Pull gfs2 fixes from Andreas Gruenbacher:
 "Fix gfs2 readahead deadlocks by adding a IOCB_NOIO flag that allows
  gfs2 to use the generic fiel read iterator functions without having to
  worry about being called back while holding locks".

* tag 'gfs2-v5.8-rc4.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Rework read and page fault locking
  fs: Add IOCB_NOIO flag for generic_file_read_iter

Pull arm64 fixes from Will Deacon:
 "An unfortunately large collection of arm64 fixes for -rc5.

  Some of this is absolutely trivial, but the alternatives, vDSO and CPU
  errata workaround fixes are significant. At least people are finding
  and fixing these things, I suppose.

   - Fix workaround for CPU erratum #1418040 to disable the compat vDSO

   - Fix Oops when single-stepping with KGDB

   - Fix memory attributes for hypervisor device mappings at EL2

   - Fix memory leak in PSCI and remove useless variable assignment

   - Fix up some comments and asm labels in our entry code

   - Fix broken register table formatting in our generated html docs

   - Fix missing NULL sentinel in CPU errata workaround list

   - Fix patching of branches in alternative instruction sections"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/alternatives: don't patch up internal branches
  arm64: Add missing sentinel to erratum_1463225
  arm64: Documentation: Fix broken table in generated HTML
  arm64: kgdb: Fix single-step exception handling oops
  arm64: entry: Tidy up block comments and label numbers
  arm64: Rework ARM_ERRATUM_1414080 handling
  arm64: arch_timer: Disable the compat vdso for cores affected by ARM64_WORKAROUND_1418040
  arm64: arch_timer: Allow an workaround descriptor to disable compat vdso
  arm64: Introduce a way to disable the 32bit vdso
  arm64: entry: Fix the typo in the comment of el1_dbg()
  drivers/firmware/psci: Assign @err directly in hotplug_tests()
  drivers/firmware/psci: Fix memory leakage in alloc_init_cpu_groups()
  KVM: arm64: Fix definition of PAGE_HYP_DEVICE

Pull s390 fixes from Heiko Carstens:
 "This is mainly due to the fact that Gerald Schaefer's and also my old
  email addresses currently do not work any longer. Therefore we decided
  to switch to new email addresses and reflect that in the MAINTAINERS
  file.

   - Update email addresses in MAINTAINERS file and add .mailmap entries
     for Gerald Schaefer and Heiko Carstens.

   - Fix huge pte soft dirty copying"

* tag 's390-5.8-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  MAINTAINERS: update email address for Gerald Schaefer
  MAINTAINERS: update email address for Heiko Carstens
  s390/mm: fix huge pte soft dirty copying

Pull vkm fixes from Paolo Bonzini:
 "Two simple but important bugfixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: MIPS: Fix build errors for 32bit kernel
  KVM: nVMX: fixes for preemption timer migration

Pull MMC fixes from Ulf Hansson:

 - Override DLL_CONFIG only with valid values in sdhci-msm

 - Get rid of of_match_ptr() macro to fix warning in owl-mmc

 - Limit segments to 1 to fix meson-gx G12A/G12B SoCs

* tag 'mmc-v5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: sdhci-msm: Override DLL_CONFIG only if the valid value is supplied
  mmc: owl-mmc: Get rid of of_match_ptr() macro
  mmc: meson-gx: limit segments to 1 when dram-access-quirk is needed

Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Commit dc6d95b1 ("KVM: MIPS: Add more MMIO load/store
instructions emulation") introduced some 64bit load/store instructions
emulation which are unavailable on 32bit platform, and it causes build
errors:

arch/mips/kvm/emulate.c: In function 'kvm_mips_emulate_store':
arch/mips/kvm/emulate.c:1734:6: error: right shift count >= width of type [-Werror]
      ((vcpu->arch.gprs[rt] >> 56) & 0xff);
      ^
arch/mips/kvm/emulate.c:1738:6: error: right shift count >= width of type [-Werror]
      ((vcpu->arch.gprs[rt] >> 48) & 0xffff);
      ^
arch/mips/kvm/emulate.c:1742:6: error: right shift count >= width of type [-Werror]
      ((vcpu->arch.gprs[rt] >> 40) & 0xffffff);
      ^
arch/mips/kvm/emulate.c:1746:6: error: right shift count >= width of type [-Werror]
      ((vcpu->arch.gprs[rt] >> 32) & 0xffffffff);
      ^
arch/mips/kvm/emulate.c:1796:6: error: left shift count >= width of type [-Werror]
      (vcpu->arch.gprs[rt] << 32);
      ^
arch/mips/kvm/emulate.c:1800:6: error: left shift count >= width of type [-Werror]
      (vcpu->arch.gprs[rt] << 40);
      ^
arch/mips/kvm/emulate.c:1804:6: error: left shift count >= width of type [-Werror]
      (vcpu->arch.gprs[rt] << 48);
      ^
arch/mips/kvm/emulate.c:1808:6: error: left shift count >= width of type [-Werror]
      (vcpu->arch.gprs[rt] << 56);
      ^
cc1: all warnings being treated as errors
make[3]: *** [arch/mips/kvm/emulate.o] Error 1

So, use #if defined(CONFIG_64BIT) && defined(CONFIG_KVM_MIPS_VZ) to
guard the 64bit load/store instructions emulation.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: dc6d95b1 ("KVM: MIPS: Add more MMIO load/store instructions emulation")
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Message-Id: <1594365797-536-1-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Commit 850448f3 ("KVM: nVMX: Fix VMX preemption timer migration",
2020-06-01) accidentally broke nVMX live migration from older version
by changing the userspace ABI.  Restore it and, while at it, ensure
that vmx->nested.has_preemption_timer_deadline is always initialized
according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.

Cc: Makarand Sonare <makarandsonare@google.com>
Fixes: 850448f3 ("KVM: nVMX: Fix VMX preemption timer migration")
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Pull drm fixes from Dave Airlie:
 "I've been off most of the week, but some fixes have piled up. Seems a
  bit busier than last week, but they are pretty spread out across a
  bunch of drivers, none of them seem that big or worried me too much.

  amdgpu:
   - Fix a suspend/resume issue with PSP
   - Backlight fix for Renoir
   - Fix for gpu recovery debugging

  radeon:
   - Fix a double free in error path

  i915:
   - fbc fencing fix
   - debugfs panic fix
   - gem vma constuction fix
   - gem pin under vm->nutex fix

  nouveau:
   - SVM fixes
   - display fixes

  meson:
   - OSD burst length fixes

  hibmc:
   - runtime warning fix

  mediatek:
   - cmdq, mmsys fixes
   - visibility check fixes"

* tag 'drm-fixes-2020-07-10' of git://anongit.freedesktop.org/drm/drm: (24 commits)
  drm/amdgpu: don't do soft recovery if gpu_recovery=0
  drm/radeon: fix double free
  drm/amd/display: add dmcub check on RENOIR
  drm/amdgpu: add TMR destory function for psp
  drm/amdgpu: asd function needs to be unloaded in suspend phase
  drm/hisilicon/hibmc: Move drm_fbdev_generic_setup() down to avoid the splat
  drm/nouveau/nouveau: fix page fault on device private memory
  drm/nouveau/svm: fix migrate page regression
  drm/nouveau/i2c/g94-: increase NV_PMGR_DP_AUXCTL_TRANSACTREQ timeout
  drm/nouveau/kms/nv50-: bail from nv50_audio_disable() early if audio not enabled
  drm/i915/gt: Pin the rings before marking active
  drm/i915: Also drop vm.ref along error paths for vma construction
  drm/i915: Drop vm.ref for duplicate vma on construction
  drm/i915/fbc: Fix fence_y_offset handling
  drm/i915: Skip stale object handle for debugfs per-file-stats
  drm/mediatek: mtk_hdmi: Remove debug messages for function calls
  drm/mediatek: mtk_mt8173_hdmi_phy: Remove unnused const variables
  drm/mediatek: Delete not used of_device_get_match_data
  drm/mediatek: Remove unnecessary conversion to bool
  drm/meson: viu: fix setting the OSD burst length in VIU_OSD1_FIFO_CTRL_STAT
  ...

While raising the gcc version requirement to 4.9, the compile-time check
in the unroll macro was accidentally changed from being used on gcc and
clang to being used on clang only.

Restore the gcc check, changing it from "gcc >= 4.7" to "all gcc".

[ We should probably remove this all entirely: if we remove the check
  for CLANG, then the check for GCC can go away. Older versions of clang
  are not really appropriate or supported for kernel builds - Linus ]

Fixes: 6ec4476a ("Raise gcc version requirement to 4.9")
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.eti.br>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

-Wtype-limits is included in -Wextra which is added at W=1. It warns
(among other things) that 'comparison of an unsigned variable `< 0` is
always false. This causes noisy warnings, especially when used in
macros, hence it is more suitable for W=2.

Link: https://lore.kernel.org/lkml/CAHk-=wiKCXEWKJ9dWUimGbrVRo_N2RosESUw8E7m9AEtyZcu=w@mail.gmail.com/Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'amd-drm-fixes-5.8-2020-07-09' of git://people.freedesktop.org/~agd5f/linux into drm-fixes

amd-drm-fixes-5.8-2020-07-09:

amdgpu:
- Fix a suspend/resume issue with PSP
- Backlight fix for Renoir
- Fix for gpu recovery debugging

radeon:
- Fix a double free in error path
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Alex Deucher <alexdeucher@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200709185221.44895-1-alexander.deucher@amd.com

Merge tag 'drm-intel-fixes-2020-07-08' of git://anongit.freedesktop.org/drm/drm-intel into drm-fixes

One display's fbc patch fixing fence_y_offset calculation
from Ville and 4 patches from Chris on GEM: 1 fixing a debugfs
panic and others fixing vma construction and pin under vm->mutex.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200708190654.GA3924867@intel.com

- SVM fixes
- display fixes
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Ben Skeggs <skeggsb@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ <CACAvsv5i-dc0Onbk8FWzd-PTgXHHWi6jcE3O0hVx8+V5qEOeqg@mail.gmail.com

 * meson: OSD burst-length fixes
 * hibmc: fix runtime warning by setting up generic fbdev after
   registering device
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20200708121050.GA29420@linux-uq9g

Merge tag 'mediatek-drm-fixes-5.8' of https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux into drm-fixes

Mediatek DRM Fixes for Linux 5.8

This include fixup for cmdq, mmsys, visibility checking and some refinement.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200707153944.604-1-chunkuang.hu@kernel.org

Merge tag 'for-5.8/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:

 - A request-based DM fix to not use a waitqueue to wait for blk-mq IO
   completion because doing so is racey.

 - A couple more DM zoned target fixes to address issues introduced
   during the 5.8 cycle.

 - A DM core fix to use proper interface to cleanup DM's static flush
   bio.

 - A DM core fix to prevent mm recursion during memory allocation needed
   by dm_kobject_uevent.

* tag 'for-5.8/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: use noio when sending kobject event
  dm zoned: Fix zone reclaim trigger
  dm zoned: fix unused but set variable warnings
  dm writecache: reject asynchronous pmem devices
  dm: use bio_uninit instead of bio_disassociate_blkg
  dm: do not use waitqueue for request-based DM

Merge tag 'kallsyms_show_value-v5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull kallsyms fix from Kees Cook:
 "Refactor kallsyms_show_value() users for correct cred.

  I'm not delighted by the timing of getting these changes to you, but
  it does fix a handful of kernel address exposures, and no one has
  screamed yet at the patches.

  Several users of kallsyms_show_value() were performing checks not
  during "open". Refactor everything needed to gain proper checks
  against file->f_cred for modules, kprobes, and bpf"

* tag 'kallsyms_show_value-v5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  selftests: kmod: Add module address visibility test
  bpf: Check correct cred for CAP_SYSLOG in bpf_dump_raw_ok()
  kprobes: Do not expose probe addresses to non-CAP_SYSLOG
  module: Do not expose section addresses to non-CAP_SYSLOG
  module: Refactor section attr into bin attribute
  kallsyms: Refactor kallsyms_show_value() to take cred

It's impossible to debug shader hangs with soft recovery.
Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

clang static analysis flags this error

drivers/gpu/drm/radeon/ci_dpm.c:5652:9: warning: Use of memory after it is freed [unix.Malloc]
                kfree(rdev->pm.dpm.ps[i].ps_priv);
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/ci_dpm.c:5654:2: warning: Attempt to free released memory [unix.Malloc]
        kfree(rdev->pm.dpm.ps);
        ^~~~~~~~~~~~~~~~~~~~~~

problem is reported in ci_dpm_fini, with these code blocks.

	for (i = 0; i < rdev->pm.dpm.num_ps; i++) {
		kfree(rdev->pm.dpm.ps[i].ps_priv);
	}
	kfree(rdev->pm.dpm.ps);

The first free happens in ci_parse_power_table where it cleans up locally
on a failure.  ci_dpm_fini also does a cleanup.

	ret = ci_parse_power_table(rdev);
	if (ret) {
		ci_dpm_fini(rdev);
		return ret;
	}

So remove the cleanup in ci_parse_power_table and
move the num_ps calculation to inside the loop so ci_dpm_fini
will know how many array elements to free.

Fixes: cc8dbbb4 ("drm/radeon: add dpm support for CI dGPUs (v2)")
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

RENOIR loads dmub fw not dmcu, check dmcu only will prevent loading iram,
it breaks backlight control.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=208277Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

TMR is required to be destoried with GFX_CMD_ID_DESTROY_TMR while the
system goes to suspend. Otherwise, PSP may return the failure state
(0xFFFF007) on Gfx-2-PSP command GFX_CMD_ID_SETUP_TMR after do multiple
times suspend/resume.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Unload ASD function in suspend phase.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Commit f7b93d42 ("arm64/alternatives: use subsections for replacement
sequences") moved the alternatives replacement sequences into subsections,
in order to keep the as close as possible to the code that they replace.

Unfortunately, this broke the logic in branch_insn_requires_update,
which assumed that any branch into kernel executable code was a branch
that required updating, which is no longer the case now that the code
sequences that are patched in are in the same section as the patch site
itself.

So the only way to discriminate branches that require updating and ones
that don't is to check whether the branch targets the replacement sequence
itself, and so we can drop the call to kernel_text_address() entirely.

Fixes: f7b93d42 ("arm64/alternatives: use subsections for replacement sequences")
Reported-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20200709125953.30918-1-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

If the pmd is soft dirty we must mark the pte as soft dirty (and not dirty).
This fixes some cases for guest migration with huge page backings.

Cc: <stable@vger.kernel.org> # 4.8
Fixes: bc29b7ac ("s390/mm: clean up pte/pmd encoding")
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

When the erratum_1463225 array was introduced a sentinel at the end was
missing thus causing a KASAN: global-out-of-bounds in
is_affected_midr_range_list on arm64 error.

Fixes: a9e821b8 ("arm64: Add KRYO4XX gold CPU cores to erratum list 1463225 and 1418040")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Link: https://lore.kernel.org/linux-arm-kernel/CA+G9fYs3EavpU89-rTQfqQ9GgxAMgMAk7jiiVrfP0yxj5s+Q6g@mail.gmail.com/
Link: https://lore.kernel.org/r/20200709051345.14544-1-f.fainelli@gmail.comSigned-off-by: Will Deacon <will@kernel.org>

Make sure we don't regress the CAP_SYSLOG behavior of the module address
visibility via /proc/modules nor /sys/module/*/sections/*.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

When evaluating access control over kallsyms visibility, credentials at
open() time need to be used, not the "current" creds (though in BPF's
case, this has likely always been the same). Plumb access to associated
file->f_cred down through bpf_dump_raw_ok() and its callers now that
kallsysm_show_value() has been refactored to take struct cred.

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: 7105e828 ("bpf: allow for correlation of maps and helpers in dump")
Signed-off-by: Kees Cook <keescook@chromium.org>

The kprobe show() functions were using "current"'s creds instead
of the file opener's creds for kallsyms visibility. Fix to use
seq_file->file->f_cred.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 81365a94 ("kprobes: Show address of kprobes if kallsyms does")
Fixes: ffb9bd68 ("kprobes: Show blacklist addresses as same as kallsyms does")
Signed-off-by: Kees Cook <keescook@chromium.org>

The printing of section addresses in /sys/module/*/sections/* was not
using the correct credentials to evaluate visibility.

Before:

 # cat /sys/module/*/sections/.*text
 0xffffffffc0458000
 ...
 # capsh --drop=CAP_SYSLOG -- -c "cat /sys/module/*/sections/.*text"
 0xffffffffc0458000
 ...

After:

 # cat /sys/module/*/sections/*.text
 0xffffffffc0458000
 ...
 # capsh --drop=CAP_SYSLOG -- -c "cat /sys/module/*/sections/.*text"
 0x0000000000000000
 ...

Additionally replaces the existing (safe) /proc/modules check with
file->f_cred for consistency.
Reported-by: Dominik Czarnota <dominik.czarnota@trailofbits.com>
Fixes: be71eda5 ("module: Fix display of wrong module .text address")
Cc: stable@vger.kernel.org
Tested-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

In order to gain access to the open file's f_cred for kallsym visibility
permission checks, refactor the module section attributes to use the
bin_attribute instead of attribute interface. Additionally removes the
redundant "name" struct member.

Cc: stable@vger.kernel.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

In order to perform future tests against the cred saved during open(),
switch kallsyms_show_value() to operate on a cred, and have all current
callers pass current_cred(). This makes it very obvious where callers
are checking the wrong credential in their "read" contexts. These will
be fixed in the coming patches.

Additionally switch return value to bool, since it is always used as a
direct permission check, not a 0-on-success, negative-on-error style
function return.

Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

cpu-feature-registers.rst is missing a new line before a couple
of tables listing the visible fields, causing broken tables in
the HTML documentation generated by "make htmldocs". Fix this
by adding the missing new line.
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200707143152.154541-1-suzuki.poulose@arm.comSigned-off-by: Will Deacon <will@kernel.org>

After entering kdb due to breakpoint, when we execute 'ss' or 'go' (will
delay installing breakpoints, do single-step first), it won't work
correctly, and it will enter kdb due to oops.

It's because the reason gotten in kdb_stub() is not as expected, and it
seems that the ex_vector for single-step should be 0, like what arch
powerpc/sh/parisc has implemented.

Before the patch:
Entering kdb (current=0xffff8000119e2dc0, pid 0) on processor 0 due to Keyboard Entry
[0]kdb> bp printk
Instruction(i) BP #0 at 0xffff8000101486cc (printk)
    is enabled   addr at ffff8000101486cc, hardtype=0 installed=0

[0]kdb> g

/ # echo h > /proc/sysrq-trigger

Entering kdb (current=0xffff0000fa878040, pid 266) on processor 3 due to Breakpoint @ 0xffff8000101486cc
[3]kdb> ss

Entering kdb (current=0xffff0000fa878040, pid 266) on processor 3 Oops: (null)
due to oops @ 0xffff800010082ab8
CPU: 3 PID: 266 Comm: sh Not tainted 5.7.0-rc4-13839-gf0e5ad491718 #6
Hardware name: linux,dummy-virt (DT)
pstate: 00000085 (nzcv daIf -PAN -UAO)
pc : el1_irq+0x78/0x180
lr : __handle_sysrq+0x80/0x190
sp : ffff800015003bf0
x29: ffff800015003d20 x28: ffff0000fa878040
x27: 0000000000000000 x26: ffff80001126b1f0
x25: ffff800011b6a0d8 x24: 0000000000000000
x23: 0000000080200005 x22: ffff8000101486cc
x21: ffff800015003d30 x20: 0000ffffffffffff
x19: ffff8000119f2000 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000
x15: 0000000000000000 x14: 0000000000000000
x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000
x9 : 0000000000000000 x8 : ffff800015003e50
x7 : 0000000000000002 x6 : 00000000380b9990
x5 : ffff8000106e99e8 x4 : ffff0000fadd83c0
x3 : 0000ffffffffffff x2 : ffff800011b6a0d8
x1 : ffff800011b6a000 x0 : ffff80001130c9d8
Call trace:
 el1_irq+0x78/0x180
 printk+0x0/0x84
 write_sysrq_trigger+0xb0/0x118
 proc_reg_write+0xb4/0xe0
 __vfs_write+0x18/0x40
 vfs_write+0xb0/0x1b8
 ksys_write+0x64/0xf0
 __arm64_sys_write+0x14/0x20
 el0_svc_common.constprop.2+0xb0/0x168
 do_el0_svc+0x20/0x98
 el0_sync_handler+0xec/0x1a8
 el0_sync+0x140/0x180

[3]kdb>

After the patch:
Entering kdb (current=0xffff8000119e2dc0, pid 0) on processor 0 due to Keyboard Entry
[0]kdb> bp printk
Instruction(i) BP #0 at 0xffff8000101486cc (printk)
    is enabled   addr at ffff8000101486cc, hardtype=0 installed=0

[0]kdb> g

/ # echo h > /proc/sysrq-trigger

Entering kdb (current=0xffff0000fa852bc0, pid 268) on processor 0 due to Breakpoint @ 0xffff8000101486cc
[0]kdb> g

Entering kdb (current=0xffff0000fa852bc0, pid 268) on processor 0 due to Breakpoint @ 0xffff8000101486cc
[0]kdb> ss

Entering kdb (current=0xffff0000fa852bc0, pid 268) on processor 0 due to SS trap @ 0xffff800010082ab8
[0]kdb>

Fixes: 44679a4f ("arm64: KGDB: Add step debugging support")
Signed-off-by: Wei Li <liwei391@huawei.com>
Tested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200509214159.19680-2-liwei391@huawei.comSigned-off-by: Will Deacon <will@kernel.org>

Continually butchering our entry code with CPU errata workarounds has
led to it looking a little scruffy. Consistently used /* */ comment
style for multi-line block comments and ensure that small numeric labels
use consecutive integers.

No functional change, but the state of things was irritating.
Signed-off-by: Will Deacon <will@kernel.org>

The current handling of erratum 1414080 has the side effect that
cntkctl_el1 can get changed for both 32 and 64bit tasks.

This isn't a problem so far, but if we ever need to mitigate another
of these errata on the 64bit side, we'd better keep the messing with
cntkctl_el1 local to 32bit tasks.

For that, make sure that on entering the kernel from a 32bit tasks,
userspace access to cntvct gets enabled, and disabled returning to
userspace, while it never gets changed for 64bit tasks.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200706163802.1836732-5-maz@kernel.org
[will: removed branch instructions per Mark's review comments]
Signed-off-by: Will Deacon <will@kernel.org>

ARM64_WORKAROUND_1418040 requires that AArch32 EL0 accesses to
the virtual counter register are trapped and emulated by the kernel.
This makes the vdso pretty pointless, and in some cases livelock
prone.

Provide a workaround entry that limits the vdso to 64bit tasks.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200706163802.1836732-4-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

As we are about to disable the vdso for compat tasks in some circumstances,
let's allow a workaround descriptor to express exactly that.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200706163802.1836732-3-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

We have a class of errata (grouped under the ARM64_WORKAROUND_1418040
banner) that force the trapping of counter access from 32bit EL0.

We would normally disable the whole vdso for such defect, except that
it would disable it for 64bit userspace as well, which is a shame.

Instead, add a new vdso_clock_mode, which signals that the vdso
isn't usable for compat tasks.  This gets checked in the new
vdso_clocksource_ok() helper, now provided for the 32bit vdso.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200706163802.1836732-2-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>