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 #include <asm/asm-compat.h> 18 19 /* Flags for create_branch: 20 * "b" == create_branch(addr, target, 0); 21 * "ba" == create_branch(addr, target, BRANCH_ABSOLUTE); 22 * "bl" == create_branch(addr, target, BRANCH_SET_LINK); 23 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK); 24 */ 25 #define BRANCH_SET_LINK 0x1 26 #define BRANCH_ABSOLUTE 0x2 27 28 bool is_offset_in_branch_range(long offset); 29 unsigned int create_branch(const unsigned int *addr, 30 unsigned long target, int flags); 31 unsigned int create_cond_branch(const unsigned int *addr, 32 unsigned long target, int flags); 33 int patch_branch(unsigned int *addr, unsigned long target, int flags); 34 int patch_instruction(unsigned int *addr, unsigned int instr); 35 int raw_patch_instruction(unsigned int *addr, unsigned int instr); 36 int patch_instruction_site(s32 *addr, unsigned int instr); 37 int patch_branch_site(s32 *site, unsigned long target, int flags); 38 39 static inline unsigned long patch_site_addr(s32 *site) 40 { 41 return (unsigned long)site + *site; 42 } 43 44 int instr_is_relative_branch(unsigned int instr); 45 int instr_is_relative_link_branch(unsigned int instr); 46 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr); 47 unsigned long branch_target(const unsigned int *instr); 48 unsigned int translate_branch(const unsigned int *dest, 49 const unsigned int *src); 50 extern bool is_conditional_branch(unsigned int instr); 51 #ifdef CONFIG_PPC_BOOK3E_64 52 void __patch_exception(int exc, unsigned long addr); 53 #define patch_exception(exc, name) do { \ 54 extern unsigned int name; \ 55 __patch_exception((exc), (unsigned long)&name); \ 56 } while (0) 57 #endif 58 59 #define OP_RT_RA_MASK 0xffff0000UL 60 #define LIS_R2 0x3c020000UL 61 #define ADDIS_R2_R12 0x3c4c0000UL 62 #define ADDI_R2_R2 0x38420000UL 63 64 static inline unsigned long ppc_function_entry(void *func) 65 { 66 #ifdef PPC64_ELF_ABI_v2 67 u32 *insn = func; 68 69 /* 70 * A PPC64 ABIv2 function may have a local and a global entry 71 * point. We need to use the local entry point when patching 72 * functions, so identify and step over the global entry point 73 * sequence. 74 * 75 * The global entry point sequence is always of the form: 76 * 77 * addis r2,r12,XXXX 78 * addi r2,r2,XXXX 79 * 80 * A linker optimisation may convert the addis to lis: 81 * 82 * lis r2,XXXX 83 * addi r2,r2,XXXX 84 */ 85 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) || 86 ((*insn & OP_RT_RA_MASK) == LIS_R2)) && 87 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2)) 88 return (unsigned long)(insn + 2); 89 else 90 return (unsigned long)func; 91 #elif defined(PPC64_ELF_ABI_v1) 92 /* 93 * On PPC64 ABIv1 the function pointer actually points to the 94 * function's descriptor. The first entry in the descriptor is the 95 * address of the function text. 96 */ 97 return ((func_descr_t *)func)->entry; 98 #else 99 return (unsigned long)func; 100 #endif 101 } 102 103 static inline unsigned long ppc_global_function_entry(void *func) 104 { 105 #ifdef PPC64_ELF_ABI_v2 106 /* PPC64 ABIv2 the global entry point is at the address */ 107 return (unsigned long)func; 108 #else 109 /* All other cases there is no change vs ppc_function_entry() */ 110 return ppc_function_entry(func); 111 #endif 112 } 113 114 /* 115 * Wrapper around kallsyms_lookup() to return function entry address: 116 * - For ABIv1, we lookup the dot variant. 117 * - For ABIv2, we return the local entry point. 118 */ 119 static inline unsigned long ppc_kallsyms_lookup_name(const char *name) 120 { 121 unsigned long addr; 122 #ifdef PPC64_ELF_ABI_v1 123 /* check for dot variant */ 124 char dot_name[1 + KSYM_NAME_LEN]; 125 bool dot_appended = false; 126 127 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) 128 return 0; 129 130 if (name[0] != '.') { 131 dot_name[0] = '.'; 132 dot_name[1] = '\0'; 133 strlcat(dot_name, name, sizeof(dot_name)); 134 dot_appended = true; 135 } else { 136 dot_name[0] = '\0'; 137 strlcat(dot_name, name, sizeof(dot_name)); 138 } 139 addr = kallsyms_lookup_name(dot_name); 140 if (!addr && dot_appended) 141 /* Let's try the original non-dot symbol lookup */ 142 addr = kallsyms_lookup_name(name); 143 #elif defined(PPC64_ELF_ABI_v2) 144 addr = kallsyms_lookup_name(name); 145 if (addr) 146 addr = ppc_function_entry((void *)addr); 147 #else 148 addr = kallsyms_lookup_name(name); 149 #endif 150 return addr; 151 } 152 153 #ifdef CONFIG_PPC64 154 /* 155 * Some instruction encodings commonly used in dynamic ftracing 156 * and function live patching. 157 */ 158 159 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */ 160 #ifdef PPC64_ELF_ABI_v2 161 #define R2_STACK_OFFSET 24 162 #else 163 #define R2_STACK_OFFSET 40 164 #endif 165 166 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \ 167 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET) 168 169 /* usually preceded by a mflr r0 */ 170 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \ 171 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF) 172 #endif /* CONFIG_PPC64 */ 173 174 #endif /* _ASM_POWERPC_CODE_PATCHING_H */ 175