tools/perf/util/symbol-minimal.c

#include "dso.h"
#include "symbol.h"
#include "symsrc.h"

#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <byteswap.h>
#include <sys/stat.h>
#include <linux/zalloc.h>
#include <internal/lib.h>

static bool check_need_swap(int file_endian)
{
	const int data = 1;
	u8 *check = (u8 *)&data;
	int host_endian;

	if (check[0] == 1)
		host_endian = ELFDATA2LSB;
	else
		host_endian = ELFDATA2MSB;

	return host_endian != file_endian;
}

#define NOTE_ALIGN(sz) (((sz) + 3) & ~3)

#define NT_GNU_BUILD_ID	3

static int read_build_id(void *note_data, size_t note_len, struct build_id *bid,
			 bool need_swap)
{
	size_t size = sizeof(bid->data);
	struct {
		u32 n_namesz;
		u32 n_descsz;
		u32 n_type;
	} *nhdr;
	void *ptr;

	ptr = note_data;
	while (ptr < (note_data + note_len)) {
		const char *name;
		size_t namesz, descsz;

		nhdr = ptr;
		if (need_swap) {
			nhdr->n_namesz = bswap_32(nhdr->n_namesz);
			nhdr->n_descsz = bswap_32(nhdr->n_descsz);
			nhdr->n_type = bswap_32(nhdr->n_type);
		}

		namesz = NOTE_ALIGN(nhdr->n_namesz);
		descsz = NOTE_ALIGN(nhdr->n_descsz);

		ptr += sizeof(*nhdr);
		name = ptr;
		ptr += namesz;
		if (nhdr->n_type == NT_GNU_BUILD_ID &&
		    nhdr->n_namesz == sizeof("GNU")) {
			if (memcmp(name, "GNU", sizeof("GNU")) == 0) {
				size_t sz = min(size, descsz);
				memcpy(bid->data, ptr, sz);
				memset(bid->data + sz, 0, size - sz);
				bid->size = sz;
				return 0;
			}
		}
		ptr += descsz;
	}

	return -1;
}

int filename__read_debuglink(const char *filename __maybe_unused,
			     char *debuglink __maybe_unused,
			     size_t size __maybe_unused)
{
	return -1;
}

/*
 * Just try PT_NOTE header otherwise fails
 */
int filename__read_build_id(const char *filename, struct build_id *bid, bool block)
{
	int fd, ret = -1;
	bool need_swap = false, elf32;
	union {
		struct {
			Elf32_Ehdr ehdr32;
			Elf32_Phdr *phdr32;
		};
		struct {
			Elf64_Ehdr ehdr64;
			Elf64_Phdr *phdr64;
		};
	} hdrs;
	void *phdr, *buf = NULL;
	ssize_t phdr_size, ehdr_size, buf_size = 0;

	fd = open(filename, block ? O_RDONLY : (O_RDONLY | O_NONBLOCK));
	if (fd < 0)
		return -1;

	if (read(fd, hdrs.ehdr32.e_ident, EI_NIDENT) != EI_NIDENT)
		goto out;

	if (memcmp(hdrs.ehdr32.e_ident, ELFMAG, SELFMAG) ||
	    hdrs.ehdr32.e_ident[EI_VERSION] != EV_CURRENT)
		goto out;

	need_swap = check_need_swap(hdrs.ehdr32.e_ident[EI_DATA]);
	elf32 = hdrs.ehdr32.e_ident[EI_CLASS] == ELFCLASS32;
	ehdr_size = (elf32 ? sizeof(hdrs.ehdr32) : sizeof(hdrs.ehdr64)) - EI_NIDENT;

	if (read(fd,
		 (elf32 ? (void *)&hdrs.ehdr32 : (void *)&hdrs.ehdr64) + EI_NIDENT,
		 ehdr_size) != ehdr_size)
		goto out;

	if (need_swap) {
		if (elf32) {
			hdrs.ehdr32.e_phoff = bswap_32(hdrs.ehdr32.e_phoff);
			hdrs.ehdr32.e_phentsize = bswap_16(hdrs.ehdr32.e_phentsize);
			hdrs.ehdr32.e_phnum = bswap_16(hdrs.ehdr32.e_phnum);
		} else {
			hdrs.ehdr64.e_phoff = bswap_64(hdrs.ehdr64.e_phoff);
			hdrs.ehdr64.e_phentsize = bswap_16(hdrs.ehdr64.e_phentsize);
			hdrs.ehdr64.e_phnum = bswap_16(hdrs.ehdr64.e_phnum);
		}
	}
	if ((elf32 && hdrs.ehdr32.e_phentsize != sizeof(Elf32_Phdr)) ||
	    (!elf32 && hdrs.ehdr64.e_phentsize != sizeof(Elf64_Phdr)))
		goto out;

	phdr_size = elf32 ? sizeof(Elf32_Phdr) * hdrs.ehdr32.e_phnum
			  : sizeof(Elf64_Phdr) * hdrs.ehdr64.e_phnum;
	phdr = malloc(phdr_size);
	if (phdr == NULL)
		goto out;

	lseek(fd, elf32 ? hdrs.ehdr32.e_phoff : hdrs.ehdr64.e_phoff, SEEK_SET);
	if (read(fd, phdr, phdr_size) != phdr_size)
		goto out_free;

	if (elf32)
		hdrs.phdr32 = phdr;
	else
		hdrs.phdr64 = phdr;

	for (int i = 0; i < (elf32 ? hdrs.ehdr32.e_phnum : hdrs.ehdr64.e_phnum); i++) {
		ssize_t p_filesz;

		if (need_swap) {
			if (elf32) {
				hdrs.phdr32[i].p_type = bswap_32(hdrs.phdr32[i].p_type);
				hdrs.phdr32[i].p_offset = bswap_32(hdrs.phdr32[i].p_offset);
				hdrs.phdr32[i].p_filesz = bswap_32(hdrs.phdr32[i].p_offset);
			} else {
				hdrs.phdr64[i].p_type = bswap_32(hdrs.phdr64[i].p_type);
				hdrs.phdr64[i].p_offset = bswap_64(hdrs.phdr64[i].p_offset);
				hdrs.phdr64[i].p_filesz = bswap_64(hdrs.phdr64[i].p_filesz);
			}
		}
		if ((elf32 ? hdrs.phdr32[i].p_type : hdrs.phdr64[i].p_type) != PT_NOTE)
			continue;

		p_filesz = elf32 ? hdrs.phdr32[i].p_filesz : hdrs.phdr64[i].p_filesz;
		if (p_filesz > buf_size) {
			void *tmp;

			buf_size = p_filesz;
			tmp = realloc(buf, buf_size);
			if (tmp == NULL)
				goto out_free;
			buf = tmp;
		}
		lseek(fd, elf32 ? hdrs.phdr32[i].p_offset : hdrs.phdr64[i].p_offset, SEEK_SET);
		if (read(fd, buf, p_filesz) != p_filesz)
			goto out_free;

		ret = read_build_id(buf, p_filesz, bid, need_swap);
		if (ret == 0) {
			ret = bid->size;
			break;
		}
	}
out_free:
	free(buf);
	free(phdr);
out:
	close(fd);
	return ret;
}

int sysfs__read_build_id(const char *filename, struct build_id *bid)
{
	int fd;
	int ret = -1;
	struct stat stbuf;
	size_t buf_size;
	void *buf;

	fd = open(filename, O_RDONLY);
	if (fd < 0)
		return -1;

	if (fstat(fd, &stbuf) < 0)
		goto out;

	buf_size = stbuf.st_size;
	buf = malloc(buf_size);
	if (buf == NULL)
		goto out;

	if (read(fd, buf, buf_size) != (ssize_t) buf_size)
		goto out_free;

	ret = read_build_id(buf, buf_size, bid, false);
out_free:
	free(buf);
out:
	close(fd);
	return ret;
}

int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
	         enum dso_binary_type type)
{
	int fd = open(name, O_RDONLY);
	if (fd < 0)
		goto out_errno;

	ss->name = strdup(name);
	if (!ss->name)
		goto out_close;

	ss->fd = fd;
	ss->type = type;

	return 0;
out_close:
	close(fd);
out_errno:
	RC_CHK_ACCESS(dso)->load_errno = errno;
	return -1;
}

bool symsrc__possibly_runtime(struct symsrc *ss __maybe_unused)
{
	/* Assume all sym sources could be a runtime image. */
	return true;
}

bool symsrc__has_symtab(struct symsrc *ss __maybe_unused)
{
	return false;
}

void symsrc__destroy(struct symsrc *ss)
{
	zfree(&ss->name);
	close(ss->fd);
}

int dso__synthesize_plt_symbols(struct dso *dso __maybe_unused,
				struct symsrc *ss __maybe_unused)
{
	return 0;
}

static int fd__is_64_bit(int fd)
{
	u8 e_ident[EI_NIDENT];

	if (lseek(fd, 0, SEEK_SET))
		return -1;

	if (readn(fd, e_ident, sizeof(e_ident)) != sizeof(e_ident))
		return -1;

	if (memcmp(e_ident, ELFMAG, SELFMAG) ||
	    e_ident[EI_VERSION] != EV_CURRENT)
		return -1;

	return e_ident[EI_CLASS] == ELFCLASS64;
}

enum dso_type dso__type_fd(int fd)
{
	Elf64_Ehdr ehdr;
	int ret;

	ret = fd__is_64_bit(fd);
	if (ret < 0)
		return DSO__TYPE_UNKNOWN;

	if (ret)
		return DSO__TYPE_64BIT;

	if (readn(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr))
		return DSO__TYPE_UNKNOWN;

	if (ehdr.e_machine == EM_X86_64)
		return DSO__TYPE_X32BIT;

	return DSO__TYPE_32BIT;
}

int dso__load_sym(struct dso *dso, struct map *map __maybe_unused,
		  struct symsrc *ss,
		  struct symsrc *runtime_ss __maybe_unused,
		  int kmodule __maybe_unused)
{
	struct build_id bid = { .size = 0, };
	int ret;

	ret = fd__is_64_bit(ss->fd);
	if (ret >= 0)
		RC_CHK_ACCESS(dso)->is_64_bit = ret;

	if (filename__read_build_id(ss->name, &bid, /*block=*/true) > 0)
		dso__set_build_id(dso, &bid);
	return 0;
}

int file__read_maps(int fd __maybe_unused, bool exe __maybe_unused,
		    mapfn_t mapfn __maybe_unused, void *data __maybe_unused,
		    bool *is_64_bit __maybe_unused)
{
	return -1;
}

int kcore_extract__create(struct kcore_extract *kce __maybe_unused)
{
	return -1;
}

void kcore_extract__delete(struct kcore_extract *kce __maybe_unused)
{
}

int kcore_copy(const char *from_dir __maybe_unused,
	       const char *to_dir __maybe_unused)
{
	return -1;
}

void symbol__elf_init(void)
{
}

bool filename__has_section(const char *filename __maybe_unused, const char *sec __maybe_unused)
{
	return false;
}