// SPDX-License-Identifier: GPL-2.0
/*
* Functions for working with device tree overlays
*
* Copyright (C) 2012 Pantelis Antoniou <[email protected]>
* 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
* @overlay: pointer to the __overlay__ node
* @target: target of the overlay operation
*/
struct fragment {
struct device_node *overlay;
struct device_node *target;
};
/**
* struct overlay_changeset
* @id: changeset identifier
* @ovcs_list: list on which we are located
* @new_fdt: Memory allocated to hold unflattened aligned FDT
* @overlay_mem: the memory chunk that contains @overlay_root
* @overlay_root: expanded device tree that contains the fragment nodes
* @notify_state: most recent notify action used on overlay
* @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 *new_fdt;
const void *overlay_mem;
struct device_node *overlay_root;
enum of_overlay_notify_action notify_state;
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_unregister() - 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 int overlay_notify(struct overlay_changeset *ovcs,
enum of_overlay_notify_action action)
{
struct of_overlay_notify_data nd;
int i, ret;
ovcs->notify_state = action;
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_root. 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_root, 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:
__of_prop_free(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.
*
* Return: 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)
__of_prop_free(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.
*
* Return: 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);
if (!tchild->name)
tchild->name = "<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.
*
* Return: 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 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_scoped(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);
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 symbols prop @%pOF/%s, err=%d\n",
target->np, prop->name, ret);
return ret;
}
}
return 0;
}
static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
struct of_changeset_entry *ce_1)
{
struct of_changeset_entry *ce_2;
char *fn_1, *fn_2;
int node_path_match;
if (ce_1->action != OF_RECONFIG_ATTACH_NODE &&
ce_1->action != OF_RECONFIG_DETACH_NODE)
return 0;
ce_2 = ce_1;
list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
if ((ce_2->action != OF_RECONFIG_ATTACH_NODE &&
ce_2->action != OF_RECONFIG_DETACH_NODE) ||
of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
continue;
fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
node_path_match = !fn_1 || !fn_2 || !strcmp(fn_1, fn_2);
kfree(fn_1);
kfree(fn_2);
if (node_path_match) {
pr_err("ERROR: multiple fragments add and/or delete node %pOF\n",
ce_1->np);
return -EINVAL;
}
}
return 0;
}
static int find_dup_cset_prop(struct overlay_changeset *ovcs,
struct of_changeset_entry *ce_1)
{
struct of_changeset_entry *ce_2;
char *fn_1, *fn_2;
int node_path_match;
if (ce_1->action != OF_RECONFIG_ADD_PROPERTY &&
ce_1->action != OF_RECONFIG_REMOVE_PROPERTY &&
ce_1->action != OF_RECONFIG_UPDATE_PROPERTY)
return 0;
ce_2 = ce_1;
list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
if ((ce_2->action != OF_RECONFIG_ADD_PROPERTY &&
ce_2->action != OF_RECONFIG_REMOVE_PROPERTY &&
ce_2->action != OF_RECONFIG_UPDATE_PROPERTY) ||
of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
continue;
fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
node_path_match = !fn_1 || !fn_2 || !strcmp(fn_1, fn_2);
kfree(fn_1);
kfree(fn_2);
if (node_path_match &&
!of_prop_cmp(ce_1->prop->name, ce_2->prop->name)) {
pr_err("ERROR: multiple fragments add, update, and/or delete property %pOF/%s\n",
ce_1->np, ce_1->prop->name);
return -EINVAL;
}
}
return 0;
}
/**
* changeset_dup_entry_check() - check for duplicate entries
* @ovcs: Overlay changeset
*
* Check changeset @ovcs->cset for multiple {add or delete} node entries for
* the same node or duplicate {add, delete, or update} properties entries
* for the same property.
*
* Return: 0 on success, or -EINVAL if duplicate changeset entry found.
*/
static int changeset_dup_entry_check(struct overlay_changeset *ovcs)
{
struct of_changeset_entry *ce_1;
int dup_entry = 0;
list_for_each_entry(ce_1, &ovcs->cset.entries, node) {
dup_entry |= find_dup_cset_node_entry(ovcs, ce_1);
dup_entry |= find_dup_cset_prop(ovcs, ce_1);
}
return dup_entry ? -EINVAL : 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.
*
* Return: 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("fragment 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("symbols fragment apply failed '%pOF'\n",
fragment->target);
return ret;
}
}
return changeset_dup_entry_check(ovcs);
}
/*
* 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 *target_base)
{
struct device_node *node;
char *target_path;
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) {
if (target_base) {
target_path = kasprintf(GFP_KERNEL, "%pOF%s", target_base, path);
if (!target_path)
return NULL;
node = of_find_node_by_path(target_path);
if (!node) {
pr_err("find target, node: %pOF, path '%s' not found\n",
info_node, target_path);
}
kfree(target_path);
} else {
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
* @target_base: Point to the target node to apply overlay
*
* Initialize @ovcs. Populate @ovcs->fragments with node information from
* the top level of @overlay_root. The relevant top level nodes are the
* fragment nodes and the __symbols__ node. Any other top level node will
* be ignored. Populate other @ovcs fields.
*
* Return: 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
* detected in @overlay_root. On error return, the caller of
* init_overlay_changeset() must call free_overlay_changeset().
*/
static int init_overlay_changeset(struct overlay_changeset *ovcs,
struct device_node *target_base)
{
struct device_node *node, *overlay_node;
struct fragment *fragment;
struct fragment *fragments;
int cnt, ret;
/*
* None of the resources allocated by this function will be freed in
* the error paths. Instead the caller of this function is required
* to call free_overlay_changeset() (which will free the resources)
* if error return.
*/
/*
* 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(ovcs->overlay_root, OF_DYNAMIC))
pr_debug("%s() ovcs->overlay_root is not dynamic\n", __func__);
if (!of_node_check_flag(ovcs->overlay_root, OF_DETACHED))
pr_debug("%s() ovcs->overlay_root is not detached\n", __func__);
if (!of_node_is_root(ovcs->overlay_root))
pr_debug("%s() ovcs->overlay_root is not root\n", __func__);
cnt = 0;
/* fragment nodes */
for_each_child_of_node(ovcs->overlay_root, 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(ovcs->overlay_root, "__symbols__");
if (node) {
cnt++;
of_node_put(node);
}
fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
if (!fragments) {
ret = -ENOMEM;
goto err_out;
}
ovcs->fragments = fragments;
cnt = 0;
for_each_child_of_node(ovcs->overlay_root, 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, target_base);
if (!fragment->target) {
of_node_put(fragment->overlay);
ret = -EINVAL;
of_node_put(node);
goto err_out;
}
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(ovcs->overlay_root, "__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;
of_node_put(node);
goto err_out;
}
cnt++;
}
if (!cnt) {
pr_err("no fragments or symbols in overlay\n");
ret = -EINVAL;
goto err_out;
}
ovcs->count = cnt;
return 0;
err_out:
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);
list_del(&ovcs->ovcs_list);
ovcs->id = 0;
}
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_mem and
* ovcs->new_fdt due to the policy that overlay notifiers are not
* allowed to retain pointers into the overlay devicetree other
* than during the window from OF_OVERLAY_PRE_APPLY overlay
* notifiers until the OF_OVERLAY_POST_REMOVE overlay notifiers.
*
* A memory leak will occur here if within the window.
*/
if (ovcs->notify_state == OF_OVERLAY_INIT ||
ovcs->notify_state == OF_OVERLAY_POST_REMOVE) {
kfree(ovcs->overlay_mem);
kfree(ovcs->new_fdt);
}
kfree(ovcs);
}
/*
* internal documentation
*
* of_overlay_apply() - Create and apply an overlay changeset
* @ovcs: overlay changeset
* @base: point to the target node to apply overlay
*
* Creates and applies an overlay changeset.
*
* If an error is returned by an overlay changeset pre-apply notifier
* then no further overlay changeset pre-apply notifier will be called.
*
* 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. On error return,
* the caller of of_overlay_apply() must call free_overlay_changeset().
*/
static int of_overlay_apply(struct overlay_changeset *ovcs,
struct device_node *base)
{
int ret = 0, ret_revert, ret_tmp;
ret = of_resolve_phandles(ovcs->overlay_root);
if (ret)
goto out;
ret = init_overlay_changeset(ovcs, base);
if (ret)
goto out;
ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
if (ret)
goto out;
ret = build_changeset(ovcs);
if (ret)
goto out;
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 out;
}
ret = __of_changeset_apply_notify(&ovcs->cset);
if (ret)
pr_err("overlay apply changeset entry notify error %d\n", ret);
/* notify failure is not fatal, continue */
ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
if (ret_tmp)
if (!ret)
ret = ret_tmp;
out:
pr_debug("%s() err=%d\n", __func__, ret);
return ret;
}
/**
* of_overlay_fdt_apply() - Create and apply an overlay changeset
* @overlay_fdt: pointer to overlay FDT
* @overlay_fdt_size: number of bytes in @overlay_fdt
* @ret_ovcs_id: pointer for returning created changeset id
* @base: pointer for the target node to apply overlay
*
* Creates and applies an overlay changeset.
*
* See of_overlay_apply() for important behavior information.
*
* Return: 0 on success, or a negative error number. *@ret_ovcs_id is set to
* the value of overlay changeset id, which can be passed to of_overlay_remove()
* to remove the overlay.
*
* On error return, the changeset may be partially applied. This is especially
* likely if an OF_OVERLAY_POST_APPLY notifier returns an error. In this case
* the caller should call of_overlay_remove() with the value in *@ret_ovcs_id.
*/
int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
int *ret_ovcs_id, struct device_node *base)
{
void *new_fdt;
void *new_fdt_align;
void *overlay_mem;
int ret;
u32 size;
struct overlay_changeset *ovcs;
*ret_ovcs_id = 0;
if (devicetree_corrupt()) {
pr_err("devicetree state suspect, refuse to apply overlay\n");
return -EBUSY;
}
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;
ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
if (!ovcs)
return -ENOMEM;
of_overlay_mutex_lock();
mutex_lock(&of_mutex);
/*
* ovcs->notify_state must be set to OF_OVERLAY_INIT before allocating
* ovcs resources, implicitly set by kzalloc() of ovcs
*/
ovcs->id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
if (ovcs->id <= 0) {
ret = ovcs->id;
goto err_free_ovcs;
}
INIT_LIST_HEAD(&ovcs->ovcs_list);
list_add_tail(&ovcs->ovcs_list, &ovcs_list);
of_changeset_init(&ovcs->cset);
/*
* 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 = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL);
if (!new_fdt) {
ret = -ENOMEM;
goto err_free_ovcs;
}
ovcs->new_fdt = new_fdt;
new_fdt_align = PTR_ALIGN(new_fdt, FDT_ALIGN_SIZE);
memcpy(new_fdt_align, overlay_fdt, size);
overlay_mem = of_fdt_unflatten_tree(new_fdt_align, NULL,
&ovcs->overlay_root);
if (!overlay_mem) {
pr_err("unable to unflatten overlay_fdt\n");
ret = -EINVAL;
goto err_free_ovcs;
}
ovcs->overlay_mem = overlay_mem;
ret = of_overlay_apply(ovcs, base);
/*
* If of_overlay_apply() error, calling free_overlay_changeset() may
* result in a memory leak if the apply partly succeeded, so do NOT
* goto err_free_ovcs. Instead, the caller of of_overlay_fdt_apply()
* can call of_overlay_remove();
*/
*ret_ovcs_id = ovcs->id;
goto out_unlock;
err_free_ovcs:
free_overlay_changeset(ovcs);
out_unlock:
mutex_unlock(&of_mutex);
of_overlay_mutex_unlock();
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)
{
if (tree == np)
return 1;
for_each_child_of_node_scoped(tree, child) {
if (find_node(child, np))
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 permitted.
*/
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.
*
* Return: 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;
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 err_unlock;
}
if (!overlay_removal_is_ok(ovcs)) {
ret = -EBUSY;
goto err_unlock;
}
ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
if (ret)
goto err_unlock;
ret_apply = 0;
ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
if (ret) {
if (ret_apply)
devicetree_state_flags |= DTSF_REVERT_FAIL;
goto err_unlock;
}
ret = __of_changeset_revert_notify(&ovcs->cset);
if (ret)
pr_err("overlay remove changeset entry notify error %d\n", ret);
/* notify failure is not fatal, continue */
*ovcs_id = 0;
/*
* Note that the overlay memory will be kfree()ed by
* free_overlay_changeset() even if the notifier for
* OF_OVERLAY_POST_REMOVE returns an error.
*/
ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
if (ret_tmp)
if (!ret)
ret = ret_tmp;
free_overlay_changeset(ovcs);
err_unlock:
/*
* If jumped over free_overlay_changeset(), then did not kfree()
* overlay related memory. This is a memory leak unless a subsequent
* of_overlay_remove() of this overlay is successful.
*/
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.
*
* Return: 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);
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