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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hAxus-0007K5-TA; Mon, 01 Apr 2019 14:28:02 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hAxup-0007Ja-Qk for linux-arm-kernel@lists.infradead.org; Mon, 01 Apr 2019 14:28:01 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9417980D; Mon, 1 Apr 2019 07:27:58 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 83EF63F690; Mon, 1 Apr 2019 07:27:57 -0700 (PDT) Date: Mon, 1 Apr 2019 15:27:55 +0100 From: Catalin Marinas To: Vincenzo Frascino Subject: Re: [PATCH 1/4] arm64: compat: Alloc separate pages for vectors and sigpage Message-ID: <20190401142754.GF14874@arrakis.emea.arm.com> References: <20190401112025.40807-1-vincenzo.frascino@arm.com> <20190401112025.40807-2-vincenzo.frascino@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190401112025.40807-2-vincenzo.frascino@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190401_072759_872172_3B760A14 X-CRM114-Status: GOOD ( 19.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Mark Rutland , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Apr 01, 2019 at 12:20:22PM +0100, Vincenzo Frascino wrote: > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c > index 2d419006ad43..9556ad2036ef 100644 > --- a/arch/arm64/kernel/vdso.c > +++ b/arch/arm64/kernel/vdso.c > @@ -1,5 +1,7 @@ > /* > - * VDSO implementation for AArch64 and vector page setup for AArch32. > + * VDSO implementation for AArch64 and for AArch32: > + * AArch64: vDSO implementation contains pages setup and data page update. > + * AArch32: vDSO implementation contains sigreturn and kuser pages setup. > * > * Copyright (C) 2012 ARM Limited > * > @@ -53,61 +55,117 @@ struct vdso_data *vdso_data = &vdso_data_store.data; > /* > * Create and map the vectors page for AArch32 tasks. > */ > -static struct page *vectors_page[1] __ro_after_init; > +/* > + * aarch32_vdso_pages: > + * 0 - kuser helpers > + * 1 - sigreturn code > + */ > +static struct page *aarch32_vdso_pages[2] __ro_after_init; More of a nitpick, the code may be easier to follow if we had two separate variables. Does the array buy us anything? > +static const struct vm_special_mapping aarch32_vdso_spec[2] = { > + { > + /* Must be named [vectors] for compatibility with arm. */ > + .name = "[vectors]", > + .pages = &aarch32_vdso_pages[0], > + }, > + { > + /* Must be named [sigpage] for compatibility with arm. */ > + .name = "[sigpage]", > + .pages = &aarch32_vdso_pages[1], > + }, > +}; [...] > -int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp) > +static int aarch32_kuser_helpers_setup(struct mm_struct *mm) > { > - struct mm_struct *mm = current->mm; > - unsigned long addr = AARCH32_VECTORS_BASE; > - static const struct vm_special_mapping spec = { > - .name = "[vectors]", > - .pages = vectors_page, > + void *ret; > + > + /* The kuser helpers must be mapped at the ABI-defined high address */ > + ret = _install_special_mapping(mm, AARCH32_KUSER_BASE, PAGE_SIZE, > + VM_READ | VM_EXEC | > + VM_MAYREAD | VM_MAYEXEC, > + &aarch32_vdso_spec[0]); > + > + return PTR_ERR_OR_ZERO(ret); > +} > > - }; > +static int aarch32_sigreturn_setup(struct mm_struct *mm) > +{ > + unsigned long addr; > void *ret; > > - if (down_write_killable(&mm->mmap_sem)) > - return -EINTR; > - current->mm->context.vdso = (void *)addr; > + addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); > + if (IS_ERR_VALUE(addr)) { > + ret = ERR_PTR(addr); > + goto out; > + } > > - /* Map vectors page at the high address. */ > ret = _install_special_mapping(mm, addr, PAGE_SIZE, > - VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC, > - &spec); > + VM_READ | VM_EXEC | VM_MAYREAD | > + VM_MAYWRITE | VM_MAYEXEC, > + &aarch32_vdso_spec[1]); Any reason for setting VM_MAYWRITE here? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel