138 lines
3.4 KiB
C
138 lines
3.4 KiB
C
// 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 <jbaron@redhat.com>
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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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static void bug_at(const void *ip, int line)
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{
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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) %d\n", ip, ip, ip, line);
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BUG();
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}
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static const void *
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__jump_label_set_jump_code(struct jump_entry *entry, enum jump_label_type type)
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{
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const void *expect, *code;
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const void *addr, *dest;
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int line;
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addr = (void *)jump_entry_code(entry);
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dest = (void *)jump_entry_target(entry);
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code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest);
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if (type == JUMP_LABEL_JMP) {
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expect = x86_nops[5]; line = __LINE__;
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} else {
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expect = code; line = __LINE__;
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}
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if (memcmp(addr, expect, JUMP_LABEL_NOP_SIZE))
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bug_at(addr, line);
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if (type == JUMP_LABEL_NOP)
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code = x86_nops[5];
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return code;
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}
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static inline void __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 void *opcode = __jump_label_set_jump_code(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), opcode,
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JUMP_LABEL_NOP_SIZE);
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return;
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}
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text_poke_bp((void *)jump_entry_code(entry), opcode, JUMP_LABEL_NOP_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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const void *opcode;
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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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opcode = __jump_label_set_jump_code(entry, type);
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text_poke_queue((void *)jump_entry_code(entry),
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opcode, JUMP_LABEL_NOP_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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