Add LSM hooks for use by the new mount API and filesystem context code.
This includes:
(1) Hooks to handle allocation, duplication and freeing of the security
record attached to a filesystem context.
(2) A hook to snoop source specifications. There may be multiple of these
if the filesystem supports it. They will to be local files/devices if
fs_context::source_is_dev is true and will be something else, possibly
remote server specifications, if false.
(3) A hook to snoop superblock configuration options in key[=val] form.
If the LSM decides it wants to handle it, it can suppress the option
being passed to the filesystem. Note that 'val' may include commas
and binary data with the fsopen patch.
(4) A hook to perform validation and allocation after the configuration
has been done but before the superblock is allocated and set up.
(5) A hook to transfer the security from the context to a newly created
superblock.
(6) A hook to rule on whether a path point can be used as a mountpoint.
These are intended to replace:
security_sb_copy_data
security_sb_kern_mount
security_sb_mount
security_sb_set_mnt_opts
security_sb_clone_mnt_opts
security_sb_parse_opts_str
[AV -- some of the methods being replaced are already gone, some of the
methods are not added for the lack of need]
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-security-module@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Because the new API passes in key,value parameters, match_token() cannot be
used with it. Instead, provide three new helpers to aid with parsing:
(1) fs_parse(). This takes a parameter and a simple static description of
all the parameters and maps the key name to an ID. It returns 1 on a
match, 0 on no match if unknowns should be ignored and some other
negative error code on a parse error.
The parameter description includes a list of key names to IDs, desired
parameter types and a list of enumeration name -> ID mappings.
[!] Note that for the moment I've required that the key->ID mapping
array is expected to be sorted and unterminated. The size of the
array is noted in the fsconfig_parser struct. This allows me to use
bsearch(), but I'm not sure any performance gain is worth the hassle
of requiring people to keep the array sorted.
The parameter type array is sized according to the number of parameter
IDs and is indexed directly. The optional enum mapping array is an
unterminated, unsorted list and the size goes into the fsconfig_parser
struct.
The function can do some additional things:
(a) If it's not ambiguous and no value is given, the prefix "no" on
a key name is permitted to indicate that the parameter should
be considered negatory.
(b) If the desired type is a single simple integer, it will perform
an appropriate conversion and store the result in a union in
the parse result.
(c) If the desired type is an enumeration, {key ID, name} will be
looked up in the enumeration list and the matching value will
be stored in the parse result union.
(d) Optionally generate an error if the key is unrecognised.
This is called something like:
enum rdt_param {
Opt_cdp,
Opt_cdpl2,
Opt_mba_mpbs,
nr__rdt_params
};
const struct fs_parameter_spec rdt_param_specs[nr__rdt_params] = {
[Opt_cdp] = { fs_param_is_bool },
[Opt_cdpl2] = { fs_param_is_bool },
[Opt_mba_mpbs] = { fs_param_is_bool },
};
const const char *const rdt_param_keys[nr__rdt_params] = {
[Opt_cdp] = "cdp",
[Opt_cdpl2] = "cdpl2",
[Opt_mba_mpbs] = "mba_mbps",
};
const struct fs_parameter_description rdt_parser = {
.name = "rdt",
.nr_params = nr__rdt_params,
.keys = rdt_param_keys,
.specs = rdt_param_specs,
.no_source = true,
};
int rdt_parse_param(struct fs_context *fc,
struct fs_parameter *param)
{
struct fs_parse_result parse;
struct rdt_fs_context *ctx = rdt_fc2context(fc);
int ret;
ret = fs_parse(fc, &rdt_parser, param, &parse);
if (ret < 0)
return ret;
switch (parse.key) {
case Opt_cdp:
ctx->enable_cdpl3 = true;
return 0;
case Opt_cdpl2:
ctx->enable_cdpl2 = true;
return 0;
case Opt_mba_mpbs:
ctx->enable_mba_mbps = true;
return 0;
}
return -EINVAL;
}
(2) fs_lookup_param(). This takes a { dirfd, path, LOOKUP_EMPTY? } or
string value and performs an appropriate path lookup to convert it
into a path object, which it will then return.
If the desired type was a blockdev, the type of the looked up inode
will be checked to make sure it is one.
This can be used like:
enum foo_param {
Opt_source,
nr__foo_params
};
const struct fs_parameter_spec foo_param_specs[nr__foo_params] = {
[Opt_source] = { fs_param_is_blockdev },
};
const char *char foo_param_keys[nr__foo_params] = {
[Opt_source] = "source",
};
const struct constant_table foo_param_alt_keys[] = {
{ "device", Opt_source },
};
const struct fs_parameter_description foo_parser = {
.name = "foo",
.nr_params = nr__foo_params,
.nr_alt_keys = ARRAY_SIZE(foo_param_alt_keys),
.keys = foo_param_keys,
.alt_keys = foo_param_alt_keys,
.specs = foo_param_specs,
};
int foo_parse_param(struct fs_context *fc,
struct fs_parameter *param)
{
struct fs_parse_result parse;
struct foo_fs_context *ctx = foo_fc2context(fc);
int ret;
ret = fs_parse(fc, &foo_parser, param, &parse);
if (ret < 0)
return ret;
switch (parse.key) {
case Opt_source:
return fs_lookup_param(fc, &foo_parser, param,
&parse, &ctx->source);
default:
return -EINVAL;
}
}
(3) lookup_constant(). This takes a table of named constants and looks up
the given name within it. The table is expected to be sorted such
that bsearch() be used upon it.
Possibly I should require the table be terminated and just use a
for-loop to scan it instead of using bsearch() to reduce hassle.
Tables look something like:
static const struct constant_table bool_names[] = {
{ "0", false },
{ "1", true },
{ "false", false },
{ "no", false },
{ "true", true },
{ "yes", true },
};
and a lookup is done with something like:
b = lookup_constant(bool_names, param->string, -1);
Additionally, optional validation routines for the parameter description
are provided that can be enabled at compile time. A later patch will
invoke these when a filesystem is registered.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Introduce a set of logging functions through which informational messages,
warnings and error messages incurred by the mount procedure can be logged
and, in a future patch, passed to userspace instead by way of the
filesystem configuration context file descriptor.
There are four functions:
(1) infof(const char *fmt, ...);
Logs an informational message.
(2) warnf(const char *fmt, ...);
Logs a warning message.
(3) errorf(const char *fmt, ...);
Logs an error message.
(4) invalf(const char *fmt, ...);
As errof(), but returns -EINVAL so can be used on a return statement.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This is an eventual replacement for vfs_submount() uses. Unlike the
"mount" and "remount" cases, the users of that thing are not in VFS -
they are buried in various ->d_automount() instances and rather than
converting them all at once we introduce the (thankfully small and
simple) infrastructure here and deal with the prospective users in
afs, nfs, etc. parts of the series.
Here we just introduce a new constructor (fs_context_for_submount())
along with the corresponding enum constant to be put into fc->purpose
for those.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Replace do_remount_sb() with a function, reconfigure_super(), that's
fs_context aware. The fs_context is expected to be parameterised already
and have ->root pointing to the superblock to be reconfigured.
A legacy wrapper is provided that is intended to be called from the
fs_context ops when those appear, but for now is called directly from
reconfigure_super(). This wrapper invokes the ->remount_fs() superblock op
for the moment. It is intended that the remount_fs() op will be phased
out.
The fs_context->purpose is set to FS_CONTEXT_FOR_RECONFIGURE to indicate
that the context is being used for reconfiguration.
do_umount_root() is provided to consolidate remount-to-R/O for umount and
emergency remount by creating a context and invoking reconfiguration.
do_remount(), do_umount() and do_emergency_remount_callback() are switched
to use the new process.
[AV -- fold UMOUNT and EMERGENCY_REMOUNT in; fixes the
umount / bug, gets rid of pointless complexity]
[AV -- set ->net_ns in all cases; nfs remount will need that]
[AV -- shift security_sb_remount() call into reconfigure_super(); the callers
that didn't do security_sb_remount() have NULL fc->security anyway, so it's
a no-op for them]
Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Roll the handling of subtypes into do_new_mount() and vfs_get_tree(). The
former determines any subtype string and hangs it off the fs_context; the
latter applies it.
Make do_new_mount() create, parameterise and commit an fs_context and
create a mount for itself rather than calling vfs_kern_mount().
[AV -- missing kstrdup()]
[AV -- ... and no kstrdup() if we get to setting ->s_submount - we
simply transfer it from fc, leaving NULL behind]
[AV -- constify ->s_submount, while we are at it]
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Create a new helper, vfs_create_mount(), that creates a detached vfsmount
object from an fs_context that has a superblock attached to it.
Almost all uses will be paired with immediately preceding vfs_get_tree();
add a helper for such combination.
Switch vfs_kern_mount() to use this.
NOTE: mild behaviour change; passing NULL as 'device name' to
something like procfs will change /proc/*/mountstats - "device none"
instead on "no device". That is consistent with /proc/mounts et.al.
[do'h - EXPORT_SYMBOL_GPL slipped in by mistake; removed]
[AV -- remove confused comment from vfs_create_mount()]
[AV -- removed the second argument]
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Introduce a filesystem context concept to be used during superblock
creation for mount and superblock reconfiguration for remount. This is
allocated at the beginning of the mount procedure and into it is placed:
(1) Filesystem type.
(2) Namespaces.
(3) Source/Device names (there may be multiple).
(4) Superblock flags (SB_*).
(5) Security details.
(6) Filesystem-specific data, as set by the mount options.
Accessor functions are then provided to set up a context, parameterise it
from monolithic mount data (the data page passed to mount(2)) and tear it
down again.
A legacy wrapper is provided that implements what will be the basic
operations, wrapping access to filesystems that aren't yet aware of the
fs_context.
Finally, vfs_kern_mount() is changed to make use of the fs_context and
mount_fs() is replaced by vfs_get_tree(), called from vfs_kern_mount().
[AV -- add missing kstrdup()]
[AV -- put_cred() can be unconditional - fc->cred can't be NULL]
[AV -- take legacy_validate() contents into legacy_parse_monolithic()]
[AV -- merge KERNEL_MOUNT and USER_MOUNT]
[AV -- don't unlock superblock on success return from vfs_get_tree()]
[AV -- kill 'reference' argument of init_fs_context()]
Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull ARM SoC fixes from Olof Johansson:
"A bigger batch than I anticipated this week, for two reasons:
- Some fallout on Davinci from board file -> DTB conversion, that
also includes a few longer-standing fixes (i.e. not recent
regressions).
- drivers/reset material that has been in linux-next for a while, but
didn't get sent to us until now for a variety of reasons
(maintainer out sick, holidays, etc). There's a functional
dependency in there such that one platform (Altera's SoCFPGA) won't
boot without one of the patches; instead of reverting the patch
that got merged, I looked at this set and decided it was small
enough that I'll pick it up anyway. If you disagree I can revisit
with a smaller set.
That being said, there's also a handful of the usual stuff:
- Fix for a crash on Armada 7K/8K when the kernel touches
PSCI-reserved memory
- Fix for PCIe reset on Macchiatobin (Armada 8K development board,
what this email is sent from in fact :)
- Enable a few new-merged modules for Amlogic in arm64 defconfig
- Error path fixes on Integrator
- Build fix for Renesas and Qualcomm
- Initialization fix for Renesas RZ/G2E
.. plus a few more fixlets"
* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (28 commits)
ARM: integrator: impd1: use struct_size() in devm_kzalloc()
qcom-scm: Include <linux/err.h> header
gpio: pl061: handle failed allocations
ARM: dts: kirkwood: Fix polarity of GPIO fan lines
arm64: dts: marvell: mcbin: fix PCIe reset signal
arm64: dts: marvell: armada-ap806: reserve PSCI area
ARM: dts: da850-lcdk: Correct the sound card name
ARM: dts: da850-lcdk: Correct the audio codec regulators
ARM: dts: da850-evm: Correct the sound card name
ARM: dts: da850-evm: Correct the audio codec regulators
ARM: davinci: omapl138-hawk: fix label names in GPIO lookup entries
ARM: davinci: dm644x-evm: fix label names in GPIO lookup entries
ARM: davinci: dm355-evm: fix label names in GPIO lookup entries
ARM: davinci: da850-evm: fix label names in GPIO lookup entries
ARM: davinci: da830-evm: fix label names in GPIO lookup entries
arm64: defconfig: enable modules for amlogic s400 sound card
reset: uniphier-glue: Add AHCI reset control support in glue layer
dt-bindings: reset: uniphier: Add AHCI core reset description
reset: uniphier-usb3: Rename to reset-uniphier-glue
dt-bindings: reset: uniphier: Replace the expression of USB3 with generic peripherals
...
Late reset controller changes for v5.0
This adds missing deassert functionality to the ARC HSDK reset driver,
fixes some indentation and grammar issues in the kernel docs, adds a
helper to count the number of resets on a device for the non-DT case
as well, adds an early reset driver for SoCFPGA and simple reset driver
support for Stratix10, and generalizes the uniphier USB3 glue layer
reset to also cover AHCI.
* tag 'reset-for-5.0-rc2' of git://git.pengutronix.de/git/pza/linux:
reset: uniphier-glue: Add AHCI reset control support in glue layer
dt-bindings: reset: uniphier: Add AHCI core reset description
reset: uniphier-usb3: Rename to reset-uniphier-glue
dt-bindings: reset: uniphier: Replace the expression of USB3 with generic peripherals
ARM: socfpga: dts: document "altr,stratix10-rst-mgr" binding
reset: socfpga: add an early reset driver for SoCFPGA
reset: fix null pointer dereference on dev by dev_name
reset: Add reset_control_get_count()
reset: Improve reset controller kernel docs
ARC: HSDK: improve reset driver
Signed-off-by: Olof Johansson <olof@lixom.net>
Commit 49e54187ae ("ata: libahci_platform: comply to PHY framework") uses
the PHY_MODE_SATA, but that enum had not yet been added. This caused a
build failure for me, with today's linux.git.
Also, there is a potentially conflicting (mis-named) PHY_MODE_SATA, hiding
in the Marvell Berlin SATA PHY driver.
Fix the build by:
1) Renaming Marvell's defined value to a more scoped name,
in order to avoid any potential conflicts: PHY_BERLIN_MODE_SATA.
2) Adding the missing enum, which was going to be added anyway as part
of [1].
[1] https://lkml.kernel.org/r/20190108163124.6409-3-miquel.raynal@bootlin.com
Fixes: 49e54187ae ("ata: libahci_platform: comply to PHY framework")
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Olof Johansson <olof@lixom.net>
Cc: Grzegorz Jaszczyk <jaz@semihalf.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull dma_zalloc_coherent() removal from Christoph Hellwig:
"We've always had a weird situation around dma_zalloc_coherent. To
safely support mapping the allocations to userspace major
architectures like x86 and arm have always zeroed allocations from
dma_alloc_coherent, but a couple other architectures were missing that
zeroing either always or in corner cases.
Then later we grew anothe dma_zalloc_coherent interface to explicitly
request zeroing, but that just added __GFP_ZERO to the allocation
flags, which for some allocators that didn't end up using the page
allocator ended up being a no-op and still not zeroing the
allocations.
So for this merge window I fixed up all remaining architectures to
zero the memory in dma_alloc_coherent, and made dma_zalloc_coherent a
no-op wrapper around dma_alloc_coherent, which fixes all of the above
issues.
dma_zalloc_coherent is now pointless and can go away, and Luis helped
me writing a cocchinelle script and patch series to kill it, which I
think we should apply now just after -rc1 to finally settle these
issue"
* tag 'remove-dma_zalloc_coherent-5.0' of git://git.infradead.org/users/hch/dma-mapping:
dma-mapping: remove dma_zalloc_coherent()
cross-tree: phase out dma_zalloc_coherent() on headers
cross-tree: phase out dma_zalloc_coherent()
Pull ceph updates from Ilya Dryomov:
"A patch to allow setting abort_on_full and a fix for an old "rbd
unmap" edge case, marked for stable"
* tag 'ceph-for-5.0-rc2' of git://github.com/ceph/ceph-client:
rbd: don't return 0 on unmap if RBD_DEV_FLAG_REMOVING is set
ceph: use vmf_error() in ceph_filemap_fault()
libceph: allow setting abort_on_full for rbd
Pull x86 fixes from Ingo Molnar:
"A 32-bit build fix, CONFIG_RETPOLINE fixes and rename CONFIG_RESCTRL
to CONFIG_X86_RESCTRL"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, modpost: Replace last remnants of RETPOLINE with CONFIG_RETPOLINE
x86/cache: Rename config option to CONFIG_X86_RESCTRL
samples/seccomp: Fix 32-bit build
Pull power management updates from Rafael Wysocki:
"These fix fallout after starting to use hrtimers in the runtime PM
framework, fix a few cpufreq issues, fix a recently broken reference
to cpuidle documentation, update MAINTAINERS entries for cpufreq and
cpuidle and make the recently added system suspend and resume support
in devfreq actually work.
Specifics:
- Prevent integer overflows from occurring on 32-bit when converting
milliseconds to nanoseconds in the runtime PM framework and update
comments that still refer to jiffies in it (Vincent Guittot,
Ladislav Michl).
- Fix the SCMI cpufreq driver to always use the same frequency units
for arch_set_freq_scale() and make the scale-invariant load
tracking acutally work with this driver (Quentin Perret).
- Fix freeing of dynamic OPPs in the SCPI and SCMI cpufreq drivers
broken during the 4.20 defelopment cycle (Viresh Kumar).
- Prevent the cpufreq core from attempting to return the current
frequency of offline CPUs (Sudeep Holla).
- Add devfreq suspend and resume hooks (missed previously) to the PM
core to make the recently added system suspend and resume support
in devfreq actually work (Lukasz Luba).
- Update MAINTAINERS entries for cpufreq and cpuidle, mostly to add
references to new/current documentation to them (Rafael Wysocki).
- Fix a recently broken reference to cpuidle documentation (Otto
Sabart)"
* tag 'pm-5.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM-runtime: Fix autosuspend_delay on 32bits arch
PM-runtime: Fix 'jiffies' in comments after switch to hrtimers
cpufreq: scmi: Fix frequency invariance in slow path
doc: trace: fix reference to cpuidle documentation file
cpufreq: check if policy is inactive early in __cpufreq_get()
cpufreq: scpi/scmi: Fix freeing of dynamic OPPs
cpuidle / Documentation: Update cpuidle MAINTAINERS entry
cpufreq / Documentation: Update cpufreq MAINTAINERS entry
PM: sleep: call devfreq suspend/resume
Since commit e6f6d63ed1 ("drm/msm: add headless gpu device for imx5")
the DRM_MSM symbol can be selected by SOC_IMX5 causing the following
error when building imx_v6_v7_defconfig:
In file included from ../drivers/gpu/drm/msm/adreno/a5xx_gpu.c:17:0:
../include/linux/qcom_scm.h: In function 'qcom_scm_set_cold_boot_addr':
../include/linux/qcom_scm.h:73:10: error: 'ENODEV' undeclared (first use in this function)
return -ENODEV;
Include the <linux/err.h> header file to fix this problem.
Reported-by: kernelci.org bot <bot@kernelci.org>
Fixes: e6f6d63ed1 ("drm/msm: add headless gpu device for imx5")
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
syzbot reported the following regression in the latest merge window and
it was confirmed by Qian Cai that a similar bug was visible from a
different context.
======================================================
WARNING: possible circular locking dependency detected
4.20.0+ #297 Not tainted
------------------------------------------------------
syz-executor0/8529 is trying to acquire lock:
000000005e7fb829 (&pgdat->kswapd_wait){....}, at:
__wake_up_common_lock+0x19e/0x330 kernel/sched/wait.c:120
but task is already holding lock:
000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: spin_lock
include/linux/spinlock.h:329 [inline]
000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: rmqueue_bulk
mm/page_alloc.c:2548 [inline]
000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: __rmqueue_pcplist
mm/page_alloc.c:3021 [inline]
000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: rmqueue_pcplist
mm/page_alloc.c:3050 [inline]
000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: rmqueue
mm/page_alloc.c:3072 [inline]
000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at:
get_page_from_freelist+0x1bae/0x52a0 mm/page_alloc.c:3491
It appears to be a false positive in that the only way the lock ordering
should be inverted is if kswapd is waking itself and the wakeup
allocates debugging objects which should already be allocated if it's
kswapd doing the waking. Nevertheless, the possibility exists and so
it's best to avoid the problem.
This patch flags a zone as needing a kswapd using the, surprisingly,
unused zone flag field. The flag is read without the lock held to do
the wakeup. It's possible that the flag setting context is not the same
as the flag clearing context or for small races to occur. However, each
race possibility is harmless and there is no visible degredation in
fragmentation treatment.
While zone->flag could have continued to be unused, there is potential
for moving some existing fields into the flags field instead.
Particularly read-mostly ones like zone->initialized and
zone->contiguous.
Link: http://lkml.kernel.org/r/20190103225712.GJ31517@techsingularity.net
Fixes: 1c30844d2d ("mm: reclaim small amounts of memory when an external fragmentation event occurs")
Reported-by: syzbot+93d94a001cfbce9e60e1@syzkaller.appspotmail.com
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Qian Cai <cai@lca.pw>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
dma_zalloc_coherent() is no longer needed as it has no users because
dma_alloc_coherent() already zeroes out memory for us.
The Coccinelle grammar rule that used to check for dma_alloc_coherent()
+ memset() is modified so that it just tells the user that the memset is
not needed anymore.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
We already need to zero out memory for dma_alloc_coherent(), as such
using dma_zalloc_coherent() is superflous. Phase it out.
This change was generated with the following Coccinelle SmPL patch:
@ replace_dma_zalloc_coherent @
expression dev, size, data, handle, flags;
@@
-dma_zalloc_coherent(dev, size, handle, flags)
+dma_alloc_coherent(dev, size, handle, flags)
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
[hch: re-ran the script on the latest tree]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Introduce a new option abort_on_full, default to false. Then
we can get -ENOSPC when the pool is full, or reaches quota.
[ Don't show abort_on_full in /proc/mounts. ]
Signed-off-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Currently the reset core has internal support for counting the number of
resets for a device described in DT. Generalize this to devices using
lookup resets, and export it for public use.
This will be used by generic drivers that need to be sure a device is
controlled by a single, dedicated reset line (e.g. vfio-platform).
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[p.zabel@pengutronix.de: fixed a typo in reset_control_get_count comment]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Pull more Kbuild updates from Masahiro Yamada:
- improve boolinit.cocci and use_after_iter.cocci semantic patches
- fix alignment for kallsyms
- move 'asm goto' compiler test to Kconfig and clean up jump_label
CONFIG option
- generate asm-generic wrappers automatically if arch does not
implement mandatory UAPI headers
- remove redundant generic-y defines
- misc cleanups
* tag 'kbuild-v4.21-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kconfig: rename generated .*conf-cfg to *conf-cfg
kbuild: remove unnecessary stubs for archheader and archscripts
kbuild: use assignment instead of define ... endef for filechk_* rules
arch: remove redundant UAPI generic-y defines
kbuild: generate asm-generic wrappers if mandatory headers are missing
arch: remove stale comments "UAPI Header export list"
riscv: remove redundant kernel-space generic-y
kbuild: change filechk to surround the given command with { }
kbuild: remove redundant target cleaning on failure
kbuild: clean up rule_dtc_dt_yaml
kbuild: remove UIMAGE_IN and UIMAGE_OUT
jump_label: move 'asm goto' support test to Kconfig
kallsyms: lower alignment on ARM
scripts: coccinelle: boolinit: drop warnings on named constants
scripts: coccinelle: check for redeclaration
kconfig: remove unused "file" field of yylval union
nds32: remove redundant kernel-space generic-y
nios2: remove unneeded HAS_DMA define
Pull dma-mapping fixes from Christoph Hellwig:
"Fix various regressions introduced in this cycles:
- fix dma-debug tracking for the map_page / map_single
consolidatation
- properly stub out DMA mapping symbols for !HAS_DMA builds to avoid
link failures
- fix AMD Gart direct mappings
- setup the dma address for no kernel mappings using the remap
allocator"
* tag 'dma-mapping-4.21-1' of git://git.infradead.org/users/hch/dma-mapping:
dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING for remapped allocations
x86/amd_gart: fix unmapping of non-GART mappings
dma-mapping: remove a few unused exports
dma-mapping: properly stub out the DMA API for !CONFIG_HAS_DMA
dma-mapping: remove dmam_{declare,release}_coherent_memory
dma-mapping: implement dmam_alloc_coherent using dmam_alloc_attrs
dma-mapping: implement dma_map_single_attrs using dma_map_page_attrs
Pull chrome platform updates from Benson Leung:
- Changes for EC_MKBP_EVENT_SENSOR_FIFO handling.
- Also, maintainership changes. Olofj out, Enric balletbo in.
* tag 'tag-chrome-platform-for-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/bleung/chrome-platform:
MAINTAINERS: add maintainers for ChromeOS EC sub-drivers
MAINTAINERS: platform/chrome: Add Enric as a maintainer
MAINTAINERS: platform/chrome: remove myself as maintainer
platform/chrome: don't report EC_MKBP_EVENT_SENSOR_FIFO as wakeup
platform/chrome: straighten out cros_ec_get_{next,host}_event() error codes
Pull block updates and fixes from Jens Axboe:
- Pulled in MD changes that Shaohua had queued up for 4.21.
Unfortunately we lost Shaohua late 2018, I'm sending these in on his
behalf.
- In conjunction with the above, I added a CREDITS entry for Shaoua.
- sunvdc queue restart fix (Ming)
* tag 'for-linus-20190104' of git://git.kernel.dk/linux-block:
Add CREDITS entry for Shaohua Li
block: sunvdc: don't run hw queue synchronously from irq context
md: fix raid10 hang issue caused by barrier
raid10: refactor common wait code from regular read/write request
md: remvoe redundant condition check
lib/raid6: add option to skip algo benchmarking
lib/raid6: sort algos in rough performance order
lib/raid6: check for assembler SSSE3 support
lib/raid6: avoid __attribute_const__ redefinition
lib/raid6: add missing include for raid6test
md: remove set but not used variable 'bi_rdev'
Pull fbdev updates from Bartlomiej Zolnierkiewicz:
"This time the pull request is really small.
The most notable changes are fixing fbcon to not cause crash on
unregister_framebuffer() operation when there is more than one
framebuffer, adding config option to center the bootup logo and making
FB_BACKLIGHT config option tristate (which in turn uncovered incorrect
FB_BACKLIGHT usage by DRM's nouveau driver).
Summary:
- fix fbcon to not cause crash on unregister_framebuffer() when there
is more than one framebuffer (Noralf Trønnes)
- improve support for small rotated displays (Peter Rosin)
- fix probe failure handling in udlfb driver (Dan Carpenter)
- add config option to center the bootup logo (Peter Rosin)
- make FB_BACKLIGHT config option tristate (Rob Clark)
- remove superfluous HAS_DMA dependency for goldfishfb driver (Geert
Uytterhoeven)
- misc fixes (Alexey Khoroshilov, YueHaibing, Colin Ian King, Lubomir
Rintel)
- misc cleanups (Yangtao Li, Wen Yang)
also there is DRM's nouveau driver fix for wrong FB_BACKLIGHT config
option usage (FB_BACKLIGHT is for internal fbdev subsystem use only)"
* tag 'fbdev-v4.21' of git://github.com/bzolnier/linux:
drm/nouveau: fix incorrect FB_BACKLIGHT usage in Kconfig
fbdev: fbcon: Fix unregister crash when more than one framebuffer
fbdev: Remove depends on HAS_DMA in case of platform dependency
pxa168fb: trivial typo fix
fbdev: fsl-diu: remove redundant null check on cmap
fbdev: omap2: omapfb: convert to DEFINE_SHOW_ATTRIBUTE
fbdev: uvesafb: fix spelling mistake "memoery" -> "memory"
fbdev: fbmem: add config option to center the bootup logo
fbdev: fbmem: make fb_show_logo_line return the end instead of the height
video: fbdev: pxafb: Fix "WARNING: invalid free of devm_ allocated data"
fbdev: fbmem: behave better with small rotated displays and many CPUs
video: clps711x-fb: release disp device node in probe()
fbdev: make FB_BACKLIGHT a tristate
udlfb: fix some inconsistent NULL checking
Pull HID updates from Jiri Kosina:
- high-resolution scrolling support that gracefully handles differences
between MS and Logitech implementations in HW, from Peter Hutterer
and Harry Cutts
- MSI IRQ support for intel-ish driver, from Song Hongyan
- support for new hardware (Cougar 700K, Odys Winbook 13, ASUS FX503VD,
ASUS T101HA) from Daniel M. Lambea, Hans de Goede and Aleix Roca
Nonell
- other small assorted fixups
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid: (22 commits)
HID: i2c-hid: Add Odys Winbook 13 to descriptor override
HID: lenovo: Add checks to fix of_led_classdev_register
HID: intel-ish-hid: add MSI interrupt support
HID: debug: Change to use DEFINE_SHOW_ATTRIBUTE macro
HID: doc: fix wrong data structure reference for UHID_OUTPUT
HID: intel-ish-hid: fixes incorrect error handling
HID: asus: Add support for the ASUS T101HA keyboard dock
HID: logitech: Use LDJ_DEVICE macro for existing Logitech mice
HID: logitech: Enable high-resolution scrolling on Logitech mice
HID: logitech: Add function to enable HID++ 1.0 "scrolling acceleration"
HID: logitech-hidpp: fix typo, hiddpp to hidpp
HID: input: use the Resolution Multiplier for high-resolution scrolling
HID: core: process the Resolution Multiplier
HID: core: store the collections as a basic tree
Input: add `REL_WHEEL_HI_RES` and `REL_HWHEEL_HI_RES`
HID: input: support Microsoft wireless radio control hotkey
HID: use macros in IS_INPUT_APPLICATION
HID: asus: Add support for the ASUS FX503VD laptop
HID: asus: Add event handler to catch unmapped Asus Vendor UsagePage codes
HID: cougar: Add support for Cougar 700K Gaming Keyboard
...
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label".
The jump label is controlled by HAVE_JUMP_LABEL, which is defined
like this:
#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
# define HAVE_JUMP_LABEL
#endif
We can improve this by testing 'asm goto' support in Kconfig, then
make JUMP_LABEL depend on CC_HAS_ASM_GOTO.
Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will
match to the real kernel capability.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Pull vfs mount API prep from Al Viro:
"Mount API prereqs.
Mostly that's LSM mount options cleanups. There are several minor
fixes in there, but nothing earth-shattering (leaks on failure exits,
mostly)"
* 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (27 commits)
mount_fs: suppress MAC on MS_SUBMOUNT as well as MS_KERNMOUNT
smack: rewrite smack_sb_eat_lsm_opts()
smack: get rid of match_token()
smack: take the guts of smack_parse_opts_str() into a new helper
LSM: new method: ->sb_add_mnt_opt()
selinux: rewrite selinux_sb_eat_lsm_opts()
selinux: regularize Opt_... names a bit
selinux: switch away from match_token()
selinux: new helper - selinux_add_opt()
LSM: bury struct security_mnt_opts
smack: switch to private smack_mnt_opts
selinux: switch to private struct selinux_mnt_opts
LSM: hide struct security_mnt_opts from any generic code
selinux: kill selinux_sb_get_mnt_opts()
LSM: turn sb_eat_lsm_opts() into a method
nfs_remount(): don't leak, don't ignore LSM options quietly
btrfs: sanitize security_mnt_opts use
selinux; don't open-code a loop in sb_finish_set_opts()
LSM: split ->sb_set_mnt_opts() out of ->sb_kern_mount()
new helper: security_sb_eat_lsm_opts()
...
Pull trivial vfs updates from Al Viro:
"A few cleanups + Neil's namespace_unlock() optimization"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
exec: make prepare_bprm_creds static
genheaders: %-<width>s had been there since v6; %-*s - since v7
VFS: use synchronize_rcu_expedited() in namespace_unlock()
iov_iter: reduce code duplication
Pull more ARM SoC updates from Olof Johansson:
"A few updates that we merged late but are low risk for regressions for
other platforms (and a few other straggling patches):
- I mis-tagged the 'drivers' branch, and missed 3 patches. Merged in
here. They're for a driver for the PL353 SRAM controller and a
build fix for the qualcomm scm driver.
- A new platform, RDA Micro RDA8810PL (Cortex-A5 w/ integrated
Vivante GPU, 256MB RAM, Wifi). This includes some acked
platform-specific drivers (serial, etc). This also include DTs for
two boards with this SoC, OrangePi 2G and OrangePi i86.
- i.MX8 is another new platform (NXP, 4x Cortex-A53 + Cortex-M4, 4K
video playback offload). This is the first i.MX 64-bit SoC.
- Some minor updates to Samsung boards (adding a few peripherals in
DTs).
- Small rework for SMP bootup on STi platforms.
- A couple of TEE driver fixes.
- A couple of new config options (bcm2835 thermal, Uniphier MDMAC)
enabled in defconfigs"
* tag 'armsoc-late' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (27 commits)
ARM: multi_v7_defconfig: enable CONFIG_UNIPHIER_MDMAC
arm64: defconfig: Re-enable bcm2835-thermal driver
MAINTAINERS: Add entry for RDA Micro SoC architecture
tty: serial: Add RDA8810PL UART driver
ARM: dts: rda8810pl: Add interrupt support for UART
dt-bindings: serial: Document RDA Micro UART
ARM: dts: rda8810pl: Add timer support
ARM: dts: Add devicetree for OrangePi i96 board
ARM: dts: Add devicetree for OrangePi 2G IoT board
ARM: dts: Add devicetree for RDA8810PL SoC
ARM: Prepare RDA8810PL SoC
dt-bindings: arm: Document RDA8810PL and reference boards
dt-bindings: Add RDA Micro vendor prefix
ARM: sti: remove pen_release and boot_lock
arm64: dts: exynos: Add Bluetooth chip to TM2(e) boards
arm64: dts: imx8mq-evk: enable watchdog
arm64: dts: imx8mq: add watchdog devices
MAINTAINERS: add i.MX8 DT path to i.MX architecture
arm64: add support for i.MX8M EVK board
arm64: add basic DTS for i.MX8MQ
...
Merge more updates from Andrew Morton:
- procfs updates
- various misc bits
- lib/ updates
- epoll updates
- autofs
- fatfs
- a few more MM bits
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (58 commits)
mm/page_io.c: fix polled swap page in
checkpatch: add Co-developed-by to signature tags
docs: fix Co-Developed-by docs
drivers/base/platform.c: kmemleak ignore a known leak
fs: don't open code lru_to_page()
fs/: remove caller signal_pending branch predictions
mm/: remove caller signal_pending branch predictions
arch/arc/mm/fault.c: remove caller signal_pending_branch predictions
kernel/sched/: remove caller signal_pending branch predictions
kernel/locking/mutex.c: remove caller signal_pending branch predictions
mm: select HAVE_MOVE_PMD on x86 for faster mremap
mm: speed up mremap by 20x on large regions
mm: treewide: remove unused address argument from pte_alloc functions
initramfs: cleanup incomplete rootfs
scripts/gdb: fix lx-version string output
kernel/kcov.c: mark write_comp_data() as notrace
kernel/sysctl: add panic_print into sysctl
panic: add options to print system info when panic happens
bfs: extra sanity checking and static inode bitmap
exec: separate MM_ANONPAGES and RLIMIT_STACK accounting
...
Merge in a few missing patches from the pull request (my copy of the
branch was behind the staged version in linux-next).
* next/drivers:
memory: pl353: Add driver for arm pl353 static memory controller
dt-bindings: memory: Add pl353 smc controller devicetree binding information
firmware: qcom: scm: fix compilation error when disabled
Signed-off-by: Olof Johansson <olof@lixom.net>
Patch series "Add support for fast mremap".
This series speeds up the mremap(2) syscall by copying page tables at
the PMD level even for non-THP systems. There is concern that the extra
'address' argument that mremap passes to pte_alloc may do something
subtle architecture related in the future that may make the scheme not
work. Also we find that there is no point in passing the 'address' to
pte_alloc since its unused. This patch therefore removes this argument
tree-wide resulting in a nice negative diff as well. Also ensuring
along the way that the enabled architectures do not do anything funky
with the 'address' argument that goes unnoticed by the optimization.
Build and boot tested on x86-64. Build tested on arm64. The config
enablement patch for arm64 will be posted in the future after more
testing.
The changes were obtained by applying the following Coccinelle script.
(thanks Julia for answering all Coccinelle questions!).
Following fix ups were done manually:
* Removal of address argument from pte_fragment_alloc
* Removal of pte_alloc_one_fast definitions from m68k and microblaze.
// Options: --include-headers --no-includes
// Note: I split the 'identifier fn' line, so if you are manually
// running it, please unsplit it so it runs for you.
virtual patch
@pte_alloc_func_def depends on patch exists@
identifier E2;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
type T2;
@@
fn(...
- , T2 E2
)
{ ... }
@pte_alloc_func_proto_noarg depends on patch exists@
type T1, T2, T3, T4;
identifier fn =~ "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
(
- T3 fn(T1, T2);
+ T3 fn(T1);
|
- T3 fn(T1, T2, T4);
+ T3 fn(T1, T2);
)
@pte_alloc_func_proto depends on patch exists@
identifier E1, E2, E4;
type T1, T2, T3, T4;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
(
- T3 fn(T1 E1, T2 E2);
+ T3 fn(T1 E1);
|
- T3 fn(T1 E1, T2 E2, T4 E4);
+ T3 fn(T1 E1, T2 E2);
)
@pte_alloc_func_call depends on patch exists@
expression E2;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
fn(...
-, E2
)
@pte_alloc_macro depends on patch exists@
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
identifier a, b, c;
expression e;
position p;
@@
(
- #define fn(a, b, c) e
+ #define fn(a, b) e
|
- #define fn(a, b) e
+ #define fn(a) e
)
Link: http://lkml.kernel.org/r/20181108181201.88826-2-joelaf@google.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Suggested-by: Kirill A. Shutemov <kirill@shutemov.name>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
get_arg_page() checks bprm->rlim_stack.rlim_cur and re-calculates the
"extra" size for argv/envp pointers every time, this is a bit ugly and
even not strictly correct: acct_arg_size() must not account this size.
Remove all the rlimit code in get_arg_page(). Instead, add bprm->argmin
calculated once at the start of __do_execve_file() and change
copy_strings to check bprm->p >= bprm->argmin.
The patch adds the new helper, prepare_arg_pages() which initializes
bprm->argc/envc and bprm->argmin.
[oleg@redhat.com: fix !CONFIG_MMU version of get_arg_page()]
Link: http://lkml.kernel.org/r/20181126122307.GA1660@redhat.com
[akpm@linux-foundation.org: use max_t]
Link: http://lkml.kernel.org/r/20181112160910.GA28440@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
gen_pool_alloc_algo() uses different allocation functions implementing
different allocation algorithms. With gen_pool_first_fit_align()
allocation function, the returned address should be aligned on the
requested boundary.
If chunk start address isn't aligned on the requested boundary, the
returned address isn't aligned too. The only way to get properly
aligned address is to initialize the pool with chunks aligned on the
requested boundary. If want to have an ability to allocate buffers
aligned on different boundaries (for example, 4K, 1MB, ...), the chunk
start address should be aligned on the max possible alignment.
This happens because gen_pool_first_fit_align() looks for properly
aligned memory block without taking into account the chunk start address
alignment.
To fix this, we provide chunk start address to
gen_pool_first_fit_align() and change its implementation such that it
starts looking for properly aligned block with appropriate offset
(exactly as is done in CMA).
Link: https://lkml.kernel.org/lkml/a170cf65-6884-3592-1de9-4c235888cc8a@intel.com
Link: http://lkml.kernel.org/r/1541690953-4623-1-git-send-email-alexey.skidanov@intel.com
Signed-off-by: Alexey Skidanov <alexey.skidanov@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Daniel Mentz <danielmentz@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Laura Abbott <labbott@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The introduction of these dummy BUILD_BUG_ON stubs dates back to commmit
903c0c7cdc ("sparse: define dummy BUILD_BUG_ON definition for
sparse").
At that time, BUILD_BUG_ON() was implemented with the negative array
trick *and* the link-time trick, like this:
extern int __build_bug_on_failed;
#define BUILD_BUG_ON(condition) \
do { \
((void)sizeof(char[1 - 2*!!(condition)])); \
if (condition) __build_bug_on_failed = 1; \
} while(0)
Sparse is more strict about the negative array trick than GCC because
Sparse requires the array length to be really constant.
Here is the simple test code for the macro above:
static const int x = 0;
BUILD_BUG_ON(x);
GCC is absolutely fine with it (-Wvla was enabled only very recently),
but Sparse warns like this:
error: bad constant expression
error: cannot size expression
(If you are using a newer version of Sparse, you will see a different
warning message, "warning: Variable length array is used".)
Anyway, Sparse was producing many false positives, and noisier than it
should be at that time.
With the previous commit, the leftover negative array trick is gone.
Sparse is fine with the current BUILD_BUG_ON(), which is implemented by
using the 'error' attribute.
I am keeping the stub for BUILD_BUG_ON_ZERO(). Otherwise, Sparse would
complain about the following code, which GCC is fine with:
static const int x = 0;
int y = BUILD_BUG_ON_ZERO(x);
Link: http://lkml.kernel.org/r/1542856462-18836-3-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Originally, the rule used to be that you'd have to do access_ok()
separately, and then user_access_begin() before actually doing the
direct (optimized) user access.
But experience has shown that people then decide not to do access_ok()
at all, and instead rely on it being implied by other operations or
similar. Which makes it very hard to verify that the access has
actually been range-checked.
If you use the unsafe direct user accesses, hardware features (either
SMAP - Supervisor Mode Access Protection - on x86, or PAN - Privileged
Access Never - on ARM) do force you to use user_access_begin(). But
nothing really forces the range check.
By putting the range check into user_access_begin(), we actually force
people to do the right thing (tm), and the range check vill be visible
near the actual accesses. We have way too long a history of people
trying to avoid them.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
