psymtab.c

Sun Solaris 10 中的 DTrace 组件的源代码。请参看: http://www.sun.com/software/solaris/observability.jsp

	if (P->rap == NULL && P->state != PS_DEAD && P->state != PS_IDLE) {
		Pupdate_maps(P);
		if (P->num_files == 0)
			load_static_maps(P);
		rd_log(_libproc_debug);
		if ((P->rap = rd_new(P)) != NULL)
			(void) rd_loadobj_iter(P->rap, map_iter, P);
	}
	return (P->rap);
}

/*
 * Return the prmap_t structure containing 'addr', but only if it
 * is in the dynamic linker's link map and is the text section.
 */
const prmap_t *
Paddr_to_text_map(struct ps_prochandle *P, uintptr_t addr)
{
	map_info_t *mptr;

	if (!P->info_valid)
		Pupdate_maps(P);

	if ((mptr = Paddr2mptr(P, addr)) != NULL) {
		file_info_t *fptr = build_map_symtab(P, mptr);
		const prmap_t *pmp = &mptr->map_pmap;

		if (fptr != NULL && fptr->file_lo != NULL &&
		    fptr->file_lo->rl_base >= pmp->pr_vaddr &&
		    fptr->file_lo->rl_base < pmp->pr_vaddr + pmp->pr_size)
			return (pmp);
	}

	return (NULL);
}

/*
 * Return the prmap_t structure containing 'addr' (no restrictions on
 * the type of mapping).
 */
const prmap_t *
Paddr_to_map(struct ps_prochandle *P, uintptr_t addr)
{
	map_info_t *mptr;

	if (!P->info_valid)
		Pupdate_maps(P);

	if ((mptr = Paddr2mptr(P, addr)) != NULL)
		return (&mptr->map_pmap);

	return (NULL);
}

/*
 * Convert a full or partial load object name to the prmap_t for its
 * corresponding primary text mapping.
 */
const prmap_t *
Plmid_to_map(struct ps_prochandle *P, Lmid_t lmid, const char *name)
{
	map_info_t *mptr;

	if (name == PR_OBJ_EVERY)
		return (NULL); /* A reasonable mistake */

	if ((mptr = object_name_to_map(P, lmid, name)) != NULL)
		return (&mptr->map_pmap);

	return (NULL);
}

const prmap_t *
Pname_to_map(struct ps_prochandle *P, const char *name)
{
	return (Plmid_to_map(P, PR_LMID_EVERY, name));
}

const rd_loadobj_t *
Paddr_to_loadobj(struct ps_prochandle *P, uintptr_t addr)
{
	map_info_t *mptr;

	if (!P->info_valid)
		Pupdate_maps(P);

	if ((mptr = Paddr2mptr(P, addr)) == NULL)
		return (NULL);

	/*
	 * By building the symbol table, we implicitly bring the PLT
	 * information up to date in the load object.
	 */
	(void) build_map_symtab(P, mptr);

	return (mptr->map_file->file_lo);
}

const rd_loadobj_t *
Plmid_to_loadobj(struct ps_prochandle *P, Lmid_t lmid, const char *name)
{
	map_info_t *mptr;

	if (name == PR_OBJ_EVERY)
		return (NULL);

	if ((mptr = object_name_to_map(P, lmid, name)) == NULL)
		return (NULL);

	/*
	 * By building the symbol table, we implicitly bring the PLT
	 * information up to date in the load object.
	 */
	(void) build_map_symtab(P, mptr);

	return (mptr->map_file->file_lo);
}

const rd_loadobj_t *
Pname_to_loadobj(struct ps_prochandle *P, const char *name)
{
	return (Plmid_to_loadobj(P, PR_LMID_EVERY, name));
}

ctf_file_t *
Pbuild_file_ctf(struct ps_prochandle *P, file_info_t *fptr)
{
	ctf_sect_t ctdata, symtab, strtab;
	sym_tbl_t *symp;
	int err;

	if (fptr->file_ctfp != NULL)
		return (fptr->file_ctfp);

	Pbuild_file_symtab(P, fptr);

	if (fptr->file_ctf_size == 0)
		return (NULL);

	symp = fptr->file_ctf_dyn ? &fptr->file_dynsym : &fptr->file_symtab;
	if (symp->sym_data == NULL)
		return (NULL);

	/*
	 * The buffer may alread be allocated if this is a core file that
	 * contained CTF data for this file.
	 */
	if (fptr->file_ctf_buf == NULL) {
		fptr->file_ctf_buf = malloc(fptr->file_ctf_size);
		if (fptr->file_ctf_buf == NULL) {
			dprintf("failed to allocate ctf buffer\n");
			return (NULL);
		}

		if (pread(fptr->file_fd, fptr->file_ctf_buf,
		    fptr->file_ctf_size, fptr->file_ctf_off) !=
		    fptr->file_ctf_size) {
			free(fptr->file_ctf_buf);
			fptr->file_ctf_buf = NULL;
			dprintf("failed to read ctf data\n");
			return (NULL);
		}
	}

	ctdata.cts_name = ".SUNW_ctf";
	ctdata.cts_type = SHT_PROGBITS;
	ctdata.cts_flags = 0;
	ctdata.cts_data = fptr->file_ctf_buf;
	ctdata.cts_size = fptr->file_ctf_size;
	ctdata.cts_entsize = 1;
	ctdata.cts_offset = 0;

	symtab.cts_name = fptr->file_ctf_dyn ? ".dynsym" : ".symtab";
	symtab.cts_type = symp->sym_hdr.sh_type;
	symtab.cts_flags = symp->sym_hdr.sh_flags;
	symtab.cts_data = symp->sym_data->d_buf;
	symtab.cts_size = symp->sym_hdr.sh_size;
	symtab.cts_entsize = symp->sym_hdr.sh_entsize;
	symtab.cts_offset = symp->sym_hdr.sh_offset;

	strtab.cts_name = fptr->file_ctf_dyn ? ".dynstr" : ".strtab";
	strtab.cts_type = symp->sym_strhdr.sh_type;
	strtab.cts_flags = symp->sym_strhdr.sh_flags;
	strtab.cts_data = symp->sym_strs;
	strtab.cts_size = symp->sym_strhdr.sh_size;
	strtab.cts_entsize = symp->sym_strhdr.sh_entsize;
	strtab.cts_offset = symp->sym_strhdr.sh_offset;

	fptr->file_ctfp = ctf_bufopen(&ctdata, &symtab, &strtab, &err);
	if (fptr->file_ctfp == NULL) {
		free(fptr->file_ctf_buf);
		fptr->file_ctf_buf = NULL;
		return (NULL);
	}

	dprintf("loaded %lu bytes of CTF data for %s\n",
	    (ulong_t)fptr->file_ctf_size, fptr->file_pname);

	return (fptr->file_ctfp);
}

ctf_file_t *
Paddr_to_ctf(struct ps_prochandle *P, uintptr_t addr)
{
	map_info_t *mptr;
	file_info_t *fptr;

	if (!P->info_valid)
		Pupdate_maps(P);

	if ((mptr = Paddr2mptr(P, addr)) == NULL ||
	    (fptr = mptr->map_file) == NULL)
		return (NULL);

	return (Pbuild_file_ctf(P, fptr));
}

ctf_file_t *
Plmid_to_ctf(struct ps_prochandle *P, Lmid_t lmid, const char *name)
{
	map_info_t *mptr;
	file_info_t *fptr;

	if (name == PR_OBJ_EVERY)
		return (NULL);

	if ((mptr = object_name_to_map(P, lmid, name)) == NULL ||
	    (fptr = mptr->map_file) == NULL)
		return (NULL);

	return (Pbuild_file_ctf(P, fptr));
}

ctf_file_t *
Pname_to_ctf(struct ps_prochandle *P, const char *name)
{
	return (Plmid_to_ctf(P, PR_LMID_EVERY, name));
}

/*
 * If we're not a core file, re-read the /proc/<pid>/auxv file and store
 * its contents in P->auxv.  In the case of a core file, we either
 * initialized P->auxv in Pcore() from the NT_AUXV, or we don't have an
 * auxv because the note was missing.
 */
void
Preadauxvec(struct ps_prochandle *P)
{
	char auxfile[64];
	struct stat statb;
	ssize_t naux;
	int fd;

	if (P->state == PS_DEAD)
		return; /* Already read during Pgrab_core() */
	if (P->state == PS_IDLE)
		return; /* No aux vec for Pgrab_file() */

	if (P->auxv != NULL) {
		free(P->auxv);
		P->auxv = NULL;
		P->nauxv = 0;
	}

	(void) sprintf(auxfile, "/proc/%d/auxv", (int)P->pid);
	if ((fd = open(auxfile, O_RDONLY)) < 0)
		return;

	if (fstat(fd, &statb) == 0 &&
	    statb.st_size >= sizeof (auxv_t) &&
	    (P->auxv = malloc(statb.st_size + sizeof (auxv_t))) != NULL) {
		if ((naux = read(fd, P->auxv, statb.st_size)) < 0 ||
		    (naux /= sizeof (auxv_t)) < 1) {
			free(P->auxv);
			P->auxv = NULL;
		} else {
			P->auxv[naux].a_type = AT_NULL;
			P->auxv[naux].a_un.a_val = 0L;
			P->nauxv = (int)naux;
		}
	}

	(void) close(fd);
}

/*
 * Return a requested element from the process's aux vector.
 * Return -1 on failure (this is adequate for our purposes).
 */
long
Pgetauxval(struct ps_prochandle *P, int type)
{
	auxv_t *auxv;

	if (P->auxv == NULL)
		Preadauxvec(P);

	if (P->auxv == NULL)
		return (-1);

	for (auxv = P->auxv; auxv->a_type != AT_NULL; auxv++) {
		if (auxv->a_type == type)
			return (auxv->a_un.a_val);
	}

	return (-1);
}

/*
 * Return a pointer to our internal copy of the process's aux vector.
 * The caller should not hold on to this pointer across any libproc calls.
 */
const auxv_t *
Pgetauxvec(struct ps_prochandle *P)
{
	static const auxv_t empty = { AT_NULL, 0L };

	if (P->auxv == NULL)
		Preadauxvec(P);

	if (P->auxv == NULL)
		return (&empty);

	return (P->auxv);
}

/*
 * Find or build the symbol table for the given mapping.
 */
static file_info_t *
build_map_symtab(struct ps_prochandle *P, map_info_t *mptr)
{
	prmap_t *pmap = &mptr->map_pmap;
	file_info_t *fptr;
	rd_loadobj_t *lop;
	uint_t i;

	if ((fptr = mptr->map_file) != NULL) {
		Pbuild_file_symtab(P, fptr);
		return (fptr);
	}

	if (pmap->pr_mapname[0] == '\0')
		return (NULL);

	/*
	 * Attempt to find a matching file.
	 * (A file can be mapped at several different addresses.)
	 */
	for (i = 0, fptr = list_next(&P->file_head); i < P->num_files;
	    i++, fptr = list_next(fptr)) {
		if (strcmp(fptr->file_pname, pmap->pr_mapname) == 0 &&
		    (lop = fptr->file_lo) != NULL &&
		    ((pmap->pr_vaddr <= lop->rl_base &&
		    lop->rl_base < pmap->pr_vaddr + pmap->pr_size) ||
		    (pmap->pr_vaddr <= lop->rl_data_base &&
		    lop->rl_data_base < pmap->pr_vaddr + pmap->pr_size))) {
			mptr->map_file = fptr;
			fptr->file_ref++;
			Pbuild_file_symtab(P, fptr);
			return (fptr);
		}
	}

	/*
	 * If we need to create a new file_info structure, iterate
	 * through the load objects in order to attempt to connect
	 * this new file with its primary text mapping.  We again
	 * need to handle ld.so as a special case because we need
	 * to be able to bootstrap librtld_db.
	 */
	if ((fptr = file_info_new(P, mptr)) == NULL)
		return (NULL);

	if (P->map_ldso != mptr) {
		if (P->rap != NULL)
			(void) rd_loadobj_iter(P->rap, map_iter, P);
		else
			(void) Prd_agent(P);
	} else {
		fptr->file_map = mptr;
	}

	/*
	 * If librtld_db wasn't able to help us connect the file to a primary
	 * text mapping, set file_map to the current mapping because we require
	 * fptr->file_map to be set in Pbuild_file_symtab.  librtld_db may be
	 * unaware of what's going on in the rare case that a legitimate ELF
	 * file has been mmap(2)ed into the process address space *without*
	 * the use of dlopen(3x).  Why would this happen?  See pwdx ... :)
	 */
	if (fptr->file_map == NULL)
		fptr->file_map = mptr;

	Pbuild_file_symtab(P, fptr);

	return (fptr);
}

static int
read_ehdr32(struct ps_prochandle *P, Elf32_Ehdr *ehdr, uintptr_t addr)
{
	if (Pread(P, ehdr, sizeof (*ehdr), addr) != sizeof (*ehdr))
		return (-1);

	if (ehdr->e_ident[EI_MAG0] != ELFMAG0 ||
	    ehdr->e_ident[EI_MAG1] != ELFMAG1 ||
	    ehdr->e_ident[EI_MAG2] != ELFMAG2 ||
	    ehdr->e_ident[EI_MAG3] != ELFMAG3 ||
	    ehdr->e_ident[EI_CLASS] != ELFCLASS32 ||
#ifdef _BIG_ENDIAN
	    ehdr->e_ident[EI_DATA] != ELFDATA2MSB ||
#else
	    ehdr->e_ident[EI_DATA] != ELFDATA2LSB ||
#endif
	    ehdr->e_ident[EI_VERSION] != EV_CURRENT)
		return (-1);

	return (0);
}

static int
read_dynamic_phdr32(struct ps_prochandle *P, const Elf32_Ehdr *ehdr,
    Elf32_Phdr *phdr, uintptr_t addr)
{
	uint_t i;

	for (i = 0; i < ehdr->e_phnum; i++) {
		uintptr_t a = addr + ehdr->e_phoff + i * ehdr->e_phentsize;
		if (Pread(P, phdr, sizeof (*phdr), a) != sizeof (*phdr))
			return (-1);

		if (phdr->p_type == PT_DYNAMIC)
			return (0);
	}

	return (-1);
}

#ifdef _LP64
static int
read_ehdr64(struct ps_prochandle *P, Elf64_Ehdr *ehdr, uintptr_t addr)
{
	if (Pread(P, ehdr, sizeof (Elf64_Ehdr), addr) != sizeof (Elf64_Ehdr))
		return (-1);

	if (ehdr->e_ident[EI_MAG0] != ELFMAG0 ||
	    ehdr->e_ident[EI_MAG1] != ELFMAG1 ||
	    ehdr->e_ident[EI_MAG2] != ELFMAG2 ||
	    ehdr->e_ident[EI_MAG3] != ELFMAG3 ||
	    ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||
#ifdef _BIG_ENDIAN
	    ehdr->e_ident[EI_DATA] != ELFDATA2MSB ||
#else
	    ehdr->e_ident[EI_DATA] != ELFDATA2LSB ||
#endif
	    ehdr->e_ident[EI_VERSION] != EV_CURRENT)
		return (-1);

	return (0);
}

static int
read_dynamic_phdr64(struct ps_prochandle *P, const Elf64_Ehdr *ehdr,
    Elf64_Phdr *phdr, uintptr_t addr)
{
	uint_t i;

	for (i = 0; i < ehdr->e_phnum; i++) {
		uintptr_t a = addr + ehdr->e_phoff + i * ehdr->e_phentsize;
		if (Pread(P, phdr, sizeof (*phdr), a) != sizeof (*phdr))
			return (-1);

		if (phdr->p_type == PT_DYNAMIC)
			return (0);
	}

	return (-1);
}
#endif	/* _LP64 */

/*
 * The text segment for each load object contains the elf header and
 * program headers. We can use this information to determine if the
 * file that corresponds to the load object is the same file that
 * was loaded into the process's address space. There can be a discrepency
 * if a file is recompiled after the process is started or if the target
 * represents a core file from a differently configured system -- two
 * common examples. The DT_CHECKSUM entry in the dynamic section
 * provides an easy method of comparison. It is important to note that
 * the dynamic section usually lives in the data segment, but the meta
 * data we use to find the dynamic section lives in the text segment so
 * if either of those segments is absent we can't proceed.
 *
 * We're looking through the elf file for several items: the symbol tables
 * (both dynsym and symtab), the procedure linkage table (PLT) base,
 * size, and relocation base, and the CTF information. Most of this can
 * be recovered from the loaded image of the file itself, the exceptions
 * being the symtab and CTF data.
 *
 * First we try to open the file that we think corresponds to the load
 * object, if the DT_CHECKSUM values match, we're all set, and can simply
 * recover all the information we need from the file. If the values of
 * DT_CHECKSUM don't match, or if we can't access the file for whatever
 * reasaon, we fake up a elf file to use in its stead. If we can't read
 * the elf data in the process's address space, we fall back to using
 * the file even though it may give inaccurate information.
 *
 * The elf file that we fake up has to consist of sections for the
 * dynsym, the PLT and the dynamic section. Note that in the case of a
 * core file, we'll get the CTF data in the file_info_t later on from
 * a section embedded the core file (if it's present).
 *
 * file_differs() conservatively looks for mismatched files, identifying
 * a match when there is any ambiguity (since that's the legacy behavior).