diff options
Diffstat (limited to 'drivers/of/overlay.c')
| -rw-r--r-- | drivers/of/overlay.c | 1203 |
1 files changed, 1203 insertions, 0 deletions
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c new file mode 100644 index 000000000..fef5b6c2f --- /dev/null +++ b/drivers/of/overlay.c @@ -0,0 +1,1203 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Functions for working with device tree overlays + * + * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com> + * Copyright (C) 2012 Texas Instruments Inc. + */ + +#define pr_fmt(fmt) "OF: overlay: " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/of_fdt.h> +#include <linux/string.h> +#include <linux/ctype.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/libfdt.h> +#include <linux/err.h> +#include <linux/idr.h> + +#include "of_private.h" + +/** + * struct target - info about current target node as recursing through overlay + * @np: node where current level of overlay will be applied + * @in_livetree: @np is a node in the live devicetree + * + * Used in the algorithm to create the portion of a changeset that describes + * an overlay fragment, which is a devicetree subtree. Initially @np is a node + * in the live devicetree where the overlay subtree is targeted to be grafted + * into. When recursing to the next level of the overlay subtree, the target + * also recurses to the next level of the live devicetree, as long as overlay + * subtree node also exists in the live devicetree. When a node in the overlay + * subtree does not exist at the same level in the live devicetree, target->np + * points to a newly allocated node, and all subsequent targets in the subtree + * will be newly allocated nodes. + */ +struct target { + struct device_node *np; + bool in_livetree; +}; + +/** + * struct fragment - info about fragment nodes in overlay expanded device tree + * @target: target of the overlay operation + * @overlay: pointer to the __overlay__ node + */ +struct fragment { + struct device_node *target; + struct device_node *overlay; +}; + +/** + * struct overlay_changeset + * @id: changeset identifier + * @ovcs_list: list on which we are located + * @fdt: FDT that was unflattened to create @overlay_tree + * @overlay_tree: expanded device tree that contains the fragment nodes + * @count: count of fragment structures + * @fragments: fragment nodes in the overlay expanded device tree + * @symbols_fragment: last element of @fragments[] is the __symbols__ node + * @cset: changeset to apply fragments to live device tree + */ +struct overlay_changeset { + int id; + struct list_head ovcs_list; + const void *fdt; + struct device_node *overlay_tree; + int count; + struct fragment *fragments; + bool symbols_fragment; + struct of_changeset cset; +}; + +/* flags are sticky - once set, do not reset */ +static int devicetree_state_flags; +#define DTSF_APPLY_FAIL 0x01 +#define DTSF_REVERT_FAIL 0x02 + +/* + * If a changeset apply or revert encounters an error, an attempt will + * be made to undo partial changes, but may fail. If the undo fails + * we do not know the state of the devicetree. + */ +static int devicetree_corrupt(void) +{ + return devicetree_state_flags & + (DTSF_APPLY_FAIL | DTSF_REVERT_FAIL); +} + +static int build_changeset_next_level(struct overlay_changeset *ovcs, + struct target *target, const struct device_node *overlay_node); + +/* + * of_resolve_phandles() finds the largest phandle in the live tree. + * of_overlay_apply() may add a larger phandle to the live tree. + * Do not allow race between two overlays being applied simultaneously: + * mutex_lock(&of_overlay_phandle_mutex) + * of_resolve_phandles() + * of_overlay_apply() + * mutex_unlock(&of_overlay_phandle_mutex) + */ +static DEFINE_MUTEX(of_overlay_phandle_mutex); + +void of_overlay_mutex_lock(void) +{ + mutex_lock(&of_overlay_phandle_mutex); +} + +void of_overlay_mutex_unlock(void) +{ + mutex_unlock(&of_overlay_phandle_mutex); +} + + +static LIST_HEAD(ovcs_list); +static DEFINE_IDR(ovcs_idr); + +static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain); + +/** + * of_overlay_notifier_register() - Register notifier for overlay operations + * @nb: Notifier block to register + * + * Register for notification on overlay operations on device tree nodes. The + * reported actions definied by @of_reconfig_change. The notifier callback + * furthermore receives a pointer to the affected device tree node. + * + * Note that a notifier callback is not supposed to store pointers to a device + * tree node or its content beyond @OF_OVERLAY_POST_REMOVE corresponding to the + * respective node it received. + */ +int of_overlay_notifier_register(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&overlay_notify_chain, nb); +} +EXPORT_SYMBOL_GPL(of_overlay_notifier_register); + +/** + * of_overlay_notifier_register() - Unregister notifier for overlay operations + * @nb: Notifier block to unregister + */ +int of_overlay_notifier_unregister(struct notifier_block *nb) +{ + return blocking_notifier_chain_unregister(&overlay_notify_chain, nb); +} +EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister); + +static char *of_overlay_action_name[] = { + "pre-apply", + "post-apply", + "pre-remove", + "post-remove", +}; + +static int overlay_notify(struct overlay_changeset *ovcs, + enum of_overlay_notify_action action) +{ + struct of_overlay_notify_data nd; + int i, ret; + + for (i = 0; i < ovcs->count; i++) { + struct fragment *fragment = &ovcs->fragments[i]; + + nd.target = fragment->target; + nd.overlay = fragment->overlay; + + ret = blocking_notifier_call_chain(&overlay_notify_chain, + action, &nd); + if (notifier_to_errno(ret)) { + ret = notifier_to_errno(ret); + pr_err("overlay changeset %s notifier error %d, target: %pOF\n", + of_overlay_action_name[action], ret, nd.target); + return ret; + } + } + + return 0; +} + +/* + * The values of properties in the "/__symbols__" node are paths in + * the ovcs->overlay_tree. When duplicating the properties, the paths + * need to be adjusted to be the correct path for the live device tree. + * + * The paths refer to a node in the subtree of a fragment node's "__overlay__" + * node, for example "/fragment@0/__overlay__/symbol_path_tail", + * where symbol_path_tail can be a single node or it may be a multi-node path. + * + * The duplicated property value will be modified by replacing the + * "/fragment_name/__overlay/" portion of the value with the target + * path from the fragment node. + */ +static struct property *dup_and_fixup_symbol_prop( + struct overlay_changeset *ovcs, const struct property *prop) +{ + struct fragment *fragment; + struct property *new_prop; + struct device_node *fragment_node; + struct device_node *overlay_node; + const char *path; + const char *path_tail; + const char *target_path; + int k; + int overlay_name_len; + int path_len; + int path_tail_len; + int target_path_len; + + if (!prop->value) + return NULL; + if (strnlen(prop->value, prop->length) >= prop->length) + return NULL; + path = prop->value; + path_len = strlen(path); + + if (path_len < 1) + return NULL; + fragment_node = __of_find_node_by_path(ovcs->overlay_tree, path + 1); + overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/"); + of_node_put(fragment_node); + of_node_put(overlay_node); + + for (k = 0; k < ovcs->count; k++) { + fragment = &ovcs->fragments[k]; + if (fragment->overlay == overlay_node) + break; + } + if (k >= ovcs->count) + return NULL; + + overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay); + + if (overlay_name_len > path_len) + return NULL; + path_tail = path + overlay_name_len; + path_tail_len = strlen(path_tail); + + target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target); + if (!target_path) + return NULL; + target_path_len = strlen(target_path); + + new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL); + if (!new_prop) + goto err_free_target_path; + + new_prop->name = kstrdup(prop->name, GFP_KERNEL); + new_prop->length = target_path_len + path_tail_len + 1; + new_prop->value = kzalloc(new_prop->length, GFP_KERNEL); + if (!new_prop->name || !new_prop->value) + goto err_free_new_prop; + + strcpy(new_prop->value, target_path); + strcpy(new_prop->value + target_path_len, path_tail); + + of_property_set_flag(new_prop, OF_DYNAMIC); + + kfree(target_path); + + return new_prop; + +err_free_new_prop: + kfree(new_prop->name); + kfree(new_prop->value); + kfree(new_prop); +err_free_target_path: + kfree(target_path); + + return NULL; +} + +/** + * add_changeset_property() - add @overlay_prop to overlay changeset + * @ovcs: overlay changeset + * @target: where @overlay_prop will be placed + * @overlay_prop: property to add or update, from overlay tree + * @is_symbols_prop: 1 if @overlay_prop is from node "/__symbols__" + * + * If @overlay_prop does not already exist in live devicetree, add changeset + * entry to add @overlay_prop in @target, else add changeset entry to update + * value of @overlay_prop. + * + * @target may be either in the live devicetree or in a new subtree that + * is contained in the changeset. + * + * Some special properties are not added or updated (no error returned): + * "name", "phandle", "linux,phandle". + * + * Properties "#address-cells" and "#size-cells" are not updated if they + * are already in the live tree, but if present in the live tree, the values + * in the overlay must match the values in the live tree. + * + * Update of property in symbols node is not allowed. + * + * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if + * invalid @overlay. + */ +static int add_changeset_property(struct overlay_changeset *ovcs, + struct target *target, struct property *overlay_prop, + bool is_symbols_prop) +{ + struct property *new_prop = NULL, *prop; + int ret = 0; + + if (target->in_livetree) + if (!of_prop_cmp(overlay_prop->name, "name") || + !of_prop_cmp(overlay_prop->name, "phandle") || + !of_prop_cmp(overlay_prop->name, "linux,phandle")) + return 0; + + if (target->in_livetree) + prop = of_find_property(target->np, overlay_prop->name, NULL); + else + prop = NULL; + + if (prop) { + if (!of_prop_cmp(prop->name, "#address-cells")) { + if (!of_prop_val_eq(prop, overlay_prop)) { + pr_err("ERROR: changing value of #address-cells is not allowed in %pOF\n", + target->np); + ret = -EINVAL; + } + return ret; + + } else if (!of_prop_cmp(prop->name, "#size-cells")) { + if (!of_prop_val_eq(prop, overlay_prop)) { + pr_err("ERROR: changing value of #size-cells is not allowed in %pOF\n", + target->np); + ret = -EINVAL; + } + return ret; + } + } + + if (is_symbols_prop) { + if (prop) + return -EINVAL; + new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop); + } else { + new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL); + } + + if (!new_prop) + return -ENOMEM; + + if (!prop) { + if (!target->in_livetree) { + new_prop->next = target->np->deadprops; + target->np->deadprops = new_prop; + } + ret = of_changeset_add_property(&ovcs->cset, target->np, + new_prop); + } else { + ret = of_changeset_update_property(&ovcs->cset, target->np, + new_prop); + } + + if (!of_node_check_flag(target->np, OF_OVERLAY)) + pr_err("WARNING: memory leak will occur if overlay removed, property: %pOF/%s\n", + target->np, new_prop->name); + + if (ret) { + kfree(new_prop->name); + kfree(new_prop->value); + kfree(new_prop); + } + return ret; +} + +/** + * add_changeset_node() - add @node (and children) to overlay changeset + * @ovcs: overlay changeset + * @target: where @node will be placed in live tree or changeset + * @node: node from within overlay device tree fragment + * + * If @node does not already exist in @target, add changeset entry + * to add @node in @target. + * + * If @node already exists in @target, and the existing node has + * a phandle, the overlay node is not allowed to have a phandle. + * + * If @node has child nodes, add the children recursively via + * build_changeset_next_level(). + * + * NOTE_1: A live devicetree created from a flattened device tree (FDT) will + * not contain the full path in node->full_name. Thus an overlay + * created from an FDT also will not contain the full path in + * node->full_name. However, a live devicetree created from Open + * Firmware may have the full path in node->full_name. + * + * add_changeset_node() follows the FDT convention and does not include + * the full path in node->full_name. Even though it expects the overlay + * to not contain the full path, it uses kbasename() to remove the + * full path should it exist. It also uses kbasename() in comparisons + * to nodes in the live devicetree so that it can apply an overlay to + * a live devicetree created from Open Firmware. + * + * NOTE_2: Multiple mods of created nodes not supported. + * If more than one fragment contains a node that does not already exist + * in the live tree, then for each fragment of_changeset_attach_node() + * will add a changeset entry to add the node. When the changeset is + * applied, __of_attach_node() will attach the node twice (once for + * each fragment). At this point the device tree will be corrupted. + * + * TODO: add integrity check to ensure that multiple fragments do not + * create the same node. + * + * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if + * invalid @overlay. + */ +static int add_changeset_node(struct overlay_changeset *ovcs, + struct target *target, struct device_node *node) +{ + const char *node_kbasename; + const __be32 *phandle; + struct device_node *tchild; + struct target target_child; + int ret = 0, size; + + node_kbasename = kbasename(node->full_name); + + for_each_child_of_node(target->np, tchild) + if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name))) + break; + + if (!tchild) { + tchild = __of_node_dup(NULL, node_kbasename); + if (!tchild) + return -ENOMEM; + + tchild->parent = target->np; + tchild->name = __of_get_property(node, "name", NULL); + tchild->type = __of_get_property(node, "device_type", NULL); + + if (!tchild->name) + tchild->name = "<NULL>"; + if (!tchild->type) + tchild->type = "<NULL>"; + + /* ignore obsolete "linux,phandle" */ + phandle = __of_get_property(node, "phandle", &size); + if (phandle && (size == 4)) + tchild->phandle = be32_to_cpup(phandle); + + of_node_set_flag(tchild, OF_OVERLAY); + + ret = of_changeset_attach_node(&ovcs->cset, tchild); + if (ret) + return ret; + + target_child.np = tchild; + target_child.in_livetree = false; + + ret = build_changeset_next_level(ovcs, &target_child, node); + of_node_put(tchild); + return ret; + } + + if (node->phandle && tchild->phandle) { + ret = -EINVAL; + } else { + target_child.np = tchild; + target_child.in_livetree = target->in_livetree; + ret = build_changeset_next_level(ovcs, &target_child, node); + } + of_node_put(tchild); + + return ret; +} + +/** + * build_changeset_next_level() - add level of overlay changeset + * @ovcs: overlay changeset + * @target: where to place @overlay_node in live tree + * @overlay_node: node from within an overlay device tree fragment + * + * Add the properties (if any) and nodes (if any) from @overlay_node to the + * @ovcs->cset changeset. If an added node has child nodes, they will + * be added recursively. + * + * Do not allow symbols node to have any children. + * + * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if + * invalid @overlay_node. + */ +static int build_changeset_next_level(struct overlay_changeset *ovcs, + struct target *target, const struct device_node *overlay_node) +{ + struct device_node *child; + struct property *prop; + int ret; + + for_each_property_of_node(overlay_node, prop) { + ret = add_changeset_property(ovcs, target, prop, 0); + if (ret) { + pr_debug("Failed to apply prop @%pOF/%s, err=%d\n", + target->np, prop->name, ret); + return ret; + } + } + + for_each_child_of_node(overlay_node, child) { + ret = add_changeset_node(ovcs, target, child); + if (ret) { + pr_debug("Failed to apply node @%pOF/%pOFn, err=%d\n", + target->np, child, ret); + of_node_put(child); + return ret; + } + } + + return 0; +} + +/* + * Add the properties from __overlay__ node to the @ovcs->cset changeset. + */ +static int build_changeset_symbols_node(struct overlay_changeset *ovcs, + struct target *target, + const struct device_node *overlay_symbols_node) +{ + struct property *prop; + int ret; + + for_each_property_of_node(overlay_symbols_node, prop) { + ret = add_changeset_property(ovcs, target, prop, 1); + if (ret) { + pr_debug("Failed to apply prop @%pOF/%s, err=%d\n", + target->np, prop->name, ret); + return ret; + } + } + + return 0; +} + +/** + * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments + * @ovcs: Overlay changeset + * + * Create changeset @ovcs->cset to contain the nodes and properties of the + * overlay device tree fragments in @ovcs->fragments[]. If an error occurs, + * any portions of the changeset that were successfully created will remain + * in @ovcs->cset. + * + * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if + * invalid overlay in @ovcs->fragments[]. + */ +static int build_changeset(struct overlay_changeset *ovcs) +{ + struct fragment *fragment; + struct target target; + int fragments_count, i, ret; + + /* + * if there is a symbols fragment in ovcs->fragments[i] it is + * the final element in the array + */ + if (ovcs->symbols_fragment) + fragments_count = ovcs->count - 1; + else + fragments_count = ovcs->count; + + for (i = 0; i < fragments_count; i++) { + fragment = &ovcs->fragments[i]; + + target.np = fragment->target; + target.in_livetree = true; + ret = build_changeset_next_level(ovcs, &target, + fragment->overlay); + if (ret) { + pr_debug("apply failed '%pOF'\n", fragment->target); + return ret; + } + } + + if (ovcs->symbols_fragment) { + fragment = &ovcs->fragments[ovcs->count - 1]; + + target.np = fragment->target; + target.in_livetree = true; + ret = build_changeset_symbols_node(ovcs, &target, + fragment->overlay); + if (ret) { + pr_debug("apply failed '%pOF'\n", fragment->target); + return ret; + } + } + + return 0; +} + +/* + * Find the target node using a number of different strategies + * in order of preference: + * + * 1) "target" property containing the phandle of the target + * 2) "target-path" property containing the path of the target + */ +static struct device_node *find_target(struct device_node *info_node) +{ + struct device_node *node; + const char *path; + u32 val; + int ret; + + ret = of_property_read_u32(info_node, "target", &val); + if (!ret) { + node = of_find_node_by_phandle(val); + if (!node) + pr_err("find target, node: %pOF, phandle 0x%x not found\n", + info_node, val); + return node; + } + + ret = of_property_read_string(info_node, "target-path", &path); + if (!ret) { + node = of_find_node_by_path(path); + if (!node) + pr_err("find target, node: %pOF, path '%s' not found\n", + info_node, path); + return node; + } + + pr_err("find target, node: %pOF, no target property\n", info_node); + + return NULL; +} + +/** + * init_overlay_changeset() - initialize overlay changeset from overlay tree + * @ovcs: Overlay changeset to build + * @fdt: the FDT that was unflattened to create @tree + * @tree: Contains all the overlay fragments and overlay fixup nodes + * + * Initialize @ovcs. Populate @ovcs->fragments with node information from + * the top level of @tree. The relevant top level nodes are the fragment + * nodes and the __symbols__ node. Any other top level node will be ignored. + * + * Returns 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error + * detected in @tree, or -ENOSPC if idr_alloc() error. + */ +static int init_overlay_changeset(struct overlay_changeset *ovcs, + const void *fdt, struct device_node *tree) +{ + struct device_node *node, *overlay_node; + struct fragment *fragment; + struct fragment *fragments; + int cnt, id, ret; + + /* + * Warn for some issues. Can not return -EINVAL for these until + * of_unittest_apply_overlay() is fixed to pass these checks. + */ + if (!of_node_check_flag(tree, OF_DYNAMIC)) + pr_debug("%s() tree is not dynamic\n", __func__); + + if (!of_node_check_flag(tree, OF_DETACHED)) + pr_debug("%s() tree is not detached\n", __func__); + + if (!of_node_is_root(tree)) + pr_debug("%s() tree is not root\n", __func__); + + ovcs->overlay_tree = tree; + ovcs->fdt = fdt; + + INIT_LIST_HEAD(&ovcs->ovcs_list); + + of_changeset_init(&ovcs->cset); + + id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL); + if (id <= 0) + return id; + + cnt = 0; + + /* fragment nodes */ + for_each_child_of_node(tree, node) { + overlay_node = of_get_child_by_name(node, "__overlay__"); + if (overlay_node) { + cnt++; + of_node_put(overlay_node); + } + } + + node = of_get_child_by_name(tree, "__symbols__"); + if (node) { + cnt++; + of_node_put(node); + } + + fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL); + if (!fragments) { + ret = -ENOMEM; + goto err_free_idr; + } + + cnt = 0; + for_each_child_of_node(tree, node) { + overlay_node = of_get_child_by_name(node, "__overlay__"); + if (!overlay_node) + continue; + + fragment = &fragments[cnt]; + fragment->overlay = overlay_node; + fragment->target = find_target(node); + if (!fragment->target) { + of_node_put(fragment->overlay); + ret = -EINVAL; + goto err_free_fragments; + } + + cnt++; + } + + /* + * if there is a symbols fragment in ovcs->fragments[i] it is + * the final element in the array + */ + node = of_get_child_by_name(tree, "__symbols__"); + if (node) { + ovcs->symbols_fragment = 1; + fragment = &fragments[cnt]; + fragment->overlay = node; + fragment->target = of_find_node_by_path("/__symbols__"); + + if (!fragment->target) { + pr_err("symbols in overlay, but not in live tree\n"); + ret = -EINVAL; + goto err_free_fragments; + } + + cnt++; + } + + if (!cnt) { + pr_err("no fragments or symbols in overlay\n"); + ret = -EINVAL; + goto err_free_fragments; + } + + ovcs->id = id; + ovcs->count = cnt; + ovcs->fragments = fragments; + + return 0; + +err_free_fragments: + kfree(fragments); +err_free_idr: + idr_remove(&ovcs_idr, id); + + pr_err("%s() failed, ret = %d\n", __func__, ret); + + return ret; +} + +static void free_overlay_changeset(struct overlay_changeset *ovcs) +{ + int i; + + if (ovcs->cset.entries.next) + of_changeset_destroy(&ovcs->cset); + + if (ovcs->id) + idr_remove(&ovcs_idr, ovcs->id); + + for (i = 0; i < ovcs->count; i++) { + of_node_put(ovcs->fragments[i].target); + of_node_put(ovcs->fragments[i].overlay); + } + kfree(ovcs->fragments); + /* + * There should be no live pointers into ovcs->overlay_tree and + * ovcs->fdt due to the policy that overlay notifiers are not allowed + * to retain pointers into the overlay devicetree. + */ + kfree(ovcs->overlay_tree); + kfree(ovcs->fdt); + kfree(ovcs); +} + +/* + * internal documentation + * + * of_overlay_apply() - Create and apply an overlay changeset + * @fdt: the FDT that was unflattened to create @tree + * @tree: Expanded overlay device tree + * @ovcs_id: Pointer to overlay changeset id + * + * Creates and applies an overlay changeset. + * + * If an error occurs in a pre-apply notifier, then no changes are made + * to the device tree. + * + + * A non-zero return value will not have created the changeset if error is from: + * - parameter checks + * - building the changeset + * - overlay changeset pre-apply notifier + * + * If an error is returned by an overlay changeset pre-apply notifier + * then no further overlay changeset pre-apply notifier will be called. + * + * A non-zero return value will have created the changeset if error is from: + * - overlay changeset entry notifier + * - overlay changeset post-apply notifier + * + * If an error is returned by an overlay changeset post-apply notifier + * then no further overlay changeset post-apply notifier will be called. + * + * If more than one notifier returns an error, then the last notifier + * error to occur is returned. + * + * If an error occurred while applying the overlay changeset, then an + * attempt is made to revert any changes that were made to the + * device tree. If there were any errors during the revert attempt + * then the state of the device tree can not be determined, and any + * following attempt to apply or remove an overlay changeset will be + * refused. + * + * Returns 0 on success, or a negative error number. Overlay changeset + * id is returned to *ovcs_id. + */ + +static int of_overlay_apply(const void *fdt, struct device_node *tree, + int *ovcs_id) +{ + struct overlay_changeset *ovcs; + int ret = 0, ret_revert, ret_tmp; + + /* + * As of this point, fdt and tree belong to the overlay changeset. + * overlay changeset code is responsible for freeing them. + */ + + if (devicetree_corrupt()) { + pr_err("devicetree state suspect, refuse to apply overlay\n"); + kfree(fdt); + kfree(tree); + ret = -EBUSY; + goto out; + } + + ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL); + if (!ovcs) { + kfree(fdt); + kfree(tree); + ret = -ENOMEM; + goto out; + } + + of_overlay_mutex_lock(); + mutex_lock(&of_mutex); + + ret = of_resolve_phandles(tree); + if (ret) + goto err_free_tree; + + ret = init_overlay_changeset(ovcs, fdt, tree); + if (ret) + goto err_free_tree; + + /* + * after overlay_notify(), ovcs->overlay_tree related pointers may have + * leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree; + * and can not free fdt, aka ovcs->fdt + */ + ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY); + if (ret) { + pr_err("overlay changeset pre-apply notify error %d\n", ret); + goto err_free_overlay_changeset; + } + + ret = build_changeset(ovcs); + if (ret) + goto err_free_overlay_changeset; + + ret_revert = 0; + ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert); + if (ret) { + if (ret_revert) { + pr_debug("overlay changeset revert error %d\n", + ret_revert); + devicetree_state_flags |= DTSF_APPLY_FAIL; + } + goto err_free_overlay_changeset; + } + + of_populate_phandle_cache(); + + ret = __of_changeset_apply_notify(&ovcs->cset); + if (ret) + pr_err("overlay changeset entry notify error %d\n", ret); + /* notify failure is not fatal, continue */ + + list_add_tail(&ovcs->ovcs_list, &ovcs_list); + *ovcs_id = ovcs->id; + + ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY); + if (ret_tmp) { + pr_err("overlay changeset post-apply notify error %d\n", + ret_tmp); + if (!ret) + ret = ret_tmp; + } + + goto out_unlock; + +err_free_tree: + kfree(fdt); + kfree(tree); + +err_free_overlay_changeset: + free_overlay_changeset(ovcs); + +out_unlock: + mutex_unlock(&of_mutex); + of_overlay_mutex_unlock(); + +out: + pr_debug("%s() err=%d\n", __func__, ret); + + return ret; +} + +int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size, + int *ovcs_id) +{ + const void *new_fdt; + int ret; + u32 size; + struct device_node *overlay_root; + + *ovcs_id = 0; + ret = 0; + + if (overlay_fdt_size < sizeof(struct fdt_header) || + fdt_check_header(overlay_fdt)) { + pr_err("Invalid overlay_fdt header\n"); + return -EINVAL; + } + + size = fdt_totalsize(overlay_fdt); + if (overlay_fdt_size < size) + return -EINVAL; + + /* + * Must create permanent copy of FDT because of_fdt_unflatten_tree() + * will create pointers to the passed in FDT in the unflattened tree. + */ + new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL); + if (!new_fdt) + return -ENOMEM; + + of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root); + if (!overlay_root) { + pr_err("unable to unflatten overlay_fdt\n"); + ret = -EINVAL; + goto out_free_new_fdt; + } + + ret = of_overlay_apply(new_fdt, overlay_root, ovcs_id); + if (ret < 0) { + /* + * new_fdt and overlay_root now belong to the overlay + * changeset. + * overlay changeset code is responsible for freeing them. + */ + goto out; + } + + return 0; + + +out_free_new_fdt: + kfree(new_fdt); + +out: + return ret; +} +EXPORT_SYMBOL_GPL(of_overlay_fdt_apply); + +/* + * Find @np in @tree. + * + * Returns 1 if @np is @tree or is contained in @tree, else 0 + */ +static int find_node(struct device_node *tree, struct device_node *np) +{ + struct device_node *child; + + if (tree == np) + return 1; + + for_each_child_of_node(tree, child) { + if (find_node(child, np)) { + of_node_put(child); + return 1; + } + } + + return 0; +} + +/* + * Is @remove_ce_node a child of, a parent of, or the same as any + * node in an overlay changeset more topmost than @remove_ovcs? + * + * Returns 1 if found, else 0 + */ +static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs, + struct device_node *remove_ce_node) +{ + struct overlay_changeset *ovcs; + struct of_changeset_entry *ce; + + list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) { + if (ovcs == remove_ovcs) + break; + + list_for_each_entry(ce, &ovcs->cset.entries, node) { + if (find_node(ce->np, remove_ce_node)) { + pr_err("%s: #%d overlaps with #%d @%pOF\n", + __func__, remove_ovcs->id, ovcs->id, + remove_ce_node); + return 1; + } + if (find_node(remove_ce_node, ce->np)) { + pr_err("%s: #%d overlaps with #%d @%pOF\n", + __func__, remove_ovcs->id, ovcs->id, + remove_ce_node); + return 1; + } + } + } + + return 0; +} + +/* + * We can safely remove the overlay only if it's the top-most one. + * Newly applied overlays are inserted at the tail of the overlay list, + * so a top most overlay is the one that is closest to the tail. + * + * The topmost check is done by exploiting this property. For each + * affected device node in the log list we check if this overlay is + * the one closest to the tail. If another overlay has affected this + * device node and is closest to the tail, then removal is not permited. + */ +static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs) +{ + struct of_changeset_entry *remove_ce; + + list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) { + if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) { + pr_err("overlay #%d is not topmost\n", remove_ovcs->id); + return 0; + } + } + + return 1; +} + +/** + * of_overlay_remove() - Revert and free an overlay changeset + * @ovcs_id: Pointer to overlay changeset id + * + * Removes an overlay if it is permissible. @ovcs_id was previously returned + * by of_overlay_fdt_apply(). + * + * If an error occurred while attempting to revert the overlay changeset, + * then an attempt is made to re-apply any changeset entry that was + * reverted. If an error occurs on re-apply then the state of the device + * tree can not be determined, and any following attempt to apply or remove + * an overlay changeset will be refused. + * + * A non-zero return value will not revert the changeset if error is from: + * - parameter checks + * - overlay changeset pre-remove notifier + * - overlay changeset entry revert + * + * If an error is returned by an overlay changeset pre-remove notifier + * then no further overlay changeset pre-remove notifier will be called. + * + * If more than one notifier returns an error, then the last notifier + * error to occur is returned. + * + * A non-zero return value will revert the changeset if error is from: + * - overlay changeset entry notifier + * - overlay changeset post-remove notifier + * + * If an error is returned by an overlay changeset post-remove notifier + * then no further overlay changeset post-remove notifier will be called. + * + * Returns 0 on success, or a negative error number. *ovcs_id is set to + * zero after reverting the changeset, even if a subsequent error occurs. + */ +int of_overlay_remove(int *ovcs_id) +{ + struct overlay_changeset *ovcs; + int ret, ret_apply, ret_tmp; + + ret = 0; + + if (devicetree_corrupt()) { + pr_err("suspect devicetree state, refuse to remove overlay\n"); + ret = -EBUSY; + goto out; + } + + mutex_lock(&of_mutex); + + ovcs = idr_find(&ovcs_idr, *ovcs_id); + if (!ovcs) { + ret = -ENODEV; + pr_err("remove: Could not find overlay #%d\n", *ovcs_id); + goto out_unlock; + } + + if (!overlay_removal_is_ok(ovcs)) { + ret = -EBUSY; + goto out_unlock; + } + + ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE); + if (ret) { + pr_err("overlay changeset pre-remove notify error %d\n", ret); + goto out_unlock; + } + + list_del(&ovcs->ovcs_list); + + /* + * Disable phandle cache. Avoids race condition that would arise + * from removing cache entry when the associated node is deleted. + */ + of_free_phandle_cache(); + + ret_apply = 0; + ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply); + + of_populate_phandle_cache(); + + if (ret) { + if (ret_apply) + devicetree_state_flags |= DTSF_REVERT_FAIL; + goto out_unlock; + } + + ret = __of_changeset_revert_notify(&ovcs->cset); + if (ret) + pr_err("overlay changeset entry notify error %d\n", ret); + /* notify failure is not fatal, continue */ + + *ovcs_id = 0; + + ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE); + if (ret_tmp) { + pr_err("overlay changeset post-remove notify error %d\n", + ret_tmp); + if (!ret) + ret = ret_tmp; + } + + free_overlay_changeset(ovcs); + +out_unlock: + mutex_unlock(&of_mutex); + +out: + pr_debug("%s() err=%d\n", __func__, ret); + + return ret; +} +EXPORT_SYMBOL_GPL(of_overlay_remove); + +/** + * of_overlay_remove_all() - Reverts and frees all overlay changesets + * + * Removes all overlays from the system in the correct order. + * + * Returns 0 on success, or a negative error number + */ +int of_overlay_remove_all(void) +{ + struct overlay_changeset *ovcs, *ovcs_n; + int ret; + + /* the tail of list is guaranteed to be safe to remove */ + list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) { + ret = of_overlay_remove(&ovcs->id); + if (ret) + return ret; + } + + return 0; +} +EXPORT_SYMBOL_GPL(of_overlay_remove_all); |