeval. The functions read and write values of the appropriate
// size out of buffers, swapping them if necessary. readval and
// writeval are overloaded to take pointers to the appropriate type or
// pointers to unsigned char.
template<int size, bool big_endian>
struct Swap
{
typedef typename Valtype_base<size>::Valtype Valtype;
static inline Valtype
readval(const Valtype* wv)
{ return Convert<size, big_endian>::convert_host(*wv); }
static inline void
writeval(Valtype* wv, Valtype v)
{ *wv = Convert<size, big_endian>::convert_host(v); }
static inline Valtype
readval(const unsigned char* wv)
{ return readval(reinterpret_cast<const Valtype*>(wv)); }
static inline void
writeval(unsigned char* wv, Valtype v)
{ writeval(reinterpret_cast<Valtype*>(wv), v); }
};
// We need to specialize the 8-bit version of Swap to avoid
// conflicting overloads, since both versions of readval and writeval
// will have the same type parameters.
template<bool big_endian>
struct Swap<8, big_endian>
{
typedef typename Valtype_base<8>::Valtype Valtype;
static inline Valtype
readval(const Valtype* wv)
{ return *wv; }
static inline void
writeval(Valtype* wv, Valtype v)
{ *wv = v; }
};
// Swap_unaligned is a template based on size and on whether the
// target is big endian. It defines the type Valtype and the
// functions readval and writeval. The functions read and write
// values of the appropriate size out of buffers which may be
// misaligned.
template<int size, bool big_endian>
struct Swap_unaligned;
template<bool big_endian>
struct Swap_unaligned<8, big_endian>
{
typedef typename Valtype_base<8>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{ return *wv; }
static inline void
writeval(unsigned char* wv, Valtype v)
{ *wv = v; }
};
template<>
struct Swap_unaligned<16, false>
{
typedef Valtype_base<16>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{
return (wv[1] << 8) | wv[0];
}
static inline void
writeval(unsigned char* wv, Valtype v)
{
wv[1] = v >> 8;
wv[0] = v;
}
};
template<>
struct Swap_unaligned<16, true>
{
typedef Valtype_base<16>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{
return (wv[0] << 8) | wv[1];
}
static inline void
writeval(unsigned char* wv, Valtype v)
{
wv[0] = v >> 8;
wv[1] = v;
}
};
template<>
struct Swap_unaligned<32, false>
{
typedef Valtype_base<32>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{
return (wv[3] << 24) | (wv[2] << 16) | (wv[1] << 8) | wv[0];
}
static inline void
writeval(unsigned char* wv, Valtype v)
{
wv[3] = v >> 24;
wv[2] = v >> 16;
wv[1] = v >> 8;
wv[0] = v;
}
};
template<>
struct Swap_unaligned<32, true>
{
typedef Valtype_base<32>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{
return (wv[0] << 24) | (wv[1] << 16) | (wv[2] << 8) | wv[3];
}
static inline void
writeval(unsigned char* wv, Valtype v)
{
wv[0] = v >> 24;
wv[1] = v >> 16;
wv[2] = v >> 8;
wv[3] = v;
}
};
template<>
struct Swap_unaligned<64, false>
{
typedef Valtype_base<64>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{
return ((static_cast<Valtype>(wv[7]) << 56)
| (static_cast<Valtype>(wv[6]) << 48)
| (static_cast<Valtype>(wv[5]) << 40)
| (static_cast<Valtype>(wv[4]) << 32)
| (static_cast<Valtype>(wv[3]) << 24)
| (static_cast<Valtype>(wv[2]) << 16)
| (static_cast<Valtype>(wv[1]) << 8)
| static_cast<Valtype>(wv[0]));
}
static inline void
writeval(unsigned char* wv, Valtype v)
{
wv[7] = v >> 56;
wv[6] = v >> 48;
wv[5] = v >> 40;
wv[4] = v >> 32;
wv[3] = v >> 24;
wv[2] = v >> 16;
wv[1] = v >> 8;
wv[0] = v;
}
};
template<>
struct Swap_unaligned<64, true>
{
typedef Valtype_base<64>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{
return ((static_cast<Valtype>(wv[0]) << 56)
| (static_cast<Valtype>(wv[1]) << 48)
| (static_cast<Valtype>(wv[2]) << 40)
| (static_cast<Valtype>(wv[3]) << 32)
| (static_cast<Valtype>(wv[4]) << 24)
| (static_cast<Valtype>(wv[5]) << 16)
| (static_cast<Valtype>(wv[6]) << 8)
| static_cast<Valtype>(wv[7]));
}
static inline void
writeval(unsigned char* wv, Valtype v)
{
wv[0] = v >> 56;
wv[1] = v >> 48;
wv[2] = v >> 40;
wv[3] = v >> 32;
wv[4] = v >> 24;
wv[5] = v >> 16;
wv[6] = v >> 8;
wv[7] = v;
}
};
// Swap_aligned32 is a template based on size and on whether the
// target is big endian. It defines the type Valtype and the
// functions readval and writeval. The functions read and write
// values of the appropriate size out of buffers which may not be
// 64-bit aligned, but are 32-bit aligned.
template<int size, bool big_endian>
struct Swap_aligned32
{
typedef typename Valtype_base<size>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{ return Swap<size, big_endian>::readval(
reinterpret_cast<const Valtype*>(wv)); }
static inline void
writeval(unsigned char* wv, Valtype v)
{ Swap<size, big_endian>::writeval(reinterpret_cast<Valtype*>(wv), v); }
};
template<>
struct Swap_aligned32<64, true>
{
typedef Valtype_base<64>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{
return ((static_cast<Valtype>(Swap<32, true>::readval(wv)) << 32)
| static_cast<Valtype>(Swap<32, true>::readval(wv + 4)));
}
static inline void
writeval(unsigned char* wv, Valtype v)
{
typedef Valtype_base<32>::Valtype Valtype32;
Swap<32, true>::writeval(wv, static_cast<Valtype32>(v >> 32));
Swap<32, true>::writeval(wv + 4, static_cast<Valtype32>(v));
}
};
template<>
struct Swap_aligned32<64, false>
{
typedef Valtype_base<64>::Valtype Valtype;
static inline Valtype
readval(const unsigned char* wv)
{
return ((static_cast<Valtype>(Swap<32, false>::readval(wv + 4)) << 32)
| static_cast<Valtype>(Swap<32, false>::readval(wv)));
}
static inline void
writeval(unsigned char* wv, Valtype v)
{
typedef Valtype_base<32>::Valtype Valtype32;
Swap<32, false>::writeval(wv + 4, static_cast<Valtype32>(v >> 32));
Swap<32, false>::writeval(wv, static_cast<Valtype32>(v));
}
};
} // End namespace elfcpp.
#endif // !defined(ELFCPP_SWAP_H)