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161 lines
3.9 KiB
161 lines
3.9 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* jump label x86 support |
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* |
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* Copyright (C) 2009 Jason Baron <[email protected]> |
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* |
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*/ |
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#include <linux/jump_label.h> |
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#include <linux/memory.h> |
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#include <linux/uaccess.h> |
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#include <linux/module.h> |
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#include <linux/list.h> |
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#include <linux/jhash.h> |
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#include <linux/cpu.h> |
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#include <asm/kprobes.h> |
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#include <asm/alternative.h> |
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#include <asm/text-patching.h> |
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#include <asm/insn.h> |
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int arch_jump_entry_size(struct jump_entry *entry) |
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{ |
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struct insn insn = {}; |
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insn_decode_kernel(&insn, (void *)jump_entry_code(entry)); |
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BUG_ON(insn.length != 2 && insn.length != 5); |
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return insn.length; |
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} |
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struct jump_label_patch { |
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const void *code; |
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int size; |
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}; |
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static struct jump_label_patch |
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__jump_label_patch(struct jump_entry *entry, enum jump_label_type type) |
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{ |
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const void *expect, *code, *nop; |
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const void *addr, *dest; |
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int size; |
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addr = (void *)jump_entry_code(entry); |
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dest = (void *)jump_entry_target(entry); |
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size = arch_jump_entry_size(entry); |
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switch (size) { |
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case JMP8_INSN_SIZE: |
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code = text_gen_insn(JMP8_INSN_OPCODE, addr, dest); |
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nop = x86_nops[size]; |
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break; |
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case JMP32_INSN_SIZE: |
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code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest); |
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nop = x86_nops[size]; |
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break; |
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default: BUG(); |
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} |
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if (type == JUMP_LABEL_JMP) |
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expect = nop; |
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else |
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expect = code; |
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if (memcmp(addr, expect, size)) { |
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/* |
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* The location is not an op that we were expecting. |
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* Something went wrong. Crash the box, as something could be |
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* corrupting the kernel. |
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*/ |
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pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph != %5ph)) size:%d type:%d\n", |
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addr, addr, addr, expect, size, type); |
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BUG(); |
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} |
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if (type == JUMP_LABEL_NOP) |
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code = nop; |
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return (struct jump_label_patch){.code = code, .size = size}; |
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} |
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static __always_inline void |
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__jump_label_transform(struct jump_entry *entry, |
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enum jump_label_type type, |
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int init) |
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{ |
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const struct jump_label_patch jlp = __jump_label_patch(entry, type); |
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/* |
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* As long as only a single processor is running and the code is still |
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* not marked as RO, text_poke_early() can be used; Checking that |
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* system_state is SYSTEM_BOOTING guarantees it. It will be set to |
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* SYSTEM_SCHEDULING before other cores are awaken and before the |
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* code is write-protected. |
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* |
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* At the time the change is being done, just ignore whether we |
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* are doing nop -> jump or jump -> nop transition, and assume |
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* always nop being the 'currently valid' instruction |
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*/ |
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if (init || system_state == SYSTEM_BOOTING) { |
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text_poke_early((void *)jump_entry_code(entry), jlp.code, jlp.size); |
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return; |
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} |
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text_poke_bp((void *)jump_entry_code(entry), jlp.code, jlp.size, NULL); |
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} |
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static void __ref jump_label_transform(struct jump_entry *entry, |
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enum jump_label_type type, |
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int init) |
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{ |
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mutex_lock(&text_mutex); |
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__jump_label_transform(entry, type, init); |
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mutex_unlock(&text_mutex); |
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} |
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void arch_jump_label_transform(struct jump_entry *entry, |
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enum jump_label_type type) |
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{ |
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jump_label_transform(entry, type, 0); |
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} |
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bool arch_jump_label_transform_queue(struct jump_entry *entry, |
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enum jump_label_type type) |
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{ |
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struct jump_label_patch jlp; |
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if (system_state == SYSTEM_BOOTING) { |
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/* |
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* Fallback to the non-batching mode. |
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*/ |
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arch_jump_label_transform(entry, type); |
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return true; |
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} |
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mutex_lock(&text_mutex); |
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jlp = __jump_label_patch(entry, type); |
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text_poke_queue((void *)jump_entry_code(entry), jlp.code, jlp.size, NULL); |
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mutex_unlock(&text_mutex); |
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return true; |
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} |
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void arch_jump_label_transform_apply(void) |
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{ |
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mutex_lock(&text_mutex); |
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text_poke_finish(); |
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mutex_unlock(&text_mutex); |
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} |
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static enum { |
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JL_STATE_START, |
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JL_STATE_NO_UPDATE, |
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JL_STATE_UPDATE, |
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} jlstate __initdata_or_module = JL_STATE_START; |
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__init_or_module void arch_jump_label_transform_static(struct jump_entry *entry, |
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enum jump_label_type type) |
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{ |
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if (jlstate == JL_STATE_UPDATE) |
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jump_label_transform(entry, type, 1); |
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}
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