Documentation/process/botching-up-ioctls.rst was orignally written as
a blog post for DRM driver writers, so it it misses some points while
going into a lot of detail on others.

Try to provide a replacement that addresses typical issues across a wider
range of subsystems, and follows the style of the core-api documentation
better.

Many improvements to the document are suggested by Ben Hutchings
<ben.hutchings@codethink.co.uk>, Jonathan Corbet <corbet@lwn.net> and
Geert Uytterhoeven <geert@linux-m68k.org>.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Having separate implementations of blkdev_ioctl() often leads to these
getting out of sync, despite the comment at the top.

Since most of the ioctl commands are compatible, and we try very hard
not to add any new incompatible ones, move all the common bits into a
shared function and leave only the ones that are historically different
in separate functions for native/compat mode.

To deal with the compat_ptr() conversion, pass both the integer
argument and the pointer argument into the new blkdev_common_ioctl()
and make sure to always use the correct one of these.

blkdev_ioctl() is now only kept as a separate exported interfact
for drivers/char/raw.c, which lacks a compat_ioctl variant.
We should probably either move raw.c to staging if there are no
more users, or export blkdev_compat_ioctl() as well.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

There is no need to go through a compat_alloc_user_space()
copy any more, just wrap the function in a small helper that
works the same way for native and compat mode.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Having both in the same file allows a number of simplifications
to the compat path, and makes it more likely that changes to
the native path get applied to the compat version as well.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Most of the HDIO ioctls are only used by the obsolete drivers/ide
subsystem, these can be handled by changing ide_cmd_ioctl() to be aware
of compat mode and doing the correct transformations in place and using
it as both native and compat handlers for all drivers.

The SCSI drivers implementing the same commands are already doing
this in the drivers, so the compat_blkdev_driver_ioctl() function
is no longer needed now.

The BLKSECTSET and HDIO_GETGEO_BIG ioctls are not implemented
in any driver any more and no longer need any conversion.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The ata_sas_scsi_ioctl() function implements a number of HDIO_* commands
for SCSI devices, it is used by all libata drivers as well as a few
drivers that support SAS attached SATA drives.

The only command that is not safe for compat ioctls here is
HDIO_GET_32BIT. Change the implementation to check for in_compat_syscall()
in order to do both cases correctly, and change all callers to use it
as both native and compat callback pointers, including the indirect
callers through sas_ioctl and ata_scsi_ioctl.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

There is no need for the special cases for the cdrom ioctls any more now,
so make sure that each cdrom driver has a .compat_ioctl() callback and
calls cdrom_compat_ioctl() directly there.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Now that both native and compat ioctl syscalls are
in the same file, a couple of simplifications can
be made, bringing the implementation closer together:

- do_vfs_ioctl(), ioctl_preallocate(), and compat_ioctl_preallocate()
  can become static, allowing the compiler to optimize better

- slightly update the coding style for consistency between
  the functions.

- rather than listing each command in two switch statements
  for the compat case, just call a single function that has
  all the common commands.

As a side-effect, FS_IOC_RESVSP/FS_IOC_RESVSP64 are now available
to x86 compat tasks, along with FS_IOC_RESVSP_32/FS_IOC_RESVSP64_32.
This is harmless for i386 emulation, and can be considered a bugfix
for x32 emulation, which never supported these in the past.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The rest of the fs/compat_ioctl.c file is no longer useful now,
so move the actual syscall as planned.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Each driver calling scsi_ioctl() gets an equivalent compat_ioctl()
handler that implements the same commands by calling scsi_compat_ioctl().

The scsi_cmd_ioctl() and scsi_cmd_blk_ioctl() functions are compatible
at this point, so any driver that calls those can do so for both native
and compat mode, with the argument passed through compat_ptr().

With this, we can remove the entries from fs/compat_ioctl.c.  The new
code is larger, but should be easier to maintain and keep updated with
newly added commands.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Rather than relying on fs/compat_ioctl.c, this adds support
for a compat_ioctl() callback in the ide-floppy driver directly,
which lets it translate the scsi commands.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

bsg_ioctl() calls into scsi_cmd_ioctl() for a couple of generic commands
and relies on fs/compat_ioctl.c to handle it correctly in compat mode.

Adding a private compat_ioctl() handler avoids that round-trip and lets
us get rid of the generic emulation once this is done.

Note that bsg implements an SG_IO command that is different from the
other drivers and does not need emulation.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

In order to move the compat handling for SCSI ioctl commands out of
fs/compat_ioctl.c into the individual drivers, we need a helper function
first to match the native ioctl handler called by sd, sr, st, etc.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Various block drivers implement the CDROMMULTISESSION,
CDROM_GET_CAPABILITY, and CDROMEJECT ioctl commands, relying on the
block layer to handle compat_ioctl mode for them.

Move this into the drivers directly as a preparation for simplifying
the block layer later.

When only integer arguments or no arguments are passed, the
same handler can be used for .ioctl and .compat_ioctl, and
when only pointer arguments are passed, the newly added
blkdev_compat_ptr_ioctl can be used.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

This is the only ioctl command that does not have a proper
compat handler. Making the normal implementation do the
right thing is actually very simply, so just do that by
using an in_compat_syscall() check to avoid the special
case in the pkcdvd driver.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Again, there is only one file that needs this, so move the conversion
handler into the native implementation.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

There is only one implementation of this ioctl, so move the handling out
of the common block layer code into the place where it's actually needed.

It also gets called indirectly through pktcdvd, which needs to be aware
of this change.

As I noticed, the old implementation of the compat handler failed to
convert the structure on the way out, so the updated fields never got
written back to user space. This is either not important, or it has
never worked and should be fixed now.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

These drivers implement the HDIO_GET_IDENTITY and CDROMVOLREAD ioctl
commands, which are compatible between 32-bit and 64-bit user space and
traditionally handled by compat_blkdev_driver_ioctl().

As a prerequisite to removing that function, make both drivers use
blkdev_compat_ptr_ioctl() as their .compat_ioctl callback.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

A lot of block drivers need only a trivial .compat_ioctl callback.

Add a helper function that can be set as the callback pointer
to only convert the argument using the compat_ptr() conversion
and otherwise assume all input and output data is compatible,
or handled using in_compat_syscall() checks.

This mirrors the compat_ptr_ioctl() helper function used in
character devices.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

In the v5.4 merge window, a cleanup patch from Al Viro conflicted
with my rework of the compat handling for sg.c read(). Linus Torvalds
did a correct merge but pointed out that the resulting code is still
unsatisfactory.

I later noticed that the sg_new_read() function still gets the compat
mode wrong, when the 'count' argument is large enough to pass a
compat_sg_io_hdr object, but not a nativ sg_io_hdr.

To address both of these, move the definition of compat_sg_io_hdr
into a scsi/sg.h to make it visible to sg.c and rewrite the logic
for reading req_pack_id as well as the size check to a simpler
version that gets the expected results.

Fixes: c35a5cfb ("scsi: sg: sg_read(): simplify reading ->pack_id of userland sg_io_hdr_t")
Fixes: 98aaaec4 ("compat_ioctl: reimplement SG_IO handling")
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

In order to avoid needless #ifdef CONFIG_COMPAT checks,
move the compat_ptr() definition to linux/compat.h
where it can be seen by any file regardless of the
architecture.

Only s390 needs a special definition, this can use the
self-#define trick we have elsewhere.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

In order to use compat_* type defininitions in device drivers
outside of CONFIG_COMPAT, move the inclusion of asm-generic/compat.h
ahead of the #ifdef.

All other architectures already do this.
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Pull RISC-V fixes from Paul Walmsley:
 "One important fix for RISC-V:

   - Redirect any incoming syscall with an ID less than -1 to
     sys_ni_syscall, rather than allowing them to fall through into the
     syscall handler.

  and two minor build fixes:

   - Export __asm_copy_{from,to}_user() from where they are defined.
     This fixes a build error triggered by some randconfigs.

   - Export flush_icache_all(). I'd resisted this before, since
     historically we didn't want modules to be able to flush the I$
     directly; but apparently everyone else is doing it now"

* tag 'riscv/for-v5.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: export flush_icache_all to modules
  riscv: reject invalid syscalls below -1
  riscv: fix compile failure with EXPORT_SYMBOL() & !MMU

Pull /proc/locks formatting fix from Jeff Layton:
 "This is a trivial fix for a _very_ long standing bug in /proc/locks
  formatting. Ordinarily, I'd wait for the merge window for something
  like this, but it is making it difficult to validate some overlayfs
  fixes.

  I've also gone ahead and marked this for stable"

* tag 'locks-v5.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  locks: print unsigned ino in /proc/locks

Pull cifs fixes from Steve French:
 "One performance fix for large directory searches, and one minor style
  cleanup noticed by Clang"

* tag '5.5-rc3-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: Optimize readdir on reparse points
  cifs: Adjust indentation in smb2_open_file

An ino is unsigned, so display it as such in /proc/locks.

Cc: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>

This is needed by LKDTM (crash dump test module), it calls
flush_icache_range(), which on RISC-V turns into flush_icache_all(). On
other architectures, the actual implementation is exported, so follow
that precedence and export it here too.

Fixes build of CONFIG_LKDTM that fails with:
ERROR: "flush_icache_all" [drivers/misc/lkdtm/lkdtm.ko] undefined!
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

Running "stress-ng --enosys 4 -t 20 -v" showed a large number of kernel oops
with "Unable to handle kernel paging request at virtual address" message. This
happens when enosys stressor starts testing random non-valid syscalls.

I forgot to redirect any syscall below -1 to sys_ni_syscall.

With the patch kernel oops messages are gone while running stress-ng enosys
stressor.
Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com>
Fixes: 5340627e ("riscv: add support for SECCOMP and SECCOMP_FILTER")
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

When support for !MMU was added, the declaration of
__asm_copy_to_user() & __asm_copy_from_user() were #ifdefed
out hence their EXPORT_SYMBOL() give an error message like:
  .../riscv_ksyms.c:13:15: error: '__asm_copy_to_user' undeclared here
  .../riscv_ksyms.c:14:15: error: '__asm_copy_from_user' undeclared here

Since these symbols are not defined with !MMU it's wrong to export them.
Same for __clear_user() (even though this one is also declared in
include/asm-generic/uaccess.h and thus doesn't give an error message).

Fix this by doing the EXPORT_SYMBOL() directly where these symbols
are defined: inside lib/uaccess.S itself.

Fixes: 6bd33e1e ("riscv: fix compile failure with EXPORT_SYMBOL() & !MMU")
Reported-by: kbuild test robot <lkp@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

Pull SCSI fixes from James Bottomley:
 "Four fixes and one spelling update, all in drivers: two in lpfc and
  the rest in mp3sas, cxgbi and target"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: target/iblock: Fix protection error with blocks greater than 512B
  scsi: libcxgbi: fix NULL pointer dereference in cxgbi_device_destroy()
  scsi: lpfc: fix spelling mistakes of asynchronous
  scsi: lpfc: fix build failure with DEBUGFS disabled
  scsi: mpt3sas: Fix double free in attach error handling

Pull drm fixes from Dave Airlie:
 "Post-xmas food coma recovery fixes. Only three fixes for i915 since I
  expect most people are holidaying.

  i915:
   - power management rc6 fix
   - framebuffer tracking fix
   - display power management ratelimit fix"

* tag 'drm-fixes-2019-12-28' of git://anongit.freedesktop.org/drm/drm:
  drm/i915: Hold reference to intel_frontbuffer as we track activity
  drm/i915/gt: Ratelimit display power w/a
  drm/i915/pmu: Ensure monotonic rc6

Merge tag 'linux-kselftest-5.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull Kselftest fixes from Shuah Khan:

 - rseq build failures fixes related to glibc 2.30 compatibility from
   Mathieu Desnoyers

 - Kunit fixes and cleanups from SeongJae Park

 - Fixes to filesystems/epoll, firmware, and livepatch build failures
   and skip handling.

* tag 'linux-kselftest-5.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  rseq/selftests: Clarify rseq_prepare_unload() helper requirements
  rseq/selftests: Fix: Namespace gettid() for compatibility with glibc 2.30
  rseq/selftests: Turn off timeout setting
  kunit/kunit_tool_test: Test '--build_dir' option run
  kunit: Rename 'kunitconfig' to '.kunitconfig'
  kunit: Place 'test.log' under the 'build_dir'
  kunit: Create default config in '--build_dir'
  kunit: Remove duplicated defconfig creation
  docs/kunit/start: Use in-tree 'kunit_defconfig'
  selftests: livepatch: Fix it to do root uid check and skip
  selftests: firmware: Fix it to do root uid check and skip
  selftests: filesystems/epoll: fix build error

Pull power management fixes from Rafael Wysocki:
 "Fix compile test of the Tegra devfreq driver (Arnd Bergmann) and
  remove redundant Kconfig dependencies from multiple devfreq drivers
  (Leonard Crestez)"

* tag 'pm-5.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM / devfreq: tegra: Add COMMON_CLK dependency
  PM / devfreq: Drop explicit selection of PM_OPP

Pull io_uring fixes from Jens Axboe:

 - Removal of now unused busy wqe list (Hillf)

 - Add cond_resched() to io-wq work processing (Hillf)

 - And then the series that I hinted at from last week, which removes
   the sqe from the io_kiocb and keeps all sqe handling on the prep
   side. This guarantees that an opcode can't do the wrong thing and
   read the sqe more than once. This is unchanged from last week, no
   issues have been observed with this in testing. Hence I really think
   we should fold this into 5.5.

* tag 'io_uring-5.5-20191226' of git://git.kernel.dk/linux-block:
  io-wq: add cond_resched() to worker thread
  io-wq: remove unused busy list from io_sqe
  io_uring: pass in 'sqe' to the prep handlers
  io_uring: standardize the prep methods
  io_uring: read 'count' for IORING_OP_TIMEOUT in prep handler
  io_uring: move all prep state for IORING_OP_{SEND,RECV}_MGS to prep handler
  io_uring: move all prep state for IORING_OP_CONNECT to prep handler
  io_uring: add and use struct io_rw for read/writes
  io_uring: use u64_to_user_ptr() consistently

Pull libata fixes from Jens Axboe:
 "Two things in here:

   - First half of a series that fixes ahci_brcm, also marked for
     stable. The other part of the series is going into 5.6 (Florian)

   - sata_nv regression fix that is also marked for stable (Sascha)"

* tag 'libata-5.5-20191226' of git://git.kernel.dk/linux-block:
  ata: ahci_brcm: Add missing clock management during recovery
  ata: ahci_brcm: BCM7425 AHCI requires AHCI_HFLAG_DELAY_ENGINE
  ata: ahci_brcm: Fix AHCI resources management
  ata: libahci_platform: Export again ahci_platform_<en/dis>able_phys()
  libata: Fix retrieving of active qcs

Pull block fixes from Jens Axboe:
 "Only thing here are the changes from Arnd from last week, which now
  have the appropriate header include to ensure they actually compile if
  COMPAT is enabled"

* tag 'block-5.5-20191226' of git://git.kernel.dk/linux-block:
  compat_ioctl: block: handle Persistent Reservations
  compat_ioctl: block: handle add zone open, close and finish ioctl
  compat_ioctl: block: handle BLKGETZONESZ/BLKGETNRZONES
  compat_ioctl: block: handle BLKREPORTZONE/BLKRESETZONE
  pktcdvd: fix regression on 64-bit architectures

Pull GPIO fixes from Linus Walleij:
 "A set of fixes for the v5.5 series:

   - Fix the build for the Xtensa driver.

   - Make sure to set up the parent device for mpc8xxx.

   - Clarify the look-up error message.

   - Fix the usage of the line direction in the mockup device.

   - Fix a type warning on the Aspeed driver.

   - Remove the pointless __exit annotation on the xgs-iproc which is
     causing a compilation problem.

   - Fix up emultation of open drain outputs .get_direction()

   - Fix the IRQ callbacks on the PCA953xx to use bitops and work
     properly.

   - Fix the Kconfig on the Tegra driver"

* tag 'gpio-v5.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: tegra186: Allow building on Tegra194-only configurations
  gpio: pca953x: Switch to bitops in IRQ callbacks
  gpiolib: fix up emulated open drain outputs
  MAINTAINERS: Append missed file to the database
  gpio: xgs-iproc: remove __exit annotation for iproc_gpio_remove
  gpio: aspeed: avoid return type warning
  gpio: mockup: Fix usage of new GPIO_LINE_DIRECTION
  gpio: Fix error message on out-of-range GPIO in lookup table
  gpio: mpc8xxx: Add platform device to gpiochip->parent
  gpio: xtensa: fix driver build

Merge tag 'drm-intel-fixes-2019-12-23' of git://anongit.freedesktop.org/drm/drm-intel into drm-fixes

i915 power and frontbuffer tracking fixes
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/87r20vdlrs.fsf@intel.com

The downstream implementation of ahci_brcm.c did contain clock
management recovery, but until recently, did that outside of the
libahci_platform helpers and this was unintentionally stripped out while
forward porting the patch upstream.

Add the missing clock management during recovery and sleep for 10
milliseconds per the design team recommendations to ensure the SATA PHY
controller and AFE have been fully quiesced.

Fixes: eb73390a ("ata: ahci_brcm: Recover from failures to identify devices")
Cc: stable@vger.kernel.org
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>