# Add your code comments below. There is no need to trim or delete # any existing content -- just insert your comments under the relevant # lines of code. Lines starting with "> " are quoted diff context and # lines starting with "| " are comments from other reviewers. # The final email will be reformatted automatically to include only # the sections that have your comments. # > Entirely remove the LUO FDT wrapper since the FDT only carries the > compatible string and the pointer to the centralized struct luo_ser. > Instead, register the struct luo_ser via the KHO raw subtree > API, placing the compatibility string inside the structure itself. > > Signed-off-by: Pasha Tatashin <[email protected]> > > diff --git a/include/linux/kho/abi/luo.h b/include/linux/kho/abi/luo.h > index 1b2f865a771a..9a4fe491812b 100644 > --- a/include/linux/kho/abi/luo.h > +++ b/include/linux/kho/abi/luo.h > @@ -10,11 +10,11 @@ > * > * Live Update Orchestrator uses the stable Application Binary Interface > * defined below to pass state from a pre-update kernel to a post-update > - * kernel. The ABI is built upon the Kexec HandOver framework and uses a > - * Flattened Device Tree to describe the preserved data. > + * kernel. The ABI is built upon the Kexec HandOver framework and registers > + * the central `struct luo_ser` via the KHO raw subtree API. > * > - * This interface is a contract. Any modification to the FDT structure, node > - * properties, compatible strings, or the layout of the `__packed` > serialization > + * This interface is a contract. Any modification to the structure fields, > + * compatible strings, or the layout of the `__packed` serialization > * structures defined here constitutes a breaking change. Such changes > require > * incrementing the version number in the relevant `_COMPATIBLE` string to > * prevent a new kernel from misinterpreting data from an old kernel. > @@ -23,31 +23,15 @@ > * however, backward/forward compatibility is only guaranteed for kernels > * supporting the same ABI version. > * > - * FDT Structure Overview: > + * KHO Structure Overview: > * The entire LUO state is encapsulated within a single KHO entry named > "LUO". > - * This entry contains an FDT with the following layout: > - * > - * .. code-block:: none > - * > - * / { > - * compatible = "luo-v2"; > - * luo-abi-header = <phys_addr_of_luo_ser>; > - * }; > - * > - * Main LUO Node (/): > - * > - * - compatible: "luo-v2" > - * Identifies the overall LUO ABI version. > - * - luo-abi-header: u64 > - * The physical address of `struct luo_ser`. > + * This entry contains the `struct luo_ser` structure. > * > * Serialization Structures: > - * The FDT properties point to memory regions containing arrays of simple, > - * `__packed` structures. These structures contain the actual preserved > state. > - * > * - struct luo_ser: > * The central ABI structure that contains the overall state of the LUO. > - * It includes the liveupdate-number and pointers to sessions and FLBs. > + * It includes the compatibility string, the liveupdate-number, and > pointers > + * to sessions and FLBs. > * > * - struct luo_session_header_ser: > * Header for the session array. Contains the total page count of the > @@ -78,26 +62,27 @@ > #ifndef _LINUX_KHO_ABI_LUO_H > #define _LINUX_KHO_ABI_LUO_H > > +#include <linux/align.h> > #include <uapi/linux/liveupdate.h> > > /* > - * The LUO FDT hooks all LUO state for sessions, fds, etc. > + * The LUO state is registered under this KHO entry name. > */ > -#define LUO_FDT_SIZE PAGE_SIZE > -#define LUO_FDT_KHO_ENTRY_NAME "LUO" > -#define LUO_FDT_COMPATIBLE "luo-v2" > -#define LUO_FDT_ABI_HEADER "luo-abi-header" > +#define LUO_KHO_ENTRY_NAME "LUO" > +#define LUO_ABI_COMPATIBLE "luo-v3" > +#define LUO_ABI_COMPAT_LEN ALIGN(sizeof(LUO_ABI_COMPATIBLE), 8) > > /** > * struct luo_ser - Centralized LUO ABI header. > + * @compatible: Compatibility string identifying the LUO ABI version. > * @liveupdate_num: A counter tracking the number of successful live updates. > * @sessions_pa: Physical address of the first session block header. > * @flbs_pa: Physical address of the FLB header. > * > - * This structure is the root of all preserved LUO state. It is pointed to by > - * the "luo-abi-header" property in the LUO FDT. > + * This structure is the root of all preserved LUO state. > */ > struct luo_ser { > + char compatible[LUO_ABI_COMPAT_LEN]; > u64 liveupdate_num; > u64 sessions_pa; > u64 flbs_pa; > @@ -111,7 +96,7 @@ struct luo_ser { > * @data: Private data > * @token: User provided token for this file > * > - * If this structure is modified, LUO_SESSION_COMPATIBLE must be updated. > + * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated. > */ > struct luo_file_ser { > char compatible[LIVEUPDATE_HNDL_COMPAT_LENGTH]; > @@ -142,7 +127,7 @@ struct luo_file_set_ser { > * physical memory preserved across the kexec. It provides the necessary > * metadata to interpret the array of session entries that follow. > * > - * If this structure is modified, `LUO_FDT_COMPATIBLE` must be updated. > + * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated. > */ > struct luo_session_header_ser { > u64 count; > @@ -159,7 +144,7 @@ struct luo_session_header_ser { > * session) is created and passed to the new kernel, allowing it to > reconstruct > * the session context. > * > - * If this structure is modified, `LUO_FDT_COMPATIBLE` must be updated. > + * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated. > */ > struct luo_session_ser { > char name[LIVEUPDATE_SESSION_NAME_LENGTH]; > @@ -180,7 +165,7 @@ struct luo_session_ser { > * This structure is located at the physical address specified by the > * flbs_pa in luo_ser. > * > - * If this structure is modified, `LUO_FDT_COMPATIBLE` must be updated. > + * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated. > */ > struct luo_flb_header_ser { > u64 pgcnt; > @@ -202,7 +187,7 @@ struct luo_flb_header_ser { > * passed to the new kernel. Each entry allows the LUO core to restore one > * global, shared object. > * > - * If this structure is modified, `LUO_FDT_COMPATIBLE` must be updated. > + * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated. > */ > struct luo_flb_ser { > char name[LIVEUPDATE_FLB_COMPAT_LENGTH]; > diff --git a/kernel/liveupdate/luo_core.c b/kernel/liveupdate/luo_core.c > index fbc18c5f4230..e261a03a1b47 100644 > --- a/kernel/liveupdate/luo_core.c > +++ b/kernel/liveupdate/luo_core.c > @@ -50,7 +50,6 @@ > #include <linux/kexec_handover.h> > #include <linux/kho/abi/luo.h> > #include <linux/kobject.h> > -#include <linux/libfdt.h> > #include <linux/liveupdate.h> > #include <linux/miscdevice.h> > #include <linux/mm.h> > @@ -63,8 +62,7 @@ > > static struct { > bool enabled; > - void *fdt_out; > - void *fdt_in; > + struct luo_ser *luo_ser_out; > u64 liveupdate_num; > } luo_global; > > @@ -81,11 +79,10 @@ early_param("liveupdate", early_liveupdate_param); > > static int __init luo_early_startup(void) > { > + phys_addr_t luo_ser_phys; > struct luo_ser *luo_ser; > - int err, header_size; > - phys_addr_t fdt_phys; > - const void *ptr; > - u64 luo_ser_pa; > + size_t len; > + int err; > > if (!kho_is_enabled()) { > if (liveupdate_enabled()) > @@ -94,40 +91,29 @@ static int __init luo_early_startup(void) > return 0; > } > > - /* Retrieve LUO subtree, and verify its format. */ > - err = kho_retrieve_subtree(LUO_FDT_KHO_ENTRY_NAME, &fdt_phys, NULL); > + /* Retrieve LUO state from KHO. */ > + err = kho_retrieve_subtree(LUO_KHO_ENTRY_NAME, &luo_ser_phys, &len); > if (err) { > if (err != -ENOENT) { > - pr_err("failed to retrieve FDT '%s' from KHO: %pe\n", > - LUO_FDT_KHO_ENTRY_NAME, ERR_PTR(err)); > + pr_err("failed to retrieve LUO state '%s' from KHO: > %pe\n", > + LUO_KHO_ENTRY_NAME, ERR_PTR(err)); > return err; > } > > return 0; > } > > - luo_global.fdt_in = phys_to_virt(fdt_phys); > - err = fdt_node_check_compatible(luo_global.fdt_in, 0, > - LUO_FDT_COMPATIBLE); > - if (err) { > - pr_err("FDT '%s' is incompatible with '%s' [%d]\n", > - LUO_FDT_KHO_ENTRY_NAME, LUO_FDT_COMPATIBLE, err); > - > + if (len < sizeof(*luo_ser)) { > + pr_err("LUO state is too small (%zu < %zu)\n", len, > sizeof(*luo_ser)); > return -EINVAL; > } > > - header_size = 0; > - ptr = fdt_getprop(luo_global.fdt_in, 0, LUO_FDT_ABI_HEADER, > &header_size); > - if (!ptr || header_size != sizeof(u64)) { > - pr_err("Unable to get ABI header '%s' [%d]\n", > - LUO_FDT_ABI_HEADER, header_size); > - > + luo_ser = phys_to_virt(luo_ser_phys); > + if (strncmp(luo_ser->compatible, LUO_ABI_COMPATIBLE, > LUO_ABI_COMPAT_LEN)) { > + pr_err("LUO state is incompatible with '%s'\n", > LUO_ABI_COMPATIBLE); > return -EINVAL; > } > > - luo_ser_pa = get_unaligned((u64 *)ptr); > - luo_ser = phys_to_virt(luo_ser_pa); > - > luo_global.liveupdate_num = luo_ser->liveupdate_num; > pr_info("Retrieved live update data, liveupdate number: %lld\n", > luo_global.liveupdate_num); > @@ -160,37 +146,20 @@ static int __init liveupdate_early_init(void) > } > early_initcall(liveupdate_early_init); > > -/* Called during boot to create outgoing LUO fdt tree */ > -static int __init luo_fdt_setup(void) > +/* Called during boot to create outgoing LUO state */ > +static int __init luo_state_setup(void) > { > struct luo_ser *luo_ser; > - u64 luo_ser_pa; > - void *fdt_out; > int err; > > - fdt_out = kho_alloc_preserve(LUO_FDT_SIZE); > - if (IS_ERR(fdt_out)) { > - pr_err("failed to allocate/preserve FDT memory\n"); > - return PTR_ERR(fdt_out); > - } > - > luo_ser = kho_alloc_preserve(sizeof(*luo_ser)); > if (IS_ERR(luo_ser)) { > - err = PTR_ERR(luo_ser); > - goto exit_free_fdt; > + pr_err("failed to allocate/preserve LUO state memory\n"); > + return PTR_ERR(luo_ser); > } > - luo_ser_pa = virt_to_phys(luo_ser); > - > - err = fdt_create(fdt_out, LUO_FDT_SIZE); > - err |= fdt_finish_reservemap(fdt_out); > - err |= fdt_begin_node(fdt_out, ""); > - err |= fdt_property_string(fdt_out, "compatible", LUO_FDT_COMPATIBLE); > - err |= fdt_property(fdt_out, LUO_FDT_ABI_HEADER, &luo_ser_pa, > - sizeof(luo_ser_pa)); > - err |= fdt_end_node(fdt_out); > - err |= fdt_finish(fdt_out); > - if (err) > - goto exit_free_luo_ser; > + > + strscpy(luo_ser->compatible, LUO_ABI_COMPATIBLE, > sizeof(luo_ser->compatible)); > + luo_ser->liveupdate_num = luo_global.liveupdate_num + 1; > > err = luo_session_setup_outgoing(&luo_ser->sessions_pa); > if (err) > @@ -200,21 +169,17 @@ static int __init luo_fdt_setup(void) > if (err) > goto exit_free_luo_ser; > > - luo_ser->liveupdate_num = luo_global.liveupdate_num + 1; > - > - err = kho_add_subtree(LUO_FDT_KHO_ENTRY_NAME, fdt_out, > - fdt_totalsize(fdt_out)); > + err = kho_add_subtree(LUO_KHO_ENTRY_NAME, luo_ser, sizeof(*luo_ser)); > if (err) > goto exit_free_luo_ser; > - luo_global.fdt_out = fdt_out; > + > + luo_global.luo_ser_out = luo_ser; > > return 0; > > exit_free_luo_ser: > kho_unpreserve_free(luo_ser); > -exit_free_fdt: > - kho_unpreserve_free(fdt_out); > - pr_err("failed to prepare LUO FDT: %d\n", err); > + pr_err("failed to prepare LUO state: %d\n", err); > > return err; > } > @@ -230,7 +195,7 @@ static int __init luo_late_startup(void) > if (!liveupdate_enabled()) > return 0; > > - err = luo_fdt_setup(); > + err = luo_state_setup(); > if (err) > luo_global.enabled = false; >
-- Sincerely yours, Mike.
