| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20251114155358.2884014-10-pasha.tatashin@soleen.com>
Date: Fri, 14 Nov 2025 10:53:54 -0500
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: akpm@...ux-foundation.org,
bhe@...hat.com,
pasha.tatashin@...een.com,
rppt@...nel.org,
jasonmiu@...gle.com,
arnd@...db.de,
coxu@...hat.com,
dave@...ilevsky.ca,
ebiggers@...gle.com,
graf@...zon.com,
kees@...nel.org,
linux-kernel@...r.kernel.org,
kexec@...ts.infradead.org,
linux-mm@...ck.org
Subject: [PATCH v1 09/13] kho: Update FDT dynamically for subtree addition/removal
Currently, sub-FDTs were tracked in a list (kho_out.sub_fdts) and the
final FDT is constructed entirely from scratch during kho_finalize().
We can maintain the FDT dynamically:
1. Initialize a valid, empty FDT in kho_init().
2. Use fdt_add_subnode and fdt_setprop in kho_add_subtree to
update the FDT immediately when a subsystem registers.
3. Use fdt_del_node in kho_remove_subtree to remove entries.
This removes the need for the intermediate sub_fdts list and the
reconstruction logic in kho_finalize(). kho_finalize() now
only needs to trigger memory map serialization.
Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
---
kernel/liveupdate/kexec_handover.c | 144 ++++++++++++++---------------
1 file changed, 68 insertions(+), 76 deletions(-)
diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
index 8ab77cb85ca9..822da961d4c9 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -102,20 +102,11 @@ struct kho_mem_track {
struct khoser_mem_chunk;
-struct kho_sub_fdt {
- struct list_head l;
- const char *name;
- void *fdt;
-};
-
struct kho_out {
void *fdt;
bool finalized;
struct mutex lock; /* protects KHO FDT finalization */
- struct list_head sub_fdts;
- struct mutex fdts_lock;
-
struct kho_mem_track track;
struct kho_debugfs dbg;
};
@@ -125,8 +116,6 @@ static struct kho_out kho_out = {
.track = {
.orders = XARRAY_INIT(kho_out.track.orders, 0),
},
- .sub_fdts = LIST_HEAD_INIT(kho_out.sub_fdts),
- .fdts_lock = __MUTEX_INITIALIZER(kho_out.fdts_lock),
.finalized = false,
};
@@ -724,37 +713,67 @@ static void __init kho_reserve_scratch(void)
*/
int kho_add_subtree(const char *name, void *fdt)
{
- struct kho_sub_fdt *sub_fdt;
+ phys_addr_t phys = virt_to_phys(fdt);
+ void *root_fdt = kho_out.fdt;
+ int err = -ENOMEM;
+ int off, fdt_err;
- sub_fdt = kmalloc(sizeof(*sub_fdt), GFP_KERNEL);
- if (!sub_fdt)
- return -ENOMEM;
+ guard(mutex)(&kho_out.lock);
+
+ fdt_err = fdt_open_into(root_fdt, root_fdt, PAGE_SIZE);
+ if (fdt_err < 0)
+ return err;
- INIT_LIST_HEAD(&sub_fdt->l);
- sub_fdt->name = name;
- sub_fdt->fdt = fdt;
+ off = fdt_add_subnode(root_fdt, 0, name);
+ if (off < 0) {
+ if (off == -FDT_ERR_EXISTS)
+ err = -EEXIST;
+ goto out_pack;
+ }
+
+ err = fdt_setprop(root_fdt, off, PROP_SUB_FDT, &phys, sizeof(phys));
+ if (err < 0)
+ goto out_pack;
- guard(mutex)(&kho_out.fdts_lock);
- list_add_tail(&sub_fdt->l, &kho_out.sub_fdts);
WARN_ON_ONCE(kho_debugfs_fdt_add(&kho_out.dbg, name, fdt, false));
- return 0;
+out_pack:
+ fdt_pack(root_fdt);
+
+ return err;
}
EXPORT_SYMBOL_GPL(kho_add_subtree);
void kho_remove_subtree(void *fdt)
{
- struct kho_sub_fdt *sub_fdt;
+ phys_addr_t target_phys = virt_to_phys(fdt);
+ void *root_fdt = kho_out.fdt;
+ int off;
+ int err;
+
+ guard(mutex)(&kho_out.lock);
- guard(mutex)(&kho_out.fdts_lock);
- list_for_each_entry(sub_fdt, &kho_out.sub_fdts, l) {
- if (sub_fdt->fdt == fdt) {
- list_del(&sub_fdt->l);
- kfree(sub_fdt);
+ err = fdt_open_into(root_fdt, root_fdt, PAGE_SIZE);
+ if (err < 0)
+ return;
+
+ for (off = fdt_first_subnode(root_fdt, 0); off >= 0;
+ off = fdt_next_subnode(root_fdt, off)) {
+ const u64 *val;
+ int len;
+
+ val = fdt_getprop(root_fdt, off, PROP_SUB_FDT, &len);
+ if (!val || len != sizeof(phys_addr_t))
+ continue;
+
+ if ((phys_addr_t)*val == target_phys) {
+ fdt_del_node(root_fdt, off);
kho_debugfs_fdt_remove(&kho_out.dbg, fdt);
break;
}
}
+
+ fdt_pack(root_fdt);
}
EXPORT_SYMBOL_GPL(kho_remove_subtree);
@@ -1145,48 +1164,6 @@ void *kho_restore_vmalloc(const struct kho_vmalloc *preservation)
}
EXPORT_SYMBOL_GPL(kho_restore_vmalloc);
-static int __kho_finalize(void)
-{
- void *root = kho_out.fdt;
- struct kho_sub_fdt *fdt;
- u64 empty_mem_map = 0;
- int err;
-
- err = fdt_create(root, PAGE_SIZE);
- err |= fdt_finish_reservemap(root);
- err |= fdt_begin_node(root, "");
- err |= fdt_property_string(root, "compatible", KHO_FDT_COMPATIBLE);
- err |= fdt_property(root, PROP_PRESERVED_MEMORY_MAP, &empty_mem_map,
- sizeof(empty_mem_map));
- if (err)
- goto err_exit;
-
- mutex_lock(&kho_out.fdts_lock);
- list_for_each_entry(fdt, &kho_out.sub_fdts, l) {
- phys_addr_t phys = virt_to_phys(fdt->fdt);
-
- err |= fdt_begin_node(root, fdt->name);
- err |= fdt_property(root, PROP_SUB_FDT, &phys, sizeof(phys));
- err |= fdt_end_node(root);
- }
- mutex_unlock(&kho_out.fdts_lock);
-
- err |= fdt_end_node(root);
- err |= fdt_finish(root);
- if (err)
- goto err_exit;
-
- err = kho_mem_serialize(&kho_out);
- if (err)
- goto err_exit;
-
- return 0;
-
-err_exit:
- pr_err("Failed to convert KHO state tree: %d\n", err);
- return err;
-}
-
int kho_finalize(void)
{
int ret;
@@ -1195,12 +1172,7 @@ int kho_finalize(void)
return -EOPNOTSUPP;
guard(mutex)(&kho_out.lock);
- if (kho_out.finalized) {
- kho_update_memory_map(NULL);
- kho_out.finalized = false;
- }
-
- ret = __kho_finalize();
+ ret = kho_mem_serialize(&kho_out);
if (ret)
return ret;
@@ -1285,6 +1257,26 @@ int kho_retrieve_subtree(const char *name, phys_addr_t *phys)
}
EXPORT_SYMBOL_GPL(kho_retrieve_subtree);
+static __init int kho_out_fdt_setup(void)
+{
+ void *root = kho_out.fdt;
+ u64 empty_mem_map = 0;
+ int err;
+
+ err = fdt_create(root, PAGE_SIZE);
+ err |= fdt_finish_reservemap(root);
+ err |= fdt_begin_node(root, "");
+ err |= fdt_property_string(root, "compatible", KHO_FDT_COMPATIBLE);
+ err |= fdt_property(root, PROP_PRESERVED_MEMORY_MAP, &empty_mem_map,
+ sizeof(empty_mem_map));
+ err |= fdt_end_node(root);
+ err |= fdt_finish(root);
+ if (err)
+ return err;
+
+ return kho_preserve_folio(virt_to_folio(kho_out.fdt));
+}
+
static __init int kho_init(void)
{
int err = 0;
@@ -1309,7 +1301,7 @@ static __init int kho_init(void)
if (err)
goto err_free_fdt;
- err = kho_preserve_folio(virt_to_folio(kho_out.fdt));
+ err = kho_out_fdt_setup();
if (err)
goto err_free_fdt;
--
2.52.0.rc1.455.g30608eb744-goog
Powered by blists - more mailing lists