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 #if defined(__FreeBSD__) && !defined(ElfW) 24 /* 25 * FreeBSD's elf.h and link.h headers do not define the ElfW(type) macro yet. 26 * If this is added to all supported FreeBSD versions in the future, this 27 * compatibility macro can be removed. 28 */ 29 #define ElfW(type) __ElfN(type) 30 #endif 31 32 #define PROF_DATA_START INSTR_PROF_SECT_START(INSTR_PROF_DATA_COMMON) 33 #define PROF_DATA_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_DATA_COMMON) 34 #define PROF_NAME_START INSTR_PROF_SECT_START(INSTR_PROF_NAME_COMMON) 35 #define PROF_NAME_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_NAME_COMMON) 36 #define PROF_CNTS_START INSTR_PROF_SECT_START(INSTR_PROF_CNTS_COMMON) 37 #define PROF_CNTS_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_CNTS_COMMON) 38 #define PROF_ORDERFILE_START INSTR_PROF_SECT_START(INSTR_PROF_ORDERFILE_COMMON) 39 #define PROF_VNODES_START INSTR_PROF_SECT_START(INSTR_PROF_VNODES_COMMON) 40 #define PROF_VNODES_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VNODES_COMMON) 41 42 /* Declare section start and stop symbols for various sections 43 * generated by compiler instrumentation. 44 */ 45 extern __llvm_profile_data PROF_DATA_START COMPILER_RT_VISIBILITY 46 COMPILER_RT_WEAK; 47 extern __llvm_profile_data PROF_DATA_STOP COMPILER_RT_VISIBILITY 48 COMPILER_RT_WEAK; 49 extern char PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 50 extern char PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 51 extern uint32_t PROF_ORDERFILE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 52 extern char PROF_NAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 53 extern char PROF_NAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 54 extern ValueProfNode PROF_VNODES_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 55 extern ValueProfNode PROF_VNODES_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 56 57 COMPILER_RT_VISIBILITY const __llvm_profile_data * 58 __llvm_profile_begin_data(void) { 59 return &PROF_DATA_START; 60 } 61 COMPILER_RT_VISIBILITY const __llvm_profile_data * 62 __llvm_profile_end_data(void) { 63 return &PROF_DATA_STOP; 64 } 65 COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) { 66 return &PROF_NAME_START; 67 } 68 COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) { 69 return &PROF_NAME_STOP; 70 } 71 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_counters(void) { 72 return &PROF_CNTS_START; 73 } 74 COMPILER_RT_VISIBILITY char *__llvm_profile_end_counters(void) { 75 return &PROF_CNTS_STOP; 76 } 77 COMPILER_RT_VISIBILITY uint32_t *__llvm_profile_begin_orderfile(void) { 78 return &PROF_ORDERFILE_START; 79 } 80 81 COMPILER_RT_VISIBILITY ValueProfNode * 82 __llvm_profile_begin_vnodes(void) { 83 return &PROF_VNODES_START; 84 } 85 COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) { 86 return &PROF_VNODES_STOP; 87 } 88 COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START; 89 COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP; 90 91 #ifdef NT_GNU_BUILD_ID 92 static size_t RoundUp(size_t size, size_t align) { 93 return (size + align - 1) & ~(align - 1); 94 } 95 96 /* 97 * Look for the note that has the name "GNU\0" and type NT_GNU_BUILD_ID 98 * that contains build id. If build id exists, write binary id. 99 * 100 * Each note in notes section starts with a struct which includes 101 * n_namesz, n_descsz, and n_type members. It is followed by the name 102 * (whose length is defined in n_namesz) and then by the descriptor 103 * (whose length is defined in n_descsz). 104 * 105 * Note sections like .note.ABI-tag and .note.gnu.build-id are aligned 106 * to 4 bytes, so round n_namesz and n_descsz to the nearest 4 bytes. 107 */ 108 static int WriteBinaryIdForNote(ProfDataWriter *Writer, 109 const ElfW(Nhdr) * Note) { 110 int BinaryIdSize = 0; 111 const char *NoteName = (const char *)Note + sizeof(ElfW(Nhdr)); 112 if (Note->n_type == NT_GNU_BUILD_ID && Note->n_namesz == 4 && 113 memcmp(NoteName, "GNU\0", 4) == 0) { 114 uint64_t BinaryIdLen = Note->n_descsz; 115 const uint8_t *BinaryIdData = 116 (const uint8_t *)(NoteName + RoundUp(Note->n_namesz, 4)); 117 uint8_t BinaryIdPadding = __llvm_profile_get_num_padding_bytes(BinaryIdLen); 118 if (Writer != NULL && 119 lprofWriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData, 120 BinaryIdPadding) == -1) 121 return -1; 122 123 BinaryIdSize = sizeof(BinaryIdLen) + BinaryIdLen + BinaryIdPadding; 124 } 125 126 return BinaryIdSize; 127 } 128 129 /* 130 * Helper function that iterates through notes section and find build ids. 131 * If writer is given, write binary ids into profiles. 132 * If an error happens while writing, return -1. 133 */ 134 static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note, 135 const ElfW(Nhdr) * NotesEnd) { 136 int BinaryIdsSize = 0; 137 while (Note < NotesEnd) { 138 int OneBinaryIdSize = WriteBinaryIdForNote(Writer, Note); 139 if (OneBinaryIdSize == -1) 140 return -1; 141 BinaryIdsSize += OneBinaryIdSize; 142 143 /* Calculate the offset of the next note in notes section. */ 144 size_t NoteOffset = sizeof(ElfW(Nhdr)) + RoundUp(Note->n_namesz, 4) + 145 RoundUp(Note->n_descsz, 4); 146 Note = (const ElfW(Nhdr) *)((const char *)(Note) + NoteOffset); 147 } 148 149 return BinaryIdsSize; 150 } 151 152 /* 153 * Write binary ids into profiles if writer is given. 154 * Return the total size of binary ids. 155 * If an error happens while writing, return -1. 156 */ 157 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 158 extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden"))); 159 const ElfW(Ehdr) *ElfHeader = &__ehdr_start; 160 const ElfW(Phdr) *ProgramHeader = 161 (const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff); 162 163 int TotalBinaryIdsSize = 0; 164 uint32_t I; 165 /* Iterate through entries in the program header. */ 166 for (I = 0; I < ElfHeader->e_phnum; I++) { 167 /* Look for the notes segment in program header entries. */ 168 if (ProgramHeader[I].p_type != PT_NOTE) 169 continue; 170 171 /* There can be multiple notes segment, and examine each of them. */ 172 const ElfW(Nhdr) * Note; 173 const ElfW(Nhdr) * NotesEnd; 174 /* 175 * When examining notes in file, use p_offset, which is the offset within 176 * the elf file, to find the start of notes. 177 */ 178 if (ProgramHeader[I].p_memsz == 0 || 179 ProgramHeader[I].p_memsz == ProgramHeader[I].p_filesz) { 180 Note = (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + 181 ProgramHeader[I].p_offset); 182 NotesEnd = (const ElfW(Nhdr) *)((const char *)(Note) + 183 ProgramHeader[I].p_filesz); 184 } else { 185 /* 186 * When examining notes in memory, use p_vaddr, which is the address of 187 * section after loaded to memory, to find the start of notes. 188 */ 189 Note = 190 (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + ProgramHeader[I].p_vaddr); 191 NotesEnd = 192 (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz); 193 } 194 195 int BinaryIdsSize = WriteBinaryIds(Writer, Note, NotesEnd); 196 if (TotalBinaryIdsSize == -1) 197 return -1; 198 199 TotalBinaryIdsSize += BinaryIdsSize; 200 } 201 202 return TotalBinaryIdsSize; 203 } 204 #elif !defined(_AIX) /* !NT_GNU_BUILD_ID */ 205 /* 206 * Fallback implementation for targets that don't support the GNU 207 * extensions NT_GNU_BUILD_ID and __ehdr_start. 208 */ 209 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 210 return 0; 211 } 212 #endif 213 214 #endif 215