mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-05-09 21:42:09 +02:00
Jason Miu
ac2d8102c4
The `struct kho_vmalloc` defines the in-memory layout for preserving vmalloc regions across kexec. This layout is a contract between kernels and part of the KHO ABI. To reflect this relationship, the related structs and helper macros are relocated to the ABI header, `include/linux/kho/abi/kexec_handover.h`. This move places the structure's definition under the protection of the KHO_FDT_COMPATIBLE version string. The structure and its components are now also documented within the ABI header to describe the contract and prevent ABI breaks. [rppt@kernel.org: update comment, per Pratyush] Link: https://lkml.kernel.org/r/aW_Mqp6HcqLwQImS@kernel.org Link: https://lkml.kernel.org/r/20260105165839.285270-6-rppt@kernel.org Signed-off-by: Jason Miu <jasonmiu@google.com> Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pratyush Yadav <pratyush@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
78 lines
2.2 KiB
C
78 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (c) 2025, Google LLC.
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* Pasha Tatashin <pasha.tatashin@soleen.com>
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*
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* Copyright (C) 2025 Amazon.com Inc. or its affiliates.
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* Pratyush Yadav <ptyadav@amazon.de>
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*/
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#ifndef _LINUX_KHO_ABI_MEMFD_H
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#define _LINUX_KHO_ABI_MEMFD_H
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#include <linux/types.h>
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#include <linux/kho/abi/kexec_handover.h>
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/**
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* DOC: memfd Live Update ABI
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*
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* memfd uses the ABI defined below for preserving its state across a kexec
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* reboot using the LUO.
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*
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* The state is serialized into a packed structure `struct memfd_luo_ser`
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* which is handed over to the next kernel via the KHO mechanism.
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*
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* This interface is a contract. Any modification to the structure layout
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* constitutes a breaking change. Such changes require incrementing the
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* version number in the MEMFD_LUO_FH_COMPATIBLE string.
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*/
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/**
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* MEMFD_LUO_FOLIO_DIRTY - The folio is dirty.
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*
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* This flag indicates the folio contains data from user. A non-dirty folio is
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* one that was allocated (say using fallocate(2)) but not written to.
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*/
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#define MEMFD_LUO_FOLIO_DIRTY BIT(0)
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/**
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* MEMFD_LUO_FOLIO_UPTODATE - The folio is up-to-date.
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*
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* An up-to-date folio has been zeroed out. shmem zeroes out folios on first
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* use. This flag tracks which folios need zeroing.
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*/
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#define MEMFD_LUO_FOLIO_UPTODATE BIT(1)
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/**
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* struct memfd_luo_folio_ser - Serialized state of a single folio.
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* @pfn: The page frame number of the folio.
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* @flags: Flags to describe the state of the folio.
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* @index: The page offset (pgoff_t) of the folio within the original file.
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*/
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struct memfd_luo_folio_ser {
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u64 pfn:52;
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u64 flags:12;
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u64 index;
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} __packed;
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/**
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* struct memfd_luo_ser - Main serialization structure for a memfd.
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* @pos: The file's current position (f_pos).
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* @size: The total size of the file in bytes (i_size).
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* @nr_folios: Number of folios in the folios array.
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* @folios: KHO vmalloc descriptor pointing to the array of
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* struct memfd_luo_folio_ser.
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*/
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struct memfd_luo_ser {
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u64 pos;
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u64 size;
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u64 nr_folios;
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struct kho_vmalloc folios;
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} __packed;
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/* The compatibility string for memfd file handler */
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#define MEMFD_LUO_FH_COMPATIBLE "memfd-v1"
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#endif /* _LINUX_KHO_ABI_MEMFD_H */
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