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/*
* libfdt - Flat Device Tree manipulation
* Copyright (C) 2013 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
* SPDX-License-Identifier: GPL-2.0+ BSD-2-Clause
*/
#include <libfdt_env.h>
#ifndef USE_HOSTCC
#include <fdt.h>
#include <libfdt.h>
#else
#include "fdt_host.h"
#endif
#include "libfdt_internal.h"
/**
* fdt_add_region() - Add a new region to our list
* @info: State information
* @offset: Start offset of region
* @size: Size of region
*
* 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.
*/
static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
{
struct fdt_region *reg;
reg = info->region ? &info->region[info->count - 1] : NULL;
if (info->can_merge && info->count &&
info->count <= info->max_regions &&
reg && offset <= reg->offset + reg->size) {
reg->size = offset + size - reg->offset;
} else if (info->count++ < info->max_regions) {
if (reg) {
reg++;
reg->offset = offset;
reg->size = size;
}
} else {
return -1;
}
return 0;
}
static int region_list_contains_offset(struct fdt_region_state *info,
const void *fdt, int target)
{
struct fdt_region *reg;
int num;
target += fdt_off_dt_struct(fdt);
for (reg = info->region, num = 0; num < info->count; reg++, num++) {
if (target >= reg->offset && target < reg->offset + reg->size)
return 1;
}
return 0;
}
/**
* fdt_add_alias_regions() - Add regions covering the aliases that we want
*
* The /aliases node is not automatically included by fdtgrep unless the
* command-line arguments cause to be included (or not excluded). However
* aliases are special in that we generally want to include those which
* reference a node that fdtgrep includes.
*
* In fact we want to include only aliases for those nodes still included in
* the fdt, and drop the other aliases since they point to nodes that will not
* be present.
*
* This function scans the aliases and adds regions for those which we want
* to keep.
*
* @fdt: Device tree to scan
* @region: List of regions
* @count: Number of regions in the list so far (i.e. starting point for this
* function)
* @max_regions: Maximum number of regions in @region list
* @info: Place to put the region state
* @return number of regions after processing, or -FDT_ERR_NOSPACE if we did
* not have enough room in the regions table for the regions we wanted to add.
*/
int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
int max_regions, struct fdt_region_state *info)
{
int base = fdt_off_dt_struct(fdt);
int node, node_end, offset;
int did_alias_header;
node = fdt_subnode_offset(fdt, 0, "aliases");
if (node < 0)
return -FDT_ERR_NOTFOUND;
/*
* Find the next node so that we know where the /aliases node ends. We
* need special handling if /aliases is the last node.
*/
node_end = fdt_next_subnode(fdt, node);
if (node_end == -FDT_ERR_NOTFOUND)
/* Move back to the FDT_END_NODE tag of '/' */
node_end = fdt_size_dt_struct(fdt) - sizeof(fdt32_t) * 2;
else if (node_end < 0) /* other error */
return node_end;
node_end -= sizeof(fdt32_t); /* Move to FDT_END_NODE tag of /aliases */
did_alias_header = 0;
info->region = region;
info->count = count;
info->can_merge = 0;
info->max_regions = max_regions;
for (offset = fdt_first_property_offset(fdt, node);
offset >= 0;
offset = fdt_next_property_offset(fdt, offset)) {
const struct fdt_property *prop;
const char *name;
int target, next;
prop = fdt_get_property_by_offset(fdt, offset, NULL);
name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
target = fdt_path_offset(fdt, name);
if (!region_list_contains_offset(info, fdt, target))
continue;
next = fdt_next_property_offset(fdt, offset);
if (next < 0)
next = node_end;
if (!did_alias_header) {
fdt_add_region(info, base + node, 12);
did_alias_header = 1;
}
fdt_add_region(info, base + offset, next - offset);
}
/* Add the FDT_END_NODE tag */
if (did_alias_header)
fdt_add_region(info, base + node_end, sizeof(fdt32_t));
return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
}
/**
* fdt_include_supernodes() - Include supernodes required by this node
* @info: State information
* @depth: Current stack depth
*
* 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.
*/
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);
int last_node = 0;
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, last_node, 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 have this done
* by the call to fdt_include_supernodes() in
* the case where it adds the node we are
* currently in, but this is 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:
last_node = offset;
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 unless
* it matches, make sure we stop *before* its tag.
*/
if (p.want == WANT_NODES_ONLY ||
!(flags & (FDT_REG_DIRECT_SUBNODES |
FDT_REG_ALL_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 = (flags & FDT_REG_ALL_SUBNODES) ?
WANT_ALL_NODES_AND_PROPS :
WANT_NODES_AND_PROPS;
}
/* If not requested, decay our 'p.want' value */
else if (p.want) {
if (p.want != WANT_ALL_NODES_AND_PROPS)
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 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) {
if (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;
}
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