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{ "id": 2229027, "url": "http://patchwork.ozlabs.org/api/1.1/covers/2229027/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/cover/cover.1777306795.git.chleroy@kernel.org/", "project": { "id": 2, "url": "http://patchwork.ozlabs.org/api/1.1/projects/2/?format=api", "name": "Linux PPC development", "link_name": "linuxppc-dev", "list_id": "linuxppc-dev.lists.ozlabs.org", "list_email": "linuxppc-dev@lists.ozlabs.org", "web_url": "https://github.com/linuxppc/wiki/wiki", "scm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git", "webscm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/" }, "msgid": "<cover.1777306795.git.chleroy@kernel.org>", "date": "2026-04-27T17:13:41", "name": "[RFC,v1,0/9] uaccess: Convert small fixed size copy_{to/from}_user() to scoped user access", "submitter": { "id": 92089, "url": "http://patchwork.ozlabs.org/api/1.1/people/92089/?format=api", "name": "Christophe Leroy (CS GROUP)", "email": "chleroy@kernel.org" }, "mbox": "http://patchwork.ozlabs.org/project/linuxppc-dev/cover/cover.1777306795.git.chleroy@kernel.org/mbox/", "series": [ { "id": 501691, "url": "http://patchwork.ozlabs.org/api/1.1/series/501691/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=501691", "date": "2026-04-27T17:13:41", "name": "uaccess: Convert small fixed size copy_{to/from}_user() to scoped user access", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/501691/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2229027/comments/", "headers": { "Return-Path": "\n <linuxppc-dev+bounces-20175-incoming=patchwork.ozlabs.org@lists.ozlabs.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linuxppc-dev@lists.ozlabs.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=U2+LLE02;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=2404:9400:21b9:f100::1; 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c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1777310218;\n\tbh=Gdo90UdOw5JDNcbBc6CTpgqBoS99tJWdzzhKt47HDkg=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=U2+LLE02v2RJdGrHn64GqYJdP4+hDdO9CRQcGon9U+fg19LBxhX5PBepS5h9HJCqe\n\t szqGGe/Sn0Ja8ufrVfKBRayklpg7ZNqhD3AjlJFyhWTD2cy+E9nyVtxoXvU6RVePwS\n\t nC/EKNFwPrGycTqEuaSwxvd9NLoS3iznsIjTk0KPgTVc+veLovfoR+uQQZvkXu6BEL\n\t XY5HSP+s8CkmcaZnZCCWlv0qtPkuKqPRoos+3EvmYxD3lbF+eVbofOW/u0ribOc9N6\n\t 46gB4iCE7qS4DHXiu+LbPED9AO2rWWkmtG0xffEU92OaQJ+vWiy9PumgjbDE3AiKLE\n\t isfjlgjrnrghg==", "From": "\"Christophe Leroy (CS GROUP)\" <chleroy@kernel.org>", "To": "Yury Norov <ynorov@nvidia.com>,\n\tAndrew Morton <akpm@linux-foundation.org>,\n\tLinus Torvalds <torvalds@linux-foundation.org>,\n\tDavid Laight <david.laight.linux@gmail.com>,\n\tThomas Gleixner <tglx@linutronix.de>", "Cc": "\"Christophe Leroy (CS GROUP)\" <chleroy@kernel.org>,\n\tlinux-alpha@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org,\n\tlinux-snps-arc@lists.infradead.org,\n\tlinux-arm-kernel@lists.infradead.org,\n\tlinux-mips@vger.kernel.org,\n\tlinuxppc-dev@lists.ozlabs.org,\n\tkvm@vger.kernel.org,\n\tlinux-riscv@lists.infradead.org,\n\tlinux-s390@vger.kernel.org,\n\tsparclinux@vger.kernel.org,\n\tlinux-um@lists.infradead.org,\n\tdmaengine@vger.kernel.org,\n\tlinux-efi@vger.kernel.org,\n\tlinux-fsi@lists.ozlabs.org,\n\tamd-gfx@lists.freedesktop.org,\n\tdri-devel@lists.freedesktop.org,\n\tintel-gfx@lists.freedesktop.org,\n\tlinux-wpan@vger.kernel.org,\n\tnetdev@vger.kernel.org,\n\tlinux-wireless@vger.kernel.org,\n\tlinux-spi@vger.kernel.org,\n\tlinux-media@vger.kernel.org,\n\tlinux-staging@lists.linux.dev,\n\tlinux-serial@vger.kernel.org,\n\tlinux-usb@vger.kernel.org,\n\txen-devel@lists.xenproject.org,\n\tlinux-fsdevel@vger.kernel.org,\n\tocfs2-devel@lists.linux.dev,\n\tbpf@vger.kernel.org,\n\tkasan-dev@googlegroups.com,\n\tlinux-mm@kvack.org,\n\tlinux-x25@vger.kernel.org,\n\trust-for-linux@vger.kernel.org,\n\tlinux-sound@vger.kernel.org,\n\tsound-open-firmware@alsa-project.org,\n\tlinux-csky@vger.kernel.org,\n\tlinux-hexagon@vger.kernel.org,\n\tloongarch@lists.linux.dev,\n\tlinux-m68k@lists.linux-m68k.org,\n\tlinux-openrisc@vger.kernel.org,\n\tlinux-parisc@vger.kernel.org,\n\tlinux-sh@vger.kernel.org,\n\tlinux-arch@vger.kernel.org", "Subject": "[RFC PATCH v1 0/9] uaccess: Convert small fixed size\n copy_{to/from}_user() to scoped user access", "Date": "Mon, 27 Apr 2026 19:13:41 +0200", "Message-ID": "<cover.1777306795.git.chleroy@kernel.org>", "X-Mailer": "git-send-email 2.49.0", "X-Mailing-List": "linuxppc-dev@lists.ozlabs.org", "List-Id": "<linuxppc-dev.lists.ozlabs.org>", "List-Help": "<mailto:linuxppc-dev+help@lists.ozlabs.org>", "List-Owner": "<mailto:linuxppc-dev+owner@lists.ozlabs.org>", "List-Post": "<mailto:linuxppc-dev@lists.ozlabs.org>", "List-Archive": "<https://lore.kernel.org/linuxppc-dev/>,\n <https://lists.ozlabs.org/pipermail/linuxppc-dev/>", "List-Subscribe": "<mailto:linuxppc-dev+subscribe@lists.ozlabs.org>,\n <mailto:linuxppc-dev+subscribe-digest@lists.ozlabs.org>,\n <mailto:linuxppc-dev+subscribe-nomail@lists.ozlabs.org>", "List-Unsubscribe": "<mailto:linuxppc-dev+unsubscribe@lists.ozlabs.org>", "Precedence": "list", "MIME-Version": "1.0", "X-Developer-Signature": "v=1; a=openpgp-sha256; l=7253; i=chleroy@kernel.org;\n h=from:subject:message-id; bh=Gdo90UdOw5JDNcbBc6CTpgqBoS99tJWdzzhKt47HDkg=;\n b=owGbwMvMwCV2d0KB2p7V54MZT6slMWS+nxkaMinl/6P42P3bc0Qj3v7nk1G4YbGg/rEse+BPv\n 7e7BNgWdJSyMIhxMciKKbIc/8+9a0bXl9T8qbv0YeawMoEMYeDiFICJRDExMmwV0vIK89sWnHjX\n Y4WN3O+gaTyvmP0m2koKTvi9YNORsocM/wPkn2xoM0q8N63lWvLNy/m/speGuG7LLGiQ1I6bVSB\n dxgQA", "X-Developer-Key": "i=chleroy@kernel.org; a=openpgp;\n fpr=10FFE6F8B390DE17ACC2632368A92FEB01B8DD78", "Content-Transfer-Encoding": "8bit", "X-Spam-Status": "No, score=-0.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,\n\tDKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS\n\tautolearn=disabled version=4.0.1", "X-Spam-Checker-Version": "SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org" }, "content": "A lot of copy_from_user() and copy_to_user() perform copies of small\nfixed size pieces of data between kernel and userspace, and don't\ncare about partial copies.\n\ncopy_from_user() and copy_to_user() are big functions optimised for\ncopying large amount of data, with cache management, etc ... This is\noften overkill for small copies that could just be inlined instead.\n\nWhat makes things a bit more tricky is that those copy functions\nare designed to handle partial copies in case of page fault. But among\nthe 6000 callers of those functions, only 2% really care about the\nquantity of no-copied data that those functions return. All other ones\nfails as soon as the returned value is not 0, returning -EACCESS.\n\nSo first step in this series is to introduce variants called\ncopy_from_user_partial() and copy_to_user_partial() which will be\ncalled by the 2% users that care about the partial copy, then the\noriginal copy_from_user() and copy_to_user() are changed to return\n-EFAULT when the copy fails.\n\nThen the second step is to implement copy of small fixed-size data\nwith scoped user access instead of calling the arch specific heavy\nuser copy functions.\n\nPatch 5, can be split in different patches for each archicture or\nsubsystem, but let's get a first feedback and agree on the principle.\n\nChristophe Leroy (CS GROUP) (9):\n uaccess: Split check_zeroed_user() out of usercopy.c\n uaccess: Convert INLINE_COPY_{TO/FROM}_USER to kconfig and reduce\n ifdefery\n x86/umip: Be stricter in fixup_umip_exception()\n uaccess: Introduce copy_{to/from}_user_partial()\n uaccess: Switch to copy_{to/from}_user_partial() when relevant\n uaccess: Change copy_{to/from}_user to return -EFAULT\n x86: Add unsafe_copy_from_user()\n arm64: Add unsafe_copy_from_user()\n uaccess: Convert small fixed size copy_{to/from}_user() to scoped user\n access\n\n arch/alpha/Kconfig | 1 +\n arch/alpha/kernel/osf_sys.c | 4 +-\n arch/alpha/kernel/termios.c | 2 +-\n arch/arc/include/asm/uaccess.h | 3 -\n arch/arc/kernel/disasm.c | 2 +-\n arch/arm/include/asm/uaccess.h | 2 -\n arch/arm64/include/asm/gcs.h | 2 +-\n arch/arm64/include/asm/uaccess.h | 30 +++--\n arch/arm64/kernel/signal32.c | 2 +-\n arch/csky/Kconfig | 1 +\n arch/hexagon/include/asm/uaccess.h | 3 -\n arch/loongarch/include/asm/uaccess.h | 3 -\n arch/m68k/include/asm/uaccess.h | 3 -\n arch/microblaze/include/asm/uaccess.h | 2 -\n arch/mips/include/asm/uaccess.h | 3 -\n arch/mips/kernel/rtlx.c | 8 +-\n arch/mips/kernel/vpe.c | 2 +-\n arch/nios2/include/asm/uaccess.h | 2 -\n arch/openrisc/include/asm/uaccess.h | 2 -\n arch/parisc/include/asm/uaccess.h | 3 -\n arch/powerpc/Kconfig | 1 +\n arch/powerpc/kvm/book3s_64_mmu_hv.c | 4 +-\n arch/powerpc/kvm/book3s_64_mmu_radix.c | 4 +-\n arch/powerpc/kvm/book3s_hv.c | 2 +-\n arch/riscv/Kconfig | 1 +\n arch/riscv/kernel/signal.c | 2 +-\n arch/s390/include/asm/idals.h | 8 +-\n arch/s390/include/asm/uaccess.h | 3 -\n arch/sh/include/asm/uaccess.h | 2 -\n arch/sparc/include/asm/uaccess_32.h | 3 -\n arch/sparc/include/asm/uaccess_64.h | 2 -\n arch/sparc/kernel/termios.c | 2 +-\n arch/um/include/asm/uaccess.h | 3 -\n arch/um/kernel/process.c | 2 +-\n arch/x86/Kconfig | 1 +\n arch/x86/include/asm/uaccess.h | 29 ++++-\n arch/x86/kernel/umip.c | 2 +-\n arch/x86/lib/insn-eval.c | 2 +-\n arch/x86/um/signal.c | 2 +-\n arch/xtensa/include/asm/uaccess.h | 2 -\n drivers/android/binder_alloc.c | 2 +-\n drivers/comedi/comedi_fops.c | 4 +-\n drivers/dma/idxd/cdev.c | 2 +-\n drivers/firmware/efi/test/efi_test.c | 2 +-\n drivers/fsi/fsi-scom.c | 2 +-\n .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 2 +-\n drivers/gpu/drm/i915/gt/intel_sseu.c | 4 +-\n drivers/gpu/drm/i915/i915_gem.c | 4 +-\n drivers/hwtracing/intel_th/msu.c | 2 +-\n drivers/misc/ibmvmc.c | 2 +-\n drivers/misc/vmw_vmci/vmci_host.c | 2 +-\n drivers/most/most_cdev.c | 2 +-\n drivers/net/ieee802154/ca8210.c | 4 +-\n drivers/net/wireless/ath/wil6210/debugfs.c | 2 +-\n .../intel/iwlwifi/pcie/gen1_2/trans.c | 2 +-\n drivers/net/wireless/ti/wlcore/debugfs.c | 2 +-\n drivers/ps3/ps3-lpm.c | 2 +-\n drivers/s390/crypto/zcrypt_api.h | 4 +-\n drivers/spi/spidev.c | 2 +-\n .../staging/media/atomisp/pci/atomisp_cmd.c | 8 +-\n drivers/tty/tty_ioctl.c | 14 +--\n drivers/tty/vt/vc_screen.c | 4 +-\n drivers/usb/gadget/function/f_hid.c | 4 +-\n drivers/usb/gadget/function/f_printer.c | 2 +-\n drivers/vfio/vfio_iommu_type1.c | 4 +-\n drivers/xen/xenbus/xenbus_dev_frontend.c | 2 +-\n fs/namespace.c | 2 +-\n fs/ocfs2/dlmfs/dlmfs.c | 2 +-\n fs/proc/base.c | 4 +-\n include/asm-generic/uaccess.h | 2 -\n include/linux/bpfptr.h | 2 +-\n include/linux/sockptr.h | 4 +-\n include/linux/uaccess.h | 107 ++++++++++++++----\n ipc/msg.c | 8 +-\n ipc/sem.c | 8 +-\n ipc/shm.c | 18 +--\n kernel/regset.c | 2 +-\n kernel/sys.c | 4 +-\n lib/Kconfig | 3 +\n lib/Makefile | 4 +-\n lib/kfifo.c | 8 +-\n lib/{usercopy.c => usercheck.c} | 22 ----\n lib/usercopy.c | 66 -----------\n mm/kasan/kasan_test_c.c | 4 +-\n mm/memory.c | 2 +-\n net/x25/af_x25.c | 2 +-\n rust/helpers/uaccess.c | 6 +-\n sound/pci/emu10k1/emufx.c | 4 +-\n sound/pci/rme9652/hdsp.c | 6 +-\n sound/soc/intel/avs/probes.c | 6 +-\n sound/soc/sof/compress.c | 12 +-\n sound/soc/sof/sof-client-probes.c | 6 +-\n 92 files changed, 269 insertions(+), 288 deletions(-)\n copy lib/{usercopy.c => usercheck.c} (73%)" }