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 ".long 1b - ., %l[l_yes] - . \n\t" 41 _ASM_PTR "%c0 + %c1 - .\n\t" 42 ".popsection \n\t" 43 : : "i" (key), "i" (branch) : : l_yes); 44 45 return false; 46 l_yes: 47 return true; 48 } 49 50 static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) 51 { 52 asm_volatile_goto("1:" 53 ".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t" 54 "2:\n\t" 55 ".pushsection __jump_table, \"aw\" \n\t" 56 _ASM_ALIGN "\n\t" 57 ".long 1b - ., %l[l_yes] - . \n\t" 58 _ASM_PTR "%c0 + %c1 - .\n\t" 59 ".popsection \n\t" 60 : : "i" (key), "i" (branch) : : l_yes); 61 62 return false; 63 l_yes: 64 return true; 65 } 66 67 #else /* __ASSEMBLY__ */ 68 69 .macro STATIC_JUMP_IF_TRUE target, key, def 70 .Lstatic_jump_\@: 71 .if \def 72 /* Equivalent to "jmp.d32 \target" */ 73 .byte 0xe9 74 .long \target - .Lstatic_jump_after_\@ 75 .Lstatic_jump_after_\@: 76 .else 77 .byte STATIC_KEY_INIT_NOP 78 .endif 79 .pushsection __jump_table, "aw" 80 _ASM_ALIGN 81 .long .Lstatic_jump_\@ - ., \target - . 82 _ASM_PTR \key - . 83 .popsection 84 .endm 85 86 .macro STATIC_JUMP_IF_FALSE target, key, def 87 .Lstatic_jump_\@: 88 .if \def 89 .byte STATIC_KEY_INIT_NOP 90 .else 91 /* Equivalent to "jmp.d32 \target" */ 92 .byte 0xe9 93 .long \target - .Lstatic_jump_after_\@ 94 .Lstatic_jump_after_\@: 95 .endif 96 .pushsection __jump_table, "aw" 97 _ASM_ALIGN 98 .long .Lstatic_jump_\@ - ., \target - . 99 _ASM_PTR \key + 1 - . 100 .popsection 101 .endm 102 103 #endif /* __ASSEMBLY__ */ 104 105 #endif 106