From: ard.biesheuvel@linaro.org (Ard Biesheuvel) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 5/9] x86: jump_label: switch to jump_entry accessors Date: Tue, 18 Sep 2018 23:51:40 -0700 Message-ID: <20180919065144.25010-6-ard.biesheuvel@linaro.org> (raw) In-Reply-To: <20180919065144.25010-1-ard.biesheuvel@linaro.org> In preparation of switching x86 to use place-relative references for the code, target and key members of struct jump_entry, replace direct references to the struct members with invocations of the new accessors. This will allow us to make the switch by modifying the accessors only. This incorporates a cleanup of __jump_label_transform() proposed by Peter. Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/x86/kernel/jump_label.c | 62 ++++++++------------ 1 file changed, 25 insertions(+), 37 deletions(-) diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c index eeea935e9bb5..aac0c1f7e354 100644 --- a/arch/x86/kernel/jump_label.c +++ b/arch/x86/kernel/jump_label.c @@ -42,55 +42,40 @@ static void __ref __jump_label_transform(struct jump_entry *entry, void *(*poker)(void *, const void *, size_t), int init) { - union jump_code_union code; + union jump_code_union jmp; const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP }; const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5]; + const void *expect, *code; + int line; + + jmp.jump = 0xe9; + jmp.offset = jump_entry_target(entry) - + (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE); if (early_boot_irqs_disabled) poker = text_poke_early; if (type == JUMP_LABEL_JMP) { if (init) { - /* - * Jump label is enabled for the first time. - * So we expect a default_nop... - */ - if (unlikely(memcmp((void *)entry->code, default_nop, 5) - != 0)) - bug_at((void *)entry->code, __LINE__); + expect = default_nop; line = __LINE__; } else { - /* - * ...otherwise expect an ideal_nop. Otherwise - * something went horribly wrong. - */ - if (unlikely(memcmp((void *)entry->code, ideal_nop, 5) - != 0)) - bug_at((void *)entry->code, __LINE__); + expect = ideal_nop; line = __LINE__; } - code.jump = 0xe9; - code.offset = entry->target - - (entry->code + JUMP_LABEL_NOP_SIZE); + code = &jmp.code; } else { - /* - * We are disabling this jump label. If it is not what - * we think it is, then something must have gone wrong. - * If this is the first initialization call, then we - * are converting the default nop to the ideal nop. - */ if (init) { - if (unlikely(memcmp((void *)entry->code, default_nop, 5) != 0)) - bug_at((void *)entry->code, __LINE__); + expect = default_nop; line = __LINE__; } else { - code.jump = 0xe9; - code.offset = entry->target - - (entry->code + JUMP_LABEL_NOP_SIZE); - if (unlikely(memcmp((void *)entry->code, &code, 5) != 0)) - bug_at((void *)entry->code, __LINE__); + expect = &jmp.code; line = __LINE__; } - memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE); + + code = ideal_nop; } + if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE)) + bug_at((void *)jump_entry_code(entry), line); + /* * Make text_poke_bp() a default fallback poker. * @@ -99,11 +84,14 @@ static void __ref __jump_label_transform(struct jump_entry *entry, * always nop being the 'currently valid' instruction * */ - if (poker) - (*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE); - else - text_poke_bp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE, - (void *)entry->code + JUMP_LABEL_NOP_SIZE); + if (poker) { + (*poker)((void *)jump_entry_code(entry), code, + JUMP_LABEL_NOP_SIZE); + return; + } + + text_poke_bp((void *)jump_entry_code(entry), code, JUMP_LABEL_NOP_SIZE, + (void *)jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE); } void arch_jump_label_transform(struct jump_entry *entry, -- 2.17.1
next prev parent reply index Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-09-19 6:51 [PATCH v3 0/9] add support for relative references in jump tables Ard Biesheuvel 2018-09-19 6:51 ` [PATCH v3 1/9] kernel/jump_label: abstract jump_entry member accessors Ard Biesheuvel 2018-09-19 6:51 ` [PATCH v3 2/9] kernel/jump_label: implement generic support for relative references Ard Biesheuvel 2018-09-19 6:51 ` [PATCH v3 3/9] arm64/kernel: jump_label: switch to " Ard Biesheuvel 2018-09-19 6:51 ` [PATCH v3 4/9] x86: add support for 64-bit place relative relocations Ard Biesheuvel 2018-09-19 6:51 ` Ard Biesheuvel [this message] 2018-09-19 6:51 ` [PATCH v3 6/9] x86/kernel: jump_table: use relative references Ard Biesheuvel 2018-09-19 6:51 ` [PATCH v3 7/9] jump_label: annotate entries that operate on __init code earlier Ard Biesheuvel 2018-09-19 6:51 ` [PATCH v3 8/9] jump_table: move entries into ro_after_init region Ard Biesheuvel 2018-09-30 15:42 ` Guenter Roeck 2018-09-19 6:51 ` [PATCH v3 9/9] s390/jump_label: switch to relative references Ard Biesheuvel 2018-09-19 13:08 ` [PATCH v3 0/9] add support for relative references in jump tables Peter Zijlstra 2018-09-27 15:22 ` Ard Biesheuvel 2018-09-27 15:46 ` Kees Cook
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