From 64045a6a173e6cf74a9c30bbe21a93d105be289e Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 16 Apr 2020 18:30:18 +0900 Subject: libfdt: split fdt_region declarations out to fdt_region APIs are not part of libfdt. They are U-Boot extension for the verified boot. Split the declarations related to fdt_region out of . This allows to become a simple wrapper file, like Linux does. Signed-off-by: Masahiro Yamada --- include/fdt_region.h | 304 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 304 insertions(+) create mode 100644 include/fdt_region.h (limited to 'include/fdt_region.h') diff --git a/include/fdt_region.h b/include/fdt_region.h new file mode 100644 index 00000000000..ff7a1ccb9af --- /dev/null +++ b/include/fdt_region.h @@ -0,0 +1,304 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _FDT_REGION_H +#define _FDT_REGION_H + +#ifndef SWIG /* Not available in Python */ +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 all supernodes of a matching node/property, useful for creating a + * valid subset tree + */ +#define FDT_REG_SUPERNODES (1 << 1) + +/* Add the FDT_BEGIN_NODE tags of subnodes, including their names */ +#define FDT_REG_DIRECT_SUBNODES (1 << 2) + +/* Add all subnodes of a matching node */ +#define FDT_REG_ALL_SUBNODES (1 << 3) + +/* Add a region for the mem_rsvmap table (always the first region) */ +#define FDT_REG_ADD_MEM_RSVMAP (1 << 4) + +/* 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_NODE_HAS_PROP (1 << 4) /* node contains prop */ + +#define FDT_ANY_GLOBAL (FDT_IS_NODE | FDT_IS_PROP | FDT_IS_VALUE | \ + FDT_IS_COMPAT) +#define FDT_IS_ANY 0x1f /* all the above */ + +/* 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, /* No properties */ + WANT_NODES_AND_PROPS, /* Everything for one level */ + WANT_ALL_NODES_AND_PROPS /* Everything for all levels */ +}; + +/* 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_find_regions() - find regions in device tree + * + * Given a list of nodes to include and properties to exclude, find + * the regions of the device tree which describe those included parts. + * + * 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. + * + * Nodes which are given in 'inc' are included in the region list, as + * are the names of the immediate subnodes nodes (but not the properties + * or subnodes of those subnodes). + * + * For eaxample "/" means to include the root node, all root properties + * and the FDT_BEGIN_NODE and FDT_END_NODE of all subnodes of /. The latter + * ensures that we capture the names of the subnodes. In a hashing situation + * 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. + * + * The device tree header is not included in the list. + * + * @fdt: Device tree to check + * @inc: List of node paths to included + * @inc_count: Number of node paths in list + * @exc_prop: List of properties names to exclude + * @exc_prop_count: Number of properties in exclude list + * @region: Returns list of regions + * @max_region: 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 + * @add_string_tab: 1 to add a region for the string table + * @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. + */ +int fdt_find_regions(const void *fdt, char * const inc[], int inc_count, + char * const exc_prop[], int exc_prop_count, + struct fdt_region region[], int max_regions, + char *path, int path_len, int add_string_tab); + +/** + * 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 many 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); + +/** + * fdt_add_alias_regions() - find aliases that point to existing regions + * + * Once a device tree grep is complete some of the nodes will be present + * and some will have been dropped. This function checks all the alias nodes + * to figure out which points point to nodes which are still present. These + * aliases need to be kept, along with the nodes they reference. + * + * Given a list of regions function finds the aliases that still apply and + * adds more regions to the list for these. This function is called after + * fdt_next_region() has finished returning regions and requires the same + * state. + * + * @fdt: Device tree file to reference + * @region: List of regions that will be kept + * @count: Number of regions + * @max_regions: Number of entries that can fit in @region + * @info: Region state as returned from fdt_next_region() + * @return new number of regions in @region (i.e. count + the number added) + * or -FDT_ERR_NOSPACE if there was not enough space. + */ +int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count, + int max_regions, struct fdt_region_state *info); +#endif /* SWIG */ + +#endif /* _FDT_REGION_H */ -- cgit v1.2.3