1 #ifndef _ASM_POWERPC_CODE_PATCHING_H 2 #define _ASM_POWERPC_CODE_PATCHING_H 3 4 /* 5 * Copyright 2008, Michael Ellerman, IBM Corporation. 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 */ 12 13 #include <asm/types.h> 14 #include <asm/ppc-opcode.h> 15 #include <linux/string.h> 16 #include <linux/kallsyms.h> 17 18 /* Flags for create_branch: 19 * "b" == create_branch(addr, target, 0); 20 * "ba" == create_branch(addr, target, BRANCH_ABSOLUTE); 21 * "bl" == create_branch(addr, target, BRANCH_SET_LINK); 22 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK); 23 */ 24 #define BRANCH_SET_LINK 0x1 25 #define BRANCH_ABSOLUTE 0x2 26 27 bool is_offset_in_branch_range(long offset); 28 unsigned int create_branch(const unsigned int *addr, 29 unsigned long target, int flags); 30 unsigned int create_cond_branch(const unsigned int *addr, 31 unsigned long target, int flags); 32 int patch_branch(unsigned int *addr, unsigned long target, int flags); 33 int patch_instruction(unsigned int *addr, unsigned int instr); 34 35 int instr_is_relative_branch(unsigned int instr); 36 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr); 37 unsigned long branch_target(const unsigned int *instr); 38 unsigned int translate_branch(const unsigned int *dest, 39 const unsigned int *src); 40 extern bool is_conditional_branch(unsigned int instr); 41 #ifdef CONFIG_PPC_BOOK3E_64 42 void __patch_exception(int exc, unsigned long addr); 43 #define patch_exception(exc, name) do { \ 44 extern unsigned int name; \ 45 __patch_exception((exc), (unsigned long)&name); \ 46 } while (0) 47 #endif 48 49 #define OP_RT_RA_MASK 0xffff0000UL 50 #define LIS_R2 0x3c020000UL 51 #define ADDIS_R2_R12 0x3c4c0000UL 52 #define ADDI_R2_R2 0x38420000UL 53 54 static inline unsigned long ppc_function_entry(void *func) 55 { 56 #ifdef PPC64_ELF_ABI_v2 57 u32 *insn = func; 58 59 /* 60 * A PPC64 ABIv2 function may have a local and a global entry 61 * point. We need to use the local entry point when patching 62 * functions, so identify and step over the global entry point 63 * sequence. 64 * 65 * The global entry point sequence is always of the form: 66 * 67 * addis r2,r12,XXXX 68 * addi r2,r2,XXXX 69 * 70 * A linker optimisation may convert the addis to lis: 71 * 72 * lis r2,XXXX 73 * addi r2,r2,XXXX 74 */ 75 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) || 76 ((*insn & OP_RT_RA_MASK) == LIS_R2)) && 77 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2)) 78 return (unsigned long)(insn + 2); 79 else 80 return (unsigned long)func; 81 #elif defined(PPC64_ELF_ABI_v1) 82 /* 83 * On PPC64 ABIv1 the function pointer actually points to the 84 * function's descriptor. The first entry in the descriptor is the 85 * address of the function text. 86 */ 87 return ((func_descr_t *)func)->entry; 88 #else 89 return (unsigned long)func; 90 #endif 91 } 92 93 static inline unsigned long ppc_global_function_entry(void *func) 94 { 95 #ifdef PPC64_ELF_ABI_v2 96 /* PPC64 ABIv2 the global entry point is at the address */ 97 return (unsigned long)func; 98 #else 99 /* All other cases there is no change vs ppc_function_entry() */ 100 return ppc_function_entry(func); 101 #endif 102 } 103 104 /* 105 * Wrapper around kallsyms_lookup() to return function entry address: 106 * - For ABIv1, we lookup the dot variant. 107 * - For ABIv2, we return the local entry point. 108 */ 109 static inline unsigned long ppc_kallsyms_lookup_name(const char *name) 110 { 111 unsigned long addr; 112 #ifdef PPC64_ELF_ABI_v1 113 /* check for dot variant */ 114 char dot_name[1 + KSYM_NAME_LEN]; 115 bool dot_appended = false; 116 117 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) 118 return 0; 119 120 if (name[0] != '.') { 121 dot_name[0] = '.'; 122 dot_name[1] = '\0'; 123 strlcat(dot_name, name, sizeof(dot_name)); 124 dot_appended = true; 125 } else { 126 dot_name[0] = '\0'; 127 strlcat(dot_name, name, sizeof(dot_name)); 128 } 129 addr = kallsyms_lookup_name(dot_name); 130 if (!addr && dot_appended) 131 /* Let's try the original non-dot symbol lookup */ 132 addr = kallsyms_lookup_name(name); 133 #elif defined(PPC64_ELF_ABI_v2) 134 addr = kallsyms_lookup_name(name); 135 if (addr) 136 addr = ppc_function_entry((void *)addr); 137 #else 138 addr = kallsyms_lookup_name(name); 139 #endif 140 return addr; 141 } 142 143 #ifdef CONFIG_PPC64 144 /* 145 * Some instruction encodings commonly used in dynamic ftracing 146 * and function live patching. 147 */ 148 149 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */ 150 #ifdef PPC64_ELF_ABI_v2 151 #define R2_STACK_OFFSET 24 152 #else 153 #define R2_STACK_OFFSET 40 154 #endif 155 156 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \ 157 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET) 158 159 /* usually preceded by a mflr r0 */ 160 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \ 161 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF) 162 #endif /* CONFIG_PPC64 */ 163 164 #endif /* _ASM_POWERPC_CODE_PATCHING_H */ 165