{"id":2229033,"url":"http://patchwork.ozlabs.org/api/1.1/covers/2229033/?format=json","web_url":"http://patchwork.ozlabs.org/project/sparclinux/cover/cover.1777306795.git.chleroy@kernel.org/","project":{"id":10,"url":"http://patchwork.ozlabs.org/api/1.1/projects/10/?format=json","name":"Linux SPARC Development ","link_name":"sparclinux","list_id":"sparclinux.vger.kernel.org","list_email":"sparclinux@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"","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=json","name":"Christophe Leroy (CS GROUP)","email":"chleroy@kernel.org"},"mbox":"http://patchwork.ozlabs.org/project/sparclinux/cover/cover.1777306795.git.chleroy@kernel.org/mbox/","series":[{"id":501694,"url":"http://patchwork.ozlabs.org/api/1.1/series/501694/?format=json","web_url":"http://patchwork.ozlabs.org/project/sparclinux/list/?series=501694","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/501694/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/covers/2229033/comments/","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","sparclinux@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@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=ozlabs.org\n (client-ip=2404:9400:2221:ea00::3; helo=mail.ozlabs.org;\n envelope-from=srs0=my4d=c2=vger.kernel.org=sparclinux+bounces-6725-patchwork-incoming=ozlabs.org@ozlabs.org;\n receiver=patchwork.ozlabs.org)","gandalf.ozlabs.org;\n arc=pass smtp.remote-ip=\"2600:3c0a:e001:db::12fc:5321\"\n arc.chain=subspace.kernel.org","gandalf.ozlabs.org;\n dmarc=pass (p=quarantine dis=none) header.from=kernel.org","gandalf.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","gandalf.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; helo=sea.lore.kernel.org;\n envelope-from=sparclinux+bounces-6725-patchwork-incoming=ozlabs.org@vger.kernel.org;\n receiver=ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=\"U2+LLE02\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=10.30.226.201"],"Received":["from mail.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1 raw public key)\n server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g49HG4G2dz1xvV\n\tfor ; Tue, 28 Apr 2026 03:17:30 +1000 (AEST)","from mail.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3])\n\tby gandalf.ozlabs.org (Postfix) with ESMTP id 4g49HG2B0Sz4wJf\n\tfor ; Tue, 28 Apr 2026 03:17:30 +1000 (AEST)","by gandalf.ozlabs.org (Postfix)\n\tid 4g49HG26HVz4wKx; Tue, 28 Apr 2026 03:17:30 +1000 (AEST)","from sea.lore.kernel.org (sea.lore.kernel.org\n [IPv6:2600:3c0a:e001:db::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby gandalf.ozlabs.org (Postfix) with ESMTPS id 4g49HB6hX6z4wJf\n\tfor ; Tue, 28 Apr 2026 03:17:26 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby sea.lore.kernel.org (Postfix) with ESMTP id 786673012C6C\n\tfor ; Mon, 27 Apr 2026 17:17:02 +0000 (UTC)","from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id CAE153E316F;\n\tMon, 27 Apr 2026 17:16:59 +0000 (UTC)","from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org\n [10.30.226.201])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby smtp.subspace.kernel.org (Postfix) with ESMTPS id 7460E29405;\n\tMon, 27 Apr 2026 17:16:59 +0000 (UTC)","by smtp.kernel.org (Postfix) with ESMTPSA id 87FE1C2BCB4;\n\tMon, 27 Apr 2026 17:16:46 +0000 (UTC)"],"ARC-Seal":["i=2; a=rsa-sha256; d=ozlabs.org; s=201707; t=1777310250; cv=pass;\n\tb=xuqZd0ZAgl2HXnc8l/If+kWYv81WK5gaMbHobSJxiO/4oOFQA3lfl+CPXYkc/um9leUz/1T/mnr5xhSwktPOoEmSY2PYgp5pPH+QwYZ/8NiZagEXzEb0cPpVfqS0AgMOmw4Sa7KLtx4c/sCg5OrUuSOyD4BhPqR31UHc3kqXV1BFxZ17Dp9Z5hWuW/YIZCH38RvRKe0MgWXDAOB7udicjSnp+kmVR7Z4/ATpcVc6hr/kdDeXMM1xqiG37uS1tkamTPXT1opxvbRB9ELi9MvfJx6EjhLvCYf3lJhjkbotIuvSEpu4yGYf3KEWfCh3TDs5cqixHa/fOU1yjeZzaD0qjg==","i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1777310219; cv=none;\n b=lnKg7BoxsEj+KpDcf/oALBrXT1ccTPBpkTI3ECVX2s5+j9fNGEdNiRPFZQ8HHDtmvwK+7jcFnrgXz6RbeU/6P/VLAj5z8DPYqKu0fs6R/6tWQQ0otKZOoYGLjzORJyOu7yinHhzzi5Rz3N/XoPqxUmBTM7+3NcZDBN5Fa5hGw78="],"ARC-Message-Signature":["i=2; a=rsa-sha256; d=ozlabs.org; s=201707;\n\tt=1777310250; c=relaxed/relaxed;\n\tbh=jhUiSYlSjWHWqHISdWgh0N8CQlPC2mYxEyllaCORLRs=;\n\th=From:To:Cc:Subject:Date:Message-ID:MIME-Version;\n b=gTn+W4v8FutIzUjp0trmK1LYzxuSS9kekYePgIB6oFuivkfl/q2BHS63sSqekxChLUWTfp74ctxeasNAkmRt2BsBDdTujpMuAD/L5GTIqwyGvk57QdXSntQAIFg16GU6dYGWJTEJ3AjuCdOJaJN/Z9LlUkNrlptsa/IHy0oLUQjS3rwjl7HUUebec/XO/gDlr0ejFp1Opj1BrmNvAVjUI7fF0LHi8mavHGMy0QiVduJuW/YOhIt8oI8ywoMA2qdpjiV9eOxLj81ZRJH0AO/zS8hAYLCV6TFyaD03aMdaoqAb0vpRzkIsm03TwHBeWc8c6mCQZHxy+JAx95DxXY0Yqw==","i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1777310219; c=relaxed/simple;\n\tbh=Gdo90UdOw5JDNcbBc6CTpgqBoS99tJWdzzhKt47HDkg=;\n\th=From:To:Cc:Subject:Date:Message-ID:MIME-Version;\n b=QCWJwhkgyQIPBwW36YBLsUTxKenVr8c/dnY28kBLLI5w/jdSgmUcTrI8h7IRMX6fYYCmnIiH5daNsx88sS8N05ODBVdWNquhCzzZoTW7kiY+fqoobv6Du/Xc5AYtVrf7QCsNShxs3Cx0dwSSwP+bsgcv8u6JdQAck3yTm/GilNE="],"ARC-Authentication-Results":["i=2; gandalf.ozlabs.org;\n dmarc=pass (p=quarantine dis=none) header.from=kernel.org;\n dkim=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; dkim-atps=neutral;\n spf=pass (client-ip=2600:3c0a:e001:db::12fc:5321; helo=sea.lore.kernel.org;\n envelope-from=sparclinux+bounces-6725-patchwork-incoming=ozlabs.org@vger.kernel.org;\n receiver=ozlabs.org) smtp.mailfrom=vger.kernel.org","i=1; smtp.subspace.kernel.org;\n dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=U2+LLE02; arc=none smtp.client-ip=10.30.226.201"],"DKIM-Signature":"v=1; a=rsa-sha256; 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)\" ","To":"Yury Norov ,\n\tAndrew Morton ,\n\tLinus Torvalds ,\n\tDavid Laight ,\n\tThomas Gleixner ","Cc":"\"Christophe Leroy (CS GROUP)\" ,\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":"","X-Mailer":"git-send-email 2.49.0","Precedence":"bulk","X-Mailing-List":"sparclinux@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","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=-1.2 required=5.0 tests=ARC_SIGNED,ARC_VALID,\n\tDKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DMARC_PASS,\n\tMAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=disabled\n\tversion=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on gandalf.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%)"}