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) 12 13 #if !defined(_AIX) 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_ORDERFILE_START INSTR_PROF_SECT_START(INSTR_PROF_ORDERFILE_COMMON) 36 #define PROF_VNODES_START INSTR_PROF_SECT_START(INSTR_PROF_VNODES_COMMON) 37 #define PROF_VNODES_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VNODES_COMMON) 38 39 /* Declare section start and stop symbols for various sections 40 * generated by compiler instrumentation. 41 */ 42 extern __llvm_profile_data PROF_DATA_START COMPILER_RT_VISIBILITY 43 COMPILER_RT_WEAK; 44 extern __llvm_profile_data PROF_DATA_STOP COMPILER_RT_VISIBILITY 45 COMPILER_RT_WEAK; 46 extern char PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 47 extern char PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 48 extern VTableProfData PROF_VTABLE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 49 extern VTableProfData PROF_VTABLE_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 50 extern char PROF_VNAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 51 extern char PROF_VNAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 52 extern char PROF_BITS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 53 extern char PROF_BITS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 54 extern uint32_t PROF_ORDERFILE_START 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 60 COMPILER_RT_VISIBILITY const __llvm_profile_data * 61 __llvm_profile_begin_data(void) { 62 return &PROF_DATA_START; 63 } 64 COMPILER_RT_VISIBILITY const __llvm_profile_data * 65 __llvm_profile_end_data(void) { 66 return &PROF_DATA_STOP; 67 } 68 COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) { 69 return &PROF_NAME_START; 70 } 71 COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) { 72 return &PROF_NAME_STOP; 73 } 74 COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_vtabnames(void) { 75 return &PROF_VNAME_START; 76 } 77 COMPILER_RT_VISIBILITY const char *__llvm_profile_end_vtabnames(void) { 78 return &PROF_VNAME_STOP; 79 } 80 COMPILER_RT_VISIBILITY const VTableProfData * 81 __llvm_profile_begin_vtables(void) { 82 return &PROF_VTABLE_START; 83 } 84 COMPILER_RT_VISIBILITY const VTableProfData *__llvm_profile_end_vtables(void) { 85 return &PROF_VTABLE_STOP; 86 } 87 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_counters(void) { 88 return &PROF_CNTS_START; 89 } 90 COMPILER_RT_VISIBILITY char *__llvm_profile_end_counters(void) { 91 return &PROF_CNTS_STOP; 92 } 93 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_bitmap(void) { 94 return &PROF_BITS_START; 95 } 96 COMPILER_RT_VISIBILITY char *__llvm_profile_end_bitmap(void) { 97 return &PROF_BITS_STOP; 98 } 99 COMPILER_RT_VISIBILITY uint32_t *__llvm_profile_begin_orderfile(void) { 100 return &PROF_ORDERFILE_START; 101 } 102 103 COMPILER_RT_VISIBILITY ValueProfNode * 104 __llvm_profile_begin_vnodes(void) { 105 return &PROF_VNODES_START; 106 } 107 COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) { 108 return &PROF_VNODES_STOP; 109 } 110 COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START; 111 COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP; 112 113 #ifdef NT_GNU_BUILD_ID 114 static size_t RoundUp(size_t size, size_t align) { 115 return (size + align - 1) & ~(align - 1); 116 } 117 118 /* 119 * Look for the note that has the name "GNU\0" and type NT_GNU_BUILD_ID 120 * that contains build id. If build id exists, write binary id. 121 * 122 * Each note in notes section starts with a struct which includes 123 * n_namesz, n_descsz, and n_type members. It is followed by the name 124 * (whose length is defined in n_namesz) and then by the descriptor 125 * (whose length is defined in n_descsz). 126 * 127 * Note sections like .note.ABI-tag and .note.gnu.build-id are aligned 128 * to 4 bytes, so round n_namesz and n_descsz to the nearest 4 bytes. 129 */ 130 static int WriteBinaryIdForNote(ProfDataWriter *Writer, 131 const ElfW(Nhdr) * Note) { 132 int BinaryIdSize = 0; 133 const char *NoteName = (const char *)Note + sizeof(ElfW(Nhdr)); 134 if (Note->n_type == NT_GNU_BUILD_ID && Note->n_namesz == 4 && 135 memcmp(NoteName, "GNU\0", 4) == 0) { 136 uint64_t BinaryIdLen = Note->n_descsz; 137 const uint8_t *BinaryIdData = 138 (const uint8_t *)(NoteName + RoundUp(Note->n_namesz, 4)); 139 uint8_t BinaryIdPadding = __llvm_profile_get_num_padding_bytes(BinaryIdLen); 140 if (Writer != NULL && 141 lprofWriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData, 142 BinaryIdPadding) == -1) 143 return -1; 144 145 BinaryIdSize = sizeof(BinaryIdLen) + BinaryIdLen + BinaryIdPadding; 146 } 147 148 return BinaryIdSize; 149 } 150 151 /* 152 * Helper function that iterates through notes section and find build ids. 153 * If writer is given, write binary ids into profiles. 154 * If an error happens while writing, return -1. 155 */ 156 static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note, 157 const ElfW(Nhdr) * NotesEnd) { 158 int BinaryIdsSize = 0; 159 while (Note < NotesEnd) { 160 int OneBinaryIdSize = WriteBinaryIdForNote(Writer, Note); 161 if (OneBinaryIdSize == -1) 162 return -1; 163 BinaryIdsSize += OneBinaryIdSize; 164 165 /* Calculate the offset of the next note in notes section. */ 166 size_t NoteOffset = sizeof(ElfW(Nhdr)) + RoundUp(Note->n_namesz, 4) + 167 RoundUp(Note->n_descsz, 4); 168 Note = (const ElfW(Nhdr) *)((const char *)(Note) + NoteOffset); 169 } 170 171 return BinaryIdsSize; 172 } 173 174 /* 175 * Write binary ids into profiles if writer is given. 176 * Return the total size of binary ids. 177 * If an error happens while writing, return -1. 178 */ 179 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 180 extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden"))); 181 const ElfW(Ehdr) *ElfHeader = &__ehdr_start; 182 const ElfW(Phdr) *ProgramHeader = 183 (const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff); 184 185 int TotalBinaryIdsSize = 0; 186 uint32_t I; 187 /* Iterate through entries in the program header. */ 188 for (I = 0; I < ElfHeader->e_phnum; I++) { 189 /* Look for the notes segment in program header entries. */ 190 if (ProgramHeader[I].p_type != PT_NOTE) 191 continue; 192 193 /* There can be multiple notes segment, and examine each of them. */ 194 const ElfW(Nhdr) * Note; 195 const ElfW(Nhdr) * NotesEnd; 196 /* 197 * When examining notes in file, use p_offset, which is the offset within 198 * the elf file, to find the start of notes. 199 */ 200 if (ProgramHeader[I].p_memsz == 0 || 201 ProgramHeader[I].p_memsz == ProgramHeader[I].p_filesz) { 202 Note = (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + 203 ProgramHeader[I].p_offset); 204 NotesEnd = (const ElfW(Nhdr) *)((const char *)(Note) + 205 ProgramHeader[I].p_filesz); 206 } else { 207 /* 208 * When examining notes in memory, use p_vaddr, which is the address of 209 * section after loaded to memory, to find the start of notes. 210 */ 211 Note = 212 (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + ProgramHeader[I].p_vaddr); 213 NotesEnd = 214 (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz); 215 } 216 217 int BinaryIdsSize = WriteBinaryIds(Writer, Note, NotesEnd); 218 if (TotalBinaryIdsSize == -1) 219 return -1; 220 221 TotalBinaryIdsSize += BinaryIdsSize; 222 } 223 224 return TotalBinaryIdsSize; 225 } 226 #elif !defined(_AIX) /* !NT_GNU_BUILD_ID */ 227 /* 228 * Fallback implementation for targets that don't support the GNU 229 * extensions NT_GNU_BUILD_ID and __ehdr_start. 230 */ 231 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 232 return 0; 233 } 234 #endif 235 236 #endif 237