| /* |
| * 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 |