arch/x86/include/asm/linkage.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_LINKAGE_H
   3 #define _ASM_X86_LINKAGE_H
   4
   5 #include <linux/stringify.h>
   6 #include <asm/ibt.h>
   7
   8 #undef notrace
   9 #define notrace __attribute__((no_instrument_function))
  10
  11 #ifdef CONFIG_64BIT
  12 /*
  13  * The generic version tends to create spurious ENDBR instructions under
  14  * certain conditions.
  15  */
  16 #define _THIS_IP_ ({ unsigned long __here; asm ("lea 0(%%rip), %0" : "=r" (__here)); __here; })
  17 #endif
  18
  19 #ifdef CONFIG_X86_32
  20 #define asmlinkage CPP_ASMLINKAGE __attribute__((regparm(0)))
  21 #endif /* CONFIG_X86_32 */
  22
  23 #define __ALIGN         .balign CONFIG_FUNCTION_ALIGNMENT, 0x90;
  24 #define __ALIGN_STR     __stringify(__ALIGN)
  25
  26 #if defined(CONFIG_CALL_PADDING) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
  27 #define FUNCTION_PADDING        .skip CONFIG_FUNCTION_ALIGNMENT, 0x90;
  28 #else
  29 #define FUNCTION_PADDING
  30 #endif
  31
  32 #if (CONFIG_FUNCTION_ALIGNMENT > 8) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
  33 # define __FUNC_ALIGN           __ALIGN; FUNCTION_PADDING
  34 #else
  35 # define __FUNC_ALIGN           __ALIGN
  36 #endif
  37
  38 #define ASM_FUNC_ALIGN          __stringify(__FUNC_ALIGN)
  39 #define SYM_F_ALIGN             __FUNC_ALIGN
  40
  41 #ifdef __ASSEMBLY__
  42
  43 #if defined(CONFIG_RETHUNK) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
  44 #define RET     jmp __x86_return_thunk
  45 #else /* CONFIG_MITIGATION_RETPOLINE */
  46 #ifdef CONFIG_MITIGATION_SLS
  47 #define RET     ret; int3
  48 #else
  49 #define RET     ret
  50 #endif
  51 #endif /* CONFIG_MITIGATION_RETPOLINE */
  52
  53 #else /* __ASSEMBLY__ */
  54
  55 #if defined(CONFIG_RETHUNK) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
  56 #define ASM_RET "jmp __x86_return_thunk\n\t"
  57 #else /* CONFIG_MITIGATION_RETPOLINE */
  58 #ifdef CONFIG_MITIGATION_SLS
  59 #define ASM_RET "ret; int3\n\t"
  60 #else
  61 #define ASM_RET "ret\n\t"
  62 #endif
  63 #endif /* CONFIG_MITIGATION_RETPOLINE */
  64
  65 #endif /* __ASSEMBLY__ */
  66
  67 /*
  68  * Depending on -fpatchable-function-entry=N,N usage (CONFIG_CALL_PADDING) the
  69  * CFI symbol layout changes.
  70  *
  71  * Without CALL_THUNKS:
  72  *
  73  *      .align  FUNCTION_ALIGNMENT
  74  * __cfi_##name:
  75  *      .skip   FUNCTION_PADDING, 0x90
  76  *      .byte   0xb8
  77  *      .long   __kcfi_typeid_##name
  78  * name:
  79  *
  80  * With CALL_THUNKS:
  81  *
  82  *      .align FUNCTION_ALIGNMENT
  83  * __cfi_##name:
  84  *      .byte   0xb8
  85  *      .long   __kcfi_typeid_##name
  86  *      .skip   FUNCTION_PADDING, 0x90
  87  * name:
  88  *
  89  * In both cases the whole thing is FUNCTION_ALIGNMENT aligned and sized.
  90  */
  91
  92 #ifdef CONFIG_CALL_PADDING
  93 #define CFI_PRE_PADDING
  94 #define CFI_POST_PADDING        .skip   CONFIG_FUNCTION_PADDING_BYTES, 0x90;
  95 #else
  96 #define CFI_PRE_PADDING         .skip   CONFIG_FUNCTION_PADDING_BYTES, 0x90;
  97 #define CFI_POST_PADDING
  98 #endif
  99
 100 #define __CFI_TYPE(name)                                        \
 101         SYM_START(__cfi_##name, SYM_L_LOCAL, SYM_A_NONE)        \
 102         CFI_PRE_PADDING                                         \
 103         .byte 0xb8 ASM_NL                                       \
 104         .long __kcfi_typeid_##name ASM_NL                       \
 105         CFI_POST_PADDING                                        \
 106         SYM_FUNC_END(__cfi_##name)
 107
 108 /* UML needs to be able to override memcpy() and friends for KASAN. */
 109 #ifdef CONFIG_UML
 110 # define SYM_FUNC_ALIAS_MEMFUNC SYM_FUNC_ALIAS_WEAK
 111 #else
 112 # define SYM_FUNC_ALIAS_MEMFUNC SYM_FUNC_ALIAS
 113 #endif
 114
 115 /* SYM_TYPED_FUNC_START -- use for indirectly called globals, w/ CFI type */
 116 #define SYM_TYPED_FUNC_START(name)                              \
 117         SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_F_ALIGN)        \
 118         ENDBR
 119
 120 /* SYM_FUNC_START -- use for global functions */
 121 #define SYM_FUNC_START(name)                            \
 122         SYM_START(name, SYM_L_GLOBAL, SYM_F_ALIGN)      \
 123         ENDBR
 124
 125 /* SYM_FUNC_START_NOALIGN -- use for global functions, w/o alignment */
 126 #define SYM_FUNC_START_NOALIGN(name)                    \
 127         SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)       \
 128         ENDBR
 129
 130 /* SYM_FUNC_START_LOCAL -- use for local functions */
 131 #define SYM_FUNC_START_LOCAL(name)                      \
 132         SYM_START(name, SYM_L_LOCAL, SYM_F_ALIGN)       \
 133         ENDBR
 134
 135 /* SYM_FUNC_START_LOCAL_NOALIGN -- use for local functions, w/o alignment */
 136 #define SYM_FUNC_START_LOCAL_NOALIGN(name)              \
 137         SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)        \
 138         ENDBR
 139
 140 /* SYM_FUNC_START_WEAK -- use for weak functions */
 141 #define SYM_FUNC_START_WEAK(name)                       \
 142         SYM_START(name, SYM_L_WEAK, SYM_F_ALIGN)        \
 143         ENDBR
 144
 145 /* SYM_FUNC_START_WEAK_NOALIGN -- use for weak functions, w/o alignment */
 146 #define SYM_FUNC_START_WEAK_NOALIGN(name)               \
 147         SYM_START(name, SYM_L_WEAK, SYM_A_NONE)         \
 148         ENDBR
 149
 150 #endif /* _ASM_X86_LINKAGE_H */
 151