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Diffstat (limited to 'libdw/memory-access.h')
-rw-r--r-- | libdw/memory-access.h | 272 |
1 files changed, 272 insertions, 0 deletions
diff --git a/libdw/memory-access.h b/libdw/memory-access.h new file mode 100644 index 00000000..a53f7912 --- /dev/null +++ b/libdw/memory-access.h @@ -0,0 +1,272 @@ +/* Unaligned memory access functionality. + Copyright (C) 2000-2014 Red Hat, Inc. + This file is part of elfutils. + Written by Ulrich Drepper <drepper@redhat.com>, 2001. + + This file is free software; you can redistribute it and/or modify + it under the terms of either + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at + your option) any later version + + or + + * the GNU General Public License as published by the Free + Software Foundation; either version 2 of the License, or (at + your option) any later version + + or both in parallel, as here. + + elfutils 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 + General Public License for more details. + + You should have received copies of the GNU General Public License and + the GNU Lesser General Public License along with this program. If + not, see <http://www.gnu.org/licenses/>. */ + +#ifndef _MEMORY_ACCESS_H +#define _MEMORY_ACCESS_H 1 + +#include <byteswap.h> +#include <limits.h> +#include <stdint.h> + + +/* Number decoding macros. See 7.6 Variable Length Data. */ + +#define len_leb128(var) ((8 * sizeof (var) + 6) / 7) + +static inline size_t +__libdw_max_len_leb128 (const unsigned char *addr, const unsigned char *end) +{ + const size_t type_len = len_leb128 (uint64_t); + const size_t pointer_len = likely (addr < end) ? end - addr : 0; + return likely (type_len <= pointer_len) ? type_len : pointer_len; +} + +#define get_uleb128_step(var, addr, nth) \ + do { \ + unsigned char __b = *(addr)++; \ + (var) |= (typeof (var)) (__b & 0x7f) << ((nth) * 7); \ + if (likely ((__b & 0x80) == 0)) \ + return (var); \ + } while (0) + +static inline uint64_t +__libdw_get_uleb128 (const unsigned char **addrp, const unsigned char *end) +{ + uint64_t acc = 0; + + /* Unroll the first step to help the compiler optimize + for the common single-byte case. */ + get_uleb128_step (acc, *addrp, 0); + + const size_t max = __libdw_max_len_leb128 (*addrp - 1, end); + for (size_t i = 1; i < max; ++i) + get_uleb128_step (acc, *addrp, i); + /* Other implementations set VALUE to UINT_MAX in this + case. So we better do this as well. */ + return UINT64_MAX; +} + +/* Note, addr needs to me smaller than end. */ +#define get_uleb128(var, addr, end) ((var) = __libdw_get_uleb128 (&(addr), end)) + +/* The signed case is similar, but we sign-extend the result. */ + +#define get_sleb128_step(var, addr, nth) \ + do { \ + unsigned char __b = *(addr)++; \ + if (likely ((__b & 0x80) == 0)) \ + { \ + struct { signed int i:7; } __s = { .i = __b }; \ + (var) |= (typeof (var)) __s.i * ((typeof (var)) 1 << ((nth) * 7)); \ + return (var); \ + } \ + (var) |= (typeof (var)) (__b & 0x7f) << ((nth) * 7); \ + } while (0) + +static inline int64_t +__libdw_get_sleb128 (const unsigned char **addrp, const unsigned char *end) +{ + int64_t acc = 0; + + /* Unroll the first step to help the compiler optimize + for the common single-byte case. */ + get_sleb128_step (acc, *addrp, 0); + + const size_t max = __libdw_max_len_leb128 (*addrp - 1, end); + for (size_t i = 1; i < max; ++i) + get_sleb128_step (acc, *addrp, i); + /* Other implementations set VALUE to INT_MAX in this + case. So we better do this as well. */ + return INT64_MAX; +} + +#define get_sleb128(var, addr, end) ((var) = __libdw_get_sleb128 (&(addr), end)) + + +/* We use simple memory access functions in case the hardware allows it. + The caller has to make sure we don't have alias problems. */ +#if ALLOW_UNALIGNED + +# define read_2ubyte_unaligned(Dbg, Addr) \ + (unlikely ((Dbg)->other_byte_order) \ + ? bswap_16 (*((const uint16_t *) (Addr))) \ + : *((const uint16_t *) (Addr))) +# define read_2sbyte_unaligned(Dbg, Addr) \ + (unlikely ((Dbg)->other_byte_order) \ + ? (int16_t) bswap_16 (*((const int16_t *) (Addr))) \ + : *((const int16_t *) (Addr))) + +# define read_4ubyte_unaligned_noncvt(Addr) \ + *((const uint32_t *) (Addr)) +# define read_4ubyte_unaligned(Dbg, Addr) \ + (unlikely ((Dbg)->other_byte_order) \ + ? bswap_32 (*((const uint32_t *) (Addr))) \ + : *((const uint32_t *) (Addr))) +# define read_4sbyte_unaligned(Dbg, Addr) \ + (unlikely ((Dbg)->other_byte_order) \ + ? (int32_t) bswap_32 (*((const int32_t *) (Addr))) \ + : *((const int32_t *) (Addr))) + +# define read_8ubyte_unaligned_noncvt(Addr) \ + *((const uint64_t *) (Addr)) +# define read_8ubyte_unaligned(Dbg, Addr) \ + (unlikely ((Dbg)->other_byte_order) \ + ? bswap_64 (*((const uint64_t *) (Addr))) \ + : *((const uint64_t *) (Addr))) +# define read_8sbyte_unaligned(Dbg, Addr) \ + (unlikely ((Dbg)->other_byte_order) \ + ? (int64_t) bswap_64 (*((const int64_t *) (Addr))) \ + : *((const int64_t *) (Addr))) + +#else + +union unaligned + { + void *p; + uint16_t u2; + uint32_t u4; + uint64_t u8; + int16_t s2; + int32_t s4; + int64_t s8; + } __attribute__ ((packed)); + +# define read_2ubyte_unaligned(Dbg, Addr) \ + read_2ubyte_unaligned_1 ((Dbg)->other_byte_order, (Addr)) +# define read_2sbyte_unaligned(Dbg, Addr) \ + read_2sbyte_unaligned_1 ((Dbg)->other_byte_order, (Addr)) +# define read_4ubyte_unaligned(Dbg, Addr) \ + read_4ubyte_unaligned_1 ((Dbg)->other_byte_order, (Addr)) +# define read_4sbyte_unaligned(Dbg, Addr) \ + read_4sbyte_unaligned_1 ((Dbg)->other_byte_order, (Addr)) +# define read_8ubyte_unaligned(Dbg, Addr) \ + read_8ubyte_unaligned_1 ((Dbg)->other_byte_order, (Addr)) +# define read_8sbyte_unaligned(Dbg, Addr) \ + read_8sbyte_unaligned_1 ((Dbg)->other_byte_order, (Addr)) + +static inline uint16_t +read_2ubyte_unaligned_1 (bool other_byte_order, const void *p) +{ + const union unaligned *up = p; + if (unlikely (other_byte_order)) + return bswap_16 (up->u2); + return up->u2; +} +static inline int16_t +read_2sbyte_unaligned_1 (bool other_byte_order, const void *p) +{ + const union unaligned *up = p; + if (unlikely (other_byte_order)) + return (int16_t) bswap_16 (up->u2); + return up->s2; +} + +static inline uint32_t +read_4ubyte_unaligned_noncvt (const void *p) +{ + const union unaligned *up = p; + return up->u4; +} +static inline uint32_t +read_4ubyte_unaligned_1 (bool other_byte_order, const void *p) +{ + const union unaligned *up = p; + if (unlikely (other_byte_order)) + return bswap_32 (up->u4); + return up->u4; +} +static inline int32_t +read_4sbyte_unaligned_1 (bool other_byte_order, const void *p) +{ + const union unaligned *up = p; + if (unlikely (other_byte_order)) + return (int32_t) bswap_32 (up->u4); + return up->s4; +} + +static inline uint64_t +read_8ubyte_unaligned_noncvt (const void *p) +{ + const union unaligned *up = p; + return up->u8; +} +static inline uint64_t +read_8ubyte_unaligned_1 (bool other_byte_order, const void *p) +{ + const union unaligned *up = p; + if (unlikely (other_byte_order)) + return bswap_64 (up->u8); + return up->u8; +} +static inline int64_t +read_8sbyte_unaligned_1 (bool other_byte_order, const void *p) +{ + const union unaligned *up = p; + if (unlikely (other_byte_order)) + return (int64_t) bswap_64 (up->u8); + return up->s8; +} + +#endif /* allow unaligned */ + + +#define read_2ubyte_unaligned_inc(Dbg, Addr) \ + ({ uint16_t t_ = read_2ubyte_unaligned (Dbg, Addr); \ + Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2); \ + t_; }) +#define read_2sbyte_unaligned_inc(Dbg, Addr) \ + ({ int16_t t_ = read_2sbyte_unaligned (Dbg, Addr); \ + Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2); \ + t_; }) + +#define read_4ubyte_unaligned_inc(Dbg, Addr) \ + ({ uint32_t t_ = read_4ubyte_unaligned (Dbg, Addr); \ + Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4); \ + t_; }) +#define read_4sbyte_unaligned_inc(Dbg, Addr) \ + ({ int32_t t_ = read_4sbyte_unaligned (Dbg, Addr); \ + Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4); \ + t_; }) + +#define read_8ubyte_unaligned_inc(Dbg, Addr) \ + ({ uint64_t t_ = read_8ubyte_unaligned (Dbg, Addr); \ + Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8); \ + t_; }) +#define read_8sbyte_unaligned_inc(Dbg, Addr) \ + ({ int64_t t_ = read_8sbyte_unaligned (Dbg, Addr); \ + Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8); \ + t_; }) + + +#define read_addr_unaligned_inc(Nbytes, Dbg, Addr) \ + (assert ((Nbytes) == 4 || (Nbytes) == 8), \ + ((Nbytes) == 4 ? read_4ubyte_unaligned_inc (Dbg, Addr) \ + : read_8ubyte_unaligned_inc (Dbg, Addr))) + +#endif /* memory-access.h */ |