1 /*===- InstrProfilingPlatformLinux.c - Profile data Linux platform ------===*\ 2 |* 3 |* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 |* See https://llvm.org/LICENSE.txt for license information. 5 |* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 |* 7 \*===----------------------------------------------------------------------===*/ 8 9 #if defined(__linux__) || defined(__FreeBSD__) || defined(__Fuchsia__) || \ 10 (defined(__sun__) && defined(__svr4__)) || defined(__NetBSD__) || \ 11 defined(_AIX) || defined(__wasm__) || defined(__HAIKU__) 12 13 #if !defined(_AIX) && !defined(__wasm__) 14 #include <elf.h> 15 #include <link.h> 16 #endif 17 #include <stdlib.h> 18 #include <string.h> 19 20 #include "InstrProfiling.h" 21 #include "InstrProfilingInternal.h" 22 23 #define PROF_DATA_START INSTR_PROF_SECT_START(INSTR_PROF_DATA_COMMON) 24 #define PROF_DATA_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_DATA_COMMON) 25 #define PROF_NAME_START INSTR_PROF_SECT_START(INSTR_PROF_NAME_COMMON) 26 #define PROF_NAME_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_NAME_COMMON) 27 #define PROF_VNAME_START INSTR_PROF_SECT_START(INSTR_PROF_VNAME_COMMON) 28 #define PROF_VNAME_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VNAME_COMMON) 29 #define PROF_CNTS_START INSTR_PROF_SECT_START(INSTR_PROF_CNTS_COMMON) 30 #define PROF_CNTS_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_CNTS_COMMON) 31 #define PROF_VTABLE_START INSTR_PROF_SECT_START(INSTR_PROF_VTAB_COMMON) 32 #define PROF_VTABLE_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VTAB_COMMON) 33 #define PROF_BITS_START INSTR_PROF_SECT_START(INSTR_PROF_BITS_COMMON) 34 #define PROF_BITS_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_BITS_COMMON) 35 #define PROF_VNODES_START INSTR_PROF_SECT_START(INSTR_PROF_VNODES_COMMON) 36 #define PROF_VNODES_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VNODES_COMMON) 37 #define PROF_COVINIT_START INSTR_PROF_SECT_START(INSTR_PROF_COVINIT_COMMON) 38 #define PROF_COVINIT_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_COVINIT_COMMON) 39 40 /* Declare section start and stop symbols for various sections 41 * generated by compiler instrumentation. 42 */ 43 extern __llvm_profile_data PROF_DATA_START COMPILER_RT_VISIBILITY 44 COMPILER_RT_WEAK; 45 extern __llvm_profile_data PROF_DATA_STOP COMPILER_RT_VISIBILITY 46 COMPILER_RT_WEAK; 47 extern char PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 48 extern char PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 49 extern VTableProfData PROF_VTABLE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 50 extern VTableProfData PROF_VTABLE_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 51 extern char PROF_VNAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 52 extern char PROF_VNAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 53 extern char PROF_BITS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 54 extern char PROF_BITS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 55 extern char PROF_NAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 56 extern char PROF_NAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 57 extern ValueProfNode PROF_VNODES_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 58 extern ValueProfNode PROF_VNODES_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 59 extern __llvm_gcov_init_func_struct PROF_COVINIT_START COMPILER_RT_VISIBILITY 60 COMPILER_RT_WEAK; 61 extern __llvm_gcov_init_func_struct PROF_COVINIT_STOP COMPILER_RT_VISIBILITY 62 COMPILER_RT_WEAK; 63 64 COMPILER_RT_VISIBILITY const __llvm_profile_data * 65 __llvm_profile_begin_data(void) { 66 return &PROF_DATA_START; 67 } 68 COMPILER_RT_VISIBILITY const __llvm_profile_data * 69 __llvm_profile_end_data(void) { 70 return &PROF_DATA_STOP; 71 } 72 COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) { 73 return &PROF_NAME_START; 74 } 75 COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) { 76 return &PROF_NAME_STOP; 77 } 78 COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_vtabnames(void) { 79 return &PROF_VNAME_START; 80 } 81 COMPILER_RT_VISIBILITY const char *__llvm_profile_end_vtabnames(void) { 82 return &PROF_VNAME_STOP; 83 } 84 COMPILER_RT_VISIBILITY const VTableProfData * 85 __llvm_profile_begin_vtables(void) { 86 return &PROF_VTABLE_START; 87 } 88 COMPILER_RT_VISIBILITY const VTableProfData *__llvm_profile_end_vtables(void) { 89 return &PROF_VTABLE_STOP; 90 } 91 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_counters(void) { 92 return &PROF_CNTS_START; 93 } 94 COMPILER_RT_VISIBILITY char *__llvm_profile_end_counters(void) { 95 return &PROF_CNTS_STOP; 96 } 97 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_bitmap(void) { 98 return &PROF_BITS_START; 99 } 100 COMPILER_RT_VISIBILITY char *__llvm_profile_end_bitmap(void) { 101 return &PROF_BITS_STOP; 102 } 103 104 COMPILER_RT_VISIBILITY ValueProfNode * 105 __llvm_profile_begin_vnodes(void) { 106 return &PROF_VNODES_START; 107 } 108 COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) { 109 return &PROF_VNODES_STOP; 110 } 111 COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START; 112 COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP; 113 114 COMPILER_RT_VISIBILITY const __llvm_gcov_init_func_struct * 115 __llvm_profile_begin_covinit() { 116 return &PROF_COVINIT_START; 117 } 118 119 COMPILER_RT_VISIBILITY const __llvm_gcov_init_func_struct * 120 __llvm_profile_end_covinit() { 121 return &PROF_COVINIT_STOP; 122 } 123 124 #ifdef NT_GNU_BUILD_ID 125 static size_t RoundUp(size_t size, size_t align) { 126 return (size + align - 1) & ~(align - 1); 127 } 128 129 /* 130 * Look for the note that has the name "GNU\0" and type NT_GNU_BUILD_ID 131 * that contains build id. If build id exists, write binary id. 132 * 133 * Each note in notes section starts with a struct which includes 134 * n_namesz, n_descsz, and n_type members. It is followed by the name 135 * (whose length is defined in n_namesz) and then by the descriptor 136 * (whose length is defined in n_descsz). 137 * 138 * Note sections like .note.ABI-tag and .note.gnu.build-id are aligned 139 * to 4 bytes, so round n_namesz and n_descsz to the nearest 4 bytes. 140 */ 141 static int WriteBinaryIdForNote(ProfDataWriter *Writer, 142 const ElfW(Nhdr) * Note) { 143 int BinaryIdSize = 0; 144 const char *NoteName = (const char *)Note + sizeof(ElfW(Nhdr)); 145 if (Note->n_type == NT_GNU_BUILD_ID && Note->n_namesz == 4 && 146 memcmp(NoteName, "GNU\0", 4) == 0) { 147 uint64_t BinaryIdLen = Note->n_descsz; 148 const uint8_t *BinaryIdData = 149 (const uint8_t *)(NoteName + RoundUp(Note->n_namesz, 4)); 150 uint8_t BinaryIdPadding = __llvm_profile_get_num_padding_bytes(BinaryIdLen); 151 if (Writer != NULL && 152 lprofWriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData, 153 BinaryIdPadding) == -1) 154 return -1; 155 156 BinaryIdSize = sizeof(BinaryIdLen) + BinaryIdLen + BinaryIdPadding; 157 } 158 159 return BinaryIdSize; 160 } 161 162 /* 163 * Helper function that iterates through notes section and find build ids. 164 * If writer is given, write binary ids into profiles. 165 * If an error happens while writing, return -1. 166 */ 167 static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note, 168 const ElfW(Nhdr) * NotesEnd) { 169 int BinaryIdsSize = 0; 170 while (Note < NotesEnd) { 171 int OneBinaryIdSize = WriteBinaryIdForNote(Writer, Note); 172 if (OneBinaryIdSize == -1) 173 return -1; 174 BinaryIdsSize += OneBinaryIdSize; 175 176 /* Calculate the offset of the next note in notes section. */ 177 size_t NoteOffset = sizeof(ElfW(Nhdr)) + RoundUp(Note->n_namesz, 4) + 178 RoundUp(Note->n_descsz, 4); 179 Note = (const ElfW(Nhdr) *)((const char *)(Note) + NoteOffset); 180 } 181 182 return BinaryIdsSize; 183 } 184 185 /* 186 * Write binary ids into profiles if writer is given. 187 * Return the total size of binary ids. 188 * If an error happens while writing, return -1. 189 */ 190 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 191 extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden"))); 192 extern ElfW(Dyn) _DYNAMIC[] __attribute__((weak, visibility("hidden"))); 193 194 const ElfW(Ehdr) *ElfHeader = &__ehdr_start; 195 const ElfW(Phdr) *ProgramHeader = 196 (const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff); 197 198 /* Compute the added base address in case of position-independent code. */ 199 uintptr_t Base = 0; 200 for (uint32_t I = 0; I < ElfHeader->e_phnum; I++) { 201 if (ProgramHeader[I].p_type == PT_PHDR) 202 Base = (uintptr_t)ProgramHeader - ProgramHeader[I].p_vaddr; 203 if (ProgramHeader[I].p_type == PT_DYNAMIC && _DYNAMIC) 204 Base = (uintptr_t)_DYNAMIC - ProgramHeader[I].p_vaddr; 205 } 206 207 int TotalBinaryIdsSize = 0; 208 /* Iterate through entries in the program header. */ 209 for (uint32_t I = 0; I < ElfHeader->e_phnum; I++) { 210 /* Look for the notes segment in program header entries. */ 211 if (ProgramHeader[I].p_type != PT_NOTE) 212 continue; 213 214 /* There can be multiple notes segment, and examine each of them. */ 215 const ElfW(Nhdr) *Note = 216 (const ElfW(Nhdr) *)(Base + ProgramHeader[I].p_vaddr); 217 const ElfW(Nhdr) *NotesEnd = 218 (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz); 219 220 int BinaryIdsSize = WriteBinaryIds(Writer, Note, NotesEnd); 221 if (TotalBinaryIdsSize == -1) 222 return -1; 223 224 TotalBinaryIdsSize += BinaryIdsSize; 225 } 226 227 return TotalBinaryIdsSize; 228 } 229 #elif !defined(_AIX) /* !NT_GNU_BUILD_ID */ 230 /* 231 * Fallback implementation for targets that don't support the GNU 232 * extensions NT_GNU_BUILD_ID and __ehdr_start. 233 */ 234 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 235 return 0; 236 } 237 #endif 238 239 #endif 240