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 stable@vger.kernel.org.
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 paul.burton@mips.com 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 paul.burton@mips.com Reported-by: Hauke Mehrtens hauke@hauke-m.de Reported-by: Rene Nielsen rene.nielsen@microsemi.com Reported-by: Alexandre Belloni alexandre.belloni@bootlin.com Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") Patchwork: https://patchwork.linux-mips.org/patch/20344/ Tested-by: Alexandre Belloni alexandre.belloni@bootlin.com Tested-by: Hauke Mehrtens hauke@hauke-m.de Cc: James Hogan jhogan@kernel.org 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 <linux/err.h> #include <linux/init.h> #include <linux/ioport.h> +#include <linux/kernel.h> #include <linux/mm.h> #include <linux/sched.h> #include <linux/slab.h> @@ -20,6 +21,7 @@ #include <asm/abi.h> #include <asm/mips-cps.h> +#include <asm/page.h> #include <asm/vdso.h> /* 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) szlin@debian.org, 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 paul.burton@imgtec.com 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 paul.burton@imgtec.com Cc: Jason Cooper jason@lakedaemon.net Cc: Marc Zyngier marc.zyngier@arm.com Cc: Thomas Gleixner tglx@linutronix.de Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17040/ Signed-off-by: Ralf Baechle ralf@linux-mips.org Signed-off-by: SZ Lin (林上智) sz.lin@moxa.com
I do not understand. What "bug" is this fixing that this needs to be backported for?
thanks,
greg k-h