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Diffstat (limited to 'lib/libfdt/fdt_overlay.c')
| -rw-r--r-- | lib/libfdt/fdt_overlay.c | 867 |
1 files changed, 867 insertions, 0 deletions
diff --git a/lib/libfdt/fdt_overlay.c b/lib/libfdt/fdt_overlay.c new file mode 100644 index 0000000..5c0c398 --- /dev/null +++ b/lib/libfdt/fdt_overlay.c @@ -0,0 +1,867 @@ +// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause) +/* + * libfdt - Flat Device Tree manipulation + * Copyright (C) 2016 Free Electrons + * Copyright (C) 2016 NextThing Co. + */ +#include "libfdt_env.h" + +#include <fdt.h> +#include <libfdt.h> + +#include "libfdt_internal.h" + +/** + * overlay_get_target_phandle - retrieves the target phandle of a fragment + * @fdto: pointer to the device tree overlay blob + * @fragment: node offset of the fragment in the overlay + * + * overlay_get_target_phandle() retrieves the target phandle of an + * overlay fragment when that fragment uses a phandle (target + * property) instead of a path (target-path property). + * + * returns: + * the phandle pointed by the target property + * 0, if the phandle was not found + * -1, if the phandle was malformed + */ +static uint32_t overlay_get_target_phandle(const void *fdto, int fragment) +{ + const fdt32_t *val; + int len; + + val = fdt_getprop(fdto, fragment, "target", &len); + if (!val) + return 0; + + if ((len != sizeof(*val)) || (fdt32_to_cpu(*val) == (uint32_t)-1)) + return (uint32_t)-1; + + return fdt32_to_cpu(*val); +} + +int fdt_overlay_target_offset(const void *fdt, const void *fdto, + int fragment_offset, char const **pathp) +{ + uint32_t phandle; + const char *path = NULL; + int path_len = 0, ret; + + /* Try first to do a phandle based lookup */ + phandle = overlay_get_target_phandle(fdto, fragment_offset); + if (phandle == (uint32_t)-1) + return -FDT_ERR_BADPHANDLE; + + /* no phandle, try path */ + if (!phandle) { + /* And then a path based lookup */ + path = fdt_getprop(fdto, fragment_offset, "target-path", &path_len); + if (path) + ret = fdt_path_offset(fdt, path); + else + ret = path_len; + } else + ret = fdt_node_offset_by_phandle(fdt, phandle); + + /* + * If we haven't found either a target or a + * target-path property in a node that contains a + * __overlay__ subnode (we wouldn't be called + * otherwise), consider it a improperly written + * overlay + */ + if (ret < 0 && path_len == -FDT_ERR_NOTFOUND) + ret = -FDT_ERR_BADOVERLAY; + + /* return on error */ + if (ret < 0) + return ret; + + /* return pointer to path (if available) */ + if (pathp) + *pathp = path ? path : NULL; + + return ret; +} + +/** + * overlay_phandle_add_offset - Increases a phandle by an offset + * @fdt: Base device tree blob + * @node: Device tree overlay blob + * @name: Name of the property to modify (phandle or linux,phandle) + * @delta: offset to apply + * + * overlay_phandle_add_offset() increments a node phandle by a given + * offset. + * + * returns: + * 0 on success. + * Negative error code on error + */ +static int overlay_phandle_add_offset(void *fdt, int node, + const char *name, uint32_t delta) +{ + const fdt32_t *val; + uint32_t adj_val; + int len; + + val = fdt_getprop(fdt, node, name, &len); + if (!val) + return len; + + if (len != sizeof(*val)) + return -FDT_ERR_BADPHANDLE; + + adj_val = fdt32_to_cpu(*val); + if ((adj_val + delta) < adj_val) + return -FDT_ERR_NOPHANDLES; + + adj_val += delta; + if (adj_val == (uint32_t)-1) + return -FDT_ERR_NOPHANDLES; + + return fdt_setprop_inplace_u32(fdt, node, name, adj_val); +} + +/** + * overlay_adjust_node_phandles - Offsets the phandles of a node + * @fdto: Device tree overlay blob + * @node: Offset of the node we want to adjust + * @delta: Offset to shift the phandles of + * + * overlay_adjust_node_phandles() adds a constant to all the phandles + * of a given node. This is mainly use as part of the overlay + * application process, when we want to update all the overlay + * phandles to not conflict with the overlays of the base device tree. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_adjust_node_phandles(void *fdto, int node, + uint32_t delta) +{ + int child; + int ret; + + ret = overlay_phandle_add_offset(fdto, node, "phandle", delta); + if (ret && ret != -FDT_ERR_NOTFOUND) + return ret; + + ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta); + if (ret && ret != -FDT_ERR_NOTFOUND) + return ret; + + fdt_for_each_subnode(child, fdto, node) { + ret = overlay_adjust_node_phandles(fdto, child, delta); + if (ret) + return ret; + } + + return 0; +} + +/** + * overlay_adjust_local_phandles - Adjust the phandles of a whole overlay + * @fdto: Device tree overlay blob + * @delta: Offset to shift the phandles of + * + * overlay_adjust_local_phandles() adds a constant to all the + * phandles of an overlay. This is mainly use as part of the overlay + * application process, when we want to update all the overlay + * phandles to not conflict with the overlays of the base device tree. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_adjust_local_phandles(void *fdto, uint32_t delta) +{ + /* + * Start adjusting the phandles from the overlay root + */ + return overlay_adjust_node_phandles(fdto, 0, delta); +} + +/** + * overlay_update_local_node_references - Adjust the overlay references + * @fdto: Device tree overlay blob + * @tree_node: Node offset of the node to operate on + * @fixup_node: Node offset of the matching local fixups node + * @delta: Offset to shift the phandles of + * + * overlay_update_local_nodes_references() update the phandles + * pointing to a node within the device tree overlay by adding a + * constant delta. + * + * This is mainly used as part of a device tree application process, + * where you want the device tree overlays phandles to not conflict + * with the ones from the base device tree before merging them. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_update_local_node_references(void *fdto, + int tree_node, + int fixup_node, + uint32_t delta) +{ + int fixup_prop; + int fixup_child; + int ret; + + fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) { + const fdt32_t *fixup_val; + const char *tree_val; + const char *name; + int fixup_len; + int tree_len; + int i; + + fixup_val = fdt_getprop_by_offset(fdto, fixup_prop, + &name, &fixup_len); + if (!fixup_val) + return fixup_len; + + if (fixup_len % sizeof(uint32_t)) + return -FDT_ERR_BADOVERLAY; + fixup_len /= sizeof(uint32_t); + + tree_val = fdt_getprop(fdto, tree_node, name, &tree_len); + if (!tree_val) { + if (tree_len == -FDT_ERR_NOTFOUND) + return -FDT_ERR_BADOVERLAY; + + return tree_len; + } + + for (i = 0; i < fixup_len; i++) { + fdt32_t adj_val; + uint32_t poffset; + + poffset = fdt32_to_cpu(fixup_val[i]); + + /* + * phandles to fixup can be unaligned. + * + * Use a memcpy for the architectures that do + * not support unaligned accesses. + */ + memcpy(&adj_val, tree_val + poffset, sizeof(adj_val)); + + adj_val = cpu_to_fdt32(fdt32_to_cpu(adj_val) + delta); + + ret = fdt_setprop_inplace_namelen_partial(fdto, + tree_node, + name, + strlen(name), + poffset, + &adj_val, + sizeof(adj_val)); + if (ret == -FDT_ERR_NOSPACE) + return -FDT_ERR_BADOVERLAY; + + if (ret) + return ret; + } + } + + fdt_for_each_subnode(fixup_child, fdto, fixup_node) { + const char *fixup_child_name = fdt_get_name(fdto, fixup_child, + NULL); + int tree_child; + + tree_child = fdt_subnode_offset(fdto, tree_node, + fixup_child_name); + if (tree_child == -FDT_ERR_NOTFOUND) + return -FDT_ERR_BADOVERLAY; + if (tree_child < 0) + return tree_child; + + ret = overlay_update_local_node_references(fdto, + tree_child, + fixup_child, + delta); + if (ret) + return ret; + } + + return 0; +} + +/** + * overlay_update_local_references - Adjust the overlay references + * @fdto: Device tree overlay blob + * @delta: Offset to shift the phandles of + * + * overlay_update_local_references() update all the phandles pointing + * to a node within the device tree overlay by adding a constant + * delta to not conflict with the base overlay. + * + * This is mainly used as part of a device tree application process, + * where you want the device tree overlays phandles to not conflict + * with the ones from the base device tree before merging them. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_update_local_references(void *fdto, uint32_t delta) +{ + int fixups; + + fixups = fdt_path_offset(fdto, "/__local_fixups__"); + if (fixups < 0) { + /* There's no local phandles to adjust, bail out */ + if (fixups == -FDT_ERR_NOTFOUND) + return 0; + + return fixups; + } + + /* + * Update our local references from the root of the tree + */ + return overlay_update_local_node_references(fdto, 0, fixups, + delta); +} + +/** + * overlay_fixup_one_phandle - Set an overlay phandle to the base one + * @fdt: Base Device Tree blob + * @fdto: Device tree overlay blob + * @symbols_off: Node offset of the symbols node in the base device tree + * @path: Path to a node holding a phandle in the overlay + * @path_len: number of path characters to consider + * @name: Name of the property holding the phandle reference in the overlay + * @name_len: number of name characters to consider + * @poffset: Offset within the overlay property where the phandle is stored + * @label: Label of the node referenced by the phandle + * + * overlay_fixup_one_phandle() resolves an overlay phandle pointing to + * a node in the base device tree. + * + * This is part of the device tree overlay application process, when + * you want all the phandles in the overlay to point to the actual + * base dt nodes. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_fixup_one_phandle(void *fdt, void *fdto, + int symbols_off, + const char *path, uint32_t path_len, + const char *name, uint32_t name_len, + int poffset, const char *label) +{ + const char *symbol_path; + uint32_t phandle; + fdt32_t phandle_prop; + int symbol_off, fixup_off; + int prop_len; + + if (symbols_off < 0) + return symbols_off; + + symbol_path = fdt_getprop(fdt, symbols_off, label, + &prop_len); + if (!symbol_path) + return prop_len; + + symbol_off = fdt_path_offset(fdt, symbol_path); + if (symbol_off < 0) + return symbol_off; + + phandle = fdt_get_phandle(fdt, symbol_off); + if (!phandle) + return -FDT_ERR_NOTFOUND; + + fixup_off = fdt_path_offset_namelen(fdto, path, path_len); + if (fixup_off == -FDT_ERR_NOTFOUND) + return -FDT_ERR_BADOVERLAY; + if (fixup_off < 0) + return fixup_off; + + phandle_prop = cpu_to_fdt32(phandle); + return fdt_setprop_inplace_namelen_partial(fdto, fixup_off, + name, name_len, poffset, + &phandle_prop, + sizeof(phandle_prop)); +}; + +/** + * overlay_fixup_phandle - Set an overlay phandle to the base one + * @fdt: Base Device Tree blob + * @fdto: Device tree overlay blob + * @symbols_off: Node offset of the symbols node in the base device tree + * @property: Property offset in the overlay holding the list of fixups + * + * overlay_fixup_phandle() resolves all the overlay phandles pointed + * to in a __fixups__ property, and updates them to match the phandles + * in use in the base device tree. + * + * This is part of the device tree overlay application process, when + * you want all the phandles in the overlay to point to the actual + * base dt nodes. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off, + int property) +{ + const char *value; + const char *label; + int len; + + value = fdt_getprop_by_offset(fdto, property, + &label, &len); + if (!value) { + if (len == -FDT_ERR_NOTFOUND) + return -FDT_ERR_INTERNAL; + + return len; + } + + do { + const char *path, *name, *fixup_end; + const char *fixup_str = value; + uint32_t path_len, name_len; + uint32_t fixup_len; + char *sep, *endptr; + int poffset, ret; + + fixup_end = memchr(value, '\0', len); + if (!fixup_end) + return -FDT_ERR_BADOVERLAY; + fixup_len = fixup_end - fixup_str; + + len -= fixup_len + 1; + value += fixup_len + 1; + + path = fixup_str; + sep = memchr(fixup_str, ':', fixup_len); + if (!sep || *sep != ':') + return -FDT_ERR_BADOVERLAY; + + path_len = sep - path; + if (path_len == (fixup_len - 1)) + return -FDT_ERR_BADOVERLAY; + + fixup_len -= path_len + 1; + name = sep + 1; + sep = memchr(name, ':', fixup_len); + if (!sep || *sep != ':') + return -FDT_ERR_BADOVERLAY; + + name_len = sep - name; + if (!name_len) + return -FDT_ERR_BADOVERLAY; + + poffset = strtoul(sep + 1, &endptr, 10); + if ((*endptr != '\0') || (endptr <= (sep + 1))) + return -FDT_ERR_BADOVERLAY; + + ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off, + path, path_len, name, name_len, + poffset, label); + if (ret) + return ret; + } while (len > 0); + + return 0; +} + +/** + * overlay_fixup_phandles - Resolve the overlay phandles to the base + * device tree + * @fdt: Base Device Tree blob + * @fdto: Device tree overlay blob + * + * overlay_fixup_phandles() resolves all the overlay phandles pointing + * to nodes in the base device tree. + * + * This is one of the steps of the device tree overlay application + * process, when you want all the phandles in the overlay to point to + * the actual base dt nodes. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_fixup_phandles(void *fdt, void *fdto) +{ + int fixups_off, symbols_off; + int property; + + /* We can have overlays without any fixups */ + fixups_off = fdt_path_offset(fdto, "/__fixups__"); + if (fixups_off == -FDT_ERR_NOTFOUND) + return 0; /* nothing to do */ + if (fixups_off < 0) + return fixups_off; + + /* And base DTs without symbols */ + symbols_off = fdt_path_offset(fdt, "/__symbols__"); + if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND))) + return symbols_off; + + fdt_for_each_property_offset(property, fdto, fixups_off) { + int ret; + + ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property); + if (ret) + return ret; + } + + return 0; +} + +/** + * overlay_apply_node - Merges a node into the base device tree + * @fdt: Base Device Tree blob + * @target: Node offset in the base device tree to apply the fragment to + * @fdto: Device tree overlay blob + * @node: Node offset in the overlay holding the changes to merge + * + * overlay_apply_node() merges a node into a target base device tree + * node pointed. + * + * This is part of the final step in the device tree overlay + * application process, when all the phandles have been adjusted and + * resolved and you just have to merge overlay into the base device + * tree. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_apply_node(void *fdt, int target, + void *fdto, int node) +{ + int property; + int subnode; + + fdt_for_each_property_offset(property, fdto, node) { + const char *name; + const void *prop; + int prop_len; + int ret; + + prop = fdt_getprop_by_offset(fdto, property, &name, + &prop_len); + if (prop_len == -FDT_ERR_NOTFOUND) + return -FDT_ERR_INTERNAL; + if (prop_len < 0) + return prop_len; + + ret = fdt_setprop(fdt, target, name, prop, prop_len); + if (ret) + return ret; + } + + fdt_for_each_subnode(subnode, fdto, node) { + const char *name = fdt_get_name(fdto, subnode, NULL); + int nnode; + int ret; + + nnode = fdt_add_subnode(fdt, target, name); + if (nnode == -FDT_ERR_EXISTS) { + nnode = fdt_subnode_offset(fdt, target, name); + if (nnode == -FDT_ERR_NOTFOUND) + return -FDT_ERR_INTERNAL; + } + + if (nnode < 0) + return nnode; + + ret = overlay_apply_node(fdt, nnode, fdto, subnode); + if (ret) + return ret; + } + + return 0; +} + +/** + * overlay_merge - Merge an overlay into its base device tree + * @fdt: Base Device Tree blob + * @fdto: Device tree overlay blob + * + * overlay_merge() merges an overlay into its base device tree. + * + * This is the next to last step in the device tree overlay application + * process, when all the phandles have been adjusted and resolved and + * you just have to merge overlay into the base device tree. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_merge(void *fdt, void *fdto) +{ + int fragment; + + fdt_for_each_subnode(fragment, fdto, 0) { + int overlay; + int target; + int ret; + + /* + * Each fragments will have an __overlay__ node. If + * they don't, it's not supposed to be merged + */ + overlay = fdt_subnode_offset(fdto, fragment, "__overlay__"); + if (overlay == -FDT_ERR_NOTFOUND) + continue; + + if (overlay < 0) + return overlay; + + target = fdt_overlay_target_offset(fdt, fdto, fragment, NULL); + if (target < 0) + return target; + + ret = overlay_apply_node(fdt, target, fdto, overlay); + if (ret) + return ret; + } + + return 0; +} + +static int get_path_len(const void *fdt, int nodeoffset) +{ + int len = 0, namelen; + const char *name; + + FDT_RO_PROBE(fdt); + + for (;;) { + name = fdt_get_name(fdt, nodeoffset, &namelen); + if (!name) + return namelen; + + /* root? we're done */ + if (namelen == 0) + break; + + nodeoffset = fdt_parent_offset(fdt, nodeoffset); + if (nodeoffset < 0) + return nodeoffset; + len += namelen + 1; + } + + /* in case of root pretend it's "/" */ + if (len == 0) + len++; + return len; +} + +/** + * overlay_symbol_update - Update the symbols of base tree after a merge + * @fdt: Base Device Tree blob + * @fdto: Device tree overlay blob + * + * overlay_symbol_update() updates the symbols of the base tree with the + * symbols of the applied overlay + * + * This is the last step in the device tree overlay application + * process, allowing the reference of overlay symbols by subsequent + * overlay operations. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_symbol_update(void *fdt, void *fdto) +{ + int root_sym, ov_sym, prop, path_len, fragment, target; + int len, frag_name_len, ret, rel_path_len; + const char *s, *e; + const char *path; + const char *name; + const char *frag_name; + const char *rel_path; + const char *target_path; + char *buf; + void *p; + + ov_sym = fdt_subnode_offset(fdto, 0, "__symbols__"); + + /* if no overlay symbols exist no problem */ + if (ov_sym < 0) + return 0; + + root_sym = fdt_subnode_offset(fdt, 0, "__symbols__"); + + /* it no root symbols exist we should create them */ + if (root_sym == -FDT_ERR_NOTFOUND) + root_sym = fdt_add_subnode(fdt, 0, "__symbols__"); + + /* any error is fatal now */ + if (root_sym < 0) + return root_sym; + + /* iterate over each overlay symbol */ + fdt_for_each_property_offset(prop, fdto, ov_sym) { + path = fdt_getprop_by_offset(fdto, prop, &name, &path_len); + if (!path) + return path_len; + + /* verify it's a string property (terminated by a single \0) */ + if (path_len < 1 || memchr(path, '\0', path_len) != &path[path_len - 1]) + return -FDT_ERR_BADVALUE; + + /* keep end marker to avoid strlen() */ + e = path + path_len; + + if (*path != '/') + return -FDT_ERR_BADVALUE; + + /* get fragment name first */ + s = strchr(path + 1, '/'); + if (!s) { + /* Symbol refers to something that won't end + * up in the target tree */ + continue; + } + + frag_name = path + 1; + frag_name_len = s - path - 1; + + /* verify format; safe since "s" lies in \0 terminated prop */ + len = sizeof("/__overlay__/") - 1; + if ((e - s) > len && (memcmp(s, "/__overlay__/", len) == 0)) { + /* /<fragment-name>/__overlay__/<relative-subnode-path> */ + rel_path = s + len; + rel_path_len = e - rel_path - 1; + } else if ((e - s) == len + && (memcmp(s, "/__overlay__", len - 1) == 0)) { + /* /<fragment-name>/__overlay__ */ + rel_path = ""; + rel_path_len = 0; + } else { + /* Symbol refers to something that won't end + * up in the target tree */ + continue; + } + + /* find the fragment index in which the symbol lies */ + ret = fdt_subnode_offset_namelen(fdto, 0, frag_name, + frag_name_len); + /* not found? */ + if (ret < 0) + return -FDT_ERR_BADOVERLAY; + fragment = ret; + + /* an __overlay__ subnode must exist */ + ret = fdt_subnode_offset(fdto, fragment, "__overlay__"); + if (ret < 0) + return -FDT_ERR_BADOVERLAY; + + /* get the target of the fragment */ + ret = fdt_overlay_target_offset(fdt, fdto, fragment, &target_path); + if (ret < 0) + return ret; + target = ret; + + /* if we have a target path use */ + if (!target_path) { + ret = get_path_len(fdt, target); + if (ret < 0) + return ret; + len = ret; + } else { + len = strlen(target_path); + } + + ret = fdt_setprop_placeholder(fdt, root_sym, name, + len + (len > 1) + rel_path_len + 1, &p); + if (ret < 0) + return ret; + + if (!target_path) { + /* again in case setprop_placeholder changed it */ + ret = fdt_overlay_target_offset(fdt, fdto, fragment, &target_path); + if (ret < 0) + return ret; + target = ret; + } + + buf = p; + if (len > 1) { /* target is not root */ + if (!target_path) { + ret = fdt_get_path(fdt, target, buf, len + 1); + if (ret < 0) + return ret; + } else + memcpy(buf, target_path, len + 1); + + } else + len--; + + buf[len] = '/'; + memcpy(buf + len + 1, rel_path, rel_path_len); + buf[len + 1 + rel_path_len] = '\0'; + } + + return 0; +} + +int fdt_overlay_apply(void *fdt, void *fdto) +{ + uint32_t delta; + int ret; + + FDT_RO_PROBE(fdt); + FDT_RO_PROBE(fdto); + + ret = fdt_find_max_phandle(fdt, &delta); + if (ret) + goto err; + + ret = overlay_adjust_local_phandles(fdto, delta); + if (ret) + goto err; + + ret = overlay_update_local_references(fdto, delta); + if (ret) + goto err; + + ret = overlay_fixup_phandles(fdt, fdto); + if (ret) + goto err; + + ret = overlay_merge(fdt, fdto); + if (ret) + goto err; + + ret = overlay_symbol_update(fdt, fdto); + if (ret) + goto err; + + /* + * The overlay has been damaged, erase its magic. + */ + fdt_set_magic(fdto, ~0); + + return 0; + +err: + /* + * The overlay might have been damaged, erase its magic. + */ + fdt_set_magic(fdto, ~0); + + /* + * The base device tree might have been damaged, erase its + * magic. + */ + fdt_set_magic(fdt, ~0); + + return ret; +} |