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