[PATCH v2 1/3] libfdt: Add function to find regions in an FDT
Simon Glass
sjg at chromium.org
Sat Feb 16 09:49:36 EST 2013
Given a set of nodes and properties, find the regions of the device tree
which describe those parts.
A test is provided which builds a tree while tracking where the regions
should be, then calls fdt_first/next_region() to make sure that it agrees.
Further tests will come as part of fdtgrep.
Signed-off-by: Simon Glass <sjg at chromium.org>
---
Changes in v2:
- Move region code to separate fdt_region.c file
- Fix info->count <= info->max_regions in fdt_add_region() merge case
- Add new FDT_ERR_TOODEEP error type and use it
- Change returned error from BADLAYOUT to BADSTRUCTURE
- Return FDT_ERR_BADLAYOUT error if strings block is before structure block
- Add note that changes in node/property order can cause false hash misses
- Add more comments about the -1 return value from h_include
- Drop FDT_IS_COMPAT and pass node offset to h_include function
- Drop stale comment about names / wildcards
- Move to a model with fdt_first_region()/fdt_next_region()
- Add long comment explaining theory of operation
libfdt/Makefile.libfdt | 3 +-
libfdt/fdt_region.c | 452 +++++++++++++++++++++++++++++++++++++++++++++++++
libfdt/libfdt.h | 213 ++++++++++++++++++++++-
tests/.gitignore | 1 +
tests/Makefile.tests | 3 +-
tests/region_tree.c | 336 ++++++++++++++++++++++++++++++++++++
tests/run_tests.sh | 5 +
7 files changed, 1010 insertions(+), 3 deletions(-)
create mode 100644 libfdt/fdt_region.c
create mode 100644 tests/region_tree.c
diff --git a/libfdt/Makefile.libfdt b/libfdt/Makefile.libfdt
index 91126c0..84769a4 100644
--- a/libfdt/Makefile.libfdt
+++ b/libfdt/Makefile.libfdt
@@ -6,5 +6,6 @@
LIBFDT_soname = libfdt.$(SHAREDLIB_EXT).1
LIBFDT_INCLUDES = fdt.h libfdt.h libfdt_env.h
LIBFDT_VERSION = version.lds
-LIBFDT_SRCS = fdt.c fdt_ro.c fdt_wip.c fdt_sw.c fdt_rw.c fdt_strerror.c fdt_empty_tree.c
+LIBFDT_SRCS = fdt.c fdt_ro.c fdt_wip.c fdt_sw.c fdt_region.c
+LIBFDT_SRCS += fdt_rw.c fdt_strerror.c fdt_empty_tree.c
LIBFDT_OBJS = $(LIBFDT_SRCS:%.c=%.o)
diff --git a/libfdt/fdt_region.c b/libfdt/fdt_region.c
new file mode 100644
index 0000000..a830526
--- /dev/null
+++ b/libfdt/fdt_region.c
@@ -0,0 +1,452 @@
+/*
+ * libfdt - Flat Device Tree manipulation
+ * Copyright (C) 2013 Google, Inc
+ *
+ * libfdt is dual licensed: you can use it either under the terms of
+ * the GPL, or the BSD license, at your option.
+ *
+ * a) This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this library; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ *
+ * Alternatively,
+ *
+ * b) 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 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 "libfdt_env.h"
+
+#include <fdt.h>
+#include <libfdt.h>
+
+#include "libfdt_internal.h"
+
+/**
+ * fdt_add_region() - Add a new region to our list
+ *
+ * The region is added if there is space, but in any case we increment the
+ * count. If permitted, and the new region overlaps the last one, we merge
+ * them.
+ *
+ * @info: State information
+ * @offset: Start offset of region
+ * @size: Size of region
+ */
+static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
+{
+ struct fdt_region *reg = &info->region[info->count - 1];
+
+ if (info->can_merge && info->count &&
+ info->count <= info->max_regions &&
+ offset <= reg->offset + reg->size) {
+ reg->size = offset + size - reg->offset;
+ } else if (info->count++ < info->max_regions) {
+ reg++;
+ reg->offset = offset;
+ reg->size = size;
+ } else {
+ return -1;
+ }
+
+ return 0;
+}
+
+/**
+ * fdt_include_supernodes() - Include supernodes required by this node
+ *
+ * When we decided to include a node or property which is not at the top
+ * level, this function forces the inclusion of higher level nodes. For
+ * example, given this tree:
+ *
+ * / {
+ * testing {
+ * }
+ * }
+ *
+ * If we decide to include testing then we need the root node to have a valid
+ * tree. This function adds those regions.
+ *
+ * @info: State information
+ * @depth: Current stack depth
+ */
+static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
+{
+ int base = fdt_off_dt_struct(info->fdt);
+ int start, stop_at;
+ int i;
+
+ /*
+ * Work down the stack looking for supernodes that we didn't include.
+ * The algortihm here is actually pretty simple, since we know that
+ * no previous subnode had to include these nodes, or if it did, we
+ * marked them as included (on the stack) already.
+ */
+ for (i = 0; i <= depth; i++) {
+ if (!info->stack[i].included) {
+ start = info->stack[i].offset;
+
+ /* Add the FDT_BEGIN_NODE tag of this supernode */
+ fdt_next_tag(info->fdt, start, &stop_at);
+ if (fdt_add_region(info, base + start,
+ stop_at - start))
+ return -1;
+
+ /* Remember that this supernode is now included */
+ info->stack[i].included = 1;
+ info->can_merge = 1;
+ }
+
+ /* Force (later) generation of the FDT_END_NODE tag */
+ if (!info->stack[i].want)
+ info->stack[i].want = WANT_NODES_ONLY;
+ }
+
+ return 0;
+}
+
+enum {
+ FDT_DONE_NOTHING,
+ FDT_DONE_MEM_RSVMAP,
+ FDT_DONE_STRUCT,
+ FDT_DONE_END,
+ FDT_DONE_STRINGS,
+ FDT_DONE_ALL,
+};
+
+int fdt_first_region(const void *fdt,
+ int (*h_include)(void *priv, const void *fdt, int offset,
+ int type, const char *data, int size),
+ void *priv, struct fdt_region *region,
+ char *path, int path_len, int flags,
+ struct fdt_region_state *info)
+{
+ struct fdt_region_ptrs *p = &info->ptrs;
+
+ /* Set up our state */
+ info->fdt = fdt;
+ info->can_merge = 1;
+ info->max_regions = 1;
+ info->start = -1;
+ p->want = WANT_NOTHING;
+ p->end = path;
+ *p->end = '\0';
+ p->nextoffset = 0;
+ p->depth = -1;
+ p->done = FDT_DONE_NOTHING;
+
+ return fdt_next_region(fdt, h_include, priv, region,
+ path, path_len, flags, info);
+}
+
+/*
+ * Theory of operation
+ *
+ *
+ *
+
+Note: in this description 'included' means that a node (or other part of
+the tree) should be included in the region list, i.e. it will have a region
+which covers its part of the tree.
+
+This function maintains some state from the last time it is called. It
+checks the next part of the tree that it is supposed to look at
+(p.nextoffset) to see if that should be included or not. When it finds
+something to include, it sets info->start to its offset. This marks the
+start of the region we want to include.
+
+Once info->start is set to the start (i.e. not -1), we continue scanning
+until we find something that we don't want included. This will be the end
+of a region. At this point we can close off the region and add it to the
+list. So we do so, and reset info->start to -1.
+
+One complication here is that we want to merge regions. So when we come to
+add another region later, we may in fact merge it with the previous one if
+one ends where the other starts.
+
+The function fdt_add_region() will return -1 if it fails to add the region,
+because we already have a region ready to be returned, and the new one
+cannot be merged in with it. In this case, we must return the region we
+found, and wait for another call to this function. When it comes, we will
+repeat the processing of the tag and again try to add a region. This time it
+will succeed.
+
+The current state of the pointers (stack, offset, etc.) is maintained in
+a ptrs member. At the start of every loop iteration we make a copy of it.
+The copy is then updated as the tag is processed. Only if we get to the end
+of the loop iteration (and successfully call fdt_add_region() if we need
+to) can we commit the changes we have made to these pointers. For example,
+if we see an FDT_END_NODE tag we will decrement the depth value. But if we
+need to add a region for this tag (let's say because the previous tag is
+included and this FDT_END_NODE tag is not included) then we will only commit
+the result if we were able to add the region. That allows us to retry again
+next time.
+
+We keep track of a variable called 'want' which tells us what we want to
+include when there is no specific information provided by the h_include
+function for a particular property. This basically handles the inclusion of
+properties which are pulled in by virtue of the node they are in. So if you
+include a node, its properties are also included. In this case 'want' will
+be WANT_NODES_AND_PROPS. The FDT_REG_DIRECT_SUBNODES feature also makes use
+of 'want'. While we are inside the subnode, 'want' will be set to
+WANT_NODES_ONLY, so that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE
+tags will be included, and properties will be skipped. If WANT_NOTHING is
+selected, then we will just rely on what the h_include() function tells us.
+
+Using 'want' we work out 'include', which tells us whether this current tag
+should be included or not. As you can imagine, if the value of 'include'
+changes, that means we are on a boundary between nodes to include and nodes
+to exclude. At this point we either close off a previous region and add it
+to the list, or mark the start of a new region.
+
+Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the string
+list. Each of these dealt with as a whole (i.e. we create a region for each
+if it is to be included). For mem_rsvmap we don't allow it to merge with
+the first struct region. For the stringlist we don't allow it to merge with
+the last struct region (which contains at minimum the FDT_END tag).
+*/
+int fdt_next_region(const void *fdt,
+ int (*h_include)(void *priv, const void *fdt, int offset,
+ int type, const char *data, int size),
+ void *priv, struct fdt_region *region,
+ char *path, int path_len, int flags,
+ struct fdt_region_state *info)
+{
+ int base = fdt_off_dt_struct(fdt);
+ const char *str;
+
+ info->region = region;
+ info->count = 0;
+ if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
+ (flags & FDT_REG_ADD_MEM_RSVMAP)) {
+ /* Add the memory reserve map into its own region */
+ if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
+ fdt_off_dt_struct(fdt) - fdt_off_mem_rsvmap(fdt)))
+ return 0;
+ info->can_merge = 0; /* Don't allow merging with this */
+ info->ptrs.done = FDT_DONE_MEM_RSVMAP;
+ }
+
+ /*
+ * Work through the tags one by one, deciding whether each needs to
+ * be included or not. We set the variable 'include' to indicate our
+ * decision. 'want' is used to track what we want to include - it
+ * allows us to pick up all the properties (and/or subnode tags) of
+ * a node.
+ */
+ while (info->ptrs.done < FDT_DONE_STRUCT) {
+ const struct fdt_property *prop;
+ struct fdt_region_ptrs p;
+ const char *name;
+ int include = 0;
+ int stop_at = 0;
+ uint32_t tag;
+ int offset;
+ int val;
+ int len;
+
+ /*
+ * Make a copy of our pointers. If we make it to the end of
+ * this block then we will commit them back to info->ptrs.
+ * Otherwise we can try again from the same starting state
+ * next time we are called.
+ */
+ p = info->ptrs;
+
+ /*
+ * Find the tag, and the offset of the next one. If we need to
+ * stop including tags, then by default we stop *after*
+ * including the current tag
+ */
+ offset = p.nextoffset;
+ tag = fdt_next_tag(fdt, offset, &p.nextoffset);
+ stop_at = p.nextoffset;
+
+ switch (tag) {
+ case FDT_PROP:
+ stop_at = offset;
+ prop = fdt_get_property_by_offset(fdt, offset, NULL);
+ str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
+ val = h_include(priv, fdt, offset, FDT_IS_PROP, str,
+ strlen(str) + 1);
+ if (val == -1) {
+ include = p.want == WANT_NODES_AND_PROPS;
+ } else {
+ include = val;
+ /*
+ * Make sure we include the } for this block.
+ * It might be more correct to put this done
+ * by the call to fdt_include_supernodes() in
+ * the case where it adds the node we are
+ * currently in, but this is fairly
+ * equivalent.
+ */
+ if ((flags & FDT_REG_SUPERNODES) && val &&
+ !p.want)
+ p.want = WANT_NODES_ONLY;
+ }
+
+ /* Value grepping is not yet supported */
+ break;
+
+ case FDT_NOP:
+ include = p.want == WANT_NODES_AND_PROPS;
+ stop_at = offset;
+ break;
+
+ case FDT_BEGIN_NODE:
+ p.depth++;
+ if (p.depth == FDT_MAX_DEPTH)
+ return -FDT_ERR_TOODEEP;
+ name = fdt_get_name(fdt, offset, &len);
+ if (p.end - path + 2 + len >= path_len)
+ return -FDT_ERR_NOSPACE;
+
+ /* Build the full path of this node */
+ if (p.end != path + 1)
+ *p.end++ = '/';
+ strcpy(p.end, name);
+ p.end += len;
+ info->stack[p.depth].want = p.want;
+ info->stack[p.depth].offset = offset;
+
+ /*
+ * If we are not intending to include this node, make
+ * sure we stop *before* its tag.
+ */
+ if (p.want == WANT_NODES_ONLY ||
+ !(flags & FDT_REG_DIRECT_SUBNODES)) {
+ stop_at = offset;
+ p.want = WANT_NOTHING;
+ }
+ val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
+ p.end - path + 1);
+
+ /* Include this if requested */
+ if (val)
+ p.want = WANT_NODES_AND_PROPS;
+
+ /* If not requested, decay our 'p.want' value */
+ else if (p.want)
+ p.want--;
+
+ /* Not including this tag, so stop now */
+ else
+ stop_at = offset;
+
+ /*
+ * Decide whether to include this tag, and update our
+ * stack with the state for this node
+ */
+ include = p.want;
+ info->stack[p.depth].included = include;
+ break;
+
+ case FDT_END_NODE:
+ include = p.want;
+ if (p.depth < 0)
+ return -FDT_ERR_BADSTRUCTURE;
+
+ /*
+ * If we don't p.want this node, stop right away, unless
+ * we are including subnodes
+ */
+ if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
+ stop_at = offset;
+ p.want = info->stack[p.depth].want;
+ p.depth--;
+ while (p.end > path && *--p.end != '/')
+ ;
+ *p.end = '\0';
+ break;
+
+ case FDT_END:
+ /* We always include the end tag */
+ include = 1;
+ p.done = FDT_DONE_STRUCT;
+ break;
+ }
+
+ /* If this tag is to be included, mark it as region start */
+ if (include && info->start == -1) {
+ /* Include any supernodes required by this one */
+ if (flags & FDT_REG_SUPERNODES) {
+ if (fdt_include_supernodes(info, p.depth))
+ return 0;
+ }
+ info->start = offset;
+ }
+
+ /*
+ * If this tag is not to be included, finish up the current
+ * region.
+ */
+ if (!include && info->start != -1) {
+ if (fdt_add_region(info, base + info->start,
+ stop_at - info->start))
+ return 0;
+ info->start = -1;
+ info->can_merge = 1;
+ }
+
+ /* If we have made it this far, we can commit our pointers */
+ info->ptrs = p;
+ }
+
+ /* Add a region for the END tag and a separate one for string table */
+ if (info->ptrs.done < FDT_DONE_END) {
+ if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
+ return -FDT_ERR_BADSTRUCTURE;
+
+ if (fdt_add_region(info, base + info->start,
+ info->ptrs.nextoffset - info->start))
+ return 0;
+ info->ptrs.done++;
+ }
+ if (info->ptrs.done < FDT_DONE_STRINGS &&
+ (flags & FDT_REG_ADD_STRING_TAB)) {
+ info->can_merge = 0;
+ if (fdt_off_dt_strings(fdt) < base + info->ptrs.nextoffset)
+ return -FDT_ERR_BADLAYOUT;
+ if (fdt_add_region(info, fdt_off_dt_strings(fdt),
+ fdt_size_dt_strings(fdt)))
+ return 0;
+ info->ptrs.done++;
+ }
+
+ return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;
+}
diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
index 130789a..fa62ad6 100644
--- a/libfdt/libfdt.h
+++ b/libfdt/libfdt.h
@@ -116,7 +116,12 @@
* Should never be returned, if it is, it indicates a bug in
* libfdt itself. */
-#define FDT_ERR_MAX 13
+#define FDT_ERR_TOODEEP 14
+ /* FDT_ERR_TOODEEP: The depth of a node has exceeded the internal
+ * libfdt limit. This can happen if you have more than
+ * FDT_MAX_DEPTH nested nodes. */
+
+#define FDT_ERR_MAX 14
/**********************************************************************/
/* Low-level functions (you probably don't need these) */
@@ -1489,4 +1494,210 @@ int fdt_del_node(void *fdt, int nodeoffset);
const char *fdt_strerror(int errval);
+struct fdt_region {
+ int offset;
+ int size;
+};
+
+/*
+ * Flags for fdt_find_regions()
+ *
+ * Add a region for the string table (always the last region)
+ */
+#define FDT_REG_ADD_STRING_TAB (1 << 0)
+
+/* Add the FDT_BEGIN_NODE tags of subnodes, including their names */
+#define FDT_REG_DIRECT_SUBNODES (1 << 1)
+
+/*
+ * Add all supernodes of a matching node/property, useful for creating a
+ * valid subset tree
+ */
+#define FDT_REG_SUPERNODES (1 << 2)
+
+/* Add a region for the mem_rsvmap table (always the first region) */
+#define FDT_REG_ADD_MEM_RSVMAP (1 << 3)
+
+/* Indicates what an fdt part is (node, property, value) */
+#define FDT_IS_NODE (1 << 0)
+#define FDT_IS_PROP (1 << 1)
+#define FDT_IS_VALUE (1 << 2) /* not supported */
+#define FDT_IS_COMPAT (1 << 3) /* used internally */
+
+#define FDT_IS_ANY 15
+
+/* We set a reasonable limit on the number of nested nodes */
+#define FDT_MAX_DEPTH 32
+
+/* Decribes what we want to include from the current tag */
+enum want_t {
+ WANT_NOTHING,
+ WANT_NODES_ONLY,
+ WANT_NODES_AND_PROPS,
+};
+
+/* Keeps track of the state at parent nodes */
+struct fdt_subnode_stack {
+ int offset; /* Offset of node */
+ enum want_t want; /* The 'want' value here */
+ int included; /* 1 if we included this node, 0 if not */
+};
+
+struct fdt_region_ptrs {
+ int depth; /* Current tree depth */
+ int done; /* What we have completed scanning */
+ enum want_t want; /* What we are currently including */
+ char *end; /* Pointer to end of full node path */
+ int nextoffset; /* Next node offset to check */
+};
+
+/* The state of our finding algortihm */
+struct fdt_region_state {
+ struct fdt_subnode_stack stack[FDT_MAX_DEPTH]; /* node stack */
+ struct fdt_region *region; /* Contains list of regions found */
+ int count; /* Numnber of regions found */
+ const void *fdt; /* FDT blob */
+ int max_regions; /* Maximum regions to find */
+ int can_merge; /* 1 if we can merge with previous region */
+ int start; /* Start position of current region */
+ struct fdt_region_ptrs ptrs; /* Pointers for what we are up to */
+};
+
+/**
+ * fdt_first_region() - find regions in device tree
+ *
+ * Given a nodes and properties to include and properties to exclude, find
+ * the regions of the device tree which describe those included parts.
+ *
+ * The use for this function is twofold. Firstly it provides a convenient
+ * way of performing a structure-aware grep of the tree. For example it is
+ * possible to grep for a node and get all the properties associated with
+ * that node. Trees can be subsetted easily, by specifying the nodes that
+ * are required, and then writing out the regions returned by this function.
+ * This is useful for small resource-constrained systems, such as boot
+ * loaders, which want to use an FDT but do not need to know about all of
+ * it.
+ *
+ * Secondly it makes it easy to hash parts of the tree and detect changes.
+ * The intent is to get a list of regions which will be invariant provided
+ * those parts are invariant. For example, if you request a list of regions
+ * for all nodes but exclude the property "data", then you will get the
+ * same region contents regardless of any change to "data" properties.
+ *
+ * This function can be used to produce a byte-stream to send to a hashing
+ * function to verify that critical parts of the FDT have not changed.
+ * Note that semantically null changes in order could still cause false
+ * hash misses. Such reordering might happen if the tree is regenerated
+ * from source, and nodes are reordered (the bytes-stream will be emitted
+ * in a different order and mnay hash functions will detect this). However
+ * if an existing tree is modified using libfdt functions, such as
+ * fdt_add_subnode() and fdt_setprop(), then this problem is avoided.
+ *
+ * The nodes/properties to include/exclude are defined by a function
+ * provided by the caller. This function is called for each node and
+ * property, and must return:
+ *
+ * 0 - to exclude this part
+ * 1 - to include this part
+ * -1 - for FDT_IS_PROP only: no information is available, so include
+ * if its containing node is included
+ *
+ * The last case is only used to deal with properties. Often a property is
+ * included if its containing node is included - this is the case where
+ * -1 is returned.. However if the property is specifically required to be
+ * included/excluded, then 0 or 1 can be returned. Note that including a
+ * property when the FDT_REG_SUPERNODES flag is given will force its
+ * containing node to be included since it is not valid to have a property
+ * that is not in a node.
+ *
+ * Using the information provided, the inclusion of a node can be controlled
+ * either by a node name or its compatible string, or any other property
+ * that the function can determine.
+ *
+ * As an example, including node "/" means to include the root node and all
+ * root properties. A flag provides a way of also including supernodes (of
+ * which there is none for the root node), and another flag includes
+ * immediate subnodes, so in this case we would get the FDT_BEGIN_NODE and
+ * FDT_END_NODE of all subnodes of /.
+ *
+ * The subnode feature helps in a hashing situation since it prevents the
+ * root node from changing at all. Any change to non-excluded properties,
+ * names of subnodes or number of subnodes would be detected.
+ *
+ * When used with FITs this provides the ability to hash and sign parts of
+ * the FIT based on different configurations in the FIT. Then it is
+ * impossible to change anything about that configuration (include images
+ * attached to the configuration), but it may be possible to add new
+ * configurations, new images or new signatures within the existing
+ * framework.
+ *
+ * Adding new properties to a device tree may result in the string table
+ * being extended (if the new property names are different from those
+ * already added). This function can optionally include a region for
+ * the string table so that this can be part of the hash too. This is always
+ * the last region.
+ *
+ * The FDT also has a mem_rsvmap table which can also be included, and is
+ * always the first region if so.
+ *
+ * The device tree header is not included in the region list. Since the
+ * contents of the FDT are changing (shrinking, often), the caller will need
+ * to regenerate the header anyway.
+ *
+ * @fdt: Device tree to check
+ * @h_include: Function to call to determine whether to include a part or
+ * not:
+ *
+ * @priv: Private pointer as passed to fdt_find_regions()
+ * @fdt: Pointer to FDT blob
+ * @offset: Offset of this node / property
+ * @type: Type of this part, FDT_IS_...
+ * @data: Pointer to data (node name, property name, compatible
+ * string, value (not yet supported)
+ * @size: Size of data, or 0 if none
+ * @return 0 to exclude, 1 to include, -1 if no information is
+ * available
+ * @priv: Private pointer passed to h_include
+ * @region: Returns list of regions, sorted by offset
+ * @max_regions: Maximum length of region list
+ * @path: Pointer to a temporary string for the function to use for
+ * building path names
+ * @path_len: Length of path, must be large enough to hold the longest
+ * path in the tree
+ * @flags: Various flags that control the region algortihm, see
+ * FDT_REG_...
+ * @return number of regions in list. If this is >max_regions then the
+ * region array was exhausted. You should increase max_regions and try
+ * the call again. Only the first max_regions elements are available in the
+ * array.
+ *
+ * On error a -ve value is return, which can be:
+ *
+ * -FDT_ERR_BADSTRUCTURE (too deep or more END tags than BEGIN tags
+ * -FDT_ERR_BADLAYOUT
+ * -FDT_ERR_NOSPACE (path area is too small)
+ */
+int fdt_first_region(const void *fdt,
+ int (*h_include)(void *priv, const void *fdt, int offset,
+ int type, const char *data, int size),
+ void *priv, struct fdt_region *region,
+ char *path, int path_len, int flags,
+ struct fdt_region_state *info);
+
+/** fdt_next_region() - find next region
+ *
+ * See fdt_first_region() for full description. This function finds the
+ * next region according to the provided parameters, which must be the same
+ * as passed to fdt_first_region().
+ *
+ * This function can additionally return -FDT_ERR_NOTFOUND when there are no
+ * more regions
+ */
+int fdt_next_region(const void *fdt,
+ int (*h_include)(void *priv, const void *fdt, int offset,
+ int type, const char *data, int size),
+ void *priv, struct fdt_region *region,
+ char *path, int path_len, int flags,
+ struct fdt_region_state *info);
+
#endif /* _LIBFDT_H */
diff --git a/tests/.gitignore b/tests/.gitignore
index e2aa24a..ecac691 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -41,6 +41,7 @@ tmp.*
/phandle_format
/propname_escapes
/references
+/region_tree
/root_node
/rw_tree1
/set_name
diff --git a/tests/Makefile.tests b/tests/Makefile.tests
index d59bff8..10bbf1b 100644
--- a/tests/Makefile.tests
+++ b/tests/Makefile.tests
@@ -20,7 +20,8 @@ LIB_TESTS_L = get_mem_rsv \
dtb_reverse dtbs_equal_unordered \
add_subnode_with_nops path_offset_aliases \
utilfdt_test \
- integer-expressions
+ integer-expressions \
+ region_tree
LIB_TESTS = $(LIB_TESTS_L:%=$(TESTS_PREFIX)%)
LIBTREE_TESTS_L = truncated_property
diff --git a/tests/region_tree.c b/tests/region_tree.c
new file mode 100644
index 0000000..55ab2d5
--- /dev/null
+++ b/tests/region_tree.c
@@ -0,0 +1,336 @@
+/*
+ * hash_tree - Testcase for fdt_find_regions()
+ *
+ * Copyright (c) 2013, Google Inc.
+ *
+ * Copyright (C) 2006 David Gibson, IBM Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <ctype.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <libfdt_env.h>
+#include <fdt.h>
+#include <libfdt.h>
+
+#include "tests.h"
+#include "testdata.h"
+
+#define SPACE 65536
+
+#define CHECK(code) \
+ { \
+ err = (code); \
+ if (err) \
+ FAIL(#code ": %s", fdt_strerror(err)); \
+ }
+
+/*
+ * Regions we expect to see returned from fdt_find_regions(). We build up a
+ * list of these as we make the tree, then check the results of
+ * fdt_find_regions() once we are done.
+ */
+static struct fdt_region expect[20];
+
+/* Number of expected regions */
+int expect_count;
+
+/* Mark the start of a new region */
+static void start(void *fdt)
+{
+ expect[expect_count].offset = fdt_size_dt_struct(fdt);
+ verbose_printf("[%d: %x ", expect_count,
+ fdt_off_dt_struct(fdt) + expect[expect_count].offset);
+}
+
+/* Mark the end of a region */
+static void stop(void *fdt)
+{
+ expect[expect_count].size = fdt_size_dt_struct(fdt) -
+ expect[expect_count].offset;
+ expect[expect_count].offset += fdt_off_dt_struct(fdt);
+ verbose_printf("%x]\n", expect[expect_count].offset +
+ expect[expect_count].size);
+ expect_count++;
+}
+
+/**
+ * build_tree() - Build a tree
+ *
+ * @fdt: Pointer to place to put tree, assumed to be large enough
+ * @flags: Flags to control the tree creation (FDT_REG_...)
+ * @space: Amount of space to create for later tree additions
+ *
+ * This creates a tree modelled on a U-Boot FIT image, with various nodes
+ * and properties which are useful for testing the hashing features of
+ * fdt_find_regions().
+ */
+static void build_tree(void *fdt, int flags, int space)
+{
+ int direct_subnodes = flags & FDT_REG_DIRECT_SUBNODES;
+ int supernodes = flags & FDT_REG_SUPERNODES;
+ int either = direct_subnodes || supernodes;
+ int err;
+
+ CHECK(fdt_create(fdt, SPACE));
+
+ CHECK(fdt_add_reservemap_entry(fdt, TEST_ADDR_1, TEST_SIZE_1));
+ CHECK(fdt_add_reservemap_entry(fdt, TEST_ADDR_2, TEST_SIZE_2));
+ CHECK(fdt_finish_reservemap(fdt));
+
+ start(fdt); /* region 0 */
+ CHECK(fdt_begin_node(fdt, ""));
+ CHECK(fdt_property_string(fdt, "description", "kernel image"));
+ CHECK(fdt_property_u32(fdt, "#address-cells", 1));
+
+ /* /images */
+ if (!either)
+ stop(fdt);
+ CHECK(fdt_begin_node(fdt, "images"));
+ if (either)
+ stop(fdt);
+ CHECK(fdt_property_u32(fdt, "image-prop", 1));
+
+ /* /images/kernel at 1 */
+ start(fdt); /* region 1 */
+ CHECK(fdt_begin_node(fdt, "kernel at 1"));
+ CHECK(fdt_property_string(fdt, "description", "exynos kernel"));
+ stop(fdt);
+ CHECK(fdt_property_string(fdt, "data", "this is the kernel image"));
+ start(fdt); /* region 2 */
+
+ /* /images/kernel/hash at 1 */
+ CHECK(fdt_begin_node(fdt, "hash at 1"));
+ CHECK(fdt_property_string(fdt, "algo", "sha1"));
+ CHECK(fdt_end_node(fdt));
+
+ /* /images/kernel/hash at 2 */
+ if (!direct_subnodes)
+ stop(fdt);
+ CHECK(fdt_begin_node(fdt, "hash at 2"));
+ if (direct_subnodes)
+ stop(fdt);
+ CHECK(fdt_property_string(fdt, "algo", "sha1"));
+ if (direct_subnodes)
+ start(fdt); /* region 3 */
+ CHECK(fdt_end_node(fdt));
+ if (!direct_subnodes)
+ start(fdt); /* region 3 */
+
+ CHECK(fdt_end_node(fdt));
+
+ /* /images/fdt at 1 */
+ CHECK(fdt_begin_node(fdt, "fdt at 1"));
+ CHECK(fdt_property_string(fdt, "description", "snow FDT"));
+ stop(fdt);
+ CHECK(fdt_property_string(fdt, "data", "FDT data"));
+ start(fdt); /* region 4 */
+
+ /* /images/kernel/hash at 1 */
+ CHECK(fdt_begin_node(fdt, "hash at 1"));
+ CHECK(fdt_property_string(fdt, "algo", "sha1"));
+ CHECK(fdt_end_node(fdt));
+
+ CHECK(fdt_end_node(fdt));
+
+ if (!either)
+ stop(fdt);
+ CHECK(fdt_end_node(fdt));
+
+ /* /configurations */
+ CHECK(fdt_begin_node(fdt, "configurations"));
+ if (either)
+ stop(fdt);
+ CHECK(fdt_property_string(fdt, "default", "conf at 1"));
+
+ /* /configurations/conf at 1 */
+ start(fdt); /* region 6 */
+ CHECK(fdt_begin_node(fdt, "conf at 1"));
+ CHECK(fdt_property_string(fdt, "kernel", "kernel at 1"));
+ CHECK(fdt_property_string(fdt, "fdt", "fdt at 1"));
+ CHECK(fdt_end_node(fdt));
+ stop(fdt);
+
+ /* /configurations/conf at 2 */
+ CHECK(fdt_begin_node(fdt, "conf at 2"));
+ CHECK(fdt_property_string(fdt, "kernel", "kernel at 1"));
+ CHECK(fdt_property_string(fdt, "fdt", "fdt at 2"));
+ CHECK(fdt_end_node(fdt));
+
+ if (either)
+ start(fdt); /* region 7 */
+ CHECK(fdt_end_node(fdt));
+ if (!either)
+ start(fdt); /* region 7 */
+
+ CHECK(fdt_end_node(fdt));
+
+ CHECK(fdt_finish(fdt));
+ stop(fdt);
+
+ /* Add in the strings */
+ if (flags & FDT_REG_ADD_STRING_TAB) {
+ expect[expect_count].offset = fdt_off_dt_strings(fdt);
+ expect[expect_count].size = fdt_size_dt_strings(fdt);
+ expect_count++;
+ }
+
+ /* Make a bit of space */
+ if (space)
+ CHECK(fdt_open_into(fdt, fdt, fdt_totalsize(fdt) + space));
+
+ verbose_printf("Completed tree, totalsize = %d\n", fdt_totalsize(fdt));
+}
+
+/**
+ * strlist_contains() - Returns 1 if a string is contained in a list
+ *
+ * @list: List of strings
+ * @count: Number of strings in list
+ * @str: String to search for
+ */
+static int strlist_contains(const char * const list[], int count,
+ const char *str)
+{
+ int i;
+
+ for (i = 0; i < count; i++)
+ if (!strcmp(list[i], str))
+ return 1;
+
+ return 0;
+}
+
+/**
+ * h_include() - Our include handler for fdt_find_regions()
+ *
+ * This is very simple - we have a list of nodes we are looking for, and
+ * one property that we want to exclude.
+ */
+static int h_include(void *priv, const void *fdt, int offset, int type,
+ const char *data, int size)
+{
+ const char * const inc[] = {
+ "/",
+ "/images/kernel at 1",
+ "/images/fdt at 1",
+ "/configurations/conf at 1",
+ "/images/kernel at 1/hash at 1",
+ "/images/fdt at 1/hash at 1",
+ };
+
+ switch (type) {
+ case FDT_IS_NODE:
+ return strlist_contains(inc, 6, data);
+ case FDT_IS_PROP:
+ return !strcmp(data, "data") ? 0 : -1;
+ }
+
+ return 0;
+}
+
+/**
+ * check_regions() - Check that the regions are as we expect
+ *
+ * Call fdt_find_regions() and check that the results are as we expect them,
+ * matching the list of expected regions we created at the same time as
+ * the tree.
+ *
+ * @fdt: Pointer to device tree to check
+ * @flags: Flags value (FDT_REG_...)
+ * @return 0 if ok, -1 on failure
+ */
+static int check_regions(const void *fdt, int flags)
+{
+ struct fdt_region_state state;
+ struct fdt_region reg;
+ int err, ret = 0;
+ char path[1024];
+ int count;
+ int i;
+
+ ret = fdt_first_region(fdt, h_include, NULL, ®,
+ path, sizeof(path), flags, &state);
+ if (ret < 0)
+ CHECK(ret);
+
+ verbose_printf("Regions: %d\n", count);
+ for (i = 0; ; i++) {
+ struct fdt_region *exp = &expect[i];
+
+ verbose_printf("%d: %-10x %-10x\n", i, reg.offset,
+ reg.offset + reg.size);
+ if (memcmp(exp, ®, sizeof(reg))) {
+ ret = -1;
+ verbose_printf("exp: %-10x %-10x\n", exp->offset,
+ exp->offset + exp->size);
+ }
+
+ ret = fdt_next_region(fdt, h_include, NULL, ®,
+ path, sizeof(path), flags, &state);
+ if (ret < 0) {
+ if (ret == -FDT_ERR_NOTFOUND)
+ ret = 0;
+ CHECK(ret);
+ break;
+ }
+ }
+
+ return ret;
+}
+
+int main(int argc, char *argv[])
+{
+ const char *fname = NULL;
+ int flags = 0;
+ int space = 0;
+ void *fdt;
+
+ test_init(argc, argv);
+ if (argc < 2) {
+ verbose_printf("Usage: %s <flag value> [<space>]"
+ " [<output_fname.dtb>]", argv[0]);
+ FAIL();
+ }
+ flags = atoi(argv[1]);
+ if (argc >= 3)
+ space = atoi(argv[2]);
+ if (argc >= 4)
+ fname = argv[3];
+
+ /*
+ * Allocate space for the tree and build it, creating a list of
+ * expected regions.
+ */
+ fdt = xmalloc(SPACE);
+ build_tree(fdt, flags, space);
+
+ /* Write the tree out if required */
+ if (fname)
+ save_blob(fname, fdt);
+
+ /* Check the regions are what we expect */
+ if (check_regions(fdt, flags))
+ FAIL();
+ else
+ PASS();
+
+ return 0;
+}
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index b56b626..372acdd 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -246,6 +246,11 @@ libfdt_tests () {
# Specific bug tests
run_test add_subnode_with_nops
+
+ # Tests for fdt_find_regions()
+ for flags in 0 1 2 3 4 5 6 7; do
+ run_test region_tree ${flags}
+ done
}
dtc_tests () {
--
1.8.1.3
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