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|
/*===- InstrProfilingPlatformLinux.c - Profile data Linux platform ------===*\
|*
|* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|* See https://llvm.org/LICENSE.txt for license information.
|* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|*
\*===----------------------------------------------------------------------===*/
#if defined(__linux__) || defined(__FreeBSD__) || defined(__Fuchsia__) || \
(defined(__sun__) && defined(__svr4__)) || defined(__NetBSD__)
#include <elf.h>
#include <link.h>
#include <stdlib.h>
#include <string.h>
#include "InstrProfiling.h"
#include "InstrProfilingInternal.h"
#if defined(__FreeBSD__) && !defined(ElfW)
/*
* FreeBSD's elf.h and link.h headers do not define the ElfW(type) macro yet.
* If this is added to all supported FreeBSD versions in the future, this
* compatibility macro can be removed.
*/
#define ElfW(type) __ElfN(type)
#endif
#define PROF_DATA_START INSTR_PROF_SECT_START(INSTR_PROF_DATA_COMMON)
#define PROF_DATA_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_DATA_COMMON)
#define PROF_NAME_START INSTR_PROF_SECT_START(INSTR_PROF_NAME_COMMON)
#define PROF_NAME_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_NAME_COMMON)
#define PROF_CNTS_START INSTR_PROF_SECT_START(INSTR_PROF_CNTS_COMMON)
#define PROF_CNTS_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_CNTS_COMMON)
#define PROF_ORDERFILE_START INSTR_PROF_SECT_START(INSTR_PROF_ORDERFILE_COMMON)
#define PROF_VNODES_START INSTR_PROF_SECT_START(INSTR_PROF_VNODES_COMMON)
#define PROF_VNODES_STOP INSTR_PROF_SECT_STOP(INSTR_PROF_VNODES_COMMON)
/* Declare section start and stop symbols for various sections
* generated by compiler instrumentation.
*/
extern __llvm_profile_data PROF_DATA_START COMPILER_RT_VISIBILITY
COMPILER_RT_WEAK;
extern __llvm_profile_data PROF_DATA_STOP COMPILER_RT_VISIBILITY
COMPILER_RT_WEAK;
extern char PROF_CNTS_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
extern char PROF_CNTS_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
extern uint32_t PROF_ORDERFILE_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
extern char PROF_NAME_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
extern char PROF_NAME_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
extern ValueProfNode PROF_VNODES_START COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
extern ValueProfNode PROF_VNODES_STOP COMPILER_RT_VISIBILITY COMPILER_RT_WEAK;
COMPILER_RT_VISIBILITY const __llvm_profile_data *
__llvm_profile_begin_data(void) {
return &PROF_DATA_START;
}
COMPILER_RT_VISIBILITY const __llvm_profile_data *
__llvm_profile_end_data(void) {
return &PROF_DATA_STOP;
}
COMPILER_RT_VISIBILITY const char *__llvm_profile_begin_names(void) {
return &PROF_NAME_START;
}
COMPILER_RT_VISIBILITY const char *__llvm_profile_end_names(void) {
return &PROF_NAME_STOP;
}
COMPILER_RT_VISIBILITY char *__llvm_profile_begin_counters(void) {
return &PROF_CNTS_START;
}
COMPILER_RT_VISIBILITY char *__llvm_profile_end_counters(void) {
return &PROF_CNTS_STOP;
}
COMPILER_RT_VISIBILITY uint32_t *__llvm_profile_begin_orderfile(void) {
return &PROF_ORDERFILE_START;
}
COMPILER_RT_VISIBILITY ValueProfNode *
__llvm_profile_begin_vnodes(void) {
return &PROF_VNODES_START;
}
COMPILER_RT_VISIBILITY ValueProfNode *__llvm_profile_end_vnodes(void) {
return &PROF_VNODES_STOP;
}
COMPILER_RT_VISIBILITY ValueProfNode *CurrentVNode = &PROF_VNODES_START;
COMPILER_RT_VISIBILITY ValueProfNode *EndVNode = &PROF_VNODES_STOP;
#ifdef NT_GNU_BUILD_ID
static size_t RoundUp(size_t size, size_t align) {
return (size + align - 1) & ~(align - 1);
}
/*
* Write binary id length and then its data, because binary id does not
* have a fixed length.
*/
static int WriteOneBinaryId(ProfDataWriter *Writer, uint64_t BinaryIdLen,
const uint8_t *BinaryIdData,
uint64_t BinaryIdPadding) {
ProfDataIOVec BinaryIdIOVec[] = {
{&BinaryIdLen, sizeof(uint64_t), 1, 0},
{BinaryIdData, sizeof(uint8_t), BinaryIdLen, 0},
{NULL, sizeof(uint8_t), BinaryIdPadding, 1},
};
if (Writer->Write(Writer, BinaryIdIOVec,
sizeof(BinaryIdIOVec) / sizeof(*BinaryIdIOVec)))
return -1;
/* Successfully wrote binary id, report success. */
return 0;
}
/*
* Look for the note that has the name "GNU\0" and type NT_GNU_BUILD_ID
* that contains build id. If build id exists, write binary id.
*
* Each note in notes section starts with a struct which includes
* n_namesz, n_descsz, and n_type members. It is followed by the name
* (whose length is defined in n_namesz) and then by the descriptor
* (whose length is defined in n_descsz).
*
* Note sections like .note.ABI-tag and .note.gnu.build-id are aligned
* to 4 bytes, so round n_namesz and n_descsz to the nearest 4 bytes.
*/
static int WriteBinaryIdForNote(ProfDataWriter *Writer,
const ElfW(Nhdr) * Note) {
int BinaryIdSize = 0;
const char *NoteName = (const char *)Note + sizeof(ElfW(Nhdr));
if (Note->n_type == NT_GNU_BUILD_ID && Note->n_namesz == 4 &&
memcmp(NoteName, "GNU\0", 4) == 0) {
uint64_t BinaryIdLen = Note->n_descsz;
const uint8_t *BinaryIdData =
(const uint8_t *)(NoteName + RoundUp(Note->n_namesz, 4));
uint8_t BinaryIdPadding = __llvm_profile_get_num_padding_bytes(BinaryIdLen);
if (Writer != NULL && WriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData,
BinaryIdPadding) == -1)
return -1;
BinaryIdSize = sizeof(BinaryIdLen) + BinaryIdLen + BinaryIdPadding;
}
return BinaryIdSize;
}
/*
* Helper function that iterates through notes section and find build ids.
* If writer is given, write binary ids into profiles.
* If an error happens while writing, return -1.
*/
static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note,
const ElfW(Nhdr) * NotesEnd) {
int BinaryIdsSize = 0;
while (Note < NotesEnd) {
int OneBinaryIdSize = WriteBinaryIdForNote(Writer, Note);
if (OneBinaryIdSize == -1)
return -1;
BinaryIdsSize += OneBinaryIdSize;
/* Calculate the offset of the next note in notes section. */
size_t NoteOffset = sizeof(ElfW(Nhdr)) + RoundUp(Note->n_namesz, 4) +
RoundUp(Note->n_descsz, 4);
Note = (const ElfW(Nhdr) *)((const char *)(Note) + NoteOffset);
}
return BinaryIdsSize;
}
/*
* Write binary ids into profiles if writer is given.
* Return the total size of binary ids.
* If an error happens while writing, return -1.
*/
COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden")));
const ElfW(Ehdr) *ElfHeader = &__ehdr_start;
const ElfW(Phdr) *ProgramHeader =
(const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff);
int TotalBinaryIdsSize = 0;
uint32_t I;
/* Iterate through entries in the program header. */
for (I = 0; I < ElfHeader->e_phnum; I++) {
/* Look for the notes segment in program header entries. */
if (ProgramHeader[I].p_type != PT_NOTE)
continue;
/* There can be multiple notes segment, and examine each of them. */
const ElfW(Nhdr) * Note;
const ElfW(Nhdr) * NotesEnd;
/*
* When examining notes in file, use p_offset, which is the offset within
* the elf file, to find the start of notes.
*/
if (ProgramHeader[I].p_memsz == 0 ||
ProgramHeader[I].p_memsz == ProgramHeader[I].p_filesz) {
Note = (const ElfW(Nhdr) *)((uintptr_t)ElfHeader +
ProgramHeader[I].p_offset);
NotesEnd = (const ElfW(Nhdr) *)((const char *)(Note) +
ProgramHeader[I].p_filesz);
} else {
/*
* When examining notes in memory, use p_vaddr, which is the address of
* section after loaded to memory, to find the start of notes.
*/
Note =
(const ElfW(Nhdr) *)((uintptr_t)ElfHeader + ProgramHeader[I].p_vaddr);
NotesEnd =
(const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz);
}
int BinaryIdsSize = WriteBinaryIds(Writer, Note, NotesEnd);
if (TotalBinaryIdsSize == -1)
return -1;
TotalBinaryIdsSize += BinaryIdsSize;
}
return TotalBinaryIdsSize;
}
#else /* !NT_GNU_BUILD_ID */
/*
* Fallback implementation for targets that don't support the GNU
* extensions NT_GNU_BUILD_ID and __ehdr_start.
*/
COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
return 0;
}
#endif
#endif
|
