From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2933C021BE for ; Thu, 27 Feb 2025 11:13:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B8C9F6B007B; Thu, 27 Feb 2025 06:13:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B3CE06B0082; Thu, 27 Feb 2025 06:13:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A03326B0085; Thu, 27 Feb 2025 06:13:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 8357B6B007B for ; Thu, 27 Feb 2025 06:13:44 -0500 (EST) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 30770A0853 for ; Thu, 27 Feb 2025 11:13:44 +0000 (UTC) X-FDA: 83165464368.30.C13C0E2 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf08.hostedemail.com (Postfix) with ESMTP id 39DF6160049 for ; Thu, 27 Feb 2025 11:13:42 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf08.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1740654822; h=from:from:sender: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=Xs5+klIHUgwyyyEQRPQsx98Pc5etma9f9hiPcjrGdko=; b=fzvnjDdRMcwsEio+rwdtHVQbBWIW+Ig7O2TTy8Zr/iTJQbqJ8UbQYKqDwBW4qg1WPkHfmt eNPkfNRC1F1wR14yYaBoaeBQxyjv8e2vwiPf2VSL9jko68Tk8fYxzIoeYxGKnznVaIPbvF +uJ5ca6GnLYsgRVFhxDo5+jSekYgFKo= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf08.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1740654822; a=rsa-sha256; cv=none; b=WAPuJwGWhcSa8jo0zjSJqQ1iA9g7QgnGuO615lUqcV98CWFXswfBNU48N+w+T31L3KiN6P 3QRoKeinILV7rz4g4F3nlCFhAVTYeci6P5os0vXm6zRxBnUxRJAex8uuzkHnlAkEatZ0I9 Jj76ssQx92AMOcoHWyHO4vuzwFs2IYw= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B356E2C1C; Thu, 27 Feb 2025 03:13:56 -0800 (PST) Received: from [10.57.85.134] (unknown [10.57.85.134]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6FF103F6A8; Thu, 27 Feb 2025 03:13:31 -0800 (PST) Message-ID: <16863478-2195-435e-a899-559df097bc59@arm.com> Date: Thu, 27 Feb 2025 11:13:29 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 7/8] execmem: add support for cache of large ROX pages Content-Language: en-GB To: Mike Rapoport , Andrew Morton , Luis Chamberlain , Dev Jain Cc: Andreas Larsson , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Brian Cain , Catalin Marinas , Christoph Hellwig , Christophe Leroy , Dave Hansen , Dinh Nguyen , Geert Uytterhoeven , Guo Ren , Helge Deller , Huacai Chen , Ingo Molnar , Johannes Berg , John Paul Adrian Glaubitz , Kent Overstreet , "Liam R. Howlett" , Mark Rutland , Masami Hiramatsu , Matt Turner , Max Filippov , Michael Ellerman , Michal Simek , Oleg Nesterov , Palmer Dabbelt , Peter Zijlstra , Richard Weinberger , Russell King , Song Liu , Stafford Horne , Steven Rostedt , Suren Baghdasaryan , Thomas Bogendoerfer , Thomas Gleixner , Uladzislau Rezki , Vineet Gupta , Will Deacon , bpf@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-trace-kernel@vger.kernel.org, linux-um@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev, sparclinux@vger.kernel.org, x86@kernel.org References: <20241023162711.2579610-1-rppt@kernel.org> <20241023162711.2579610-8-rppt@kernel.org> From: Ryan Roberts In-Reply-To: <20241023162711.2579610-8-rppt@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 39DF6160049 X-Stat-Signature: dhsrbowf6g87b1oq53azeu347cggpc5f X-HE-Tag: 1740654822-91310 X-HE-Meta: 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 PGTh4yfy zsQqeOULf8kChNmlN8JgQcjzJQ4AZXzhnf37wT+7BNtkv0e2vve2drnT94qDaJiSdsc15+XRzVMEYb/9L7iASEf2RnIs00Jctuy6QQ94Mn+pbLCN57jqmPTxkhXW8fwCjFuhcckSb0WHVX9yoCvD4w3Cj3KzIFq3wcUkuRcq7SxvAdGzzbV8DkI/BiRllr0QexLxTI/YEYR8cgmg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Mike, Drive by review comments below... On 23/10/2024 17:27, Mike Rapoport wrote: > From: "Mike Rapoport (Microsoft)" > > Using large pages to map text areas reduces iTLB pressure and improves > performance. > > Extend execmem_alloc() with an ability to use huge pages with ROX > permissions as a cache for smaller allocations. > > To populate the cache, a writable large page is allocated from vmalloc with > VM_ALLOW_HUGE_VMAP, filled with invalid instructions and then remapped as > ROX. > > The direct map alias of that large page is exculded from the direct map. > > Portions of that large page are handed out to execmem_alloc() callers > without any changes to the permissions. > > When the memory is freed with execmem_free() it is invalidated again so > that it won't contain stale instructions. > > An architecture has to implement execmem_fill_trapping_insns() callback > and select ARCH_HAS_EXECMEM_ROX configuration option to be able to use > the ROX cache. > > The cache is enabled on per-range basis when an architecture sets > EXECMEM_ROX_CACHE flag in definition of an execmem_range. > > Signed-off-by: Mike Rapoport (Microsoft) > Reviewed-by: Luis Chamberlain > Tested-by: kdevops > --- [...] > + > +static int execmem_cache_populate(struct execmem_range *range, size_t size) > +{ > + unsigned long vm_flags = VM_ALLOW_HUGE_VMAP; > + unsigned long start, end; > + struct vm_struct *vm; > + size_t alloc_size; > + int err = -ENOMEM; > + void *p; > + > + alloc_size = round_up(size, PMD_SIZE); > + p = execmem_vmalloc(range, alloc_size, PAGE_KERNEL, vm_flags); Shouldn't this be passing PAGE_KERNEL_ROX? Otherwise I don't see how the allocated memory is ROX? I don't see any call below where you change the permission. Given the range has the pgprot in it, you could just drop passing the pgprot explicitly here and have execmem_vmalloc() use range->pgprot directly? Thanks, Ryan > + if (!p) > + return err; > + > + vm = find_vm_area(p); > + if (!vm) > + goto err_free_mem; > + > + /* fill memory with instructions that will trap */ > + execmem_fill_trapping_insns(p, alloc_size, /* writable = */ true); > + > + start = (unsigned long)p; > + end = start + alloc_size; > + > + vunmap_range(start, end); > + > + err = execmem_set_direct_map_valid(vm, false); > + if (err) > + goto err_free_mem; > + > + err = vmap_pages_range_noflush(start, end, range->pgprot, vm->pages, > + PMD_SHIFT); > + if (err) > + goto err_free_mem; > + > + err = execmem_cache_add(p, alloc_size); > + if (err) > + goto err_free_mem; > + > + return 0; > + > +err_free_mem: > + vfree(p); > + return err; > +} [...]