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Wed, 14 Apr 2021 09:00:11 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2B268203D392D; Wed, 14 Apr 2021 09:00:11 +0200 (CEST) Date: Wed, 14 Apr 2021 09:00:11 +0200 From: Peter Zijlstra To: Kees Cook Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, x86@kernel.org, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, chris@chris-wilson.co.uk, intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, hch@lst.de Subject: Re: [PATCH 4/7] mm: Introduce verify_page_range() Message-ID: References: <20210412080012.357146277@infradead.org> <20210412080611.769864829@infradead.org> <202104121302.57D7EF8@keescook> <202104131935.B5EBDAE@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202104131935.B5EBDAE@keescook> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 48761788 X-Stat-Signature: y373wd5f741y66qbif6mooa519sspibq Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf04; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618383637-259761 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: On Tue, Apr 13, 2021 at 08:01:08PM -0700, Kees Cook wrote: > So the addr can just be encoded in "int", and no structure is needed at: > > typedef bool (*vpr_fn_t)(pte_t pte); > > static int vpr_fn(pte_t *pte, unsigned long addr, void *data) > { > vpr_fn_t callback = data; > > if (!callback(*pte)) > return addr >> PAGE_SIZE; > return 0; > } > > unsigned long verify_page_range(struct mm_struct *mm, > unsigned long addr, unsigned long size, > vpr_fn_t callback) > { > return apply_to_page_range(mm, addr, size, vpr_fn, callback) << PAGE_SIZE; > } > > But maybe I'm missing something? That covers only (32+12) bits of address space and will mostly work, but we definitely support architectures (very much including x86_64) with larger address spaces than that.