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 __ASSEMBLER__
 42
 43#if defined(CONFIG_MITIGATION_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 /* __ASSEMBLER__ */
 54
 55#if defined(CONFIG_MITIGATION_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 /* __ASSEMBLER__ */
 66
 67/*
 68 * Depending on -fpatchable-function-entry=N,N usage (CONFIG_CALL_PADDING) the
 69 * CFI symbol layout changes.
 70 *
 71 * Without CALL_PADDING:
 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_PADDING:
 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
124/* SYM_FUNC_START_NOALIGN -- use for global functions, w/o alignment */
125#define SYM_FUNC_START_NOALIGN(name)			\
126	SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)
127
128/* SYM_FUNC_START_LOCAL -- use for local functions */
129#define SYM_FUNC_START_LOCAL(name)			\
130	SYM_START(name, SYM_L_LOCAL, SYM_F_ALIGN)
131
132/* SYM_FUNC_START_LOCAL_NOALIGN -- use for local functions, w/o alignment */
133#define SYM_FUNC_START_LOCAL_NOALIGN(name)		\
134	SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)
135
136/* SYM_FUNC_START_WEAK -- use for weak functions */
137#define SYM_FUNC_START_WEAK(name)			\
138	SYM_START(name, SYM_L_WEAK, SYM_F_ALIGN)
139
140/* SYM_FUNC_START_WEAK_NOALIGN -- use for weak functions, w/o alignment */
141#define SYM_FUNC_START_WEAK_NOALIGN(name)		\
142	SYM_START(name, SYM_L_WEAK, SYM_A_NONE)
143
144/*
145 * Expose 'sym' to the startup code in arch/x86/boot/startup/, by emitting an
146 * alias prefixed with __pi_
147 */
148#ifdef __ASSEMBLER__
149#define SYM_PIC_ALIAS(sym)	SYM_ALIAS(__pi_ ## sym, sym, SYM_L_GLOBAL)
150#else
151#define SYM_PIC_ALIAS(sym)	extern typeof(sym) __PASTE(__pi_, sym) __alias(sym)
152#endif
153
154#endif /* _ASM_X86_LINKAGE_H */
155