1 /* 2 * Jump label s390 support 3 * 4 * Copyright IBM Corp. 2011 5 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com> 6 */ 7 #include <linux/module.h> 8 #include <linux/uaccess.h> 9 #include <linux/stop_machine.h> 10 #include <linux/jump_label.h> 11 #include <asm/ipl.h> 12 13 #ifdef HAVE_JUMP_LABEL 14 15 struct insn { 16 u16 opcode; 17 s32 offset; 18 } __packed; 19 20 struct insn_args { 21 struct jump_entry *entry; 22 enum jump_label_type type; 23 }; 24 25 static void __jump_label_transform(struct jump_entry *entry, 26 enum jump_label_type type) 27 { 28 struct insn insn; 29 int rc; 30 31 if (type == JUMP_LABEL_ENABLE) { 32 /* brcl 15,offset */ 33 insn.opcode = 0xc0f4; 34 insn.offset = (entry->target - entry->code) >> 1; 35 } else { 36 /* brcl 0,0 */ 37 insn.opcode = 0xc004; 38 insn.offset = 0; 39 } 40 41 rc = probe_kernel_write((void *)entry->code, &insn, JUMP_LABEL_NOP_SIZE); 42 WARN_ON_ONCE(rc < 0); 43 } 44 45 static int __sm_arch_jump_label_transform(void *data) 46 { 47 struct insn_args *args = data; 48 49 __jump_label_transform(args->entry, args->type); 50 return 0; 51 } 52 53 void arch_jump_label_transform(struct jump_entry *entry, 54 enum jump_label_type type) 55 { 56 struct insn_args args; 57 58 args.entry = entry; 59 args.type = type; 60 61 stop_machine(__sm_arch_jump_label_transform, &args, NULL); 62 } 63 64 void arch_jump_label_transform_static(struct jump_entry *entry, 65 enum jump_label_type type) 66 { 67 __jump_label_transform(entry, type); 68 } 69 70 #endif 71