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charset="UTF-8" All structures in include/linux/kho/abi/block.h (struct kho_block_header_ser), include/linux/kho/abi/luo.h (struct luo_ser, struct luo_file_ser, struct luo_file_set_ser, struct luo_session_ser, struct luo_flb_header_ser, struct luo_flb_ser) and include/linux/kho/abi/memfd.h (struct memfd_luo_folio_ser, struct memfd_luo_ser) have naturally aligned fields on 64-bit architectures, with no padding holes between fields or tail padding. Assert both the structure size and 8-byte alignment under CONFIG_64BIT at compile time. Any future unaligned field addition should come with reserved field to keep the structure aligned. Signed-off-by: Tarun Sahu --- include/linux/kho/abi/block.h | 10 +++++++-- include/linux/kho/abi/luo.h | 38 +++++++++++++++++++++++++++++------ include/linux/kho/abi/memfd.h | 16 ++++++++++++--- 3 files changed, 53 insertions(+), 11 deletions(-) diff --git a/include/linux/kho/abi/block.h b/include/linux/kho/abi/block.h index d06d64b963be..36bdbaf9b3b8 100644 --- a/include/linux/kho/abi/block.h +++ b/include/linux/kho/abi/block.h @@ -12,7 +12,7 @@ * pre-update kernel to a post-update kernel. * * This interface is a contract. Any modification to the structure fields, - * compatible strings, or the layout of the `__packed` serialization + * compatible strings, or the layout of the serialization * structures defined here constitutes a breaking change. Such changes require * incrementing the version number in the `KHO_FDT_COMPATIBLE` string to * prevent a new kernel from misinterpreting data from an old kernel. @@ -26,6 +26,8 @@ #define _LINUX_KHO_ABI_BLOCK_H #include +#include +#include #include /** @@ -49,6 +51,10 @@ struct kho_block_header_ser { u64 next; u64 count; -} __packed; +}; + +static_assert(sizeof(struct kho_block_header_ser) == 16); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct kho_block_header_ser) == 8); #endif /* _LINUX_KHO_ABI_BLOCK_H */ diff --git a/include/linux/kho/abi/luo.h b/include/linux/kho/abi/luo.h index 288076de6d4a..721949374fa1 100644 --- a/include/linux/kho/abi/luo.h +++ b/include/linux/kho/abi/luo.h @@ -58,6 +58,8 @@ #define _LINUX_KHO_ABI_LUO_H #include +#include +#include #include #include @@ -82,7 +84,11 @@ struct luo_ser { u64 liveupdate_num; u64 sessions_pa; u64 flbs_pa; -} __packed; +}; + +static_assert(sizeof(struct luo_ser) == 32); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct luo_ser) == 8); #define LIVEUPDATE_HNDL_COMPAT_LENGTH 48 @@ -98,7 +104,11 @@ struct luo_file_ser { char compatible[LIVEUPDATE_HNDL_COMPAT_LENGTH]; u64 data; u64 token; -} __packed; +}; + +static_assert(sizeof(struct luo_file_ser) == 64); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct luo_file_ser) == 8); /** * struct luo_file_set_ser - Represents the serialized metadata for file set @@ -113,7 +123,11 @@ struct luo_file_ser { struct luo_file_set_ser { u64 files; u64 count; -} __packed; +}; + +static_assert(sizeof(struct luo_file_set_ser) == 16); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct luo_file_set_ser) == 8); /** * struct luo_session_ser - Represents the serialized metadata for a LUO session. @@ -131,7 +145,11 @@ struct luo_file_set_ser { struct luo_session_ser { char name[LIVEUPDATE_SESSION_NAME_LENGTH]; struct luo_file_set_ser file_set_ser; -} __packed; +}; + +static_assert(sizeof(struct luo_session_ser) == 80); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct luo_session_ser) == 8); /* The max size is set so it can be reliably used during in serialization */ #define LIVEUPDATE_FLB_COMPAT_LENGTH 48 @@ -152,7 +170,11 @@ struct luo_session_ser { struct luo_flb_header_ser { u64 pgcnt; u64 count; -} __packed; +}; + +static_assert(sizeof(struct luo_flb_header_ser) == 16); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct luo_flb_header_ser) == 8); /** * struct luo_flb_ser - Represents the serialized state of a single FLB object. @@ -175,7 +197,11 @@ struct luo_flb_ser { char name[LIVEUPDATE_FLB_COMPAT_LENGTH]; u64 data; u64 count; -} __packed; +}; + +static_assert(sizeof(struct luo_flb_ser) == 64); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct luo_flb_ser) == 8); /* Kernel Live Update Test ABI */ #ifdef CONFIG_LIVEUPDATE_TEST diff --git a/include/linux/kho/abi/memfd.h b/include/linux/kho/abi/memfd.h index 08b10fea2afc..376a724a1d8c 100644 --- a/include/linux/kho/abi/memfd.h +++ b/include/linux/kho/abi/memfd.h @@ -11,6 +11,8 @@ #ifndef _LINUX_KHO_ABI_MEMFD_H #define _LINUX_KHO_ABI_MEMFD_H +#include +#include #include #include @@ -20,7 +22,7 @@ * memfd uses the ABI defined below for preserving its state across a kexec * reboot using the LUO. * - * The state is serialized into a packed structure `struct memfd_luo_ser` + * The state is serialized into `struct memfd_luo_ser` * which is handed over to the next kernel via the KHO mechanism. * * This interface is a contract. Any modification to the structure layout @@ -54,7 +56,11 @@ struct memfd_luo_folio_ser { u64 pfn:52; u64 flags:12; u64 index; -} __packed; +}; + +static_assert(sizeof(struct memfd_luo_folio_ser) == 16); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct memfd_luo_folio_ser) == 8); /* * The set of seals this version supports preserving. If support for any new @@ -85,7 +91,11 @@ struct memfd_luo_ser { u32 flags; u64 nr_folios; struct kho_vmalloc folios; -} __packed; +}; + +static_assert(sizeof(struct memfd_luo_ser) == 48); +static_assert(!IS_ENABLED(CONFIG_64BIT) || + __alignof__(struct memfd_luo_ser) == 8); /* The compatibility string for memfd file handler */ #define MEMFD_LUO_FH_COMPATIBLE "memfd-v2" -- 2.56.0.506.g506a7eabc5-goog