1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_JUMP_LABEL_H 3 #define _ASM_X86_JUMP_LABEL_H 4 5 #ifndef HAVE_JUMP_LABEL 6 /* 7 * For better or for worse, if jump labels (the gcc extension) are missing, 8 * then the entire static branch patching infrastructure is compiled out. 9 * If that happens, the code in here will malfunction. Raise a compiler 10 * error instead. 11 * 12 * In theory, jump labels and the static branch patching infrastructure 13 * could be decoupled to fix this. 14 */ 15 #error asm/jump_label.h included on a non-jump-label kernel 16 #endif 17 18 #define JUMP_LABEL_NOP_SIZE 5 19 20 #ifdef CONFIG_X86_64 21 # define STATIC_KEY_INIT_NOP P6_NOP5_ATOMIC 22 #else 23 # define STATIC_KEY_INIT_NOP GENERIC_NOP5_ATOMIC 24 #endif 25 26 #include <asm/asm.h> 27 #include <asm/nops.h> 28 29 #ifndef __ASSEMBLY__ 30 31 #include <linux/stringify.h> 32 #include <linux/types.h> 33 34 static __always_inline bool arch_static_branch(struct static_key *key, bool branch) 35 { 36 asm_volatile_goto("1:" 37 ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t" 38 ".pushsection __jump_table, \"aw\" \n\t" 39 _ASM_ALIGN "\n\t" 40 _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t" 41 ".popsection \n\t" 42 : : "i" (key), "i" (branch) : : l_yes); 43 44 return false; 45 l_yes: 46 return true; 47 } 48 49 static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) 50 { 51 asm_volatile_goto("1:" 52 ".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t" 53 "2:\n\t" 54 ".pushsection __jump_table, \"aw\" \n\t" 55 _ASM_ALIGN "\n\t" 56 _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t" 57 ".popsection \n\t" 58 : : "i" (key), "i" (branch) : : l_yes); 59 60 return false; 61 l_yes: 62 return true; 63 } 64 65 #ifdef CONFIG_X86_64 66 typedef u64 jump_label_t; 67 #else 68 typedef u32 jump_label_t; 69 #endif 70 71 struct jump_entry { 72 jump_label_t code; 73 jump_label_t target; 74 jump_label_t key; 75 }; 76 77 #else /* __ASSEMBLY__ */ 78 79 .macro STATIC_JUMP_IF_TRUE target, key, def 80 .Lstatic_jump_\@: 81 .if \def 82 /* Equivalent to "jmp.d32 \target" */ 83 .byte 0xe9 84 .long \target - .Lstatic_jump_after_\@ 85 .Lstatic_jump_after_\@: 86 .else 87 .byte STATIC_KEY_INIT_NOP 88 .endif 89 .pushsection __jump_table, "aw" 90 _ASM_ALIGN 91 _ASM_PTR .Lstatic_jump_\@, \target, \key 92 .popsection 93 .endm 94 95 .macro STATIC_JUMP_IF_FALSE target, key, def 96 .Lstatic_jump_\@: 97 .if \def 98 .byte STATIC_KEY_INIT_NOP 99 .else 100 /* Equivalent to "jmp.d32 \target" */ 101 .byte 0xe9 102 .long \target - .Lstatic_jump_after_\@ 103 .Lstatic_jump_after_\@: 104 .endif 105 .pushsection __jump_table, "aw" 106 _ASM_ALIGN 107 _ASM_PTR .Lstatic_jump_\@, \target, \key + 1 108 .popsection 109 .endm 110 111 #endif /* __ASSEMBLY__ */ 112 113 #endif 114