freebsd-src/lib/libpmcstat/libpmcstat_image.c

/*-
 * Copyright (c) 2003-2008 Joseph Koshy
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/cpuset.h>
#include <sys/param.h>
#include <sys/endian.h>
#include <sys/pmc.h>
#include <sys/sysctl.h>
#include <sys/imgact_aout.h>
#include <sys/imgact_elf.h>

#include <netinet/in.h>

#include <assert.h>
#include <err.h>
#include <fcntl.h>
#include <pmc.h>
#include <pmclog.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

#include "libpmcstat.h"

#define	min(A,B)		((A) < (B) ? (A) : (B))
#define	max(A,B)		((A) > (B) ? (A) : (B))

/*
 * Add the list of symbols in the given section to the list associated
 * with the object.
 */
void
pmcstat_image_add_symbols(struct pmcstat_image *image, Elf *e,
    Elf_Scn *scn, GElf_Shdr *sh)
{
	int firsttime;
	size_t n, newsyms, nshsyms, nfuncsyms;
	struct pmcstat_symbol *symptr;
	char *fnname;
	GElf_Sym sym;
	Elf_Data *data;

	if ((data = elf_getdata(scn, NULL)) == NULL)
		return;

	/*
	 * Determine the number of functions named in this
	 * section.
	 */

	nshsyms = sh->sh_size / sh->sh_entsize;
	for (n = nfuncsyms = 0; n < nshsyms; n++) {
		if (gelf_getsym(data, (int) n, &sym) != &sym)
			return;
		if (GELF_ST_TYPE(sym.st_info) == STT_FUNC)
			nfuncsyms++;
	}

	if (nfuncsyms == 0)
		return;

	/*
	 * Allocate space for the new entries.
	 */
	firsttime = image->pi_symbols == NULL;
	symptr = reallocarray(image->pi_symbols,
	    image->pi_symcount + nfuncsyms, sizeof(*symptr));
	if (symptr == image->pi_symbols) /* realloc() failed. */
		return;
	image->pi_symbols = symptr;

	/*
	 * Append new symbols to the end of the current table.
	 */
	symptr += image->pi_symcount;

	for (n = newsyms = 0; n < nshsyms; n++) {
		if (gelf_getsym(data, (int) n, &sym) != &sym)
			return;
		if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
			continue;

		if (sym.st_shndx == STN_UNDEF)
			continue;

		if (!firsttime && pmcstat_symbol_search(image, sym.st_value))
			continue; /* We've seen this symbol already. */

		if ((fnname = elf_strptr(e, sh->sh_link, sym.st_name))
		    == NULL)
			continue;

#if defined(__aarch64__) || defined(__arm__)
		/* Ignore ARM mapping symbols. */
		if (fnname[0] == '$' &&
		    (fnname[1] == 'a' || fnname[1] == 't' ||
		    fnname[1] == 'd' || fnname[1] == 'x'))
			continue;

		/*
		 * Clear LSB from starting addresses for functions
		 * which execute in Thumb mode.  We should perhaps
		 * only do this for functions in a $t mapping symbol
		 * range, but parsing mapping symbols would be a lot
		 * of work and function addresses shouldn't have the
		 * LSB set otherwise.
		 */
		sym.st_value &= ~1;
#endif

		symptr->ps_name  = pmcstat_string_intern(fnname);
		symptr->ps_start = sym.st_value - image->pi_vaddr;
		symptr->ps_end   = symptr->ps_start + sym.st_size;

		symptr++;
		newsyms++;
	}

	image->pi_symcount += newsyms;
	if (image->pi_symcount == 0)
		return;

	assert(newsyms <= nfuncsyms);

	/*
	 * Return space to the system if there were duplicates.
	 */
	if (newsyms < nfuncsyms)
		image->pi_symbols = reallocarray(image->pi_symbols,
		    image->pi_symcount, sizeof(*symptr));

	/*
	 * Keep the list of symbols sorted.
	 */
	qsort(image->pi_symbols, image->pi_symcount, sizeof(*symptr),
	    pmcstat_symbol_compare);

	/*
	 * Deal with function symbols that have a size of 'zero' by
	 * making them extend to the next higher address.  These
	 * symbols are usually defined in assembly code.
	 */
	for (symptr = image->pi_symbols;
	     symptr < image->pi_symbols + (image->pi_symcount - 1);
	     symptr++)
		if (symptr->ps_start == symptr->ps_end)
			symptr->ps_end = (symptr+1)->ps_start;
}

/*
 * Record the fact that PC values from 'start' to 'end' come from
 * image 'image'.
 */

void
pmcstat_image_link(struct pmcstat_process *pp, struct pmcstat_image *image,
    uintfptr_t start)
{
	struct pmcstat_pcmap *pcm, *pcmnew;
	uintfptr_t offset;
#ifdef __powerpc__
	unsigned long kernbase;
	size_t kernbase_len;
#endif

	assert(image->pi_type != PMCSTAT_IMAGE_UNKNOWN &&
	    image->pi_type != PMCSTAT_IMAGE_INDETERMINABLE);

	if ((pcmnew = malloc(sizeof(*pcmnew))) == NULL)
		err(EX_OSERR, "ERROR: Cannot create a map entry");

	/*
	 * PowerPC kernel is of DYN type and it has a base address
	 * where it is initially loaded, before being relocated.
	 * As the address in 'start' is where the kernel was relocated to,
	 * but the symbols always use the original base address, we need to
	 * subtract it to get the correct offset.
	 */
#ifdef __powerpc__
	if (pp->pp_pid == -1) {
		kernbase = 0;
		kernbase_len = sizeof(kernbase);
		if (sysctlbyname("kern.base_address", &kernbase, &kernbase_len,
		    NULL, 0) == -1)
			warnx(
			    "WARNING: Could not retrieve kernel base address");
		else
			start -= kernbase;
	}
#endif

	/*
	 * Adjust the map entry to only cover the text portion
	 * of the object.
	 */

	offset = start - image->pi_vaddr;
	pcmnew->ppm_lowpc  = image->pi_start + offset;
	pcmnew->ppm_highpc = image->pi_end + offset;
	pcmnew->ppm_image  = image;

	assert(pcmnew->ppm_lowpc < pcmnew->ppm_highpc);

	/* Overlapped mmap()'s are assumed to never occur. */
	TAILQ_FOREACH(pcm, &pp->pp_map, ppm_next)
	    if (pcm->ppm_lowpc >= pcmnew->ppm_highpc)
		    break;

	if (pcm == NULL)
		TAILQ_INSERT_TAIL(&pp->pp_map, pcmnew, ppm_next);
	else
		TAILQ_INSERT_BEFORE(pcm, pcmnew, ppm_next);
}

/*
 * Determine whether a given executable image is an A.OUT object, and
 * if so, fill in its parameters from the text file.
 * Sets image->pi_type.
 */

void
pmcstat_image_get_aout_params(struct pmcstat_image *image,
    struct pmcstat_args *args)
{
	int fd;
	ssize_t nbytes;
	struct exec ex;
	const char *path;
	char buffer[PATH_MAX];

	path = pmcstat_string_unintern(image->pi_execpath);
	assert(path != NULL);

	if (image->pi_iskernelmodule)
		errx(EX_SOFTWARE,
		    "ERROR: a.out kernel modules are unsupported \"%s\"", path);

	(void) snprintf(buffer, sizeof(buffer), "%s%s",
	    args->pa_fsroot, path);

	if ((fd = open(buffer, O_RDONLY, 0)) < 0 ||
	    (nbytes = read(fd, &ex, sizeof(ex))) < 0) {
		if (args->pa_verbosity >= 2)
			warn("WARNING: Cannot determine type of \"%s\"",
			    path);
		image->pi_type = PMCSTAT_IMAGE_INDETERMINABLE;
		if (fd != -1)
			(void) close(fd);
		return;
	}

	(void) close(fd);

	if ((unsigned) nbytes != sizeof(ex) ||
	    N_BADMAG(ex))
		return;

	image->pi_type = PMCSTAT_IMAGE_AOUT;

	/* TODO: the rest of a.out processing */

	return;
}

/*
 * Examine an ELF file to determine the size of its text segment.
 * Sets image->pi_type if anything conclusive can be determined about
 * this image.
 */

void
pmcstat_image_get_elf_params(struct pmcstat_image *image,
    struct pmcstat_args *args)
{
	int fd;
	size_t i, nph, nsh;
	const char *path, *elfbase;
	char *p, *endp;
	bool first_exec_segment;
	uintfptr_t minva, maxva;
	Elf *e;
	Elf_Scn *scn;
	GElf_Ehdr eh;
	GElf_Phdr ph;
	GElf_Shdr sh;
	enum pmcstat_image_type image_type;
	char buffer[PATH_MAX];

	assert(image->pi_type == PMCSTAT_IMAGE_UNKNOWN);

	image->pi_start = minva = ~(uintfptr_t) 0;
	image->pi_end = maxva = (uintfptr_t) 0;
	image->pi_type = image_type = PMCSTAT_IMAGE_INDETERMINABLE;
	image->pi_isdynamic = 0;
	image->pi_dynlinkerpath = NULL;
	image->pi_vaddr = 0;

	path = pmcstat_string_unintern(image->pi_execpath);
	assert(path != NULL);

	/*
	 * Look for files under FSROOT/PATHNAME.
	 */
	(void) snprintf(buffer, sizeof(buffer), "%s%s",
	    args->pa_fsroot, path);

	e = NULL;
	fd = open(buffer, O_RDONLY, 0);
	if (fd < 0) {
		warnx("WARNING: Cannot open \"%s\".",
		    buffer);
		goto done;
	}

	if (elf_version(EV_CURRENT) == EV_NONE) {
		warnx("WARNING: failed to init elf\n");
		goto done;
	}

	if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
		warnx("WARNING: Cannot read \"%s\".",
		    buffer);
		goto done;
	}

	if (elf_kind(e) != ELF_K_ELF) {
		if (args->pa_verbosity >= 2)
			warnx("WARNING: Cannot determine the type of \"%s\".",
			    buffer);
		goto done;
	}

	if (gelf_getehdr(e, &eh) != &eh) {
		warnx(
		    "WARNING: Cannot retrieve the ELF Header for \"%s\": %s.",
		    buffer, elf_errmsg(-1));
		goto done;
	}

	if (eh.e_type != ET_EXEC && eh.e_type != ET_DYN &&
	    !(image->pi_iskernelmodule && eh.e_type == ET_REL)) {
		warnx("WARNING: \"%s\" is of an unsupported ELF type.",
		    buffer);
		goto done;
	}

	image_type = eh.e_ident[EI_CLASS] == ELFCLASS32 ?
	    PMCSTAT_IMAGE_ELF32 : PMCSTAT_IMAGE_ELF64;

	/*
	 * Determine the virtual address where an executable would be
	 * loaded.  Additionally, for dynamically linked executables,
	 * save the pathname to the runtime linker.
	 */
	if (eh.e_type != ET_REL) {
		if (elf_getphnum(e, &nph) == 0) {
			warnx(
"WARNING: Could not determine the number of program headers in \"%s\": %s.",
			    buffer,
			    elf_errmsg(-1));
			goto done;
		}
		first_exec_segment = true;
		for (i = 0; i < eh.e_phnum; i++) {
			if (gelf_getphdr(e, i, &ph) != &ph) {
				warnx(
"WARNING: Retrieval of PHDR entry #%ju in \"%s\" failed: %s.",
				    (uintmax_t) i, buffer, elf_errmsg(-1));
				goto done;
			}
			switch (ph.p_type) {
			case PT_DYNAMIC:
				image->pi_isdynamic = 1;
				break;
			case PT_INTERP:
				if ((elfbase = elf_rawfile(e, NULL)) == NULL) {
					warnx(
"WARNING: Cannot retrieve the interpreter for \"%s\": %s.",
					    buffer, elf_errmsg(-1));
					goto done;
				}
				image->pi_dynlinkerpath =
				    pmcstat_string_intern(elfbase +
				        ph.p_offset);
				break;
			case PT_LOAD:
				if ((ph.p_flags & PF_X) != 0 &&
				    first_exec_segment) {
					image->pi_vaddr = ph.p_vaddr & (-ph.p_align);
					first_exec_segment = false;
				}
				break;
			}
		}
	}

	/*
	 * Get the min and max VA associated with this ELF object.
	 */
	if (elf_getshnum(e, &nsh) == 0) {
		warnx(
"WARNING: Could not determine the number of sections for \"%s\": %s.",
		    buffer, elf_errmsg(-1));
		goto done;
	}

	for (i = 0; i < nsh; i++) {
		if ((scn = elf_getscn(e, i)) == NULL ||
		    gelf_getshdr(scn, &sh) != &sh) {
			warnx(
"WARNING: Could not retrieve section header #%ju in \"%s\": %s.",
			    (uintmax_t) i, buffer, elf_errmsg(-1));
			goto done;
		}
		if (sh.sh_flags & SHF_EXECINSTR) {
			minva = min(minva, sh.sh_addr);
			maxva = max(maxva, sh.sh_addr + sh.sh_size);
		}
		if (sh.sh_type == SHT_SYMTAB || sh.sh_type == SHT_DYNSYM)
			pmcstat_image_add_symbols(image, e, scn, &sh);
	}

	image->pi_start = minva;
	image->pi_end   = maxva;
	image->pi_type  = image_type;
	image->pi_fullpath = pmcstat_string_intern(buffer);

	/* Build display name
	 */
	endp = buffer;
	for (p = buffer; *p; p++)
		if (*p == '/')
			endp = p+1;
	image->pi_name = pmcstat_string_intern(endp);

 done:
	(void) elf_end(e);
	if (fd >= 0)
		(void) close(fd);
	return;
}

/*
 * Given an image descriptor, determine whether it is an ELF, or AOUT.
 * If no handler claims the image, set its type to 'INDETERMINABLE'.
 */

void
pmcstat_image_determine_type(struct pmcstat_image *image,
    struct pmcstat_args *args)
{
	assert(image->pi_type == PMCSTAT_IMAGE_UNKNOWN);

	/* Try each kind of handler in turn */
	if (image->pi_type == PMCSTAT_IMAGE_UNKNOWN)
		pmcstat_image_get_elf_params(image, args);
	if (image->pi_type == PMCSTAT_IMAGE_UNKNOWN)
		pmcstat_image_get_aout_params(image, args);

	/*
	 * Otherwise, remember that we tried to determine
	 * the object's type and had failed.
	 */
	if (image->pi_type == PMCSTAT_IMAGE_UNKNOWN)
		image->pi_type = PMCSTAT_IMAGE_INDETERMINABLE;
}

/*
 * Locate an image descriptor given an interned path, adding a fresh
 * descriptor to the cache if necessary.  This function also finds a
 * suitable name for this image's sample file.
 *
 * We defer filling in the file format specific parts of the image
 * structure till the time we actually see a sample that would fall
 * into this image.
 */

struct pmcstat_image *
pmcstat_image_from_path(pmcstat_interned_string internedpath,
    int iskernelmodule, struct pmcstat_args *args,
    struct pmc_plugins *plugins)
{
	int hash;
	struct pmcstat_image *pi;

	hash = pmcstat_string_lookup_hash(internedpath);

	/* First, look for an existing entry. */
	LIST_FOREACH(pi, &pmcstat_image_hash[hash], pi_next)
	    if (pi->pi_execpath == internedpath &&
		  pi->pi_iskernelmodule == iskernelmodule)
		    return (pi);

	/*
	 * Allocate a new entry and place it at the head of the hash
	 * and LRU lists.
	 */
	pi = malloc(sizeof(*pi));
	if (pi == NULL)
		return (NULL);

	pi->pi_type = PMCSTAT_IMAGE_UNKNOWN;
	pi->pi_execpath = internedpath;
	pi->pi_start = ~0;
	pi->pi_end = 0;
	pi->pi_entry = 0;
	pi->pi_vaddr = 0;
	pi->pi_isdynamic = 0;
	pi->pi_iskernelmodule = iskernelmodule;
	pi->pi_dynlinkerpath = NULL;
	pi->pi_symbols = NULL;
	pi->pi_symcount = 0;
	pi->pi_addr2line = NULL;

	if (plugins[args->pa_pplugin].pl_initimage != NULL)
		plugins[args->pa_pplugin].pl_initimage(pi);
	if (plugins[args->pa_plugin].pl_initimage != NULL)
		plugins[args->pa_plugin].pl_initimage(pi);

	LIST_INSERT_HEAD(&pmcstat_image_hash[hash], pi, pi_next);

	return (pi);
}