sysdeps/arm/sysdep.h

   1 /* Assembler macros for ARM.
   2    Copyright (C) 1997-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdeps/generic/sysdep.h>
  20 #include <features.h>
  21
  22 #ifndef __ASSEMBLER__
  23 # include <stdint.h>
  24 #endif
  25
  26 /* The __ARM_ARCH define is provided by gcc 4.8.  Construct it otherwise.  */
  27 #ifndef __ARM_ARCH
  28 # ifdef __ARM_ARCH_2__
  29 #  define __ARM_ARCH 2
  30 # elif defined (__ARM_ARCH_3__) || defined (__ARM_ARCH_3M__)
  31 #  define __ARM_ARCH 3
  32 # elif defined (__ARM_ARCH_4__) || defined (__ARM_ARCH_4T__)
  33 #  define __ARM_ARCH 4
  34 # elif defined (__ARM_ARCH_5__) || defined (__ARM_ARCH_5E__) \
  35        || defined(__ARM_ARCH_5T__) || defined(__ARM_ARCH_5TE__) \
  36        || defined(__ARM_ARCH_5TEJ__)
  37 #  define __ARM_ARCH 5
  38 # elif defined (__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) \
  39        || defined (__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) \
  40        || defined (__ARM_ARCH_6K__) || defined(__ARM_ARCH_6T2__)
  41 #  define __ARM_ARCH 6
  42 # elif defined (__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) \
  43        || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) \
  44        || defined(__ARM_ARCH_7EM__)
  45 #  define __ARM_ARCH 7
  46 # else
  47 #  error unknown arm architecture
  48 # endif
  49 #endif
  50
  51 #if __ARM_ARCH > 4 || defined (__ARM_ARCH_4T__)
  52 # define ARCH_HAS_BX
  53 #endif
  54 #if __ARM_ARCH > 4
  55 # define ARCH_HAS_BLX
  56 #endif
  57 #if __ARM_ARCH > 6 || defined (__ARM_ARCH_6K__) || defined (__ARM_ARCH_6ZK__)
  58 # define ARCH_HAS_HARD_TP
  59 #endif
  60 #if __ARM_ARCH > 6 || defined (__ARM_ARCH_6T2__)
  61 # define ARCH_HAS_T2
  62 #endif
  63
  64 #ifdef  __ASSEMBLER__
  65
  66 /* Syntactic details of assembler.  */
  67
  68 #define ALIGNARG(log2) log2
  69 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name
  70
  71 #define PLTJMP(_x)      _x##(PLT)
  72
  73 #ifdef ARCH_HAS_BX
  74 # define BX(R)          bx      R
  75 # define BXC(C, R)      bx##C   R
  76 # ifdef ARCH_HAS_BLX
  77 #  define BLX(R)        blx     R
  78 # else
  79 #  define BLX(R)        mov     lr, pc; bx R
  80 # endif
  81 #else
  82 # define BX(R)          mov     pc, R
  83 # define BXC(C, R)      mov##C  pc, R
  84 # define BLX(R)         mov     lr, pc; mov pc, R
  85 #endif
  86
  87 #define DO_RET(R)       BX(R)
  88 #define RETINSTR(C, R)  BXC(C, R)
  89
  90 /* Define an entry point visible from C.  */
  91 #define ENTRY(name)                                     \
  92         .globl  C_SYMBOL_NAME(name);                    \
  93         .type   C_SYMBOL_NAME(name),%function;          \
  94         .align  ALIGNARG(4);                            \
  95   C_LABEL(name)                                         \
  96         CFI_SECTIONS;                                   \
  97         cfi_startproc;                                  \
  98         CALL_MCOUNT
  99
 100 #define CFI_SECTIONS                                    \
 101         .cfi_sections .debug_frame
 102
 103 #undef  END
 104 #define END(name)                                       \
 105         cfi_endproc;                                    \
 106         ASM_SIZE_DIRECTIVE(name)
 107
 108 /* If compiled for profiling, call `mcount' at the start of each function.  */
 109 #ifdef  PROF
 110 /* Call __gnu_mcount_nc if GCC >= 4.4.  */
 111 #if __GNUC_PREREQ(4,4)
 112 #define CALL_MCOUNT                                     \
 113         push    {lr};                                   \
 114         cfi_adjust_cfa_offset (4);                      \
 115         cfi_rel_offset (lr, 0);                         \
 116         bl      PLTJMP(mcount);                         \
 117         cfi_adjust_cfa_offset (-4);                     \
 118         cfi_restore (lr)
 119 #else /* else call _mcount */
 120 #define CALL_MCOUNT                                     \
 121         push    {lr};                                   \
 122         cfi_adjust_cfa_offset (4);                      \
 123         cfi_rel_offset (lr, 0);                         \
 124         bl      PLTJMP(mcount);                         \
 125         pops    {lr};                                   \
 126         cfi_adjust_cfa_offset (-4);                     \
 127         cfi_restore (lr)
 128 #endif
 129 #else
 130 #define CALL_MCOUNT             /* Do nothing.  */
 131 #endif
 132
 133 /* Since C identifiers are not normally prefixed with an underscore
 134    on this system, the asm identifier `syscall_error' intrudes on the
 135    C name space.  Make sure we use an innocuous name.  */
 136 #define syscall_error   __syscall_error
 137 #if __GNUC_PREREQ(4,4)
 138 #define mcount          __gnu_mcount_nc
 139 #else
 140 #define mcount          _mcount
 141 #endif
 142
 143 /* Tag_ABI_align8_preserved: This code preserves 8-byte
 144    alignment in any callee.  */
 145         .eabi_attribute 25, 1
 146 /* Tag_ABI_align8_needed: This code may require 8-byte alignment from
 147    the caller.  */
 148         .eabi_attribute 24, 1
 149
 150 /* The thumb2 encoding is reasonably complete.  Unless suppressed, use it.  */
 151         .syntax unified
 152 # if defined(__thumb2__) && !defined(NO_THUMB)
 153         .thumb
 154 #else
 155 #  undef __thumb__
 156 #  undef __thumb2__
 157         .arm
 158 # endif
 159
 160 /* Load or store to/from a pc-relative EXPR into/from R, using T.  */
 161 # ifdef __thumb2__
 162 #  define LDST_PCREL(OP, R, T, EXPR) \
 163         ldr     T, 98f;                                 \
 164         .subsection 2;                                  \
 165 98:     .word   EXPR - 99f - PC_OFS;                    \
 166         .previous;                                      \
 167 99:     add     T, T, pc;                               \
 168         OP      R, [T]
 169 # else
 170 #  define LDST_PCREL(OP, R, T, EXPR) \
 171         ldr     T, 98f;                                 \
 172         .subsection 2;                                  \
 173 98:     .word   EXPR - 99f - PC_OFS;                    \
 174         .previous;                                      \
 175 99:     OP      R, [pc, T]
 176 # endif
 177
 178 /* Load or store to/from a global EXPR into/from R, using T.  */
 179 # define LDST_GLOBAL(OP, R, T, EXPR)                    \
 180         ldr     T, 99f;                                 \
 181         ldr     R, 100f;                                \
 182 98:     add     T, T, pc;                               \
 183         ldr     T, [T, R];                              \
 184         .subsection 2;                                  \
 185 99:     .word   _GLOBAL_OFFSET_TABLE_ - 98b - PC_OFS;   \
 186 100:    .word   EXPR##(GOT);                            \
 187         .previous;                                      \
 188         OP      R, [T]
 189
 190 /* Cope with negative memory offsets, which thumb can't encode.
 191    Use NEGOFF_ADJ_BASE to (conditionally) alter the base register,
 192    and then NEGOFF_OFF1 to use 0 for thumb and the offset for arm,
 193    or NEGOFF_OFF2 to use A-B for thumb and A for arm.  */
 194 # ifdef __thumb2__
 195 #  define NEGOFF_ADJ_BASE(R, OFF)       add R, R, $OFF
 196 #  define NEGOFF_ADJ_BASE2(D, S, OFF)   add D, S, $OFF
 197 #  define NEGOFF_OFF1(R, OFF)           [R]
 198 #  define NEGOFF_OFF2(R, OFFA, OFFB)    [R, $((OFFA) - (OFFB))]
 199 # else
 200 #  define NEGOFF_ADJ_BASE(R, OFF)
 201 #  define NEGOFF_ADJ_BASE2(D, S, OFF)   mov D, S
 202 #  define NEGOFF_OFF1(R, OFF)           [R, $OFF]
 203 #  define NEGOFF_OFF2(R, OFFA, OFFB)    [R, $OFFA]
 204 # endif
 205
 206 /* Helper to get the TLS base pointer.  The interface is that TMP is a
 207    register that may be used to hold the LR, if necessary.  TMP may be
 208    LR itself to indicate that LR need not be saved.  The base pointer
 209    is returned in R0.  Only R0 and TMP are modified.  */
 210
 211 # ifdef ARCH_HAS_HARD_TP
 212 /* If the cpu has cp15 available, use it.  */
 213 #  define GET_TLS(TMP)          mrc p15, 0, r0, c13, c0, 3
 214 # else
 215 /* At this generic level we have no tricks to pull.  Call the ABI routine.  */
 216 #  define GET_TLS(TMP)                                  \
 217         push    { r1, r2, r3, lr };                     \
 218         cfi_remember_state;                             \
 219         cfi_adjust_cfa_offset (16);                     \
 220         cfi_rel_offset (r1, 0);                         \
 221         cfi_rel_offset (r2, 4);                         \
 222         cfi_rel_offset (r3, 8);                         \
 223         cfi_rel_offset (lr, 12);                        \
 224         bl      __aeabi_read_tp;                        \
 225         pop     { r1, r2, r3, lr };                     \
 226         cfi_restore_state
 227 # endif /* ARCH_HAS_HARD_TP */
 228
 229 # ifndef ARM_SFI_MACROS
 230 # define ARM_SFI_MACROS 1
 231 /* This assembly macro is prepended to any load/store instruction,
 232    pulling the base register out of the addressing mode syntax and
 233    making it the first operand of the macro.  For example:
 234         ldr r0, [r1]
 235    becomes:
 236         sfi_breg r1, ldr r0, [\B]
 237    The \B stands in for the base register that is the first operand
 238    to the macro, so we can avoid error-prone repetition of the base
 239    register in two places on the line.
 240
 241    This is used for all memory access through a base register other
 242    than PC or SP.  It's intended to support SFI schemes such as
 243    Native Client, where the OS will enforce that all load/store
 244    instructions use a special form.  In any such configuration,
 245    another sysdep.h file will have defined ARM_SFI_MACROS and
 246    provided its own assembly macros with the same interface.  */
 247
 248         .macro sfi_breg basereg, insn, operands:vararg
 249                 .macro _sfi_breg_doit B
 250                 \insn \operands
 251                 .endm
 252                 _sfi_breg_doit \basereg
 253                 .purgem _sfi_breg_doit
 254         .endm
 255
 256 /* This assembly macro replaces the "pld" instruction.
 257    The syntax:
 258         sfi_pld REGISTER, #OFFSET
 259    is exactly equivalent to:
 260         sfi_breg REGISTER, pld [\B, #OFFSET]
 261    (and ", #OFFSET" is optional).  We have a separate macro
 262    only to work around a bug in GAS versions prior to 2.23.2,
 263    that misparses the sfi_breg macro expansion in this case.  */
 264
 265         .macro sfi_pld basereg, offset=#0
 266                 pld [\basereg, \offset]
 267         .endm
 268
 269 /* This macro precedes any instruction that directly changes the SP.
 270    It's not needed for push/pop or for any kind of load or store that
 271    implicitly changes the SP via the ! syntax.  */
 272 # define sfi_sp /* Nothing to do.  */
 273
 274 # endif
 275
 276 /* These are the directives used for EABI unwind info.
 277    Wrap them in macros so another configuration's sysdep.h
 278    file can define them away if it doesn't use EABI unwind info.  */
 279 # define eabi_fnstart           .fnstart
 280 # define eabi_fnend             .fnend
 281 # define eabi_save(...)         .save __VA_ARGS__
 282 # define eabi_cantunwind        .cantunwind
 283 # define eabi_pad(n)            .pad n
 284
 285 #endif  /* __ASSEMBLER__ */
 286
 287 /* This number is the offset from the pc at the current location.  */
 288 #ifdef __thumb__
 289 # define PC_OFS  4
 290 #else
 291 # define PC_OFS  8
 292 #endif
 293
 294 /* Pointer mangling support.  */
 295 #if (defined IS_IN_rtld || \
 296      (!defined SHARED && (!defined NOT_IN_libc || defined IS_IN_libpthread)))
 297 # ifdef __ASSEMBLER__
 298 #  define PTR_MANGLE_LOAD(guard, tmp)                                   \
 299   LDST_PCREL(ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard_local));
 300 #  define PTR_MANGLE(dst, src, guard, tmp)                              \
 301   PTR_MANGLE_LOAD(guard, tmp);                                          \
 302   PTR_MANGLE2(dst, src, guard)
 303 /* Use PTR_MANGLE2 for efficiency if guard is already loaded.  */
 304 #  define PTR_MANGLE2(dst, src, guard)          \
 305   eor dst, src, guard
 306 #  define PTR_DEMANGLE(dst, src, guard, tmp)    \
 307   PTR_MANGLE (dst, src, guard, tmp)
 308 #  define PTR_DEMANGLE2(dst, src, guard)        \
 309   PTR_MANGLE2 (dst, src, guard)
 310 # else
 311 extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
 312 #  define PTR_MANGLE(var) \
 313   (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
 314 #  define PTR_DEMANGLE(var)     PTR_MANGLE (var)
 315 # endif
 316 #else
 317 # ifdef __ASSEMBLER__
 318 #  define PTR_MANGLE_LOAD(guard, tmp)                                   \
 319   LDST_GLOBAL(ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard));
 320 #  define PTR_MANGLE(dst, src, guard, tmp)                              \
 321   PTR_MANGLE_LOAD(guard, tmp);                                          \
 322   PTR_MANGLE2(dst, src, guard)
 323 /* Use PTR_MANGLE2 for efficiency if guard is already loaded.  */
 324 #  define PTR_MANGLE2(dst, src, guard)          \
 325   eor dst, src, guard
 326 #  define PTR_DEMANGLE(dst, src, guard, tmp)    \
 327   PTR_MANGLE (dst, src, guard, tmp)
 328 #  define PTR_DEMANGLE2(dst, src, guard)        \
 329   PTR_MANGLE2 (dst, src, guard)
 330 # else
 331 extern uintptr_t __pointer_chk_guard attribute_relro;
 332 #  define PTR_MANGLE(var) \
 333   (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard)
 334 #  define PTR_DEMANGLE(var)     PTR_MANGLE (var)
 335 # endif
 336 #endif