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fdt_overlay.c
// 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; }
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