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) || defined(__wasm__) || defined(__HAIKU__)
12
13#if !defined(_AIX) && !defined(__wasm__)
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_VNODES_START INSTR_PROF_SECT_START(INSTR_PROF_VNODES_COMMON)
36#define PROF_VNODES_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VNODES_COMMON)
37#define PROF_COVINIT_START INSTR_PROF_SECT_START(INSTR_PROF_COVINIT_COMMON)
38#define PROF_COVINIT_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_COVINIT_COMMON)
39
40/* Declare section start and stop symbols for various sections
41 * generated by compiler instrumentation.
42 */
43extern __llvm_profile_data PROF_DATA_START COMPILER_RT_VISIBILITY
44 COMPILER_RT_WEAK;
45extern __llvm_profile_data PROF_DATA_STOP COMPILER_RT_VISIBILITY
46 COMPILER_RT_WEAK;
47extern char PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
48extern char PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
49extern VTableProfData PROF_VTABLE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
50extern VTableProfData PROF_VTABLE_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
51extern char PROF_VNAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
52extern char PROF_VNAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
53extern char PROF_BITS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
54extern char PROF_BITS_STOP 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;
59extern __llvm_gcov_init_func_struct PROF_COVINIT_START COMPILER_RT_VISIBILITY
60 COMPILER_RT_WEAK;
61extern __llvm_gcov_init_func_struct PROF_COVINIT_STOP COMPILER_RT_VISIBILITY
62 COMPILER_RT_WEAK;
63
64COMPILER_RT_VISIBILITY const __llvm_profile_data *
65__llvm_profile_begin_data(void) {
66 return &PROF_DATA_START;
67}
68COMPILER_RT_VISIBILITY const __llvm_profile_data *
69__llvm_profile_end_data(void) {
70 return &PROF_DATA_STOP;
71}
72COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) {
73 return &PROF_NAME_START;
74}
75COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) {
76 return &PROF_NAME_STOP;
77}
78COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_vtabnames(void) {
79 return &PROF_VNAME_START;
80}
81COMPILER_RT_VISIBILITY const char *__llvm_profile_end_vtabnames(void) {
82 return &PROF_VNAME_STOP;
83}
84COMPILER_RT_VISIBILITY const VTableProfData *
85__llvm_profile_begin_vtables(void) {
86 return &PROF_VTABLE_START;
87}
88COMPILER_RT_VISIBILITY const VTableProfData *__llvm_profile_end_vtables(void) {
89 return &PROF_VTABLE_STOP;
90}
91COMPILER_RT_VISIBILITY char *__llvm_profile_begin_counters(void) {
92 return &PROF_CNTS_START;
93}
94COMPILER_RT_VISIBILITY char *__llvm_profile_end_counters(void) {
95 return &PROF_CNTS_STOP;
96}
97COMPILER_RT_VISIBILITY char *__llvm_profile_begin_bitmap(void) {
98 return &PROF_BITS_START;
99}
100COMPILER_RT_VISIBILITY char *__llvm_profile_end_bitmap(void) {
101 return &PROF_BITS_STOP;
102}
103
104COMPILER_RT_VISIBILITY ValueProfNode *
105__llvm_profile_begin_vnodes(void) {
106 return &PROF_VNODES_START;
107}
108COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) {
109 return &PROF_VNODES_STOP;
110}
111COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START;
112COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP;
113
114COMPILER_RT_VISIBILITY const __llvm_gcov_init_func_struct *
115__llvm_profile_begin_covinit() {
116 return &PROF_COVINIT_START;
117}
118
119COMPILER_RT_VISIBILITY const __llvm_gcov_init_func_struct *
120__llvm_profile_end_covinit() {
121 return &PROF_COVINIT_STOP;
122}
123
124#ifdef NT_GNU_BUILD_ID
125static size_t RoundUp(size_t size, size_t align) {
126 return (size + align - 1) & ~(align - 1);
127}
128
129/*
130 * Look for the note that has the name "GNU\0" and type NT_GNU_BUILD_ID
131 * that contains build id. If build id exists, write binary id.
132 *
133 * Each note in notes section starts with a struct which includes
134 * n_namesz, n_descsz, and n_type members. It is followed by the name
135 * (whose length is defined in n_namesz) and then by the descriptor
136 * (whose length is defined in n_descsz).
137 *
138 * Note sections like .note.ABI-tag and .note.gnu.build-id are aligned
139 * to 4 bytes, so round n_namesz and n_descsz to the nearest 4 bytes.
140 */
141static int WriteBinaryIdForNote(ProfDataWriter *Writer,
142 const ElfW(Nhdr) * Note) {
143 int BinaryIdSize = 0;
144 const char *NoteName = (const char *)Note + sizeof(ElfW(Nhdr));
145 if (Note->n_type == NT_GNU_BUILD_ID && Note->n_namesz == 4 &&
146 memcmp(s1: NoteName, s2: "GNU\0", n: 4) == 0) {
147 uint64_t BinaryIdLen = Note->n_descsz;
148 const uint8_t *BinaryIdData =
149 (const uint8_t *)(NoteName + RoundUp(size: Note->n_namesz, align: 4));
150 uint8_t BinaryIdPadding = __llvm_profile_get_num_padding_bytes(SizeInBytes: BinaryIdLen);
151 if (Writer != NULL &&
152 lprofWriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData,
153 BinaryIdPadding) == -1)
154 return -1;
155
156 BinaryIdSize = sizeof(BinaryIdLen) + BinaryIdLen + BinaryIdPadding;
157 }
158
159 return BinaryIdSize;
160}
161
162/*
163 * Helper function that iterates through notes section and find build ids.
164 * If writer is given, write binary ids into profiles.
165 * If an error happens while writing, return -1.
166 */
167static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note,
168 const ElfW(Nhdr) * NotesEnd) {
169 int BinaryIdsSize = 0;
170 while (Note < NotesEnd) {
171 int OneBinaryIdSize = WriteBinaryIdForNote(Writer, Note);
172 if (OneBinaryIdSize == -1)
173 return -1;
174 BinaryIdsSize += OneBinaryIdSize;
175
176 /* Calculate the offset of the next note in notes section. */
177 size_t NoteOffset = sizeof(ElfW(Nhdr)) + RoundUp(size: Note->n_namesz, align: 4) +
178 RoundUp(size: Note->n_descsz, align: 4);
179 Note = (const ElfW(Nhdr) *)((const char *)(Note) + NoteOffset);
180 }
181
182 return BinaryIdsSize;
183}
184
185/*
186 * Write binary ids into profiles if writer is given.
187 * Return the total size of binary ids.
188 * If an error happens while writing, return -1.
189 */
190COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
191 extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden")));
192 extern ElfW(Dyn) _DYNAMIC[] __attribute__((weak, visibility("hidden")));
193
194 const ElfW(Ehdr) *ElfHeader = &__ehdr_start;
195 const ElfW(Phdr) *ProgramHeader =
196 (const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff);
197
198 /* Compute the added base address in case of position-independent code. */
199 uintptr_t Base = 0;
200 for (uint32_t I = 0; I < ElfHeader->e_phnum; I++) {
201 if (ProgramHeader[I].p_type == PT_PHDR)
202 Base = (uintptr_t)ProgramHeader - ProgramHeader[I].p_vaddr;
203 if (ProgramHeader[I].p_type == PT_DYNAMIC && _DYNAMIC)
204 Base = (uintptr_t)_DYNAMIC - ProgramHeader[I].p_vaddr;
205 }
206
207 int TotalBinaryIdsSize = 0;
208 /* Iterate through entries in the program header. */
209 for (uint32_t I = 0; I < ElfHeader->e_phnum; I++) {
210 /* Look for the notes segment in program header entries. */
211 if (ProgramHeader[I].p_type != PT_NOTE)
212 continue;
213
214 /* There can be multiple notes segment, and examine each of them. */
215 const ElfW(Nhdr) *Note =
216 (const ElfW(Nhdr) *)(Base + ProgramHeader[I].p_vaddr);
217 const ElfW(Nhdr) *NotesEnd =
218 (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz);
219
220 int BinaryIdsSize = WriteBinaryIds(Writer, Note, NotesEnd);
221 if (TotalBinaryIdsSize == -1)
222 return -1;
223
224 TotalBinaryIdsSize += BinaryIdsSize;
225 }
226
227 return TotalBinaryIdsSize;
228}
229#elif !defined(_AIX) /* !NT_GNU_BUILD_ID */
230/*
231 * Fallback implementation for targets that don't support the GNU
232 * extensions NT_GNU_BUILD_ID and __ehdr_start.
233 */
234COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
235 return 0;
236}
237#endif
238
239#endif
240