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_CNTS_START INSTR_PROF_SECT_START(INSTR_PROF_CNTS_COMMON) 28 #define PROF_CNTS_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_CNTS_COMMON) 29 #define PROF_BITS_START INSTR_PROF_SECT_START(INSTR_PROF_BITS_COMMON) 30 #define PROF_BITS_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_BITS_COMMON) 31 #define PROF_ORDERFILE_START INSTR_PROF_SECT_START(INSTR_PROF_ORDERFILE_COMMON) 32 #define PROF_VNODES_START INSTR_PROF_SECT_START(INSTR_PROF_VNODES_COMMON) 33 #define PROF_VNODES_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VNODES_COMMON) 34 35 /* Declare section start and stop symbols for various sections 36 * generated by compiler instrumentation. 37 */ 38 extern __llvm_profile_data PROF_DATA_START COMPILER_RT_VISIBILITY 39 COMPILER_RT_WEAK; 40 extern __llvm_profile_data PROF_DATA_STOP COMPILER_RT_VISIBILITY 41 COMPILER_RT_WEAK; 42 extern char PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 43 extern char PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 44 extern char PROF_BITS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 45 extern char PROF_BITS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 46 extern uint32_t PROF_ORDERFILE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 47 extern char PROF_NAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 48 extern char PROF_NAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 49 extern ValueProfNode PROF_VNODES_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 50 extern ValueProfNode PROF_VNODES_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK; 51 52 COMPILER_RT_VISIBILITY const __llvm_profile_data * 53 __llvm_profile_begin_data(void) { 54 return &PROF_DATA_START; 55 } 56 COMPILER_RT_VISIBILITY const __llvm_profile_data * 57 __llvm_profile_end_data(void) { 58 return &PROF_DATA_STOP; 59 } 60 COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) { 61 return &PROF_NAME_START; 62 } 63 COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) { 64 return &PROF_NAME_STOP; 65 } 66 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_counters(void) { 67 return &PROF_CNTS_START; 68 } 69 COMPILER_RT_VISIBILITY char *__llvm_profile_end_counters(void) { 70 return &PROF_CNTS_STOP; 71 } 72 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_bitmap(void) { 73 return &PROF_BITS_START; 74 } 75 COMPILER_RT_VISIBILITY char *__llvm_profile_end_bitmap(void) { 76 return &PROF_BITS_STOP; 77 } 78 COMPILER_RT_VISIBILITY uint32_t *__llvm_profile_begin_orderfile(void) { 79 return &PROF_ORDERFILE_START; 80 } 81 82 COMPILER_RT_VISIBILITY ValueProfNode * 83 __llvm_profile_begin_vnodes(void) { 84 return &PROF_VNODES_START; 85 } 86 COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) { 87 return &PROF_VNODES_STOP; 88 } 89 COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START; 90 COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP; 91 92 #ifdef NT_GNU_BUILD_ID 93 static size_t RoundUp(size_t size, size_t align) { 94 return (size + align - 1) & ~(align - 1); 95 } 96 97 /* 98 * Look for the note that has the name "GNU\0" and type NT_GNU_BUILD_ID 99 * that contains build id. If build id exists, write binary id. 100 * 101 * Each note in notes section starts with a struct which includes 102 * n_namesz, n_descsz, and n_type members. It is followed by the name 103 * (whose length is defined in n_namesz) and then by the descriptor 104 * (whose length is defined in n_descsz). 105 * 106 * Note sections like .note.ABI-tag and .note.gnu.build-id are aligned 107 * to 4 bytes, so round n_namesz and n_descsz to the nearest 4 bytes. 108 */ 109 static int WriteBinaryIdForNote(ProfDataWriter *Writer, 110 const ElfW(Nhdr) * Note) { 111 int BinaryIdSize = 0; 112 const char *NoteName = (const char *)Note + sizeof(ElfW(Nhdr)); 113 if (Note->n_type == NT_GNU_BUILD_ID && Note->n_namesz == 4 && 114 memcmp(NoteName, "GNU\0", 4) == 0) { 115 uint64_t BinaryIdLen = Note->n_descsz; 116 const uint8_t *BinaryIdData = 117 (const uint8_t *)(NoteName + RoundUp(Note->n_namesz, 4)); 118 uint8_t BinaryIdPadding = __llvm_profile_get_num_padding_bytes(BinaryIdLen); 119 if (Writer != NULL && 120 lprofWriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData, 121 BinaryIdPadding) == -1) 122 return -1; 123 124 BinaryIdSize = sizeof(BinaryIdLen) + BinaryIdLen + BinaryIdPadding; 125 } 126 127 return BinaryIdSize; 128 } 129 130 /* 131 * Helper function that iterates through notes section and find build ids. 132 * If writer is given, write binary ids into profiles. 133 * If an error happens while writing, return -1. 134 */ 135 static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note, 136 const ElfW(Nhdr) * NotesEnd) { 137 int BinaryIdsSize = 0; 138 while (Note < NotesEnd) { 139 int OneBinaryIdSize = WriteBinaryIdForNote(Writer, Note); 140 if (OneBinaryIdSize == -1) 141 return -1; 142 BinaryIdsSize += OneBinaryIdSize; 143 144 /* Calculate the offset of the next note in notes section. */ 145 size_t NoteOffset = sizeof(ElfW(Nhdr)) + RoundUp(Note->n_namesz, 4) + 146 RoundUp(Note->n_descsz, 4); 147 Note = (const ElfW(Nhdr) *)((const char *)(Note) + NoteOffset); 148 } 149 150 return BinaryIdsSize; 151 } 152 153 /* 154 * Write binary ids into profiles if writer is given. 155 * Return the total size of binary ids. 156 * If an error happens while writing, return -1. 157 */ 158 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 159 extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden"))); 160 const ElfW(Ehdr) *ElfHeader = &__ehdr_start; 161 const ElfW(Phdr) *ProgramHeader = 162 (const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff); 163 164 int TotalBinaryIdsSize = 0; 165 uint32_t I; 166 /* Iterate through entries in the program header. */ 167 for (I = 0; I < ElfHeader->e_phnum; I++) { 168 /* Look for the notes segment in program header entries. */ 169 if (ProgramHeader[I].p_type != PT_NOTE) 170 continue; 171 172 /* There can be multiple notes segment, and examine each of them. */ 173 const ElfW(Nhdr) * Note; 174 const ElfW(Nhdr) * NotesEnd; 175 /* 176 * When examining notes in file, use p_offset, which is the offset within 177 * the elf file, to find the start of notes. 178 */ 179 if (ProgramHeader[I].p_memsz == 0 || 180 ProgramHeader[I].p_memsz == ProgramHeader[I].p_filesz) { 181 Note = (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + 182 ProgramHeader[I].p_offset); 183 NotesEnd = (const ElfW(Nhdr) *)((const char *)(Note) + 184 ProgramHeader[I].p_filesz); 185 } else { 186 /* 187 * When examining notes in memory, use p_vaddr, which is the address of 188 * section after loaded to memory, to find the start of notes. 189 */ 190 Note = 191 (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + ProgramHeader[I].p_vaddr); 192 NotesEnd = 193 (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz); 194 } 195 196 int BinaryIdsSize = WriteBinaryIds(Writer, Note, NotesEnd); 197 if (TotalBinaryIdsSize == -1) 198 return -1; 199 200 TotalBinaryIdsSize += BinaryIdsSize; 201 } 202 203 return TotalBinaryIdsSize; 204 } 205 #elif !defined(_AIX) /* !NT_GNU_BUILD_ID */ 206 /* 207 * Fallback implementation for targets that don't support the GNU 208 * extensions NT_GNU_BUILD_ID and __ehdr_start. 209 */ 210 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) { 211 return 0; 212 } 213 #endif 214 215 #endif 216