libipt/src/pt_image.c

/*
 * Copyright (c) 2013-2019, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *  * 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.
 *  * Neither the name of Intel Corporation nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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 "pt_image.h"
#include "pt_section.h"
#include "pt_asid.h"
#include "pt_image_section_cache.h"

#include <stdlib.h>
#include <string.h>


static char *dupstr(const char *str)
{
	char *dup;
	size_t len;

	if (!str)
		return NULL;

	/* Silently truncate the name if it gets too big. */
	len = strnlen(str, 4096ul);

	dup = malloc(len + 1);
	if (!dup)
		return NULL;

	dup[len] = 0;

	return memcpy(dup, str, len);
}

static struct pt_section_list *pt_mk_section_list(struct pt_section *section,
						  const struct pt_asid *asid,
						  uint64_t vaddr,
						  uint64_t offset,
						  uint64_t size, int isid)
{
	struct pt_section_list *list;
	int errcode;

	list = malloc(sizeof(*list));
	if (!list)
		return NULL;

	memset(list, 0, sizeof(*list));

	errcode = pt_section_get(section);
	if (errcode < 0)
		goto out_mem;

	pt_msec_init(&list->section, section, asid, vaddr, offset, size);
	list->isid = isid;

	return list;

out_mem:
	free(list);
	return NULL;
}

static void pt_section_list_free(struct pt_section_list *list)
{
	if (!list)
		return;

	pt_section_put(list->section.section);
	pt_msec_fini(&list->section);
	free(list);
}

static void pt_section_list_free_tail(struct pt_section_list *list)
{
	while (list) {
		struct pt_section_list *trash;

		trash = list;
		list = list->next;

		pt_section_list_free(trash);
	}
}

void pt_image_init(struct pt_image *image, const char *name)
{
	if (!image)
		return;

	memset(image, 0, sizeof(*image));

	image->name = dupstr(name);
}

void pt_image_fini(struct pt_image *image)
{
	if (!image)
		return;

	pt_section_list_free_tail(image->sections);
	free(image->name);

	memset(image, 0, sizeof(*image));
}

struct pt_image *pt_image_alloc(const char *name)
{
	struct pt_image *image;

	image = malloc(sizeof(*image));
	if (image)
		pt_image_init(image, name);

	return image;
}

void pt_image_free(struct pt_image *image)
{
	pt_image_fini(image);
	free(image);
}

const char *pt_image_name(const struct pt_image *image)
{
	if (!image)
		return NULL;

	return image->name;
}

int pt_image_add(struct pt_image *image, struct pt_section *section,
		 const struct pt_asid *asid, uint64_t vaddr, int isid)
{
	struct pt_section_list **list, *next, *removed, *new;
	uint64_t size, begin, end;
	int errcode;

	if (!image || !section)
		return -pte_internal;

	size = pt_section_size(section);
	begin = vaddr;
	end = begin + size;

	next = pt_mk_section_list(section, asid, begin, 0ull, size, isid);
	if (!next)
		return -pte_nomem;

	removed = NULL;
	errcode = 0;

	/* Check for overlaps while we move to the end of the list. */
	list = &(image->sections);
	while (*list) {
		const struct pt_mapped_section *msec;
		const struct pt_asid *masid;
		struct pt_section_list *current;
		struct pt_section *lsec;
		uint64_t lbegin, lend, loff;

		current = *list;
		msec = &current->section;
		masid = pt_msec_asid(msec);

		errcode = pt_asid_match(masid, asid);
		if (errcode < 0)
			break;

		if (!errcode) {
			list = &((*list)->next);
			continue;
		}

		lbegin = pt_msec_begin(msec);
		lend = pt_msec_end(msec);

		if ((end <= lbegin) || (lend <= begin)) {
			list = &((*list)->next);
			continue;
		}

		/* The new section overlaps with @msec's section. */
		lsec = pt_msec_section(msec);
		loff = pt_msec_offset(msec);

		/* We remove @msec and insert new sections for the remaining
		 * parts, if any.  Those new sections are not mapped initially
		 * and need to be added to the end of the section list.
		 */
		*list = current->next;

		/* Keep a list of removed sections so we can re-add them in case
		 * of errors.
		 */
		current->next = removed;
		removed = current;

		/* Add a section covering the remaining bytes at the front. */
		if (lbegin < begin) {
			new = pt_mk_section_list(lsec, masid, lbegin, loff,
						 begin - lbegin, current->isid);
			if (!new) {
				errcode = -pte_nomem;
				break;
			}

			new->next = next;
			next = new;
		}

		/* Add a section covering the remaining bytes at the back. */
		if (end < lend) {
			new = pt_mk_section_list(lsec, masid, end,
						 loff + (end - lbegin),
						 lend - end, current->isid);
			if (!new) {
				errcode = -pte_nomem;
				break;
			}

			new->next = next;
			next = new;
		}
	}

	if (errcode < 0) {
		pt_section_list_free_tail(next);

		/* Re-add removed sections to the tail of the section list. */
		for (; *list; list = &((*list)->next))
			;

		*list = removed;
		return errcode;
	}

	pt_section_list_free_tail(removed);

	*list = next;
	return 0;
}

int pt_image_remove(struct pt_image *image, struct pt_section *section,
		    const struct pt_asid *asid, uint64_t vaddr)
{
	struct pt_section_list **list;

	if (!image || !section)
		return -pte_internal;

	for (list = &image->sections; *list; list = &((*list)->next)) {
		struct pt_mapped_section *msec;
		const struct pt_section *sec;
		const struct pt_asid *masid;
		struct pt_section_list *trash;
		uint64_t begin;
		int errcode;

		trash = *list;
		msec = &trash->section;
		masid = pt_msec_asid(msec);

		errcode = pt_asid_match(masid, asid);
		if (errcode < 0)
			return errcode;

		if (!errcode)
			continue;

		begin = pt_msec_begin(msec);
		sec = pt_msec_section(msec);
		if (sec == section && begin == vaddr) {
			*list = trash->next;
			pt_section_list_free(trash);

			return 0;
		}
	}

	return -pte_bad_image;
}

int pt_image_add_file(struct pt_image *image, const char *filename,
		      uint64_t offset, uint64_t size,
		      const struct pt_asid *uasid, uint64_t vaddr)
{
	struct pt_section *section;
	struct pt_asid asid;
	int errcode;

	if (!image || !filename)
		return -pte_invalid;

	errcode = pt_asid_from_user(&asid, uasid);
	if (errcode < 0)
		return errcode;

	section = NULL;
	errcode = pt_mk_section(&section, filename, offset, size);
	if (errcode < 0)
		return errcode;

	errcode = pt_image_add(image, section, &asid, vaddr, 0);
	if (errcode < 0) {
		(void) pt_section_put(section);
		return errcode;
	}

	/* The image list got its own reference; let's drop ours. */
	errcode = pt_section_put(section);
	if (errcode < 0)
		return errcode;

	return 0;
}

int pt_image_copy(struct pt_image *image, const struct pt_image *src)
{
	struct pt_section_list *list;
	int ignored;

	if (!image || !src)
		return -pte_invalid;

	/* There is nothing to do if we copy an image to itself.
	 *
	 * Besides, pt_image_add() may move sections around, which would
	 * interfere with our section iteration.
	 */
	if (image == src)
		return 0;

	ignored = 0;
	for (list = src->sections; list; list = list->next) {
		int errcode;

		errcode = pt_image_add(image, list->section.section,
				       &list->section.asid,
				       list->section.vaddr,
				       list->isid);
		if (errcode < 0)
			ignored += 1;
	}

	return ignored;
}

int pt_image_remove_by_filename(struct pt_image *image, const char *filename,
				const struct pt_asid *uasid)
{
	struct pt_section_list **list;
	struct pt_asid asid;
	int errcode, removed;

	if (!image || !filename)
		return -pte_invalid;

	errcode = pt_asid_from_user(&asid, uasid);
	if (errcode < 0)
		return errcode;

	removed = 0;
	for (list = &image->sections; *list;) {
		struct pt_mapped_section *msec;
		const struct pt_section *sec;
		const struct pt_asid *masid;
		struct pt_section_list *trash;
		const char *tname;

		trash = *list;
		msec = &trash->section;
		masid = pt_msec_asid(msec);

		errcode = pt_asid_match(masid, &asid);
		if (errcode < 0)
			return errcode;

		if (!errcode) {
			list = &trash->next;
			continue;
		}

		sec = pt_msec_section(msec);
		tname = pt_section_filename(sec);

		if (tname && (strcmp(tname, filename) == 0)) {
			*list = trash->next;
			pt_section_list_free(trash);

			removed += 1;
		} else
			list = &trash->next;
	}

	return removed;
}

int pt_image_remove_by_asid(struct pt_image *image,
			    const struct pt_asid *uasid)
{
	struct pt_section_list **list;
	struct pt_asid asid;
	int errcode, removed;

	if (!image)
		return -pte_invalid;

	errcode = pt_asid_from_user(&asid, uasid);
	if (errcode < 0)
		return errcode;

	removed = 0;
	for (list = &image->sections; *list;) {
		struct pt_mapped_section *msec;
		const struct pt_asid *masid;
		struct pt_section_list *trash;

		trash = *list;
		msec = &trash->section;
		masid = pt_msec_asid(msec);

		errcode = pt_asid_match(masid, &asid);
		if (errcode < 0)
			return errcode;

		if (!errcode) {
			list = &trash->next;
			continue;
		}

		*list = trash->next;
		pt_section_list_free(trash);

		removed += 1;
	}

	return removed;
}

int pt_image_set_callback(struct pt_image *image,
			  read_memory_callback_t *callback, void *context)
{
	if (!image)
		return -pte_invalid;

	image->readmem.callback = callback;
	image->readmem.context = context;

	return 0;
}

static int pt_image_read_callback(struct pt_image *image, int *isid,
				  uint8_t *buffer, uint16_t size,
				  const struct pt_asid *asid, uint64_t addr)
{
	read_memory_callback_t *callback;

	if (!image || !isid)
		return -pte_internal;

	callback = image->readmem.callback;
	if (!callback)
		return -pte_nomap;

	*isid = 0;

	return callback(buffer, size, asid, addr, image->readmem.context);
}

/* Check whether a mapped section contains an address.
 *
 * Returns zero if @msec contains @vaddr.
 * Returns a negative error code otherwise.
 * Returns -pte_nomap if @msec does not contain @vaddr.
 */
static inline int pt_image_check_msec(const struct pt_mapped_section *msec,
				      const struct pt_asid *asid,
				      uint64_t vaddr)
{
	const struct pt_asid *masid;
	uint64_t begin, end;
	int errcode;

	if (!msec)
		return -pte_internal;

	begin = pt_msec_begin(msec);
	end = pt_msec_end(msec);
	if (vaddr < begin || end <= vaddr)
		return -pte_nomap;

	masid = pt_msec_asid(msec);
	errcode = pt_asid_match(masid, asid);
	if (errcode <= 0) {
		if (!errcode)
			errcode = -pte_nomap;

		return errcode;
	}

	return 0;
}

/* Find the section containing a given address in a given address space.
 *
 * On success, the found section is moved to the front of the section list.
 * If caching is enabled, maps the section.
 *
 * Returns zero on success, a negative error code otherwise.
 */
static int pt_image_fetch_section(struct pt_image *image,
				  const struct pt_asid *asid, uint64_t vaddr)
{
	struct pt_section_list **start, **list;

	if (!image)
		return -pte_internal;

	start = &image->sections;
	for (list = start; *list;) {
		struct pt_mapped_section *msec;
		struct pt_section_list *elem;
		int errcode;

		elem = *list;
		msec = &elem->section;

		errcode = pt_image_check_msec(msec, asid, vaddr);
		if (errcode < 0) {
			if (errcode != -pte_nomap)
				return errcode;

			list = &elem->next;
			continue;
		}

		/* Move the section to the front if it isn't already. */
		if (list != start) {
			*list = elem->next;
			elem->next = *start;
			*start = elem;
		}

		return 0;
	}

	return -pte_nomap;
}

int pt_image_read(struct pt_image *image, int *isid, uint8_t *buffer,
		  uint16_t size, const struct pt_asid *asid, uint64_t addr)
{
	struct pt_mapped_section *msec;
	struct pt_section_list *slist;
	struct pt_section *section;
	int errcode, status;

	if (!image || !isid)
		return -pte_internal;

	errcode = pt_image_fetch_section(image, asid, addr);
	if (errcode < 0) {
		if (errcode != -pte_nomap)
			return errcode;

		return pt_image_read_callback(image, isid, buffer, size, asid,
					      addr);
	}

	slist = image->sections;
	if (!slist)
		return -pte_internal;

	*isid = slist->isid;
	msec = &slist->section;

	section = pt_msec_section(msec);

	errcode = pt_section_map(section);
	if (errcode < 0)
		return errcode;

	status = pt_msec_read(msec, buffer, size, addr);

	errcode = pt_section_unmap(section);
		if (errcode < 0)
			return errcode;

	if (status < 0) {
		if (status != -pte_nomap)
			return status;

		return pt_image_read_callback(image, isid, buffer, size, asid,
					      addr);
	}

	return status;
}

int pt_image_add_cached(struct pt_image *image,
			struct pt_image_section_cache *iscache, int isid,
			const struct pt_asid *uasid)
{
	struct pt_section *section;
	struct pt_asid asid;
	uint64_t vaddr;
	int errcode, status;

	if (!image || !iscache)
		return -pte_invalid;

	errcode = pt_iscache_lookup(iscache, &section, &vaddr, isid);
	if (errcode < 0)
		return errcode;

	errcode = pt_asid_from_user(&asid, uasid);
	if (errcode < 0)
		return errcode;

	status = pt_image_add(image, section, &asid, vaddr, isid);

	/* We grab a reference when we add the section.  Drop the one we
	 * obtained from cache lookup.
	 */
	errcode = pt_section_put(section);
	if (errcode < 0)
		return errcode;

	return status;
}

int pt_image_find(struct pt_image *image, struct pt_mapped_section *usec,
		  const struct pt_asid *asid, uint64_t vaddr)
{
	struct pt_mapped_section *msec;
	struct pt_section_list *slist;
	struct pt_section *section;
	int errcode;

	if (!image || !usec)
		return -pte_internal;

	errcode = pt_image_fetch_section(image, asid, vaddr);
	if (errcode < 0)
		return errcode;

	slist = image->sections;
	if (!slist)
		return -pte_internal;

	msec = &slist->section;
	section = pt_msec_section(msec);

	errcode = pt_section_get(section);
	if (errcode < 0)
		return errcode;

	*usec = *msec;

	return slist->isid;
}

int pt_image_validate(const struct pt_image *image,
		      const struct pt_mapped_section *usec, uint64_t vaddr,
		      int isid)
{
	const struct pt_section_list *slist;
	uint64_t begin, end;
	int status;

	if (!image || !usec)
		return -pte_internal;

	/* Check that @vaddr lies within @usec. */
	begin = pt_msec_begin(usec);
	end = pt_msec_end(usec);
	if (vaddr < begin || end <= vaddr)
		return -pte_nomap;

	/* We assume that @usec is a copy of the top of our stack and accept
	 * sporadic validation fails if it isn't, e.g. because it has moved
	 * down.
	 *
	 * A failed validation requires decoders to re-fetch the section so it
	 * only results in a (relatively small) performance loss.
	 */
	slist = image->sections;
	if (!slist)
		return -pte_nomap;

	if (slist->isid != isid)
		return -pte_nomap;

	status = memcmp(&slist->section, usec, sizeof(*usec));
	if (status)
		return -pte_nomap;

	return 0;
}