1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 #ifndef _ASM_POWERPC_CODE_PATCHING_H 3 #define _ASM_POWERPC_CODE_PATCHING_H 4 5 /* 6 * Copyright 2008, Michael Ellerman, IBM Corporation. 7 */ 8 9 #include <asm/types.h> 10 #include <asm/ppc-opcode.h> 11 #include <linux/string.h> 12 #include <linux/kallsyms.h> 13 #include <asm/asm-compat.h> 14 15 /* Flags for create_branch: 16 * "b" == create_branch(addr, target, 0); 17 * "ba" == create_branch(addr, target, BRANCH_ABSOLUTE); 18 * "bl" == create_branch(addr, target, BRANCH_SET_LINK); 19 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK); 20 */ 21 #define BRANCH_SET_LINK 0x1 22 #define BRANCH_ABSOLUTE 0x2 23 24 bool is_offset_in_branch_range(long offset); 25 unsigned int create_branch(const unsigned int *addr, 26 unsigned long target, int flags); 27 unsigned int create_cond_branch(const unsigned int *addr, 28 unsigned long target, int flags); 29 int patch_branch(unsigned int *addr, unsigned long target, int flags); 30 int patch_instruction(unsigned int *addr, unsigned int instr); 31 int raw_patch_instruction(unsigned int *addr, unsigned int instr); 32 33 static inline unsigned long patch_site_addr(s32 *site) 34 { 35 return (unsigned long)site + *site; 36 } 37 38 static inline int patch_instruction_site(s32 *site, unsigned int instr) 39 { 40 return patch_instruction((unsigned int *)patch_site_addr(site), instr); 41 } 42 43 static inline int patch_branch_site(s32 *site, unsigned long target, int flags) 44 { 45 return patch_branch((unsigned int *)patch_site_addr(site), target, flags); 46 } 47 48 static inline int modify_instruction(unsigned int *addr, unsigned int clr, 49 unsigned int set) 50 { 51 return patch_instruction(addr, (*addr & ~clr) | set); 52 } 53 54 static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set) 55 { 56 return modify_instruction((unsigned int *)patch_site_addr(site), clr, set); 57 } 58 59 int instr_is_relative_branch(unsigned int instr); 60 int instr_is_relative_link_branch(unsigned int instr); 61 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr); 62 unsigned long branch_target(const unsigned int *instr); 63 unsigned int translate_branch(const unsigned int *dest, 64 const unsigned int *src); 65 extern bool is_conditional_branch(unsigned int instr); 66 #ifdef CONFIG_PPC_BOOK3E_64 67 void __patch_exception(int exc, unsigned long addr); 68 #define patch_exception(exc, name) do { \ 69 extern unsigned int name; \ 70 __patch_exception((exc), (unsigned long)&name); \ 71 } while (0) 72 #endif 73 74 #define OP_RT_RA_MASK 0xffff0000UL 75 #define LIS_R2 0x3c020000UL 76 #define ADDIS_R2_R12 0x3c4c0000UL 77 #define ADDI_R2_R2 0x38420000UL 78 79 static inline unsigned long ppc_function_entry(void *func) 80 { 81 #ifdef PPC64_ELF_ABI_v2 82 u32 *insn = func; 83 84 /* 85 * A PPC64 ABIv2 function may have a local and a global entry 86 * point. We need to use the local entry point when patching 87 * functions, so identify and step over the global entry point 88 * sequence. 89 * 90 * The global entry point sequence is always of the form: 91 * 92 * addis r2,r12,XXXX 93 * addi r2,r2,XXXX 94 * 95 * A linker optimisation may convert the addis to lis: 96 * 97 * lis r2,XXXX 98 * addi r2,r2,XXXX 99 */ 100 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) || 101 ((*insn & OP_RT_RA_MASK) == LIS_R2)) && 102 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2)) 103 return (unsigned long)(insn + 2); 104 else 105 return (unsigned long)func; 106 #elif defined(PPC64_ELF_ABI_v1) 107 /* 108 * On PPC64 ABIv1 the function pointer actually points to the 109 * function's descriptor. The first entry in the descriptor is the 110 * address of the function text. 111 */ 112 return ((func_descr_t *)func)->entry; 113 #else 114 return (unsigned long)func; 115 #endif 116 } 117 118 static inline unsigned long ppc_global_function_entry(void *func) 119 { 120 #ifdef PPC64_ELF_ABI_v2 121 /* PPC64 ABIv2 the global entry point is at the address */ 122 return (unsigned long)func; 123 #else 124 /* All other cases there is no change vs ppc_function_entry() */ 125 return ppc_function_entry(func); 126 #endif 127 } 128 129 /* 130 * Wrapper around kallsyms_lookup() to return function entry address: 131 * - For ABIv1, we lookup the dot variant. 132 * - For ABIv2, we return the local entry point. 133 */ 134 static inline unsigned long ppc_kallsyms_lookup_name(const char *name) 135 { 136 unsigned long addr; 137 #ifdef PPC64_ELF_ABI_v1 138 /* check for dot variant */ 139 char dot_name[1 + KSYM_NAME_LEN]; 140 bool dot_appended = false; 141 142 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) 143 return 0; 144 145 if (name[0] != '.') { 146 dot_name[0] = '.'; 147 dot_name[1] = '\0'; 148 strlcat(dot_name, name, sizeof(dot_name)); 149 dot_appended = true; 150 } else { 151 dot_name[0] = '\0'; 152 strlcat(dot_name, name, sizeof(dot_name)); 153 } 154 addr = kallsyms_lookup_name(dot_name); 155 if (!addr && dot_appended) 156 /* Let's try the original non-dot symbol lookup */ 157 addr = kallsyms_lookup_name(name); 158 #elif defined(PPC64_ELF_ABI_v2) 159 addr = kallsyms_lookup_name(name); 160 if (addr) 161 addr = ppc_function_entry((void *)addr); 162 #else 163 addr = kallsyms_lookup_name(name); 164 #endif 165 return addr; 166 } 167 168 #ifdef CONFIG_PPC64 169 /* 170 * Some instruction encodings commonly used in dynamic ftracing 171 * and function live patching. 172 */ 173 174 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */ 175 #ifdef PPC64_ELF_ABI_v2 176 #define R2_STACK_OFFSET 24 177 #else 178 #define R2_STACK_OFFSET 40 179 #endif 180 181 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \ 182 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET) 183 184 /* usually preceded by a mflr r0 */ 185 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \ 186 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF) 187 #endif /* CONFIG_PPC64 */ 188 189 #endif /* _ASM_POWERPC_CODE_PATCHING_H */ 190