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 *
__llvm_profile_begin_data(void)53 __llvm_profile_begin_data(void) {
54 return &PROF_DATA_START;
55 }
56 COMPILER_RT_VISIBILITY const __llvm_profile_data *
__llvm_profile_end_data(void)57 __llvm_profile_end_data(void) {
58 return &PROF_DATA_STOP;
59 }
__llvm_profile_begin_names(void)60 COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) {
61 return &PROF_NAME_START;
62 }
__llvm_profile_end_names(void)63 COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) {
64 return &PROF_NAME_STOP;
65 }
__llvm_profile_begin_counters(void)66 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_counters(void) {
67 return &PROF_CNTS_START;
68 }
__llvm_profile_end_counters(void)69 COMPILER_RT_VISIBILITY char *__llvm_profile_end_counters(void) {
70 return &PROF_CNTS_STOP;
71 }
__llvm_profile_begin_bitmap(void)72 COMPILER_RT_VISIBILITY char *__llvm_profile_begin_bitmap(void) {
73 return &PROF_BITS_START;
74 }
__llvm_profile_end_bitmap(void)75 COMPILER_RT_VISIBILITY char *__llvm_profile_end_bitmap(void) {
76 return &PROF_BITS_STOP;
77 }
__llvm_profile_begin_orderfile(void)78 COMPILER_RT_VISIBILITY uint32_t *__llvm_profile_begin_orderfile(void) {
79 return &PROF_ORDERFILE_START;
80 }
81
82 COMPILER_RT_VISIBILITY ValueProfNode *
__llvm_profile_begin_vnodes(void)83 __llvm_profile_begin_vnodes(void) {
84 return &PROF_VNODES_START;
85 }
__llvm_profile_end_vnodes(void)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
RoundUp(size_t size,size_t align)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 */
WriteBinaryIdForNote(ProfDataWriter * Writer,const ElfW (Nhdr)* Note)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 */
WriteBinaryIds(ProfDataWriter * Writer,const ElfW (Nhdr)* Note,const ElfW (Nhdr)* NotesEnd)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 */
__llvm_write_binary_ids(ProfDataWriter * Writer)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 */
__llvm_write_binary_ids(ProfDataWriter * Writer)210 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
211 return 0;
212 }
213 #endif
214
215 #endif
216