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 */
42extern __llvm_profile_data PROF_DATA_START COMPILER_RT_VISIBILITY
43 COMPILER_RT_WEAK;
44extern __llvm_profile_data PROF_DATA_STOP COMPILER_RT_VISIBILITY
45 COMPILER_RT_WEAK;
46extern char PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
47extern char PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
48extern VTableProfData PROF_VTABLE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
49extern VTableProfData PROF_VTABLE_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
50extern char PROF_VNAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
51extern char PROF_VNAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
52extern char PROF_BITS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
53extern char PROF_BITS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
54extern uint32_t PROF_ORDERFILE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
55extern char PROF_NAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
56extern char PROF_NAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
57extern ValueProfNode PROF_VNODES_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
58extern ValueProfNode PROF_VNODES_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
59
60COMPILER_RT_VISIBILITY const __llvm_profile_data *
61__llvm_profile_begin_data(void) {
62 return &PROF_DATA_START;
63}
64COMPILER_RT_VISIBILITY const __llvm_profile_data *
65__llvm_profile_end_data(void) {
66 return &PROF_DATA_STOP;
67}
68COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) {
69 return &PROF_NAME_START;
70}
71COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) {
72 return &PROF_NAME_STOP;
73}
74COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_vtabnames(void) {
75 return &PROF_VNAME_START;
76}
77COMPILER_RT_VISIBILITY const char *__llvm_profile_end_vtabnames(void) {
78 return &PROF_VNAME_STOP;
79}
80COMPILER_RT_VISIBILITY const VTableProfData *
81__llvm_profile_begin_vtables(void) {
82 return &PROF_VTABLE_START;
83}
84COMPILER_RT_VISIBILITY const VTableProfData *__llvm_profile_end_vtables(void) {
85 return &PROF_VTABLE_STOP;
86}
87COMPILER_RT_VISIBILITY char *__llvm_profile_begin_counters(void) {
88 return &PROF_CNTS_START;
89}
90COMPILER_RT_VISIBILITY char *__llvm_profile_end_counters(void) {
91 return &PROF_CNTS_STOP;
92}
93COMPILER_RT_VISIBILITY char *__llvm_profile_begin_bitmap(void) {
94 return &PROF_BITS_START;
95}
96COMPILER_RT_VISIBILITY char *__llvm_profile_end_bitmap(void) {
97 return &PROF_BITS_STOP;
98}
99COMPILER_RT_VISIBILITY uint32_t *__llvm_profile_begin_orderfile(void) {
100 return &PROF_ORDERFILE_START;
101}
102
103COMPILER_RT_VISIBILITY ValueProfNode *
104__llvm_profile_begin_vnodes(void) {
105 return &PROF_VNODES_START;
106}
107COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) {
108 return &PROF_VNODES_STOP;
109}
110COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START;
111COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP;
112
113#ifdef NT_GNU_BUILD_ID
114static 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 */
130static 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(s1: NoteName, s2: "GNU\0", n: 4) == 0) {
136 uint64_t BinaryIdLen = Note->n_descsz;
137 const uint8_t *BinaryIdData =
138 (const uint8_t *)(NoteName + RoundUp(size: Note->n_namesz, align: 4));
139 uint8_t BinaryIdPadding = __llvm_profile_get_num_padding_bytes(SizeInBytes: 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 */
156static 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(size: Note->n_namesz, align: 4) +
167 RoundUp(size: Note->n_descsz, align: 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 */
179COMPILER_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 */
231COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
232 return 0;
233}
234#endif
235
236#endif
237

source code of compiler-rt/lib/profile/InstrProfilingPlatformLinux.c