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Chen-Yu Tsai f3cc4e1d44 ARM: dma-api: fix max_pfn off-by-one error in __dma_supported()
max_pfn, as set in arch/arm/mm/init.c:

    static void __init find_limits(unsigned long *min,
				   unsigned long *max_low,
				   unsigned long *max_high)
    {
	    *max_low = PFN_DOWN(memblock_get_current_limit());
	    *min = PFN_UP(memblock_start_of_DRAM());
	    *max_high = PFN_DOWN(memblock_end_of_DRAM());
    }

with memblock_end_of_DRAM() pointing to the next byte after DRAM.  As
such, max_pfn points to the PFN after the end of DRAM.

Thus when using max_pfn to check DMA masks, we should subtract one when
checking DMA ranges against it.

Commit 8bf1268f48 ("ARM: dma-api: fix off-by-one error in
__dma_supported()") fixed the same issue, but missed this spot.

This issue was found while working on the sun4i-csi v4l2 driver on the
Allwinner R40 SoC.  On Allwinner SoCs, DRAM is offset at 0x40000000, and
we are starting to use of_dma_configure() with the "dma-ranges" property
in the device tree to have the DMA API handle the offset.

In this particular instance, dma-ranges was set to the same range as the
actual available (2 GiB) DRAM.  The following error appeared when the
driver attempted to allocate a buffer:

    sun4i-csi 1c09000.csi: Coherent DMA mask 0x7fffffff (pfn 0x40000-0xc0000)
    covers a smaller range of system memory than the DMA zone pfn 0x0-0xc0001
    sun4i-csi 1c09000.csi: dma_alloc_coherent of size 307200 failed

Fixing the off-by-one error makes things work.

Link: http://lkml.kernel.org/r/20191224030239.5656-1-wens@kernel.org
Fixes: 11a5aa3256 ("ARM: dma-mapping: check DMA mask against available memory")
Fixes: 9f28cde0bc ("ARM: another fix for the DMA mapping checks")
Fixes: ab746573c4 ("ARM: dma-mapping: allow larger DMA mask than supported")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-02-04 03:05:27 +00:00
arch ARM: dma-api: fix max_pfn off-by-one error in __dma_supported() 2020-02-04 03:05:27 +00:00
block SCSI misc on 20200129 2020-01-29 18:16:16 -08:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto treewide: remove redundant IS_ERR() before error code check 2020-02-04 03:05:27 +00:00
Documentation smp_mb__{before,after}_atomic(): update Documentation 2020-02-04 03:05:23 +00:00
drivers treewide: remove redundant IS_ERR() before error code check 2020-02-04 03:05:27 +00:00
fs treewide: remove redundant IS_ERR() before error code check 2020-02-04 03:05:27 +00:00
include include/linux/cpumask.h: don't calculate length of the input string 2020-02-04 03:05:27 +00:00
init init/main.c: fix misleading "This architecture does not have kernel memory protection" message 2020-01-31 10:30:41 -08:00
ipc proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
kernel proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
lib lib: new testcases for bitmap_parse{_user} 2020-02-04 03:05:27 +00:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
net treewide: remove redundant IS_ERR() before error code check 2020-02-04 03:05:27 +00:00
samples proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
scripts mm: remove __krealloc 2020-02-04 03:05:24 +00:00
security linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
sound treewide: remove redundant IS_ERR() before error code check 2020-02-04 03:05:27 +00:00
tools bitops: more BITS_TO_* macros 2020-02-04 03:05:26 +00:00
usr initramfs: do not show compression mode choice if INITRAMFS_SOURCE is empty 2020-02-03 17:31:43 +00:00
virt Merge branch 'cve-2019-3016' into kvm-next-5.6 2020-01-30 18:47:59 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap pci-v5.6-changes 2020-01-31 14:48:54 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS open: introduce openat2(2) syscall 2020-01-18 09:19:18 -05:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS pci-v5.6-changes 2020-01-31 14:48:54 -08:00
Makefile Kbuild updates for v5.6 2020-02-01 10:01:52 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.