code-patching.h (6663B)
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 25DECLARE_STATIC_KEY_FALSE(init_mem_is_free); 26 27/* 28 * Powerpc branch instruction is : 29 * 30 * 0 6 30 31 31 * +---------+----------------+---+---+ 32 * | opcode | LI |AA |LK | 33 * +---------+----------------+---+---+ 34 * Where AA = 0 and LK = 0 35 * 36 * LI is a signed 24 bits integer. The real branch offset is computed 37 * by: imm32 = SignExtend(LI:'0b00', 32); 38 * 39 * So the maximum forward branch should be: 40 * (0x007fffff << 2) = 0x01fffffc = 0x1fffffc 41 * The maximum backward branch should be: 42 * (0xff800000 << 2) = 0xfe000000 = -0x2000000 43 */ 44static inline bool is_offset_in_branch_range(long offset) 45{ 46 return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3)); 47} 48 49static inline bool is_offset_in_cond_branch_range(long offset) 50{ 51 return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3); 52} 53 54static inline int create_branch(ppc_inst_t *instr, const u32 *addr, 55 unsigned long target, int flags) 56{ 57 long offset; 58 59 *instr = ppc_inst(0); 60 offset = target; 61 if (! (flags & BRANCH_ABSOLUTE)) 62 offset = offset - (unsigned long)addr; 63 64 /* Check we can represent the target in the instruction format */ 65 if (!is_offset_in_branch_range(offset)) 66 return 1; 67 68 /* Mask out the flags and target, so they don't step on each other. */ 69 *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC)); 70 71 return 0; 72} 73 74int create_cond_branch(ppc_inst_t *instr, const u32 *addr, 75 unsigned long target, int flags); 76int patch_branch(u32 *addr, unsigned long target, int flags); 77int patch_instruction(u32 *addr, ppc_inst_t instr); 78int raw_patch_instruction(u32 *addr, ppc_inst_t instr); 79 80static inline unsigned long patch_site_addr(s32 *site) 81{ 82 return (unsigned long)site + *site; 83} 84 85static inline int patch_instruction_site(s32 *site, ppc_inst_t instr) 86{ 87 return patch_instruction((u32 *)patch_site_addr(site), instr); 88} 89 90static inline int patch_branch_site(s32 *site, unsigned long target, int flags) 91{ 92 return patch_branch((u32 *)patch_site_addr(site), target, flags); 93} 94 95static inline int modify_instruction(unsigned int *addr, unsigned int clr, 96 unsigned int set) 97{ 98 return patch_instruction(addr, ppc_inst((*addr & ~clr) | set)); 99} 100 101static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set) 102{ 103 return modify_instruction((unsigned int *)patch_site_addr(site), clr, set); 104} 105 106static inline unsigned int branch_opcode(ppc_inst_t instr) 107{ 108 return ppc_inst_primary_opcode(instr) & 0x3F; 109} 110 111static inline int instr_is_branch_iform(ppc_inst_t instr) 112{ 113 return branch_opcode(instr) == 18; 114} 115 116static inline int instr_is_branch_bform(ppc_inst_t instr) 117{ 118 return branch_opcode(instr) == 16; 119} 120 121int instr_is_relative_branch(ppc_inst_t instr); 122int instr_is_relative_link_branch(ppc_inst_t instr); 123unsigned long branch_target(const u32 *instr); 124int translate_branch(ppc_inst_t *instr, const u32 *dest, const u32 *src); 125bool is_conditional_branch(ppc_inst_t instr); 126 127#define OP_RT_RA_MASK 0xffff0000UL 128#define LIS_R2 (PPC_RAW_LIS(_R2, 0)) 129#define ADDIS_R2_R12 (PPC_RAW_ADDIS(_R2, _R12, 0)) 130#define ADDI_R2_R2 (PPC_RAW_ADDI(_R2, _R2, 0)) 131 132 133static inline unsigned long ppc_function_entry(void *func) 134{ 135#ifdef CONFIG_PPC64_ELF_ABI_V2 136 u32 *insn = func; 137 138 /* 139 * A PPC64 ABIv2 function may have a local and a global entry 140 * point. We need to use the local entry point when patching 141 * functions, so identify and step over the global entry point 142 * sequence. 143 * 144 * The global entry point sequence is always of the form: 145 * 146 * addis r2,r12,XXXX 147 * addi r2,r2,XXXX 148 * 149 * A linker optimisation may convert the addis to lis: 150 * 151 * lis r2,XXXX 152 * addi r2,r2,XXXX 153 */ 154 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) || 155 ((*insn & OP_RT_RA_MASK) == LIS_R2)) && 156 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2)) 157 return (unsigned long)(insn + 2); 158 else 159 return (unsigned long)func; 160#elif defined(CONFIG_PPC64_ELF_ABI_V1) 161 /* 162 * On PPC64 ABIv1 the function pointer actually points to the 163 * function's descriptor. The first entry in the descriptor is the 164 * address of the function text. 165 */ 166 return ((struct func_desc *)func)->addr; 167#else 168 return (unsigned long)func; 169#endif 170} 171 172static inline unsigned long ppc_global_function_entry(void *func) 173{ 174#ifdef CONFIG_PPC64_ELF_ABI_V2 175 /* PPC64 ABIv2 the global entry point is at the address */ 176 return (unsigned long)func; 177#else 178 /* All other cases there is no change vs ppc_function_entry() */ 179 return ppc_function_entry(func); 180#endif 181} 182 183/* 184 * Wrapper around kallsyms_lookup() to return function entry address: 185 * - For ABIv1, we lookup the dot variant. 186 * - For ABIv2, we return the local entry point. 187 */ 188static inline unsigned long ppc_kallsyms_lookup_name(const char *name) 189{ 190 unsigned long addr; 191#ifdef CONFIG_PPC64_ELF_ABI_V1 192 /* check for dot variant */ 193 char dot_name[1 + KSYM_NAME_LEN]; 194 bool dot_appended = false; 195 196 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) 197 return 0; 198 199 if (name[0] != '.') { 200 dot_name[0] = '.'; 201 dot_name[1] = '\0'; 202 strlcat(dot_name, name, sizeof(dot_name)); 203 dot_appended = true; 204 } else { 205 dot_name[0] = '\0'; 206 strlcat(dot_name, name, sizeof(dot_name)); 207 } 208 addr = kallsyms_lookup_name(dot_name); 209 if (!addr && dot_appended) 210 /* Let's try the original non-dot symbol lookup */ 211 addr = kallsyms_lookup_name(name); 212#elif defined(CONFIG_PPC64_ELF_ABI_V2) 213 addr = kallsyms_lookup_name(name); 214 if (addr) 215 addr = ppc_function_entry((void *)addr); 216#else 217 addr = kallsyms_lookup_name(name); 218#endif 219 return addr; 220} 221 222/* 223 * Some instruction encodings commonly used in dynamic ftracing 224 * and function live patching. 225 */ 226 227/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */ 228#ifdef CONFIG_PPC64_ELF_ABI_V2 229#define R2_STACK_OFFSET 24 230#else 231#define R2_STACK_OFFSET 40 232#endif 233 234#define PPC_INST_LD_TOC PPC_RAW_LD(_R2, _R1, R2_STACK_OFFSET) 235 236/* usually preceded by a mflr r0 */ 237#define PPC_INST_STD_LR PPC_RAW_STD(_R0, _R1, PPC_LR_STKOFF) 238 239#endif /* _ASM_POWERPC_CODE_PATCHING_H */