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Wed, 6 May 2026 14:09:17 +0000 (GMT) Message-ID: <9f85f092-c376-4350-9a12-479d7b70399a@linux.ibm.com> Date: Wed, 6 May 2026 16:09:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v14 04/19] x86/uaccess: Add unsafe_copy_from_user() implementation To: Steven Rostedt , Josh Poimboeuf , Dave Hansen , "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" , Indu Bhagat , Peter Zijlstra , Dylan Hatch , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Mathieu Desnoyers , Kees Cook , Sam James References: <20260505121718.3572346-1-jremus@linux.ibm.com> <20260505121718.3572346-5-jremus@linux.ibm.com> Content-Language: en-US From: Jens Remus Organization: IBM Deutschland Research & Development GmbH In-Reply-To: <20260505121718.3572346-5-jremus@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: 2IiCT--Vp-RQVdUGSeMKj3NgFgjYnGxT X-Proofpoint-GUID: KIizt9F92xnbY-nhRloRCta2VU3AXvFV X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA2MDEzOSBTYWx0ZWRfX9/D4gt9JjNe3 1dGTBSo20Nns4lWNkY2R57YNEBhiw6CjJFOYeKzOR9Auu8huq6ARaFbnF47vfs0iqzUPW0gQX3g Gk41rjmpwgzcz249VYsMTvez/E8WZQYBZY1oH3thtWHPZ97uWr18xWwOD8FHwgsCOPM6ysBPTlX cpL1ZL3m6lxsNe3O1IZ5qRcKdZwj7plK/csqi8Re91a4zGvn10HTOd8S71AZu/ipZjT4xPjqkWu f2AxY/01ggJqg/drUjJZxHCVfM1csDHt9KekdvSqv+xhOh/mtOzkF4P0S5XjhnXyQ9XbjHSUZcv 7+ZHoSzHJED1lCNCurZ2wA2Yt4ZNRuqVCSxa1uWf/PhP3uLF2I9/QuRIUYLkTNgp9ddF4o9rNcp cpkEn9w4R6MMVSZWxLaMfCySy3maOK7BsokLWqbFVmrxKkBmW+om+0qSPpiN+JA1ilkuA2lomMF 1KA7rirk8Kz+7jNbuJA== X-Authority-Analysis: v=2.4 cv=UbFhjqSN c=1 sm=1 tr=0 ts=69fb4b93 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=LFt20mCCc4CE-LtB3JUA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-05_03,2026-05-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 adultscore=0 priorityscore=1501 bulkscore=0 phishscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605060139 X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 8626A1C001C X-Stat-Signature: 8m1penx5y6sdo9zkfoi47ro9qnbd39hu X-Rspam-User: X-HE-Tag: 1778076616-503234 X-HE-Meta: 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 ZM3DuP3l QGMXSRjsxz65HGOTRhT2NHaBnh2f5liuCFQlVDRteFSlmBS1thmZl/ydAg1RDEM+9yY+5ZW8nykCWRTFsxa2vquaEARXmklvwrMsNjRxk2TEEOYyIySnVIFX6gnye6uXAFe254Uli5VSUsTmMnQv7dmhHk/KOFxhmc+IQyZ8XWuZJ/Le1jZheYZHCYHcDF3EvfdVFW21/In8Tvd50qdUEs8mCk1OHJBfNCKr3FSXqs5LI+plfMmcbJ86mTIBWrY9WZyJghIqOp21eMtLY429ngF0+sBR9baSsU9WRSVnT8A+Joc/TIocELnIBrOQTFmBxp1/2fd5vO4ejci1Ul0sPLklxX+GNImz1ZA0WAg3OQHdlfUWNeyLs5TPSwO1pEln61RmBf/LZfW9H0CyQBLt4FmVfqP7/ebobuVhrZe+T7vVYwo5bZ4lnQBKIDVEMPpNXA5pkES3U+MNnWvUudYs/KkXylcw2HmvmJtJT Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/5/2026 2:17 PM, Jens Remus wrote: > From: Josh Poimboeuf > > Add an x86 implementation of unsafe_copy_from_user() similar to the > existing unsafe_copy_to_user(). > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h > -#define unsafe_copy_to_user(_dst,_src,_len,label) \ > -do { \ > - char __user *__ucu_dst = (_dst); \ > - const char *__ucu_src = (_src); \ > - size_t __ucu_len = (_len); \ > - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \ > - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \ > - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \ > - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ > +#define unsafe_copy_to_user(_dst, _src, _len, label) \ > +do { \ > + void __user *__dst = (_dst); \ > + const void *__src = (_src); \ > + size_t __len = (_len); \ > + unsafe_copy_to_user_loop(__dst, __src, __len, u64, label); \ > + unsafe_copy_to_user_loop(__dst, __src, __len, u32, label); \ > + unsafe_copy_to_user_loop(__dst, __src, __len, u16, label); \ > + unsafe_copy_to_user_loop(__dst, __src, __len, u8, label); \ > +} while (0) > + > +#define unsafe_copy_from_user_loop(dst, src, len, type, label) \ > + while (len >= sizeof(type)) { \ > + unsafe_get_user(*(type *)(dst), (type __user *)(src), label); \ > + dst += sizeof(type); \ > + src += sizeof(type); \ > + len -= sizeof(type); \ > + } > + > +#define unsafe_copy_from_user(_dst, _src, _len, label) \ > +do { \ > + void *__dst = (_dst); \ > + void __user *__src = (_src); \ const void __user *__src = (_src); \ This was suggested by Sashiko AI review. Any objections? > + size_t __len = (_len); \ > + unsafe_copy_from_user_loop(__dst, __src, __len, u64, label); \ > + unsafe_copy_from_user_loop(__dst, __src, __len, u32, label); \ > + unsafe_copy_from_user_loop(__dst, __src, __len, u16, label); \ > + unsafe_copy_from_user_loop(__dst, __src, __len, u8, label); \ > } while (0) > > #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT Thanks and regards, Jens -- Jens Remus Linux on Z Development (D3303) jremus@de.ibm.com / jremus@linux.ibm.com IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Ehningen; Registergericht: Amtsgericht Stuttgart, HRB 243294 IBM Data Privacy Statement: https://www.ibm.com/privacy/