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288 lines
9.1 KiB
C
288 lines
9.1 KiB
C
/* Unaligned memory access functionality.
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Copyright (C) 2000-2014 Red Hat, Inc.
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This file is part of elfutils.
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Written by Ulrich Drepper <drepper@redhat.com>, 2001.
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This file is free software; you can redistribute it and/or modify
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it under the terms of either
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at
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your option) any later version
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at
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your option) any later version
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or both in parallel, as here.
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elfutils is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see <http://www.gnu.org/licenses/>. */
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#ifndef _MEMORY_ACCESS_H
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#define _MEMORY_ACCESS_H 1
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#include <byteswap.h>
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#include <limits.h>
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#include <stdint.h>
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/* Number decoding macros. See 7.6 Variable Length Data. */
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#define len_leb128(var) ((8 * sizeof (var) + 6) / 7)
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static inline size_t
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__libdw_max_len_leb128 (const size_t type_len,
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const unsigned char *addr, const unsigned char *end)
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{
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const size_t pointer_len = likely (addr < end) ? end - addr : 0;
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return likely (type_len <= pointer_len) ? type_len : pointer_len;
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}
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static inline size_t
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__libdw_max_len_uleb128 (const unsigned char *addr, const unsigned char *end)
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{
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const size_t type_len = len_leb128 (uint64_t);
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return __libdw_max_len_leb128 (type_len, addr, end);
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}
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static inline size_t
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__libdw_max_len_sleb128 (const unsigned char *addr, const unsigned char *end)
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{
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/* Subtract one step, so we don't shift into sign bit. */
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const size_t type_len = len_leb128 (int64_t) - 1;
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return __libdw_max_len_leb128 (type_len, addr, end);
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}
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#define get_uleb128_step(var, addr, nth) \
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do { \
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unsigned char __b = *(addr)++; \
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(var) |= (typeof (var)) (__b & 0x7f) << ((nth) * 7); \
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if (likely ((__b & 0x80) == 0)) \
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return (var); \
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} while (0)
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static inline uint64_t
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__libdw_get_uleb128 (const unsigned char **addrp, const unsigned char *end)
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{
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uint64_t acc = 0;
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/* Unroll the first step to help the compiler optimize
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for the common single-byte case. */
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get_uleb128_step (acc, *addrp, 0);
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const size_t max = __libdw_max_len_uleb128 (*addrp - 1, end);
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for (size_t i = 1; i < max; ++i)
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get_uleb128_step (acc, *addrp, i);
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/* Other implementations set VALUE to UINT_MAX in this
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case. So we better do this as well. */
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return UINT64_MAX;
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}
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/* Note, addr needs to me smaller than end. */
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#define get_uleb128(var, addr, end) ((var) = __libdw_get_uleb128 (&(addr), end))
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/* The signed case is similar, but we sign-extend the result. */
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#define get_sleb128_step(var, addr, nth) \
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do { \
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unsigned char __b = *(addr)++; \
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if (likely ((__b & 0x80) == 0)) \
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{ \
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struct { signed int i:7; } __s = { .i = __b }; \
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(var) |= (typeof (var)) __s.i * ((typeof (var)) 1 << ((nth) * 7)); \
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return (var); \
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} \
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(var) |= (typeof (var)) (__b & 0x7f) << ((nth) * 7); \
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} while (0)
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static inline int64_t
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__libdw_get_sleb128 (const unsigned char **addrp, const unsigned char *end)
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{
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int64_t acc = 0;
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/* Unroll the first step to help the compiler optimize
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for the common single-byte case. */
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get_sleb128_step (acc, *addrp, 0);
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const size_t max = __libdw_max_len_sleb128 (*addrp - 1, end);
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for (size_t i = 1; i < max; ++i)
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get_sleb128_step (acc, *addrp, i);
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/* Other implementations set VALUE to INT_MAX in this
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case. So we better do this as well. */
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return INT64_MAX;
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}
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#define get_sleb128(var, addr, end) ((var) = __libdw_get_sleb128 (&(addr), end))
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/* We use simple memory access functions in case the hardware allows it.
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The caller has to make sure we don't have alias problems. */
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#if ALLOW_UNALIGNED
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# define read_2ubyte_unaligned(Dbg, Addr) \
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(unlikely ((Dbg)->other_byte_order) \
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? bswap_16 (*((const uint16_t *) (Addr))) \
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: *((const uint16_t *) (Addr)))
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# define read_2sbyte_unaligned(Dbg, Addr) \
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(unlikely ((Dbg)->other_byte_order) \
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? (int16_t) bswap_16 (*((const int16_t *) (Addr))) \
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: *((const int16_t *) (Addr)))
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# define read_4ubyte_unaligned_noncvt(Addr) \
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*((const uint32_t *) (Addr))
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# define read_4ubyte_unaligned(Dbg, Addr) \
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(unlikely ((Dbg)->other_byte_order) \
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? bswap_32 (*((const uint32_t *) (Addr))) \
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: *((const uint32_t *) (Addr)))
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# define read_4sbyte_unaligned(Dbg, Addr) \
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(unlikely ((Dbg)->other_byte_order) \
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? (int32_t) bswap_32 (*((const int32_t *) (Addr))) \
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: *((const int32_t *) (Addr)))
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# define read_8ubyte_unaligned_noncvt(Addr) \
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*((const uint64_t *) (Addr))
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# define read_8ubyte_unaligned(Dbg, Addr) \
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(unlikely ((Dbg)->other_byte_order) \
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? bswap_64 (*((const uint64_t *) (Addr))) \
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: *((const uint64_t *) (Addr)))
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# define read_8sbyte_unaligned(Dbg, Addr) \
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(unlikely ((Dbg)->other_byte_order) \
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? (int64_t) bswap_64 (*((const int64_t *) (Addr))) \
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: *((const int64_t *) (Addr)))
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#else
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union unaligned
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{
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void *p;
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uint16_t u2;
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uint32_t u4;
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uint64_t u8;
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int16_t s2;
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int32_t s4;
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int64_t s8;
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} __attribute__ ((packed));
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# define read_2ubyte_unaligned(Dbg, Addr) \
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read_2ubyte_unaligned_1 ((Dbg)->other_byte_order, (Addr))
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# define read_2sbyte_unaligned(Dbg, Addr) \
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read_2sbyte_unaligned_1 ((Dbg)->other_byte_order, (Addr))
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# define read_4ubyte_unaligned(Dbg, Addr) \
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read_4ubyte_unaligned_1 ((Dbg)->other_byte_order, (Addr))
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# define read_4sbyte_unaligned(Dbg, Addr) \
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read_4sbyte_unaligned_1 ((Dbg)->other_byte_order, (Addr))
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# define read_8ubyte_unaligned(Dbg, Addr) \
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read_8ubyte_unaligned_1 ((Dbg)->other_byte_order, (Addr))
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# define read_8sbyte_unaligned(Dbg, Addr) \
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read_8sbyte_unaligned_1 ((Dbg)->other_byte_order, (Addr))
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static inline uint16_t
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read_2ubyte_unaligned_1 (bool other_byte_order, const void *p)
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{
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const union unaligned *up = p;
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if (unlikely (other_byte_order))
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return bswap_16 (up->u2);
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return up->u2;
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}
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static inline int16_t
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read_2sbyte_unaligned_1 (bool other_byte_order, const void *p)
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{
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const union unaligned *up = p;
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if (unlikely (other_byte_order))
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return (int16_t) bswap_16 (up->u2);
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return up->s2;
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}
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static inline uint32_t
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read_4ubyte_unaligned_noncvt (const void *p)
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{
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const union unaligned *up = p;
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return up->u4;
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}
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static inline uint32_t
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read_4ubyte_unaligned_1 (bool other_byte_order, const void *p)
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{
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const union unaligned *up = p;
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if (unlikely (other_byte_order))
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return bswap_32 (up->u4);
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return up->u4;
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}
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static inline int32_t
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read_4sbyte_unaligned_1 (bool other_byte_order, const void *p)
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{
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const union unaligned *up = p;
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if (unlikely (other_byte_order))
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return (int32_t) bswap_32 (up->u4);
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return up->s4;
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}
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static inline uint64_t
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read_8ubyte_unaligned_noncvt (const void *p)
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{
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const union unaligned *up = p;
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return up->u8;
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}
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static inline uint64_t
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read_8ubyte_unaligned_1 (bool other_byte_order, const void *p)
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{
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const union unaligned *up = p;
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if (unlikely (other_byte_order))
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return bswap_64 (up->u8);
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return up->u8;
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}
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static inline int64_t
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read_8sbyte_unaligned_1 (bool other_byte_order, const void *p)
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{
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const union unaligned *up = p;
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if (unlikely (other_byte_order))
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return (int64_t) bswap_64 (up->u8);
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return up->s8;
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}
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#endif /* allow unaligned */
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#define read_2ubyte_unaligned_inc(Dbg, Addr) \
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({ uint16_t t_ = read_2ubyte_unaligned (Dbg, Addr); \
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Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2); \
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t_; })
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#define read_2sbyte_unaligned_inc(Dbg, Addr) \
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({ int16_t t_ = read_2sbyte_unaligned (Dbg, Addr); \
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Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2); \
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t_; })
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#define read_4ubyte_unaligned_inc(Dbg, Addr) \
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({ uint32_t t_ = read_4ubyte_unaligned (Dbg, Addr); \
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Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4); \
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t_; })
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#define read_4sbyte_unaligned_inc(Dbg, Addr) \
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({ int32_t t_ = read_4sbyte_unaligned (Dbg, Addr); \
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Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4); \
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t_; })
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#define read_8ubyte_unaligned_inc(Dbg, Addr) \
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({ uint64_t t_ = read_8ubyte_unaligned (Dbg, Addr); \
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Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8); \
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t_; })
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#define read_8sbyte_unaligned_inc(Dbg, Addr) \
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({ int64_t t_ = read_8sbyte_unaligned (Dbg, Addr); \
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Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8); \
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t_; })
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#define read_addr_unaligned_inc(Nbytes, Dbg, Addr) \
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(assert ((Nbytes) == 4 || (Nbytes) == 8), \
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((Nbytes) == 4 ? read_4ubyte_unaligned_inc (Dbg, Addr) \
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: read_8ubyte_unaligned_inc (Dbg, Addr)))
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#endif /* memory-access.h */
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