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 int raw_patch_instruction(unsigned int *addr, unsigned int instr); 35 36 int instr_is_relative_branch(unsigned int instr); 37 int instr_is_relative_link_branch(unsigned int instr); 38 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr); 39 unsigned long branch_target(const unsigned int *instr); 40 unsigned int translate_branch(const unsigned int *dest, 41 const unsigned int *src); 42 extern bool is_conditional_branch(unsigned int instr); 43 #ifdef CONFIG_PPC_BOOK3E_64 44 void __patch_exception(int exc, unsigned long addr); 45 #define patch_exception(exc, name) do { \ 46 extern unsigned int name; \ 47 __patch_exception((exc), (unsigned long)&name); \ 48 } while (0) 49 #endif 50 51 #define OP_RT_RA_MASK 0xffff0000UL 52 #define LIS_R2 0x3c020000UL 53 #define ADDIS_R2_R12 0x3c4c0000UL 54 #define ADDI_R2_R2 0x38420000UL 55 56 static inline unsigned long ppc_function_entry(void *func) 57 { 58 #ifdef PPC64_ELF_ABI_v2 59 u32 *insn = func; 60 61 /* 62 * A PPC64 ABIv2 function may have a local and a global entry 63 * point. We need to use the local entry point when patching 64 * functions, so identify and step over the global entry point 65 * sequence. 66 * 67 * The global entry point sequence is always of the form: 68 * 69 * addis r2,r12,XXXX 70 * addi r2,r2,XXXX 71 * 72 * A linker optimisation may convert the addis to lis: 73 * 74 * lis r2,XXXX 75 * addi r2,r2,XXXX 76 */ 77 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) || 78 ((*insn & OP_RT_RA_MASK) == LIS_R2)) && 79 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2)) 80 return (unsigned long)(insn + 2); 81 else 82 return (unsigned long)func; 83 #elif defined(PPC64_ELF_ABI_v1) 84 /* 85 * On PPC64 ABIv1 the function pointer actually points to the 86 * function's descriptor. The first entry in the descriptor is the 87 * address of the function text. 88 */ 89 return ((func_descr_t *)func)->entry; 90 #else 91 return (unsigned long)func; 92 #endif 93 } 94 95 static inline unsigned long ppc_global_function_entry(void *func) 96 { 97 #ifdef PPC64_ELF_ABI_v2 98 /* PPC64 ABIv2 the global entry point is at the address */ 99 return (unsigned long)func; 100 #else 101 /* All other cases there is no change vs ppc_function_entry() */ 102 return ppc_function_entry(func); 103 #endif 104 } 105 106 /* 107 * Wrapper around kallsyms_lookup() to return function entry address: 108 * - For ABIv1, we lookup the dot variant. 109 * - For ABIv2, we return the local entry point. 110 */ 111 static inline unsigned long ppc_kallsyms_lookup_name(const char *name) 112 { 113 unsigned long addr; 114 #ifdef PPC64_ELF_ABI_v1 115 /* check for dot variant */ 116 char dot_name[1 + KSYM_NAME_LEN]; 117 bool dot_appended = false; 118 119 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) 120 return 0; 121 122 if (name[0] != '.') { 123 dot_name[0] = '.'; 124 dot_name[1] = '\0'; 125 strlcat(dot_name, name, sizeof(dot_name)); 126 dot_appended = true; 127 } else { 128 dot_name[0] = '\0'; 129 strlcat(dot_name, name, sizeof(dot_name)); 130 } 131 addr = kallsyms_lookup_name(dot_name); 132 if (!addr && dot_appended) 133 /* Let's try the original non-dot symbol lookup */ 134 addr = kallsyms_lookup_name(name); 135 #elif defined(PPC64_ELF_ABI_v2) 136 addr = kallsyms_lookup_name(name); 137 if (addr) 138 addr = ppc_function_entry((void *)addr); 139 #else 140 addr = kallsyms_lookup_name(name); 141 #endif 142 return addr; 143 } 144 145 #ifdef CONFIG_PPC64 146 /* 147 * Some instruction encodings commonly used in dynamic ftracing 148 * and function live patching. 149 */ 150 151 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */ 152 #ifdef PPC64_ELF_ABI_v2 153 #define R2_STACK_OFFSET 24 154 #else 155 #define R2_STACK_OFFSET 40 156 #endif 157 158 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \ 159 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET) 160 161 /* usually preceded by a mflr r0 */ 162 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \ 163 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF) 164 #endif /* CONFIG_PPC64 */ 165 166 #endif /* _ASM_POWERPC_CODE_PATCHING_H */ 167