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Orjan Eide f2bcdb43a7 ANDROID: staging: ion: Skip sync if not mapped 
Only sync the sg-list of an Ion dma-buf attachment when the attachment
is actually mapped on the device.

dma-bufs may be synced at any time. It can be reached from user space
via DMA_BUF_IOCTL_SYNC, so there are no guarantees from callers on when
syncs may be attempted, and dma_buf_end_cpu_access() and
dma_buf_begin_cpu_access() may not be paired.

Since the sg_list's dma_address isn't set up until the buffer is used
on the device, and dma_map_sg() is called on it, the dma_address will be
NULL if sync is attempted on the dma-buf before it's mapped on a device.

Before v5.0 (commit 55897af630 ("dma-direct: merge swiotlb_dma_ops
into the dma_direct code")) this was a problem as the dma-api (at least
the swiotlb_dma_ops on arm64) would use the potentially invalid
dma_address. How that failed depended on how the device handled physical
address 0. If 0 was a valid address to physical ram, that page would get
flushed a lot, while the actual pages in the buffer would not get synced
correctly. While if 0 is an invalid address it cause a fault trigger a
crash.

In v5.0 this was incidentally fixed by commit 55897af630 ("dma-direct:
merge swiotlb_dma_ops into the dma_direct code"), as this moved the
dma-api to use the page pointer in the sg_list, and (for Ion buffers at
least) this will always be valid if the sg_list exists at all.

But, this issue is re-introduced in v5.3 with
commit 449fa54d68 ("dma-direct: correct the physical addr in
dma_direct_sync_sg_for_cpu/device") moves the dma-api back to the old
behaviour and picks the dma_address that may be invalid.

dma-buf core doesn't ensure that the buffer is mapped on the device, and
thus have a valid sg_list, before calling the exporter's
begin_cpu_access.

Bug: 155685387

Change-Id: Ie4da5a875957c831ce5b1345b5794357b844c84c
Signed-off-by: Orjan Eide <orjan.eide@arm.com>
Signed-off-by: Anders Pedersen <anders.pedersen@arm.corp-partner.google.com>
(cherry picked from commit 644ae915cd5df31179144c5b949539520a14f39a)
2020-06-09 20:16:59 +00:00
arch ANDROID: GKI: Enable CONFIG_DEBUG_FS for Android S 2020-06-09 18:58:33 +00:00
block Linux 5.7 2020-06-01 09:17:17 +02:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto crypto: engine - do not requeue in case of fatal error 2020-05-28 17:27:52 +10:00
Documentation Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
drivers ANDROID: staging: ion: Skip sync if not mapped 2020-06-09 20:16:59 +00:00
fs Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
include ANDROID: staging: ion: Skip sync if not mapped 2020-06-09 20:16:59 +00:00
init Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
ipc Revert "ANDROID: vfs: Add permission2 for filesystems with per mount permissions" 2020-05-29 08:49:28 +02:00
kernel Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
lib Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
net FROMLIST: esp: select CRYPTO_SEQIV 2020-06-05 09:21:46 +02:00
samples There are a lot of objtool changes in this cycle, all across the map: 2020-06-01 13:13:00 -07:00
scripts Merge 69fc06f70f ("Merge tag 'objtool-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip") into android-mainline 2020-06-07 13:42:28 +02:00
security Merge a7092c8204 ("Merge tag 'perf-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip") into android-mainline 2020-06-09 09:55:37 +02:00
sound Linux 5.7 2020-06-01 09:17:17 +02:00
tools Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
usr kbuild: fix comment about missing include guard detection 2020-04-11 12:09:48 +09:00
virt arm64 updates for 5.8 2020-06-01 15:18:27 -07:00
.clang-format clang-format: Update with the latest for_each macro list 2020-04-18 13:49:33 +02:00
.cocciconfig
.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 .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
.mailmap i2c: use my kernel.org address from now on 2020-05-05 16:29:09 +02:00
build.config.aarch64 ANDROID: Specify MAKE_GOALS and optimize targets 2020-03-27 01:55:37 +00:00
build.config.allmodconfig ANDROID: build.config.allmodconfig: Remove outdated XFS_FS comment 2020-04-16 16:17:56 -07:00
build.config.allmodconfig.aarch64 ANDROID: create build.configs for allmodconfig 2019-09-04 15:49:40 +00:00
build.config.allmodconfig.arm ANDROID: Add build.config files for ARM 32-bit 2020-03-13 21:43:21 +00:00
build.config.allmodconfig.x86_64 ANDROID: create build.configs for allmodconfig 2019-09-04 15:49:40 +00:00
build.config.arm ANDROID: Specify MAKE_GOALS and optimize targets 2020-03-27 01:55:37 +00:00
build.config.common ANDROID: clang: update to 11.0.1 2020-05-18 19:36:33 +00:00
build.config.db845c ANDROID: db845c build: Use merge_configs 2020-04-01 11:16:34 -07:00
build.config.gki ANDROID: gki: Removed cf modules from gki_defconfig 2020-02-01 00:27:50 +00:00
build.config.gki_kasan ANDROID: Rename build.config.gki.arch_kasan 2020-05-05 20:50:47 +00:00
build.config.gki_kasan.aarch64 ANDROID: Drop ABI monitoring from KASAN build config 2020-05-06 13:08:38 +02:00
build.config.gki_kasan.x86_64 ANDROID: Rename build.config.gki.arch_kasan 2020-05-05 20:50:47 +00:00
build.config.gki.aarch64 ANDROID: Remove ABI Monitoring on android-mainline 2020-01-27 13:53:52 +00:00
build.config.gki.x86_64 ANDROID: refactor build.config files to remove duplication 2019-08-30 14:55:29 +01:00
build.config.x86_64 ANDROID: Specify MAKE_GOALS and optimize targets 2020-03-27 01:55:37 +00:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
Makefile Merge commit '533b220f7be4' ("Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux") into android-mainline 2020-06-09 14:25:19 +00:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
README.md ANDROID: README: Add requirement for "Bug:" tag for FROMLIST 2020-05-01 15:36:12 -07:00

README.md

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

    • Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux, additions of EXPORT_SYMBOL_GPL() require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export.
    • When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.

  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass script/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry picked from commit ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry picked from commit ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [joe: Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • add a Bug: tag with the Android bug (required for patches not accepted into a maintainer tree)
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)