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 12 #include <elf.h> 13 #include <link.h> 14 #include <stdlib.h> 15 #include <string.h> 16 17 #include "InstrProfiling.h" 18 #include "InstrProfilingInternal.h" 19 20 #if defined(__FreeBSD__) && !defined(ElfW) 21 /* 22 * FreeBSD's elf.h and link.h headers do not define the ElfW(type) macro yet. 23 * If this is added to all supported FreeBSD versions in the future, this 24 * compatibility macro can be removed. 25 */ 26 #define ElfW(type) __ElfN(type) 27 #endif 28 29 #define PROF_DATA_START INSTR_PROF_SECT_START(INSTR_PROF_DATA_COMMON) 30 #define PROF_DATA_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_DATA_COMMON) 31 #define PROF_NAME_START INSTR_PROF_SECT_START(INSTR_PROF_NAME_COMMON) 32 #define PROF_NAME_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_NAME_COMMON) 33 #define PROF_CNTS_START INSTR_PROF_SECT_START(INSTR_PROF_CNTS_COMMON) 34 #define PROF_CNTS_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_CNTS_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 uint64_t PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 47 extern uint64_t PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 48 extern uint32_t PROF_ORDERFILE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 49 extern char PROF_NAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 50 extern char PROF_NAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 51 extern ValueProfNode PROF_VNODES_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 52 extern ValueProfNode PROF_VNODES_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 53 54 COMPILER_RT_VISIBILITY const __llvm_profile_data * 55 __llvm_profile_begin_data(void) { 56 return &PROF_DATA_START; 57 } 58 COMPILER_RT_VISIBILITY const __llvm_profile_data * 59 __llvm_profile_end_data(void) { 60 return &PROF_DATA_STOP; 61 } 62 COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) { 63 return &PROF_NAME_START; 64 } 65 COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) { 66 return &PROF_NAME_STOP; 67 } 68 COMPILER_RT_VISIBILITY uint64_t *__llvm_profile_begin_counters(void) { 69 return &PROF_CNTS_START; 70 } 71 COMPILER_RT_VISIBILITY uint64_t *__llvm_profile_end_counters(void) { 72 return &PROF_CNTS_STOP; 73 } 74 COMPILER_RT_VISIBILITY uint32_t *__llvm_profile_begin_orderfile(void) { 75 return &PROF_ORDERFILE_START; 76 } 77 78 COMPILER_RT_VISIBILITY ValueProfNode * 79 __llvm_profile_begin_vnodes(void) { 80 return &PROF_VNODES_START; 81 } 82 COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) { 83 return &PROF_VNODES_STOP; 84 } 85 COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START; 86 COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP; 87 88 #ifdef NT_GNU_BUILD_ID 89 static size_t RoundUp(size_t size, size_t align) { 90 return (size + align - 1) & ~(align - 1); 91 } 92 93 /* 94 * Write binary id length and then its data, because binary id does not 95 * have a fixed length. 96 */ 97 static int WriteOneBinaryId(ProfDataWriter *Writer, uint64_t BinaryIdLen, 98 const uint8_t *BinaryIdData) { 99 ProfDataIOVec BinaryIdIOVec[] = { 100 {&BinaryIdLen, sizeof(uint64_t), 1, 0}, 101 {BinaryIdData, sizeof(uint8_t), BinaryIdLen, 0}}; 102 if (Writer->Write(Writer, BinaryIdIOVec, 103 sizeof(BinaryIdIOVec) / sizeof(*BinaryIdIOVec))) 104 return -1; 105 106 /* Successfully wrote binary id, report success. */ 107 return 0; 108 } 109 110 /* 111 * Look for the note that has the name "GNU\0" and type NT_GNU_BUILD_ID 112 * that contains build id. If build id exists, write binary id. 113 * 114 * Each note in notes section starts with a struct which includes 115 * n_namesz, n_descsz, and n_type members. It is followed by the name 116 * (whose length is defined in n_namesz) and then by the descriptor 117 * (whose length is defined in n_descsz). 118 * 119 * Note sections like .note.ABI-tag and .note.gnu.build-id are aligned 120 * to 4 bytes, so round n_namesz and n_descsz to the nearest 4 bytes. 121 */ 122 static int WriteBinaryIdForNote(ProfDataWriter *Writer, 123 const ElfW(Nhdr) * Note) { 124 int BinaryIdSize = 0; 125 126 const char *NoteName = (const char *)Note + sizeof(ElfW(Nhdr)); 127 if (Note->n_type == NT_GNU_BUILD_ID && Note->n_namesz == 4 && 128 memcmp(NoteName, "GNU\0", 4) == 0) { 129 130 uint64_t BinaryIdLen = Note->n_descsz; 131 const uint8_t *BinaryIdData = 132 (const uint8_t *)(NoteName + RoundUp(Note->n_namesz, 4)); 133 if (Writer != NULL && 134 WriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData) == -1) 135 return -1; 136 137 BinaryIdSize = sizeof(BinaryIdLen) + BinaryIdLen; 138 } 139 140 return BinaryIdSize; 141 } 142 143 /* 144 * Helper function that iterates through notes section and find build ids. 145 * If writer is given, write binary ids into profiles. 146 * If an error happens while writing, return -1. 147 */ 148 static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note, 149 const ElfW(Nhdr) * NotesEnd) { 150 int TotalBinaryIdsSize = 0; 151 while (Note < NotesEnd) { 152 int Result = WriteBinaryIdForNote(Writer, Note); 153 if (Result == -1) 154 return -1; 155 TotalBinaryIdsSize += Result; 156 157 /* Calculate the offset of the next note in notes section. */ 158 size_t NoteOffset = sizeof(ElfW(Nhdr)) + RoundUp(Note->n_namesz, 4) + 159 RoundUp(Note->n_descsz, 4); 160 Note = (const ElfW(Nhdr) *)((const char *)(Note) + NoteOffset); 161 } 162 163 return TotalBinaryIdsSize; 164 } 165 166 /* 167 * Write binary ids into profiles if writer is given. 168 * Return the total size of binary ids. 169 * If an error happens while writing, return -1. 170 */ 171 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 172 extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden"))); 173 const ElfW(Ehdr) *ElfHeader = &__ehdr_start; 174 const ElfW(Phdr) *ProgramHeader = 175 (const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff); 176 177 uint32_t I; 178 /* Iterate through entries in the program header. */ 179 for (I = 0; I < ElfHeader->e_phnum; I++) { 180 /* Look for the notes section in program header entries. */ 181 if (ProgramHeader[I].p_type != PT_NOTE) 182 continue; 183 184 const ElfW(Nhdr) *Note = 185 (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + ProgramHeader[I].p_offset); 186 const ElfW(Nhdr) *NotesEnd = 187 (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_filesz); 188 return WriteBinaryIds(Writer, Note, NotesEnd); 189 } 190 191 return 0; 192 } 193 #else /* !NT_GNU_BUILD_ID */ 194 /* 195 * Fallback implementation for targets that don't support the GNU 196 * extensions NT_GNU_BUILD_ID and __ehdr_start. 197 */ 198 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 199 return 0; 200 } 201 #endif 202 203 #endif 204