e50a38840d
This patch adds binary id into profiles to easily associate binaries with the corresponding profiles. There is an RFC that discusses the motivation, design and implementation in more detail: https://lists.llvm.org/pipermail/llvm-dev/2021-June/151154.html Differential Revision: https://reviews.llvm.org/D102039
184 lines
6.6 KiB
C
184 lines
6.6 KiB
C
/*===- InstrProfilingPlatformLinux.c - Profile data Linux platform ------===*\
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|*
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|* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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|* See https://llvm.org/LICENSE.txt for license information.
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|* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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|*
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\*===----------------------------------------------------------------------===*/
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#if defined(__linux__) || defined(__FreeBSD__) || defined(__Fuchsia__) || \
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(defined(__sun__) && defined(__svr4__)) || defined(__NetBSD__)
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#include <elf.h>
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#include <link.h>
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#include <stdlib.h>
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#include <string.h>
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#include "InstrProfiling.h"
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#include "InstrProfilingInternal.h"
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#define PROF_DATA_START INSTR_PROF_SECT_START(INSTR_PROF_DATA_COMMON)
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#define PROF_DATA_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_DATA_COMMON)
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#define PROF_NAME_START INSTR_PROF_SECT_START(INSTR_PROF_NAME_COMMON)
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#define PROF_NAME_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_NAME_COMMON)
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#define PROF_CNTS_START INSTR_PROF_SECT_START(INSTR_PROF_CNTS_COMMON)
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#define PROF_CNTS_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_CNTS_COMMON)
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#define PROF_ORDERFILE_START INSTR_PROF_SECT_START(INSTR_PROF_ORDERFILE_COMMON)
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#define PROF_VNODES_START INSTR_PROF_SECT_START(INSTR_PROF_VNODES_COMMON)
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#define PROF_VNODES_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VNODES_COMMON)
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/* Declare section start and stop symbols for various sections
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* generated by compiler instrumentation.
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*/
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extern __llvm_profile_data PROF_DATA_START COMPILER_RT_VISIBILITY
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COMPILER_RT_WEAK;
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extern __llvm_profile_data PROF_DATA_STOP COMPILER_RT_VISIBILITY
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COMPILER_RT_WEAK;
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extern uint64_t PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
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extern uint64_t PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
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extern uint32_t PROF_ORDERFILE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
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extern char PROF_NAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
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extern char PROF_NAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
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extern ValueProfNode PROF_VNODES_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
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extern ValueProfNode PROF_VNODES_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
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COMPILER_RT_VISIBILITY const __llvm_profile_data *
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__llvm_profile_begin_data(void) {
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return &PROF_DATA_START;
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}
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COMPILER_RT_VISIBILITY const __llvm_profile_data *
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__llvm_profile_end_data(void) {
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return &PROF_DATA_STOP;
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}
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COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) {
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return &PROF_NAME_START;
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}
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COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) {
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return &PROF_NAME_STOP;
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}
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COMPILER_RT_VISIBILITY uint64_t *__llvm_profile_begin_counters(void) {
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return &PROF_CNTS_START;
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}
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COMPILER_RT_VISIBILITY uint64_t *__llvm_profile_end_counters(void) {
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return &PROF_CNTS_STOP;
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}
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COMPILER_RT_VISIBILITY uint32_t *__llvm_profile_begin_orderfile(void) {
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return &PROF_ORDERFILE_START;
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}
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COMPILER_RT_VISIBILITY ValueProfNode *
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__llvm_profile_begin_vnodes(void) {
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return &PROF_VNODES_START;
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}
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COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) {
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return &PROF_VNODES_STOP;
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}
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COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START;
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COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP;
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static size_t RoundUp(size_t size, size_t align) {
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return (size + align - 1) & ~(align - 1);
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}
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/*
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* Write binary id length and then its data, because binary id does not
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* have a fixed length.
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*/
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int WriteOneBinaryId(ProfDataWriter *Writer, uint64_t BinaryIdLen,
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const uint8_t *BinaryIdData) {
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ProfDataIOVec BinaryIdIOVec[] = {
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{&BinaryIdLen, sizeof(uint64_t), 1, 0},
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{BinaryIdData, sizeof(uint8_t), BinaryIdLen, 0}};
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if (Writer->Write(Writer, BinaryIdIOVec,
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sizeof(BinaryIdIOVec) / sizeof(*BinaryIdIOVec)))
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return -1;
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/* Successfully wrote binary id, report success. */
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return 0;
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}
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/*
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* Look for the note that has the name "GNU\0" and type NT_GNU_BUILD_ID
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* that contains build id. If build id exists, write binary id.
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*
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* Each note in notes section starts with a struct which includes
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* n_namesz, n_descsz, and n_type members. It is followed by the name
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* (whose length is defined in n_namesz) and then by the descriptor
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* (whose length is defined in n_descsz).
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*
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* Note sections like .note.ABI-tag and .note.gnu.build-id are aligned
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* to 4 bytes, so round n_namesz and n_descsz to the nearest 4 bytes.
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*/
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int WriteBinaryIdForNote(ProfDataWriter *Writer, const ElfW(Nhdr) * Note) {
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int BinaryIdSize = 0;
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const char *NoteName = (const char *)Note + sizeof(ElfW(Nhdr));
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if (Note->n_type == NT_GNU_BUILD_ID && Note->n_namesz == 4 &&
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memcmp(NoteName, "GNU\0", 4) == 0) {
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uint64_t BinaryIdLen = Note->n_descsz;
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const uint8_t *BinaryIdData =
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(const uint8_t *)(NoteName + RoundUp(Note->n_namesz, 4));
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if (Writer != NULL &&
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WriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData) == -1)
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return -1;
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BinaryIdSize = sizeof(BinaryIdLen) + BinaryIdLen;
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}
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return BinaryIdSize;
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}
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/*
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* Helper function that iterates through notes section and find build ids.
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* If writer is given, write binary ids into profiles.
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* If an error happens while writing, return -1.
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*/
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int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note,
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const ElfW(Nhdr) * NotesEnd) {
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int TotalBinaryIdsSize = 0;
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while (Note < NotesEnd) {
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int Result = WriteBinaryIdForNote(Writer, Note);
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if (Result == -1)
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return -1;
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TotalBinaryIdsSize += Result;
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/* Calculate the offset of the next note in notes section. */
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size_t NoteOffset = sizeof(ElfW(Nhdr)) + RoundUp(Note->n_namesz, 4) +
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RoundUp(Note->n_descsz, 4);
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Note = (const ElfW(Nhdr) *)((const char *)(Note) + NoteOffset);
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}
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return TotalBinaryIdsSize;
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}
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/*
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* Write binary ids into profiles if writer is given.
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* Return the total size of binary ids.
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* If an error happens while writing, return -1.
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*/
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COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
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extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden")));
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const ElfW(Ehdr) *ElfHeader = &__ehdr_start;
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const ElfW(Phdr) *ProgramHeader =
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(const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff);
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uint32_t I;
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/* Iterate through entries in the program header. */
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for (I = 0; I < ElfHeader->e_phnum; I++) {
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/* Look for the notes section in program header entries. */
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if (ProgramHeader[I].p_type != PT_NOTE)
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continue;
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const ElfW(Nhdr) *Note =
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(const ElfW(Nhdr) *)((uintptr_t)ElfHeader + ProgramHeader[I].p_offset);
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const ElfW(Nhdr) *NotesEnd =
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(const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_filesz);
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return WriteBinaryIds(Writer, Note, NotesEnd);
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}
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return 0;
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}
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#endif
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