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 * However, we may also receive pointer to an assembly symbol. To 88 * detect that, we first check if the function pointer we receive 89 * already points to kernel/module text and we only dereference it 90 * if it doesn't. 91 */ 92 if (kernel_text_address((unsigned long)func)) 93 return (unsigned long)func; 94 else 95 return ((func_descr_t *)func)->entry; 96 #else 97 return (unsigned long)func; 98 #endif 99 } 100 101 static inline unsigned long ppc_global_function_entry(void *func) 102 { 103 #ifdef PPC64_ELF_ABI_v2 104 /* PPC64 ABIv2 the global entry point is at the address */ 105 return (unsigned long)func; 106 #else 107 /* All other cases there is no change vs ppc_function_entry() */ 108 return ppc_function_entry(func); 109 #endif 110 } 111 112 /* 113 * Wrapper around kallsyms_lookup() to return function entry address: 114 * - For ABIv1, we lookup the dot variant. 115 * - For ABIv2, we return the local entry point. 116 */ 117 static inline unsigned long ppc_kallsyms_lookup_name(const char *name) 118 { 119 unsigned long addr; 120 #ifdef PPC64_ELF_ABI_v1 121 /* check for dot variant */ 122 char dot_name[1 + KSYM_NAME_LEN]; 123 bool dot_appended = false; 124 125 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) 126 return 0; 127 128 if (name[0] != '.') { 129 dot_name[0] = '.'; 130 dot_name[1] = '\0'; 131 strlcat(dot_name, name, sizeof(dot_name)); 132 dot_appended = true; 133 } else { 134 dot_name[0] = '\0'; 135 strlcat(dot_name, name, sizeof(dot_name)); 136 } 137 addr = kallsyms_lookup_name(dot_name); 138 if (!addr && dot_appended) 139 /* Let's try the original non-dot symbol lookup */ 140 addr = kallsyms_lookup_name(name); 141 #elif defined(PPC64_ELF_ABI_v2) 142 addr = kallsyms_lookup_name(name); 143 if (addr) 144 addr = ppc_function_entry((void *)addr); 145 #else 146 addr = kallsyms_lookup_name(name); 147 #endif 148 return addr; 149 } 150 151 #ifdef CONFIG_PPC64 152 /* 153 * Some instruction encodings commonly used in dynamic ftracing 154 * and function live patching. 155 */ 156 157 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */ 158 #ifdef PPC64_ELF_ABI_v2 159 #define R2_STACK_OFFSET 24 160 #else 161 #define R2_STACK_OFFSET 40 162 #endif 163 164 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \ 165 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET) 166 167 /* usually preceded by a mflr r0 */ 168 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \ 169 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF) 170 #endif /* CONFIG_PPC64 */ 171 172 #endif /* _ASM_POWERPC_CODE_PATCHING_H */ 173