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AL+hErGZvB6JmIAHs3fkUpOFvCBYrma5mj06jskIzu1gEbjTuwd/QKqr2bxJo6OV2JZfJ9JURuzr0Fi4WXk8Cqj7SyeZ@lists.infradead.org X-Gm-Message-State: APuU4Z/ZEdbI1CQ4FbrZjxvnZ5s2Zbw9PCuWt2lws7jzGNZLaVW9LKGy EGvTr3oPNpzQ5LXi36U4VzXeLf6f68lMUbbTqowhvKYJLDV0x7Wedvrlp8US0VvhQCVBaAxqZAL siMtIc89b1fSCTw/lqA== X-Received: from ejcuu11-n1.prod.google.com ([2002:a17:907:c60b:10b0:c3f:fb8f:67f3]) (user=tarunsahu job=prod-delivery.src-stubby-dispatcher) by 2002:a17:907:9694:b0:c31:fb29:a137 with SMTP id a640c23a62f3a-c5049525569mr113201966b.21.1794286926296; Mon, 09 Nov 2026 21:02:06 -0800 (PST) Date: Tue, 10 Nov 2026 05:01:44 +0000 In-Reply-To: <20261110050202.529473-1-tarunsahu@google.com> X-Archived-By: Mime-Version: 1.0 References: <20261110050202.529473-1-tarunsahu@google.com> X-Mailer: git-send-email 2.56.0.506.g506a7eabc5-goog Message-ID: <20261110050202.529473-2-tarunsahu@google.com> Subject: [PATCH v4 01/19] liveupdate, kho: Remove __packed from KHO, LUO and memfd ABI structures From: Tarun Sahu To: Pasha Tatashin , Mike Rapoport , robin.murphy@arm.com, maz@kernel.org, will@kernel.org, David Matlack , Alexander Graf , seanjc@google.com, jgg@nvidia.com, loganodell@google.com, arnd@arndb.de, dwmw2@infradead.org, baolu.lu@linux.intel.com, Bjorn Helgaas , oupton@kernel.org, alex@shazbot.org, gle.com@google.com, pbonzini@redhat.com, Andrew Morton , kevin.tian@intel.com, joro@8bytes.org Cc: kvmarm@lists.linux.dev, linux-pci@vger.kernel.org, Pratyush Yadav , kexec@lists.infradead.org, kvm@vger.kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, skhawaja@google.com, sagis@google.com, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Tarun Sahu Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261109_210208_891180_2A87A94D X-CRM114-Status: GOOD ( 18.62 ) X-Spam-Score: -9.5 (---------) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-26.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIMWL_WL_MED,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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