From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/x86/kernel/jump_label.c | 148 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) create mode 100644 arch/x86/kernel/jump_label.c (limited to 'arch/x86/kernel/jump_label.c') diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c new file mode 100644 index 000000000..f5b8ef02d --- /dev/null +++ b/arch/x86/kernel/jump_label.c @@ -0,0 +1,148 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * jump label x86 support + * + * Copyright (C) 2009 Jason Baron + * + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +int arch_jump_entry_size(struct jump_entry *entry) +{ + struct insn insn = {}; + + insn_decode_kernel(&insn, (void *)jump_entry_code(entry)); + BUG_ON(insn.length != 2 && insn.length != 5); + + return insn.length; +} + +struct jump_label_patch { + const void *code; + int size; +}; + +static struct jump_label_patch +__jump_label_patch(struct jump_entry *entry, enum jump_label_type type) +{ + const void *expect, *code, *nop; + const void *addr, *dest; + int size; + + addr = (void *)jump_entry_code(entry); + dest = (void *)jump_entry_target(entry); + + size = arch_jump_entry_size(entry); + switch (size) { + case JMP8_INSN_SIZE: + code = text_gen_insn(JMP8_INSN_OPCODE, addr, dest); + nop = x86_nops[size]; + break; + + case JMP32_INSN_SIZE: + code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest); + nop = x86_nops[size]; + break; + + default: BUG(); + } + + if (type == JUMP_LABEL_JMP) + expect = nop; + else + expect = code; + + if (memcmp(addr, expect, size)) { + /* + * The location is not an op that we were expecting. + * Something went wrong. Crash the box, as something could be + * corrupting the kernel. + */ + pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph != %5ph)) size:%d type:%d\n", + addr, addr, addr, expect, size, type); + BUG(); + } + + if (type == JUMP_LABEL_NOP) + code = nop; + + return (struct jump_label_patch){.code = code, .size = size}; +} + +static __always_inline void +__jump_label_transform(struct jump_entry *entry, + enum jump_label_type type, + int init) +{ + const struct jump_label_patch jlp = __jump_label_patch(entry, type); + + /* + * As long as only a single processor is running and the code is still + * not marked as RO, text_poke_early() can be used; Checking that + * system_state is SYSTEM_BOOTING guarantees it. It will be set to + * SYSTEM_SCHEDULING before other cores are awaken and before the + * code is write-protected. + * + * At the time the change is being done, just ignore whether we + * are doing nop -> jump or jump -> nop transition, and assume + * always nop being the 'currently valid' instruction + */ + if (init || system_state == SYSTEM_BOOTING) { + text_poke_early((void *)jump_entry_code(entry), jlp.code, jlp.size); + return; + } + + text_poke_bp((void *)jump_entry_code(entry), jlp.code, jlp.size, NULL); +} + +static void __ref jump_label_transform(struct jump_entry *entry, + enum jump_label_type type, + int init) +{ + mutex_lock(&text_mutex); + __jump_label_transform(entry, type, init); + mutex_unlock(&text_mutex); +} + +void arch_jump_label_transform(struct jump_entry *entry, + enum jump_label_type type) +{ + jump_label_transform(entry, type, 0); +} + +bool arch_jump_label_transform_queue(struct jump_entry *entry, + enum jump_label_type type) +{ + struct jump_label_patch jlp; + + if (system_state == SYSTEM_BOOTING) { + /* + * Fallback to the non-batching mode. + */ + arch_jump_label_transform(entry, type); + return true; + } + + mutex_lock(&text_mutex); + jlp = __jump_label_patch(entry, type); + text_poke_queue((void *)jump_entry_code(entry), jlp.code, jlp.size, NULL); + mutex_unlock(&text_mutex); + return true; +} + +void arch_jump_label_transform_apply(void) +{ + mutex_lock(&text_mutex); + text_poke_finish(); + mutex_unlock(&text_mutex); +} -- cgit v1.2.3