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Message-ID: <1522431689.2693.290.camel@hpe.com> Date: Fri, 30 Mar 2018 17:41:50 +0000 From: "Kani, Toshi" <toshi.kani@....com> To: "xieyisheng1@...wei.com" <xieyisheng1@...wei.com>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org> CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "guohanjun@...wei.com" <guohanjun@...wei.com>, "tanxiaojun@...wei.com" <tanxiaojun@...wei.com>, "wangzhou1@...ilicon.com" <wangzhou1@...ilicon.com>, "kstewart@...uxfoundation.org" <kstewart@...uxfoundation.org>, "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>, "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>, "arnd@...db.de" <arnd@...db.de>, "jcm@...hat.com" <jcm@...hat.com> Subject: Re: [RFC PATCH] lib/ioremap: Avoid triggering BUG_ON when end is not PAGE_ALIGN On Fri, 2018-03-30 at 12:49 +0800, Yisheng Xie wrote: > Zhou reported a bug on Hisilicon arm64 D06 platform with 64KB page size: : > The cause is the size of PCI IO resource is 32KB, which is 4K aligned but > not 64KB aligned, so when do ioremap_pte_range(), its incoming end is not > PAGE_ALIGN on 64KB page size system, but ioremap_pte_range increase the > addr by PAGE_SIZE, which makes addr != end until trigger BUG_ON. > > This patch introduces pte_addr_end(addr, end) to resolve this problem, just > as what pmd_addr_end do. When end is not PAGE_ALIGN, it will return end > instead of addr + PAGE_SIZE, therefore ioremap_pte_range() can break out > when real end is coming. ioremap_pte_range() assumes that addr and end are aligned by PAGE_SIZE. While some improvement can be made in the range check and documentation, I do not think it is safe for letting this library function to map outside of a requested range blindly. Can you change the caller of ioremap_page_range() to align the request by PAGE_SIZE so that the caller is aware of what it's asking for? Thanks, -Toshi
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