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// SPDX-License-Identifier: GPL-2.0
/*
* Jump label s390 support
*
* Copyright IBM Corp. 2011
* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
*/
#include <linux/uaccess.h>
#include <linux/jump_label.h>
#include <linux/module.h>
#include <asm/text-patching.h>
#include <asm/ipl.h>
struct insn {
u16 opcode;
s32 offset;
} __packed;
static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn)
{
/* brcl 0,offset */
insn->opcode = 0xc004;
insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
}
static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
{
/* brcl 15,offset */
insn->opcode = 0xc0f4;
insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
}
static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
struct insn *new)
{
unsigned char *ipc = (unsigned char *)jump_entry_code(entry);
unsigned char *ipe = (unsigned char *)expected;
unsigned char *ipn = (unsigned char *)new;
pr_emerg("Jump label code mismatch at %pS [%px]\n", ipc, ipc);
pr_emerg("Found: %6ph\n", ipc);
pr_emerg("Expected: %6ph\n", ipe);
pr_emerg("New: %6ph\n", ipn);
panic("Corrupted kernel text");
}
static void jump_label_transform(struct jump_entry *entry,
enum jump_label_type type)
{
void *code = (void *)jump_entry_code(entry);
struct insn old, new;
if (type == JUMP_LABEL_JMP) {
jump_label_make_nop(entry, &old);
jump_label_make_branch(entry, &new);
} else {
jump_label_make_branch(entry, &old);
jump_label_make_nop(entry, &new);
}
if (memcmp(code, &old, sizeof(old)))
jump_label_bug(entry, &old, &new);
s390_kernel_write(code, &new, sizeof(new));
}
void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type)
{
jump_label_transform(entry, type);
text_poke_sync();
}
bool arch_jump_label_transform_queue(struct jump_entry *entry,
enum jump_label_type type)
{
jump_label_transform(entry, type);
return true;
}
void arch_jump_label_transform_apply(void)
{
text_poke_sync();
}
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