From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:45098 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727013AbeIQPFj (ORCPT ); Mon, 17 Sep 2018 11:05:39 -0400 Date: Mon, 17 Sep 2018 11:39:01 +0200 From: Greg KH To: SZ Lin =?utf-8?B?KOael+S4iuaZuik=?= Cc: stable@vger.kernel.org Subject: Re: FAILED: patch "[PATCH] MIPS: VDSO: Match data page cache colouring when D$ aliases" failed to apply to 4.4-stable tree Message-ID: <20180917093901.GE26181@kroah.com> References: <1537099893232146@kroah.com> <20180916134848.GA6645@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180916134848.GA6645@localhost> Sender: stable-owner@vger.kernel.org List-ID: On Sun, Sep 16, 2018 at 09:48:48PM +0800, SZ Lin (林上智) wrote: > Hi, > > On Sun, Sep 16, 2018 at 02:11:33PM +0200, gregkh@linuxfoundation.org wrote: > > > > The patch below does not apply to the 4.4-stable tree. > > If someone wants it applied there, or to any other stable or longterm > > tree, then please email the backport, including the original git commit > > id to . > > Please find attached patch 00578cd864d45 ("MIPS: VDSO: Drop gic_get_usm_range() usage") > and apply to {4.4,4.9}-stable tree for solving this conflict. > > Thanks! > > SZ Lin (林上智) > > > > > thanks, > > > > greg k-h > > > > ------------------ original commit in Linus's tree ------------------ > > > > From 0f02cfbc3d9e413d450d8d0fd660077c23f67eff Mon Sep 17 00:00:00 2001 > > From: Paul Burton > > Date: Thu, 30 Aug 2018 11:01:21 -0700 > > Subject: [PATCH] MIPS: VDSO: Match data page cache colouring when D$ aliases > > > > When a system suffers from dcache aliasing a user program may observe > > stale VDSO data from an aliased cache line. Notably this can break the > > expectation that clock_gettime(CLOCK_MONOTONIC, ...) is, as its name > > suggests, monotonic. > > > > In order to ensure that users observe updates to the VDSO data page as > > intended, align the user mappings of the VDSO data page such that their > > cache colouring matches that of the virtual address range which the > > kernel will use to update the data page - typically its unmapped address > > within kseg0. > > > > This ensures that we don't introduce aliasing cache lines for the VDSO > > data page, and therefore that userland will observe updates without > > requiring cache invalidation. > > > > Signed-off-by: Paul Burton > > Reported-by: Hauke Mehrtens > > Reported-by: Rene Nielsen > > Reported-by: Alexandre Belloni > > Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") > > Patchwork: https://patchwork.linux-mips.org/patch/20344/ > > Tested-by: Alexandre Belloni > > Tested-by: Hauke Mehrtens > > Cc: James Hogan > > Cc: linux-mips@linux-mips.org > > Cc: stable@vger.kernel.org # v4.4+ > > > > diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c > > index 019035d7225c..8f845f6e5f42 100644 > > --- a/arch/mips/kernel/vdso.c > > +++ b/arch/mips/kernel/vdso.c > > @@ -13,6 +13,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -20,6 +21,7 @@ > > > > #include > > #include > > +#include > > #include > > > > /* Kernel-provided data used by the VDSO. */ > > @@ -128,12 +130,30 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) > > vvar_size = gic_size + PAGE_SIZE; > > size = vvar_size + image->size; > > > > + /* > > + * Find a region that's large enough for us to perform the > > + * colour-matching alignment below. > > + */ > > + if (cpu_has_dc_aliases) > > + size += shm_align_mask + 1; > > + > > base = get_unmapped_area(NULL, 0, size, 0, 0); > > if (IS_ERR_VALUE(base)) { > > ret = base; > > goto out; > > } > > > > + /* > > + * If we suffer from dcache aliasing, ensure that the VDSO data page > > + * mapping is coloured the same as the kernel's mapping of that memory. > > + * This ensures that when the kernel updates the VDSO data userland > > + * will observe it without requiring cache invalidations. > > + */ > > + if (cpu_has_dc_aliases) { > > + base = __ALIGN_MASK(base, shm_align_mask); > > + base += ((unsigned long)&vdso_data - gic_size) & shm_align_mask; > > + } > > + > > data_addr = base + gic_size; > > vdso_addr = data_addr + PAGE_SIZE; > > > > > > -- > SZ Lin (林上智) , http://people.debian.org/~szlin > > Debian Developer, debian.org.tw Administrator > > 4096R/ 178F 8338 B314 01E3 04FC 44BA A959 B38A 9561 F3F9 > >From 890151c23e16a48ad0ba05ff60633234c1934c8b Mon Sep 17 00:00:00 2001 > From: Paul Burton > Date: Sat, 12 Aug 2017 21:36:30 -0700 > Subject: [PATCH] MIPS: VDSO: Drop gic_get_usm_range() usage > > commit 00578cd864d45ae4b8fa3f684f8d6f783dd8d15d upstream > > We don't really need gic_get_usm_range() to abstract discovery of the > address of the GIC user-visible section now that we have access to its > base address globally. > > Switch to calculating it ourselves, which will allow us to stop > requiring the irqchip driver to care about a counter exposed to userland > for use via the VDSO. > > Signed-off-by: Paul Burton > Cc: Jason Cooper > Cc: Marc Zyngier > Cc: Thomas Gleixner > Cc: linux-mips@linux-mips.org > Patchwork: https://patchwork.linux-mips.org/patch/17040/ > Signed-off-by: Ralf Baechle > Signed-off-by: SZ Lin (林上智) I do not understand. What "bug" is this fixing that this needs to be backported for? thanks, greg k-h