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Fri, 06 Nov 2026 05:52:20 -0800 (PST) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Fri, 6 Nov 2026 14:52:18 +0100 To: Andrii Nakryiko Cc: Alexei Starovoitov , Daniel Borkmann , bpf@vger.kernel.org, linux-mm@kvack.org, Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Lorenzo Stoakes , John Fastabend , Federico Di Pierro Subject: Re: [PATCHv3 bpf-next 2/8] bpf: Add user memory kfuncs Message-ID: References: <20261105102343.311331-1-jolsa@kernel.org> <20261105102343.311331-3-jolsa@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 9wmn3drxtpb6pziatzjmpkwierqyoqne X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 150C320006 X-Spam-Status: No, score=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1793973142-442115 X-HE-Meta: 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 ZtVdLvL8 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 05, 2026 at 04:34:40PM -0800, Andrii Nakryiko wrote: SNIP > > +/** > > + * bpf_copy_to_user() - Copy data to the current task's address space > > + * @unsafe_ptr__ign: Destination address in the current task's address space > > + * @src: Source address, in kernel space > > + * @src__sz: Number of bytes to copy > > + * @flags: Reserved for future use; must be zero > > + * > > + * Faults in the destination and writes the way ptrace(PTRACE_POKETEXT) does: > > + * a private mapping doesn't have to be writable. A partial copy is not undone, > > + * the bytes before the fault stay written. > > + * > > + * The caller must coordinate with other threads so they do not execute the > > + * destination range while it is being modified, and ensure execution begins > > + * only after the copy completes. > > + * > > + * Return: 0 on success, -EINVAL if @flags is non-zero, or -EFAULT if the copy > > + * fails or is partial. > > + */ > > +__bpf_kfunc int bpf_copy_to_user(void __user *unsafe_ptr__ign, const void *src, > > + u32 src__sz, u64 flags) > > you'll eventually want bpf_copy_to_user_dynptr (we already have > bpf_copy_from_user_dynptr), so might as well add it from the get go? ok, might be useful will check.. will send as follow up thanks, jirka > > > +{ > > + int ret; > > + > > + if (unlikely(flags)) > > + return -EINVAL; > > + if (unlikely(src__sz > S32_MAX)) > > + return -EINVAL; > > + if (unlikely(!src__sz)) > > + return 0; > > + ret = access_process_vm(current, (unsigned long)unsafe_ptr__ign, (void *)src, > > + src__sz, FOLL_FORCE | FOLL_WRITE); > > + return ret == src__sz ? 0 : -EFAULT; > > +} > > + > > [...]