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/*
* Jump label s390 support
*
* Copyright IBM Corp. 2011
* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
*/
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/stop_machine.h>
#include <linux/jump_label.h>
#include <asm/ipl.h>
#ifdef HAVE_JUMP_LABEL
struct insn {
u16 opcode;
s32 offset;
} __packed;
struct insn_args {
struct jump_entry *entry;
enum jump_label_type type;
};
static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn)
{
/* brcl 0,0 */
insn->opcode = 0xc004;
insn->offset = 0;
}
static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
{
/* brcl 15,offset */
insn->opcode = 0xc0f4;
insn->offset = (entry->target - entry->code) >> 1;
}
static void jump_label_bug(struct jump_entry *entry, struct insn *insn)
{
unsigned char *ipc = (unsigned char *)entry->code;
unsigned char *ipe = (unsigned char *)insn;
pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc);
pr_emerg("Found: %02x %02x %02x %02x %02x %02x\n",
ipc[0], ipc[1], ipc[2], ipc[3], ipc[4], ipc[5]);
pr_emerg("Expected: %02x %02x %02x %02x %02x %02x\n",
ipe[0], ipe[1], ipe[2], ipe[3], ipe[4], ipe[5]);
panic("Corrupted kernel text");
}
static struct insn orignop = {
.opcode = 0xc004,
.offset = JUMP_LABEL_NOP_OFFSET >> 1,
};
static void __jump_label_transform(struct jump_entry *entry,
enum jump_label_type type,
int init)
{
struct insn old, new;
if (type == JUMP_LABEL_ENABLE) {
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 (init) {
if (memcmp((void *)entry->code, &orignop, sizeof(orignop)))
jump_label_bug(entry, &old);
} else {
if (memcmp((void *)entry->code, &old, sizeof(old)))
jump_label_bug(entry, &old);
}
probe_kernel_write((void *)entry->code, &new, sizeof(new));
}
static int __sm_arch_jump_label_transform(void *data)
{
struct insn_args *args = data;
__jump_label_transform(args->entry, args->type, 0);
return 0;
}
void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type)
{
struct insn_args args;
args.entry = entry;
args.type = type;
stop_machine(__sm_arch_jump_label_transform, &args, NULL);
}
void arch_jump_label_transform_static(struct jump_entry *entry,
enum jump_label_type type)
{
__jump_label_transform(entry, type, 1);
}
#endif
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