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 #include <asm/inst.h> 15 16 /* Flags for create_branch: 17 * "b" == create_branch(addr, target, 0); 18 * "ba" == create_branch(addr, target, BRANCH_ABSOLUTE); 19 * "bl" == create_branch(addr, target, BRANCH_SET_LINK); 20 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK); 21 */ 22 #define BRANCH_SET_LINK 0x1 23 #define BRANCH_ABSOLUTE 0x2 24 25 /* 26 * Powerpc branch instruction is : 27 * 28 * 0 6 30 31 29 * +---------+----------------+---+---+ 30 * | opcode | LI |AA |LK | 31 * +---------+----------------+---+---+ 32 * Where AA = 0 and LK = 0 33 * 34 * LI is a signed 24 bits integer. The real branch offset is computed 35 * by: imm32 = SignExtend(LI:'0b00', 32); 36 * 37 * So the maximum forward branch should be: 38 * (0x007fffff << 2) = 0x01fffffc = 0x1fffffc 39 * The maximum backward branch should be: 40 * (0xff800000 << 2) = 0xfe000000 = -0x2000000 41 */ 42 static inline bool is_offset_in_branch_range(long offset) 43 { 44 return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3)); 45 } 46 47 static inline bool is_offset_in_cond_branch_range(long offset) 48 { 49 return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3); 50 } 51 52 static inline int create_branch(ppc_inst_t *instr, const u32 *addr, 53 unsigned long target, int flags) 54 { 55 long offset; 56 57 *instr = ppc_inst(0); 58 offset = target; 59 if (! (flags & BRANCH_ABSOLUTE)) 60 offset = offset - (unsigned long)addr; 61 62 /* Check we can represent the target in the instruction format */ 63 if (!is_offset_in_branch_range(offset)) 64 return 1; 65 66 /* Mask out the flags and target, so they don't step on each other. */ 67 *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC)); 68 69 return 0; 70 } 71 72 int create_cond_branch(ppc_inst_t *instr, const u32 *addr, 73 unsigned long target, int flags); 74 int patch_branch(u32 *addr, unsigned long target, int flags); 75 int patch_instruction(u32 *addr, ppc_inst_t instr); 76 int raw_patch_instruction(u32 *addr, ppc_inst_t instr); 77 78 static inline unsigned long patch_site_addr(s32 *site) 79 { 80 return (unsigned long)site + *site; 81 } 82 83 static inline int patch_instruction_site(s32 *site, ppc_inst_t instr) 84 { 85 return patch_instruction((u32 *)patch_site_addr(site), instr); 86 } 87 88 static inline int patch_branch_site(s32 *site, unsigned long target, int flags) 89 { 90 return patch_branch((u32 *)patch_site_addr(site), target, flags); 91 } 92 93 static inline int modify_instruction(unsigned int *addr, unsigned int clr, 94 unsigned int set) 95 { 96 return patch_instruction(addr, ppc_inst((*addr & ~clr) | set)); 97 } 98 99 static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set) 100 { 101 return modify_instruction((unsigned int *)patch_site_addr(site), clr, set); 102 } 103 104 static inline unsigned int branch_opcode(ppc_inst_t instr) 105 { 106 return ppc_inst_primary_opcode(instr) & 0x3F; 107 } 108 109 static inline int instr_is_branch_iform(ppc_inst_t instr) 110 { 111 return branch_opcode(instr) == 18; 112 } 113 114 static inline int instr_is_branch_bform(ppc_inst_t instr) 115 { 116 return branch_opcode(instr) == 16; 117 } 118 119 int instr_is_relative_branch(ppc_inst_t instr); 120 int instr_is_relative_link_branch(ppc_inst_t instr); 121 unsigned long branch_target(const u32 *instr); 122 int translate_branch(ppc_inst_t *instr, const u32 *dest, const u32 *src); 123 bool is_conditional_branch(ppc_inst_t instr); 124 125 #define OP_RT_RA_MASK 0xffff0000UL 126 #define LIS_R2 (PPC_RAW_LIS(_R2, 0)) 127 #define ADDIS_R2_R12 (PPC_RAW_ADDIS(_R2, _R12, 0)) 128 #define ADDI_R2_R2 (PPC_RAW_ADDI(_R2, _R2, 0)) 129 130 131 static inline unsigned long ppc_function_entry(void *func) 132 { 133 #ifdef CONFIG_PPC64_ELF_ABI_V2 134 u32 *insn = func; 135 136 /* 137 * A PPC64 ABIv2 function may have a local and a global entry 138 * point. We need to use the local entry point when patching 139 * functions, so identify and step over the global entry point 140 * sequence. 141 * 142 * The global entry point sequence is always of the form: 143 * 144 * addis r2,r12,XXXX 145 * addi r2,r2,XXXX 146 * 147 * A linker optimisation may convert the addis to lis: 148 * 149 * lis r2,XXXX 150 * addi r2,r2,XXXX 151 */ 152 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) || 153 ((*insn & OP_RT_RA_MASK) == LIS_R2)) && 154 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2)) 155 return (unsigned long)(insn + 2); 156 else 157 return (unsigned long)func; 158 #elif defined(CONFIG_PPC64_ELF_ABI_V1) 159 /* 160 * On PPC64 ABIv1 the function pointer actually points to the 161 * function's descriptor. The first entry in the descriptor is the 162 * address of the function text. 163 */ 164 return ((struct func_desc *)func)->addr; 165 #else 166 return (unsigned long)func; 167 #endif 168 } 169 170 static inline unsigned long ppc_global_function_entry(void *func) 171 { 172 #ifdef CONFIG_PPC64_ELF_ABI_V2 173 /* PPC64 ABIv2 the global entry point is at the address */ 174 return (unsigned long)func; 175 #else 176 /* All other cases there is no change vs ppc_function_entry() */ 177 return ppc_function_entry(func); 178 #endif 179 } 180 181 /* 182 * Wrapper around kallsyms_lookup() to return function entry address: 183 * - For ABIv1, we lookup the dot variant. 184 * - For ABIv2, we return the local entry point. 185 */ 186 static inline unsigned long ppc_kallsyms_lookup_name(const char *name) 187 { 188 unsigned long addr; 189 #ifdef CONFIG_PPC64_ELF_ABI_V1 190 /* check for dot variant */ 191 char dot_name[1 + KSYM_NAME_LEN]; 192 bool dot_appended = false; 193 194 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) 195 return 0; 196 197 if (name[0] != '.') { 198 dot_name[0] = '.'; 199 dot_name[1] = '\0'; 200 strlcat(dot_name, name, sizeof(dot_name)); 201 dot_appended = true; 202 } else { 203 dot_name[0] = '\0'; 204 strlcat(dot_name, name, sizeof(dot_name)); 205 } 206 addr = kallsyms_lookup_name(dot_name); 207 if (!addr && dot_appended) 208 /* Let's try the original non-dot symbol lookup */ 209 addr = kallsyms_lookup_name(name); 210 #elif defined(CONFIG_PPC64_ELF_ABI_V2) 211 addr = kallsyms_lookup_name(name); 212 if (addr) 213 addr = ppc_function_entry((void *)addr); 214 #else 215 addr = kallsyms_lookup_name(name); 216 #endif 217 return addr; 218 } 219 220 /* 221 * Some instruction encodings commonly used in dynamic ftracing 222 * and function live patching. 223 */ 224 225 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */ 226 #ifdef CONFIG_PPC64_ELF_ABI_V2 227 #define R2_STACK_OFFSET 24 228 #else 229 #define R2_STACK_OFFSET 40 230 #endif 231 232 #define PPC_INST_LD_TOC PPC_RAW_LD(_R2, _R1, R2_STACK_OFFSET) 233 234 /* usually preceded by a mflr r0 */ 235 #define PPC_INST_STD_LR PPC_RAW_STD(_R0, _R1, PPC_LR_STKOFF) 236 237 #endif /* _ASM_POWERPC_CODE_PATCHING_H */ 238