From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E1AB136A for ; Tue, 13 Jun 2023 18:56:30 +0000 (UTC) Received: from out-3.mta1.migadu.com (out-3.mta1.migadu.com [95.215.58.3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E15DB5 for ; Tue, 13 Jun 2023 11:56:28 -0700 (PDT) Date: Tue, 13 Jun 2023 14:56:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1686682581; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cI/+VKexODe7tgazUH0uBbszHN+Sh5VjQJKMcYicSKU=; b=UteSpuaAfbQ2NCJDHT0DaE6LH+0KCxqxliA1u1CiHpYLEp/BHx0yHT4z2wyOm1k0K155IH 1TdtqXMsJtk9bqAzUZ31aQXTksL2s2n1Q4RGfHebraQUDr3MhWO8yy+4wsaox2mGxQ3YRe XgmITo5ci4OCni1zywcC85bIuHv1vdI= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Kent Overstreet To: Mike Rapoport Cc: Song Liu , Mark Rutland , linux-kernel@vger.kernel.org, Andrew Morton , Catalin Marinas , Christophe Leroy , "David S. Miller" , Dinh Nguyen , Heiko Carstens , Helge Deller , Huacai Chen , Luis Chamberlain , Michael Ellerman , "Naveen N. Rao" , Palmer Dabbelt , Russell King , Steven Rostedt , Thomas Bogendoerfer , Thomas Gleixner , Will Deacon , bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev, netdev@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH 00/13] mm: jit/text allocator Message-ID: References: <20230601101257.530867-1-rppt@kernel.org> <20230605092040.GB3460@kernel.org> <20230608184116.GJ52412@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230608184116.GJ52412@kernel.org> X-Migadu-Flow: FLOW_OUT X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Thu, Jun 08, 2023 at 09:41:16PM +0300, Mike Rapoport wrote: > On Tue, Jun 06, 2023 at 11:21:59AM -0700, Song Liu wrote: > > On Mon, Jun 5, 2023 at 3:09 AM Mark Rutland wrote: > > > > [...] > > > > > > > > Can you give more detail on what parameters you need? If the only extra > > > > > > parameter is just "does this allocation need to live close to kernel > > > > > > text", that's not that big of a deal. > > > > > > > > > > My thinking was that we at least need the start + end for each caller. That > > > > > might be it, tbh. > > > > > > > > Do you mean that modules will have something like > > > > > > > > jit_text_alloc(size, MODULES_START, MODULES_END); > > > > > > > > and kprobes will have > > > > > > > > jit_text_alloc(size, KPROBES_START, KPROBES_END); > > > > ? > > > > > > Yes. > > > > How about we start with two APIs: > > jit_text_alloc(size); > > jit_text_alloc_range(size, start, end); > > > > AFAICT, arm64 is the only arch that requires the latter API. And TBH, I am > > not quite convinced it is needed. > > Right now arm64 and riscv override bpf and kprobes allocations to use the > entire vmalloc address space, but having the ability to allocate generated > code outside of modules area may be useful for other architectures. > > Still the start + end for the callers feels backwards to me because the > callers do not define the ranges, but rather the architectures, so we still > need a way for architectures to define how they want allocate memory for > the generated code. So, the start + end just comes from the need to keep relative pointers under a certain size. I think this could be just a flag, I see no reason to expose actual addresses here.