sysdeps/arm/sysdep.h

   1 /* Assembler macros for ARM.
   2    Copyright (C) 1997-2024 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdeps/generic/sysdep.h>
  20 #include <features.h>
  21
  22 #ifndef __ASSEMBLER__
  23 # include <stdint.h>
  24 #else
  25 # include <arm-features.h>
  26 #endif
  27
  28 /* The __ARM_ARCH define is provided by gcc 4.8.  Construct it otherwise.  */
  29 #ifndef __ARM_ARCH
  30 # ifdef __ARM_ARCH_2__
  31 #  define __ARM_ARCH 2
  32 # elif defined (__ARM_ARCH_3__) || defined (__ARM_ARCH_3M__)
  33 #  define __ARM_ARCH 3
  34 # elif defined (__ARM_ARCH_4__) || defined (__ARM_ARCH_4T__)
  35 #  define __ARM_ARCH 4
  36 # elif defined (__ARM_ARCH_5__) || defined (__ARM_ARCH_5E__) \
  37        || defined(__ARM_ARCH_5T__) || defined(__ARM_ARCH_5TE__) \
  38        || defined(__ARM_ARCH_5TEJ__)
  39 #  define __ARM_ARCH 5
  40 # elif defined (__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) \
  41        || defined (__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) \
  42        || defined (__ARM_ARCH_6K__) || defined(__ARM_ARCH_6T2__)
  43 #  define __ARM_ARCH 6
  44 # elif defined (__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) \
  45        || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) \
  46        || defined(__ARM_ARCH_7EM__)
  47 #  define __ARM_ARCH 7
  48 # else
  49 #  error unknown arm architecture
  50 # endif
  51 #endif
  52
  53 #if __ARM_ARCH > 4 || defined (__ARM_ARCH_4T__)
  54 # define ARCH_HAS_BX
  55 #endif
  56 #if __ARM_ARCH > 4
  57 # define ARCH_HAS_BLX
  58 #endif
  59 #if __ARM_ARCH > 6 || defined (__ARM_ARCH_6K__) || defined (__ARM_ARCH_6ZK__)
  60 # define ARCH_HAS_HARD_TP
  61 #endif
  62 #if __ARM_ARCH > 6 || defined (__ARM_ARCH_6T2__)
  63 # define ARCH_HAS_T2
  64 #endif
  65
  66 #ifdef  __ASSEMBLER__
  67
  68 /* Syntactic details of assembler.  */
  69
  70 #define ALIGNARG(log2) log2
  71 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name
  72
  73 #define PLTJMP(_x)      _x##(PLT)
  74
  75 #ifdef ARCH_HAS_BX
  76 # define BX(R)          bx      R
  77 # define BXC(C, R)      bx##C   R
  78 # ifdef ARCH_HAS_BLX
  79 #  define BLX(R)        blx     R
  80 # else
  81 #  define BLX(R)        mov     lr, pc; bx R
  82 # endif
  83 #else
  84 # define BX(R)          mov     pc, R
  85 # define BXC(C, R)      mov##C  pc, R
  86 # define BLX(R)         mov     lr, pc; mov pc, R
  87 #endif
  88
  89 #define DO_RET(R)       BX(R)
  90 #define RETINSTR(C, R)  BXC(C, R)
  91
  92 /* Define an entry point visible from C.  */
  93 #define ENTRY(name)                                     \
  94         .globl  C_SYMBOL_NAME(name);                    \
  95         .type   C_SYMBOL_NAME(name),%function;          \
  96         .align  ALIGNARG(4);                            \
  97   C_LABEL(name)                                         \
  98         CFI_SECTIONS;                                   \
  99         cfi_startproc;                                  \
 100         CALL_MCOUNT
 101
 102 #define CFI_SECTIONS                                    \
 103         .cfi_sections .debug_frame
 104
 105 #undef  END
 106 #define END(name)                                       \
 107         cfi_endproc;                                    \
 108         ASM_SIZE_DIRECTIVE(name)
 109
 110 /* If compiled for profiling, call `mcount' at the start of each function.  */
 111 #ifdef  PROF
 112 /* Call __gnu_mcount_nc (GCC >= 4.4).  */
 113 #define CALL_MCOUNT                                     \
 114         push    {lr};                                   \
 115         cfi_adjust_cfa_offset (4);                      \
 116         cfi_rel_offset (lr, 0);                         \
 117         bl      PLTJMP(mcount);                         \
 118         cfi_adjust_cfa_offset (-4);                     \
 119         cfi_restore (lr)
 120 #else
 121 #define CALL_MCOUNT             /* Do nothing.  */
 122 #endif
 123
 124 /* Since C identifiers are not normally prefixed with an underscore
 125    on this system, the asm identifier `syscall_error' intrudes on the
 126    C name space.  Make sure we use an innocuous name.  */
 127 #define syscall_error   __syscall_error
 128 #define mcount          __gnu_mcount_nc
 129
 130 /* Tag_ABI_align8_preserved: This code preserves 8-byte
 131    alignment in any callee.  */
 132         .eabi_attribute 25, 1
 133 /* Tag_ABI_align8_needed: This code may require 8-byte alignment from
 134    the caller.  */
 135         .eabi_attribute 24, 1
 136
 137 /* The thumb2 encoding is reasonably complete.  Unless suppressed, use it.  */
 138         .syntax unified
 139 # if defined(__thumb2__) && !defined(NO_THUMB)
 140         .thumb
 141 #else
 142 #  undef __thumb__
 143 #  undef __thumb2__
 144         .arm
 145 # endif
 146
 147 /* Load or store to/from address X + Y into/from R, (maybe) using T.
 148    X or Y can use T freely; T can be R if OP is a load.  The first
 149    version eschews the two-register addressing mode, while the
 150    second version uses it.  */
 151 # define LDST_INDEXED_NOINDEX(OP, R, T, X, Y)           \
 152         add     T, X, Y;                                \
 153         OP      R, [T]
 154 # define LDST_INDEXED_INDEX(OP, R, X, Y)                \
 155         OP      R, [X, Y]
 156
 157 # ifdef ARM_NO_INDEX_REGISTER
 158 /* We're never using the two-register addressing mode, so this
 159    always uses an intermediate add.  */
 160 #  define LDST_INDEXED(OP, R, T, X, Y)  LDST_INDEXED_NOINDEX (OP, R, T, X, Y)
 161 #  define LDST_PC_INDEXED(OP, R, T, X)  LDST_INDEXED_NOINDEX (OP, R, T, pc, X)
 162 # else
 163 /* The two-register addressing mode is OK, except on Thumb with pc.  */
 164 #  define LDST_INDEXED(OP, R, T, X, Y)  LDST_INDEXED_INDEX (OP, R, X, Y)
 165 #  ifdef __thumb2__
 166 #   define LDST_PC_INDEXED(OP, R, T, X) LDST_INDEXED_NOINDEX (OP, R, T, pc, X)
 167 #  else
 168 #   define LDST_PC_INDEXED(OP, R, T, X) LDST_INDEXED_INDEX (OP, R, pc, X)
 169 #  endif
 170 # endif
 171
 172 /* Load or store to/from a pc-relative EXPR into/from R, using T.  */
 173 # ifdef __thumb2__
 174 #  define LDST_PCREL(OP, R, T, EXPR) \
 175         ldr     T, 98f;                                 \
 176         .subsection 2;                                  \
 177 98:     .word   EXPR - 99f - PC_OFS;                    \
 178         .previous;                                      \
 179 99:     add     T, T, pc;                               \
 180         OP      R, [T]
 181 # elif defined (ARCH_HAS_T2) && ARM_PCREL_MOVW_OK
 182 #  define LDST_PCREL(OP, R, T, EXPR)                    \
 183         movw    T, #:lower16:EXPR - 99f - PC_OFS;       \
 184         movt    T, #:upper16:EXPR - 99f - PC_OFS;       \
 185 99:     LDST_PC_INDEXED (OP, R, T, T)
 186 # else
 187 #  define LDST_PCREL(OP, R, T, EXPR) \
 188         ldr     T, 98f;                                 \
 189         .subsection 2;                                  \
 190 98:     .word   EXPR - 99f - PC_OFS;                    \
 191         .previous;                                      \
 192 99:     OP      R, [pc, T]
 193 # endif
 194
 195 /* Load from a global SYMBOL + CONSTANT into R, using T.  */
 196 # if defined (ARCH_HAS_T2) && !defined (PIC)
 197 #  define LDR_GLOBAL(R, T, SYMBOL, CONSTANT)                            \
 198         movw    T, #:lower16:SYMBOL;                                    \
 199         movt    T, #:upper16:SYMBOL;                                    \
 200         ldr     R, [T, $CONSTANT]
 201 # elif defined (ARCH_HAS_T2) && defined (PIC) && ARM_PCREL_MOVW_OK
 202 #  define LDR_GLOBAL(R, T, SYMBOL, CONSTANT)                            \
 203         movw    R, #:lower16:_GLOBAL_OFFSET_TABLE_ - 97f - PC_OFS;      \
 204         movw    T, #:lower16:99f - 98f - PC_OFS;                        \
 205         movt    R, #:upper16:_GLOBAL_OFFSET_TABLE_ - 97f - PC_OFS;      \
 206         movt    T, #:upper16:99f - 98f - PC_OFS;                        \
 207         .pushsection .rodata.cst4, "aM", %progbits, 4;                  \
 208         .balign 4;                                                      \
 209 99:     .word   SYMBOL##(GOT);                                          \
 210         .popsection;                                                    \
 211 97:     add     R, R, pc;                                               \
 212 98:     LDST_PC_INDEXED (ldr, T, T, T);                                 \
 213         LDST_INDEXED (ldr, R, T, R, T);                                 \
 214         ldr     R, [R, $CONSTANT]
 215 # else
 216 #  define LDR_GLOBAL(R, T, SYMBOL, CONSTANT)            \
 217         ldr     T, 99f;                                 \
 218         ldr     R, 100f;                                \
 219 98:     add     T, T, pc;                               \
 220         ldr     T, [T, R];                              \
 221         .subsection 2;                                  \
 222 99:     .word   _GLOBAL_OFFSET_TABLE_ - 98b - PC_OFS;   \
 223 100:    .word   SYMBOL##(GOT);                          \
 224         .previous;                                      \
 225         ldr     R, [T, $CONSTANT]
 226 # endif
 227
 228 /* This is the same as LDR_GLOBAL, but for a SYMBOL that is known to
 229    be in the same linked object (as for one with hidden visibility).
 230    We can avoid the GOT indirection in the PIC case.  For the pure
 231    static case, LDR_GLOBAL is already optimal.  */
 232 # ifdef PIC
 233 #  define LDR_HIDDEN(R, T, SYMBOL, CONSTANT) \
 234   LDST_PCREL (ldr, R, T, SYMBOL + CONSTANT)
 235 # else
 236 #  define LDR_HIDDEN(R, T, SYMBOL, CONSTANT) \
 237   LDR_GLOBAL (R, T, SYMBOL, CONSTANT)
 238 # endif
 239
 240 /* Cope with negative memory offsets, which thumb can't encode.
 241    Use NEGOFF_ADJ_BASE to (conditionally) alter the base register,
 242    and then NEGOFF_OFF1 to use 0 for thumb and the offset for arm,
 243    or NEGOFF_OFF2 to use A-B for thumb and A for arm.  */
 244 # ifdef __thumb2__
 245 #  define NEGOFF_ADJ_BASE(R, OFF)       add R, R, $OFF
 246 #  define NEGOFF_ADJ_BASE2(D, S, OFF)   add D, S, $OFF
 247 #  define NEGOFF_OFF1(R, OFF)           [R]
 248 #  define NEGOFF_OFF2(R, OFFA, OFFB)    [R, $((OFFA) - (OFFB))]
 249 # else
 250 #  define NEGOFF_ADJ_BASE(R, OFF)
 251 #  define NEGOFF_ADJ_BASE2(D, S, OFF)   mov D, S
 252 #  define NEGOFF_OFF1(R, OFF)           [R, $OFF]
 253 #  define NEGOFF_OFF2(R, OFFA, OFFB)    [R, $OFFA]
 254 # endif
 255
 256 /* Helper to get the TLS base pointer.  The interface is that TMP is a
 257    register that may be used to hold the LR, if necessary.  TMP may be
 258    LR itself to indicate that LR need not be saved.  The base pointer
 259    is returned in R0.  Only R0 and TMP are modified.  */
 260
 261 # ifdef ARCH_HAS_HARD_TP
 262 /* If the cpu has cp15 available, use it.  */
 263 #  define GET_TLS(TMP)          mrc p15, 0, r0, c13, c0, 3
 264 # else
 265 /* At this generic level we have no tricks to pull.  Call the ABI routine.  */
 266 #  define GET_TLS(TMP)                                  \
 267         push    { r1, r2, r3, lr };                     \
 268         cfi_remember_state;                             \
 269         cfi_adjust_cfa_offset (16);                     \
 270         cfi_rel_offset (r1, 0);                         \
 271         cfi_rel_offset (r2, 4);                         \
 272         cfi_rel_offset (r3, 8);                         \
 273         cfi_rel_offset (lr, 12);                        \
 274         bl      __aeabi_read_tp;                        \
 275         pop     { r1, r2, r3, lr };                     \
 276         cfi_restore_state
 277 # endif /* ARCH_HAS_HARD_TP */
 278
 279 /* These are the directives used for EABI unwind info.
 280    Wrap them in macros so another configuration's sysdep.h
 281    file can define them away if it doesn't use EABI unwind info.  */
 282 # define eabi_fnstart           .fnstart
 283 # define eabi_fnend             .fnend
 284 # define eabi_save(...)         .save __VA_ARGS__
 285 # define eabi_cantunwind        .cantunwind
 286 # define eabi_pad(n)            .pad n
 287
 288 #endif  /* __ASSEMBLER__ */
 289
 290 /* This number is the offset from the pc at the current location.  */
 291 #ifdef __thumb__
 292 # define PC_OFS  4
 293 #else
 294 # define PC_OFS  8
 295 #endif