1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Jump label s390 support 4 * 5 * Copyright IBM Corp. 2011 6 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com> 7 */ 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_make_nop(struct jump_entry *entry, struct insn *insn) 26 { 27 /* brcl 0,0 */ 28 insn->opcode = 0xc004; 29 insn->offset = 0; 30 } 31 32 static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn) 33 { 34 /* brcl 15,offset */ 35 insn->opcode = 0xc0f4; 36 insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1; 37 } 38 39 static void jump_label_bug(struct jump_entry *entry, struct insn *expected, 40 struct insn *new) 41 { 42 unsigned char *ipc = (unsigned char *)jump_entry_code(entry); 43 unsigned char *ipe = (unsigned char *)expected; 44 unsigned char *ipn = (unsigned char *)new; 45 46 pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc); 47 pr_emerg("Found: %6ph\n", ipc); 48 pr_emerg("Expected: %6ph\n", ipe); 49 pr_emerg("New: %6ph\n", ipn); 50 panic("Corrupted kernel text"); 51 } 52 53 static struct insn orignop = { 54 .opcode = 0xc004, 55 .offset = JUMP_LABEL_NOP_OFFSET >> 1, 56 }; 57 58 static void __jump_label_transform(struct jump_entry *entry, 59 enum jump_label_type type, 60 int init) 61 { 62 void *code = (void *)jump_entry_code(entry); 63 struct insn old, new; 64 65 if (type == JUMP_LABEL_JMP) { 66 jump_label_make_nop(entry, &old); 67 jump_label_make_branch(entry, &new); 68 } else { 69 jump_label_make_branch(entry, &old); 70 jump_label_make_nop(entry, &new); 71 } 72 if (init) { 73 if (memcmp(code, &orignop, sizeof(orignop))) 74 jump_label_bug(entry, &orignop, &new); 75 } else { 76 if (memcmp(code, &old, sizeof(old))) 77 jump_label_bug(entry, &old, &new); 78 } 79 s390_kernel_write(code, &new, sizeof(new)); 80 } 81 82 static int __sm_arch_jump_label_transform(void *data) 83 { 84 struct insn_args *args = data; 85 86 __jump_label_transform(args->entry, args->type, 0); 87 return 0; 88 } 89 90 void arch_jump_label_transform(struct jump_entry *entry, 91 enum jump_label_type type) 92 { 93 struct insn_args args; 94 95 args.entry = entry; 96 args.type = type; 97 98 stop_machine_cpuslocked(__sm_arch_jump_label_transform, &args, NULL); 99 } 100 101 void arch_jump_label_transform_static(struct jump_entry *entry, 102 enum jump_label_type type) 103 { 104 __jump_label_transform(entry, type, 1); 105 } 106 107 #endif 108