diff options
Diffstat (limited to 'arch/x86/include/asm/jump_label.h')
| -rw-r--r-- | arch/x86/include/asm/jump_label.h | 72 |
1 files changed, 54 insertions, 18 deletions
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index a5fb34fe56a4..21efc9d07ed9 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -2,6 +2,19 @@ #ifndef _ASM_X86_JUMP_LABEL_H #define _ASM_X86_JUMP_LABEL_H +#ifndef HAVE_JUMP_LABEL +/* + * For better or for worse, if jump labels (the gcc extension) are missing, + * then the entire static branch patching infrastructure is compiled out. + * If that happens, the code in here will malfunction. Raise a compiler + * error instead. + * + * In theory, jump labels and the static branch patching infrastructure + * could be decoupled to fix this. + */ +#error asm/jump_label.h included on a non-jump-label kernel +#endif + #define JUMP_LABEL_NOP_SIZE 5 #ifdef CONFIG_X86_64 @@ -20,9 +33,15 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { - asm_volatile_goto("STATIC_BRANCH_NOP l_yes=\"%l[l_yes]\" key=\"%c0\" " - "branch=\"%c1\"" - : : "i" (key), "i" (branch) : : l_yes); + asm_volatile_goto("1:" + ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t" + ".pushsection __jump_table, \"aw\" \n\t" + _ASM_ALIGN "\n\t" + ".long 1b - ., %l[l_yes] - . \n\t" + _ASM_PTR "%c0 + %c1 - .\n\t" + ".popsection \n\t" + : : "i" (key), "i" (branch) : : l_yes); + return false; l_yes: return true; @@ -30,8 +49,14 @@ l_yes: static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) { - asm_volatile_goto("STATIC_BRANCH_JMP l_yes=\"%l[l_yes]\" key=\"%c0\" " - "branch=\"%c1\"" + asm_volatile_goto("1:" + ".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t" + "2:\n\t" + ".pushsection __jump_table, \"aw\" \n\t" + _ASM_ALIGN "\n\t" + ".long 1b - ., %l[l_yes] - . \n\t" + _ASM_PTR "%c0 + %c1 - .\n\t" + ".popsection \n\t" : : "i" (key), "i" (branch) : : l_yes); return false; @@ -41,26 +66,37 @@ l_yes: #else /* __ASSEMBLY__ */ -.macro STATIC_BRANCH_NOP l_yes:req key:req branch:req -.Lstatic_branch_nop_\@: - .byte STATIC_KEY_INIT_NOP -.Lstatic_branch_no_after_\@: +.macro STATIC_JUMP_IF_TRUE target, key, def +.Lstatic_jump_\@: + .if \def + /* Equivalent to "jmp.d32 \target" */ + .byte 0xe9 + .long \target - .Lstatic_jump_after_\@ +.Lstatic_jump_after_\@: + .else + .byte STATIC_KEY_INIT_NOP + .endif .pushsection __jump_table, "aw" _ASM_ALIGN - .long .Lstatic_branch_nop_\@ - ., \l_yes - . - _ASM_PTR \key + \branch - . + .long .Lstatic_jump_\@ - ., \target - . + _ASM_PTR \key - . .popsection .endm -.macro STATIC_BRANCH_JMP l_yes:req key:req branch:req -.Lstatic_branch_jmp_\@: - .byte 0xe9 - .long \l_yes - .Lstatic_branch_jmp_after_\@ -.Lstatic_branch_jmp_after_\@: +.macro STATIC_JUMP_IF_FALSE target, key, def +.Lstatic_jump_\@: + .if \def + .byte STATIC_KEY_INIT_NOP + .else + /* Equivalent to "jmp.d32 \target" */ + .byte 0xe9 + .long \target - .Lstatic_jump_after_\@ +.Lstatic_jump_after_\@: + .endif .pushsection __jump_table, "aw" _ASM_ALIGN - .long .Lstatic_branch_jmp_\@ - ., \l_yes - . - _ASM_PTR \key + \branch - . + .long .Lstatic_jump_\@ - ., \target - . + _ASM_PTR \key + 1 - . .popsection .endm |