sysdeps/x86/sysdep.h

   1 /* Assembler macros for x86.
   2    Copyright (C) 2017-2021 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 #ifndef _X86_SYSDEP_H
  20 #define _X86_SYSDEP_H 1
  21
  22 #include <sysdeps/generic/sysdep.h>
  23
  24 /* __CET__ is defined by GCC with Control-Flow Protection values:
  25
  26 enum cf_protection_level
  27 {
  28   CF_NONE = 0,
  29   CF_BRANCH = 1 << 0,
  30   CF_RETURN = 1 << 1,
  31   CF_FULL = CF_BRANCH | CF_RETURN,
  32   CF_SET = 1 << 2
  33 };
  34 */
  35
  36 /* Set if CF_BRANCH (IBT) is enabled.  */
  37 #define X86_FEATURE_1_IBT       (1U << 0)
  38 /* Set if CF_RETURN (SHSTK) is enabled.  */
  39 #define X86_FEATURE_1_SHSTK     (1U << 1)
  40
  41 #ifdef __CET__
  42 # define CET_ENABLED    1
  43 # define IBT_ENABLED    (__CET__ & X86_FEATURE_1_IBT)
  44 # define SHSTK_ENABLED  (__CET__ & X86_FEATURE_1_SHSTK)
  45 #else
  46 # define CET_ENABLED    0
  47 # define IBT_ENABLED    0
  48 # define SHSTK_ENABLED  0
  49 #endif
  50
  51 /* Offset for fxsave/xsave area used by _dl_runtime_resolve.  Also need
  52    space to preserve RCX, RDX, RSI, RDI, R8, R9 and RAX.  It must be
  53    aligned to 16 bytes for fxsave and 64 bytes for xsave.  */
  54 #define STATE_SAVE_OFFSET (8 * 7 + 8)
  55
  56 /* Save SSE, AVX, AVX512, mask and bound registers.  */
  57 #define STATE_SAVE_MASK \
  58   ((1 << 1) | (1 << 2) | (1 << 3) | (1 << 5) | (1 << 6) | (1 << 7))
  59
  60 #ifdef  __ASSEMBLER__
  61
  62 /* Syntactic details of assembler.  */
  63
  64 #ifdef _CET_ENDBR
  65 # define _CET_NOTRACK notrack
  66 #else
  67 # define _CET_ENDBR
  68 # define _CET_NOTRACK
  69 #endif
  70
  71 /* ELF uses byte-counts for .align, most others use log2 of count of bytes.  */
  72 #define ALIGNARG(log2) 1<<log2
  73 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name;
  74
  75 /* Define an entry point visible from C.  */
  76 #define ENTRY(name)                                                           \
  77   .globl C_SYMBOL_NAME(name);                                                 \
  78   .type C_SYMBOL_NAME(name),@function;                                        \
  79   .align ALIGNARG(4);                                                         \
  80   C_LABEL(name)                                                               \
  81   cfi_startproc;                                                              \
  82   _CET_ENDBR;                                                                 \
  83   CALL_MCOUNT
  84
  85 #undef  END
  86 #define END(name)                                                             \
  87   cfi_endproc;                                                                \
  88   ASM_SIZE_DIRECTIVE(name)
  89
  90 #define ENTRY_CHK(name) ENTRY (name)
  91 #define END_CHK(name) END (name)
  92
  93 /* Since C identifiers are not normally prefixed with an underscore
  94    on this system, the asm identifier `syscall_error' intrudes on the
  95    C name space.  Make sure we use an innocuous name.  */
  96 #define syscall_error   __syscall_error
  97 #define mcount          _mcount
  98
  99 #undef  PSEUDO_END
 100 #define PSEUDO_END(name)                                                      \
 101   END (name)
 102
 103 /* Local label name for asm code. */
 104 #ifndef L
 105 /* ELF-like local names start with `.L'.  */
 106 # define L(name)        .L##name
 107 #endif
 108
 109 #define atom_text_section .section ".text.atom", "ax"
 110
 111 #endif  /* __ASSEMBLER__ */
 112
 113 #endif  /* _X86_SYSDEP_H */