131 строка
3.3 KiB
C
131 строка
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* jump label x86 support
|
|
*
|
|
* Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
|
|
*
|
|
*/
|
|
#include <linux/jump_label.h>
|
|
#include <linux/memory.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/module.h>
|
|
#include <linux/list.h>
|
|
#include <linux/jhash.h>
|
|
#include <linux/cpu.h>
|
|
#include <asm/kprobes.h>
|
|
#include <asm/alternative.h>
|
|
#include <asm/text-patching.h>
|
|
|
|
union jump_code_union {
|
|
char code[JUMP_LABEL_NOP_SIZE];
|
|
struct {
|
|
char jump;
|
|
int offset;
|
|
} __attribute__((packed));
|
|
};
|
|
|
|
static void bug_at(unsigned char *ip, int line)
|
|
{
|
|
/*
|
|
* 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) %d\n", ip, ip, ip, line);
|
|
BUG();
|
|
}
|
|
|
|
static void __ref __jump_label_transform(struct jump_entry *entry,
|
|
enum jump_label_type type,
|
|
void *(*poker)(void *, const void *, size_t),
|
|
int init)
|
|
{
|
|
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) {
|
|
expect = default_nop; line = __LINE__;
|
|
} else {
|
|
expect = ideal_nop; line = __LINE__;
|
|
}
|
|
|
|
code = &jmp.code;
|
|
} else {
|
|
if (init) {
|
|
expect = default_nop; line = __LINE__;
|
|
} else {
|
|
expect = &jmp.code; line = __LINE__;
|
|
}
|
|
|
|
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.
|
|
*
|
|
* 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 (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,
|
|
enum jump_label_type type)
|
|
{
|
|
mutex_lock(&text_mutex);
|
|
__jump_label_transform(entry, type, NULL, 0);
|
|
mutex_unlock(&text_mutex);
|
|
}
|
|
|
|
static enum {
|
|
JL_STATE_START,
|
|
JL_STATE_NO_UPDATE,
|
|
JL_STATE_UPDATE,
|
|
} jlstate __initdata_or_module = JL_STATE_START;
|
|
|
|
__init_or_module void arch_jump_label_transform_static(struct jump_entry *entry,
|
|
enum jump_label_type type)
|
|
{
|
|
/*
|
|
* This function is called at boot up and when modules are
|
|
* first loaded. Check if the default nop, the one that is
|
|
* inserted at compile time, is the ideal nop. If it is, then
|
|
* we do not need to update the nop, and we can leave it as is.
|
|
* If it is not, then we need to update the nop to the ideal nop.
|
|
*/
|
|
if (jlstate == JL_STATE_START) {
|
|
const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
|
|
const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
|
|
|
|
if (memcmp(ideal_nop, default_nop, 5) != 0)
|
|
jlstate = JL_STATE_UPDATE;
|
|
else
|
|
jlstate = JL_STATE_NO_UPDATE;
|
|
}
|
|
if (jlstate == JL_STATE_UPDATE)
|
|
__jump_label_transform(entry, type, text_poke_early, 1);
|
|
}
|