Commit efa3a977 authored by Pasha Tatashin's avatar Pasha Tatashin Committed by Andrew Morton
Browse files

kho: remove global preserved_mem_map and store state in FDT 

Currently, the serialized memory map is tracked via
kho_out.preserved_mem_map and copied to the FDT during finalization.  This
double tracking is redundant.

Remove preserved_mem_map from kho_out.  Instead, maintain the physical
address of the head chunk directly in the preserved-memory-map FDT
property.

Introduce kho_update_memory_map() to manage this property. This function
handles:
1. Retrieving and freeing any existing serialized map (handling the
   abort/retry case).
2. Updating the FDT property with the new chunk address.

This establishes the FDT as the single source of truth for the handover
state.

Link: https://lkml.kernel.org/r/20251114190002.3311679-9-pasha.tatashin@soleen.com


Signed-off-by: default avatarPasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: default avatarMike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: default avatarPratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 71960fe1

kernel/liveupdate/kexec_handover.c

+26 −17
Original line number Diff line number Diff line
@@ -119,9 +119,6 @@ struct kho_out { 
	struct mutex fdts_lock;



	struct kho_mem_track track;

	/* First chunk of serialized preserved memory map */

	struct khoser_mem_chunk *preserved_mem_map;



	struct kho_debugfs dbg;

};
@@ -382,6 +379,27 @@ static void kho_mem_ser_free(struct khoser_mem_chunk *first_chunk) 
	}

}



/*

 *  Update memory map property, if old one is found discard it via

 *  kho_mem_ser_free().

 */

static void kho_update_memory_map(struct khoser_mem_chunk *first_chunk)

{

	void *ptr;

	u64 phys;



	ptr = fdt_getprop_w(kho_out.fdt, 0, PROP_PRESERVED_MEMORY_MAP, NULL);



	/* Check and discard previous memory map */

	phys = get_unaligned((u64 *)ptr);

	if (phys)

		kho_mem_ser_free((struct khoser_mem_chunk *)phys_to_virt(phys));



	/* Update with the new value */

	phys = first_chunk ? (u64)virt_to_phys(first_chunk) : 0;

	put_unaligned(phys, (u64 *)ptr);

}



static int kho_mem_serialize(struct kho_out *kho_out)

{

	struct khoser_mem_chunk *first_chunk = NULL;
@@ -422,7 +440,7 @@ static int kho_mem_serialize(struct kho_out *kho_out) 
		}

	}



	kho_out->preserved_mem_map = first_chunk;

	kho_update_memory_map(first_chunk);



	return 0;
@@ -1223,8 +1241,7 @@ int kho_abort(void) 
	if (!kho_out.finalized)

		return -ENOENT;



	kho_mem_ser_free(kho_out.preserved_mem_map);

	kho_out.preserved_mem_map = NULL;

	kho_update_memory_map(NULL);

	kho_out.finalized = false;



	return 0;
@@ -1234,21 +1251,15 @@ static int __kho_finalize(void) 
{

	void *root = kho_out.fdt;

	struct kho_sub_fdt *fdt;

	u64 *preserved_mem_map;

	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);

	/**

	 * Reserve the preserved-memory-map property in the root FDT, so

	 * that all property definitions will precede subnodes created by

	 * KHO callers.

	 */

	err |= fdt_property_placeholder(root, PROP_PRESERVED_MEMORY_MAP,

					sizeof(*preserved_mem_map),

					(void **)&preserved_mem_map);

	err |= fdt_property(root, PROP_PRESERVED_MEMORY_MAP, &empty_mem_map,

			    sizeof(empty_mem_map));

	if (err)

		goto err_exit;
@@ -1271,8 +1282,6 @@ static int __kho_finalize(void) 
	if (err)

		goto err_exit;



	*preserved_mem_map = (u64)virt_to_phys(kho_out.preserved_mem_map);



	return 0;



err_exit: