Tested using syzkaller in QEMU's riscv64 virt machine.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add ARCH_HAS_KCOV and HAVE_GCC_PLUGINS to the riscv Kconfig.
Also disable instrumentation of some early boot code and vdso.

Boot-tested on QEMU's riscv64 virt machine.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

This patch implements and enables context tracking for riscv (which is a
prerequisite for CONFIG_NO_HZ_FULL support)

It adds checking for previous state in the entry that all excepttions and
interrupts goes to and calls context_tracking_user_exit() if it comes from
user space. It also calls context_tracking_user_enter() if it will return
to user space before restore_all.

This patch is tested with the dynticks-testing testcase in
qemu-system-riscv64 virt machine and Unleashed board.
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/dynticks-testing.git

We can see the log here. The tick got mostly stopped during the execution
of the user loop.

                        _-----=> irqs-off
                       / _----=> need-resched
                      | / _---=> hardirq/softirq
                      || / _--=> preempt-depth
                      ||| /     delay
     TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
        | |       |   ||||       |         |
   <idle>-0     [001] d..2   604.183512: sched_switch: prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=taskset next_pid=273 next_prio=120
user_loop-273   [001] d.h1   604.184788: hrtimer_expire_entry: hrtimer=000000002eda5fab function=tick_sched_timer now=604176096300
user_loop-273   [001] d.s2   604.184897: workqueue_queue_work: work struct=00000000383402c2 function=vmstat_update workqueue=00000000f36d35d4 req_cpu=1 cpu=1
user_loop-273   [001] dns2   604.185039: tick_stop: success=0 dependency=SCHED
user_loop-273   [001] dn.1   604.185103: tick_stop: success=0 dependency=SCHED
user_loop-273   [001] d..2   604.185154: sched_switch: prev_comm=taskset prev_pid=273 prev_prio=120 prev_state=R+ ==> next_comm=kworker/1:1 next_pid=46 next_prio=120
    <...>-46    [001] ....   604.185194: workqueue_execute_start: work struct 00000000383402c2: function vmstat_update
    <...>-46    [001] d..2   604.185266: sched_switch: prev_comm=kworker/1:1 prev_pid=46 prev_prio=120 prev_state=I ==> next_comm=taskset next_pid=273 next_prio=120
user_loop-273   [001] d.h1   604.188812: hrtimer_expire_entry: hrtimer=000000002eda5fab function=tick_sched_timer now=604180133400
user_loop-273   [001] d..1   604.189050: tick_stop: success=1 dependency=NONE
user_loop-273   [001] d..2   614.251386: sched_switch: prev_comm=user_loop prev_pid=273 prev_prio=120 prev_state=X ==> next_comm=swapper/1 next_pid=0 next_prio=120
   <idle>-0     [001] d..2   614.315391: sched_switch: prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=taskset next_pid=276 next_prio=120
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Support for arch_irq_work_raise() and arch_irq_work_has_interrupt() was
missing from riscv (a prerequisite for FULL_NOHZ).
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Lockdep is needed by proving the spinlocks and rwlocks. To suupport
it, we need fixup TRACE_IRQFLAGS_SUPPORT in kernel/entry.S. This
patch follow Documentation/irqflags-tracing.txt.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The cpu_running is not a lock-class, it lacks the dep_map member in
completion. It causes the error as follow:

arch/riscv/kernel/smpboot.c: In function '__cpu_up':
./include/linux/lockdep.h:364:52: error: 'struct completion' has no member named 'dep_map'
  364 | #define lockdep_is_held(lock)  lock_is_held(&(lock)->dep_map)
      |                                                    ^~
./include/asm-generic/bug.h:113:25: note: in definition of macro 'WARN_ON'
  113 |  int __ret_warn_on = !!(condition);    \
      |                         ^~~~~~~~~
./include/linux/lockdep.h:390:27: note: in expansion of macro 'lockdep_is_held'
  390 |   WARN_ON(debug_locks && !lockdep_is_held(l)); \
      |                           ^~~~~~~~~~~~~~~
arch/riscv/kernel/smpboot.c:118:2: note: in expansion of macro 'lockdep_assert_held'
  118 |  lockdep_assert_held(&cpu_running);

There are a lot of archs which use cpu_running in smpboot.c (arm,
arm64, openrisc, xtensa, s390, x86, mips), but none of them try
lockdep_assert_held(&cpu_running.wait.lock). So Just remove it.
Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

When enable LOCKDEP, static_obj() will cause error. Because some
__initdata static variables is before _stext:

static int static_obj(const void *obj)
{
        unsigned long start = (unsigned long) &_stext,
                      end   = (unsigned long) &_end,
                      addr  = (unsigned long) obj;

        /*
         * static variable?
         */
        if ((addr >= start) && (addr < end))
                return 1;

[    0.067192] INFO: trying to register non-static key.
[    0.067325] the code is fine but needs lockdep annotation.
[    0.067449] turning off the locking correctness validator.
[    0.067718] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-rc7-dirty #44
[    0.067945] Call Trace:
[    0.068369] [<ffffffe00020323c>] walk_stackframe+0x0/0xa4
[    0.068506] [<ffffffe000203422>] show_stack+0x2a/0x34
[    0.068631] [<ffffffe000521e4e>] dump_stack+0x94/0xca
[    0.068757] [<ffffffe000255a4e>] register_lock_class+0x5b8/0x5bc
[    0.068969] [<ffffffe000255abe>] __lock_acquire+0x6c/0x1d5c
[    0.069101] [<ffffffe0002550fe>] lock_acquire+0xae/0x312
[    0.069228] [<ffffffe000989a8e>] _raw_spin_lock_irqsave+0x40/0x5a
[    0.069357] [<ffffffe000247c64>] complete+0x1e/0x50
[    0.069479] [<ffffffe000984c38>] rest_init+0x1b0/0x28a
[    0.069660] [<ffffffe0000016a2>] 0xffffffe0000016a2
[    0.069779] [<ffffffe000001b84>] 0xffffffe000001b84
[    0.069953] [<ffffffe000001092>] 0xffffffe000001092

static __initdata DECLARE_COMPLETION(kthreadd_done);

noinline void __ref rest_init(void)
{
	...
	complete(&kthreadd_done);
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add System RAM to /proc/iomem, various tools expect it such as kdump.
It is also needed for page_is_ram API which checks the specified address
whether registered as System RAM in iomem_resource list.
Signed-off-by: Zong Li <zong.li@sifive.com>
[Palmer: check MEMBLOCK_NOMAP]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Store the smp_processor_id() in a local variable to save some
pointer chasing.
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Select ARCH_SUPPORTS_ATOMIC_RMW by default to enable osqlocks.
Signed-off-by: Chenxi Mao <maochenxi@eswin.com>
[Palmer: commit text]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Pull ARM OMAP fixes from Arnd Bergmann:
 "The OMAP developers are particularly active at hunting down
  regressions, so this is a separate branch with OMAP specific
  fixes for v5.8:

  As Tony explains
    "The recent display subsystem (DSS) related platform data changes
     caused display related regressions for suspend and resume. Looks
     like I only tested suspend and resume before dropping the legacy
     platform data, and forgot to test it after dropping it. Turns out
     the main issue was that we no longer have platform code calling
     pm_runtime_suspend for DSS like we did for the legacy platform data
     case, and that fix is still being discussed on the dri-devel list
     and will get merged separately. The DSS related testing exposed a
     pile other other display related issues that also need fixing
     though":

   - Fix ti-sysc optional clock handling and reset status checks for
     devices that reset automatically in idle like DSS

   - Ignore ti-sysc clockactivity bit unless separately requested to
     avoid unexpected performance issues

   - Init ti-sysc framedonetv_irq to true and disable for am4

   - Avoid duplicate DSS reset for legacy mode with dts data

   - Remove LCD timings for am4 as they cause warnings now that we're
     using generic panels

  Other OMAP changes from Tony include:

   - Fix omap_prm reset deassert as we still have drivers setting the
     pm_runtime_irq_safe() flag

   - Flush posted write for ti-sysc enable and disable

   - Fix droid4 spi related errors with spi flags

   - Fix am335x USB range and a typo for softreset

   - Fix dra7 timer nodes for clocks for IPU and DSP

   - Drop duplicate mailboxes after mismerge for dra7

   - Prevent pocketgeagle header line signal from accidentally setting
     micro-SD write protection signal by removing the default mux

   - Fix NFSroot flakeyness after resume for duover by switching the
     smsc911x gpio interrupt to back to level sensitive

   - Fix regression for omap4 clockevent source after recent system
     timer changes

   - Yet another ethernet regression fix for the "rgmii" vs "rgmii-rxid"
     phy-mode

   - One patch to convert am3/am4 DT files to use the regular sdhci-omap
     driver instead of the old hsmmc driver, this was meant for the
     merge window but got lost in the process"

* tag 'arm-omap-fixes-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (21 commits)
  ARM: dts: am5729: beaglebone-ai: fix rgmii phy-mode
  ARM: dts: Fix omap4 system timer source clocks
  ARM: dts: Fix duovero smsc interrupt for suspend
  ARM: dts: am335x-pocketbeagle: Fix mmc0 Write Protect
  Revert "bus: ti-sysc: Increase max softreset wait"
  ARM: dts: am437x-epos-evm: remove lcd timings
  ARM: dts: am437x-gp-evm: remove lcd timings
  ARM: dts: am437x-sk-evm: remove lcd timings
  ARM: dts: dra7-evm-common: Fix duplicate mailbox nodes
  ARM: dts: dra7: Fix timer nodes properly for timer_sys_ck clocks
  ARM: dts: Fix am33xx.dtsi ti,sysc-mask wrong softreset flag
  ARM: dts: Fix am33xx.dtsi USB ranges length
  bus: ti-sysc: Increase max softreset wait
  ARM: OMAP2+: Fix legacy mode dss_reset
  bus: ti-sysc: Fix uninitialized framedonetv_irq
  bus: ti-sysc: Ignore clockactivity unless specified as a quirk
  bus: ti-sysc: Use optional clocks on for enable and wait for softreset bit
  ARM: dts: omap4-droid4: Fix spi configuration and increase rate
  bus: ti-sysc: Flush posted write on enable and disable
  soc: ti: omap-prm: use atomic iopoll instead of sleeping one
  ...

Pull ARM SoC fixes from Arnd Bergmann:
 "Here are a couple of bug fixes, mostly for devicetree files

  NXP i.MX:
   - Use correct voltage on some i.MX8M board device trees to avoid
     hardware damage
   - Code fixes for a compiler warning and incorrect reference counting,
     both harmless.
   - Fix the i.MX8M SoC driver to correctly identify imx8mp
   - Fix watchdog configuration in imx6ul-kontron device tree.

  Broadcom:
   - A small regression fix for the Raspberry-Pi firmware driver
   - A Kconfig change to use the correct timer driver on Northstar
   - A DT fix for the Luxul XWC-2000 machine
   - Two more DT fixes for NSP SoCs

  STmicroelectronics STI
   - Revert one broken patch for L2 cache configuration

  ARM Versatile Express:
   - Fix a regression by reverting a broken DT cleanup

  TEE drivers:
   - MAINTAINERS: change tee mailing list"

* tag 'arm-fixes-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
  Revert "ARM: sti: Implement dummy L2 cache's write_sec"
  soc: imx8m: fix build warning
  ARM: imx6: add missing put_device() call in imx6q_suspend_init()
  ARM: imx5: add missing put_device() call in imx_suspend_alloc_ocram()
  soc: imx8m: Correct i.MX8MP UID fuse offset
  ARM: dts: imx6ul-kontron: Change WDOG_ANY signal from push-pull to open-drain
  ARM: dts: imx6ul-kontron: Move watchdog from Kontron i.MX6UL/ULL board to SoM
  arm64: dts: imx8mm-beacon: Fix voltages on LDO1 and LDO2
  arm64: dts: imx8mn-ddr4-evk: correct ldo1/ldo2 voltage range
  arm64: dts: imx8mm-evk: correct ldo1/ldo2 voltage range
  ARM: dts: NSP: Correct FA2 mailbox node
  ARM: bcm2835: Fix integer overflow in rpi_firmware_print_firmware_revision()
  MAINTAINERS: change tee mailing list
  ARM: dts: NSP: Disable PL330 by default, add dma-coherent property
  ARM: bcm: Select ARM_TIMER_SP804 for ARCH_BCM_NSP
  ARM: dts: BCM5301X: Add missing memory "device_type" for Luxul XWC-2000
  arm: dts: vexpress: Move mcc node back into motherboard node

Pull timer fix from Ingo Molnar:
 "A single DocBook fix"

* tag 'timers-urgent-2020-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timekeeping: Fix kerneldoc system_device_crosststamp & al

Pull perf fix from Ingo Molnar:
 "A single Kbuild dependency fix"

* tag 'perf-urgent-2020-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/rapl: Fix RAPL config variable bug

Pull EFI fixes from Ingo Molnar:

 - Fix build regression on v4.8 and older

 - Robustness fix for TPM log parsing code

 - kobject refcount fix for the ESRT parsing code

 - Two efivarfs fixes to make it behave more like an ordinary file
   system

 - Style fixup for zero length arrays

 - Fix a regression in path separator handling in the initrd loader

 - Fix a missing prototype warning

 - Add some kerneldoc headers for newly introduced stub routines

 - Allow support for SSDT overrides via EFI variables to be disabled

 - Report CPU mode and MMU state upon entry for 32-bit ARM

 - Use the correct stack pointer alignment when entering from mixed mode

* tag 'efi-urgent-2020-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/libstub: arm: Print CPU boot mode and MMU state at boot
  efi/libstub: arm: Omit arch specific config table matching array on arm64
  efi/x86: Setup stack correctly for efi_pe_entry
  efi: Make it possible to disable efivar_ssdt entirely
  efi/libstub: Descriptions for stub helper functions
  efi/libstub: Fix path separator regression
  efi/libstub: Fix missing-prototype warning for skip_spaces()
  efi: Replace zero-length array and use struct_size() helper
  efivarfs: Don't return -EINTR when rate-limiting reads
  efivarfs: Update inode modification time for successful writes
  efi/esrt: Fix reference count leak in esre_create_sysfs_entry.
  efi/tpm: Verify event log header before parsing
  efi/x86: Fix build with gcc 4

Pull scheduler fixes from Borislav Petkov:
 "The most anticipated fix in this pull request is probably the horrible
  build fix for the RANDSTRUCT fail that didn't make -rc2. Also included
  is the cleanup that removes those BUILD_BUG_ON()s and replaces it with
  ugly unions.

  Also included is the try_to_wake_up() race fix that was first
  triggered by Paul's RCU-torture runs, but was independently hit by
  Dave Chinner's fstest runs as well"

* tag 'sched_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/cfs: change initial value of runnable_avg
  smp, irq_work: Continue smp_call_function*() and irq_work*() integration
  sched/core: s/WF_ON_RQ/WQ_ON_CPU/
  sched/core: Fix ttwu() race
  sched/core: Fix PI boosting between RT and DEADLINE tasks
  sched/deadline: Initialize ->dl_boosted
  sched/core: Check cpus_mask, not cpus_ptr in __set_cpus_allowed_ptr(), to fix mask corruption
  sched/core: Fix CONFIG_GCC_PLUGIN_RANDSTRUCT build fail

Pull x86 fixes from Borislav Petkov:

 - AMD Memory bandwidth counter width fix, by Babu Moger.

 - Use the proper length type in the 32-bit truncate() syscall variant,
   by Jiri Slaby.

 - Reinit IA32_FEAT_CTL during wakeup to fix the case where after
   resume, VMXON would #GP due to VMX not being properly enabled, by
   Sean Christopherson.

 - Fix a static checker warning in the resctrl code, by Dan Carpenter.

 - Add a CR4 pinning mask for bits which cannot change after boot, by
   Kees Cook.

 - Align the start of the loop of __clear_user() to 16 bytes, to improve
   performance on AMD zen1 and zen2 microarchitectures, by Matt Fleming.

* tag 'x86_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/asm/64: Align start of __clear_user() loop to 16-bytes
  x86/cpu: Use pinning mask for CR4 bits needing to be 0
  x86/resctrl: Fix a NULL vs IS_ERR() static checker warning in rdt_cdp_peer_get()
  x86/cpu: Reinitialize IA32_FEAT_CTL MSR on BSP during wakeup
  syscalls: Fix offset type of ksys_ftruncate()
  x86/resctrl: Fix memory bandwidth counter width for AMD

Pull RCU-vs-KCSAN fixes from Borislav Petkov:
 "A single commit that uses "arch_" atomic operations to avoid the
  instrumentation that comes with the non-"arch_" versions.

  In preparation for that commit, it also has another commit that makes
  these "arch_" atomic operations available to generic code.

  Without these commits, KCSAN uses can see pointless errors"

* tag 'rcu_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Fixup noinstr warnings
  locking/atomics: Provide the arch_atomic_ interface to generic code

Pull objtool fixes from Borislav Petkov:
 "Three fixes from Peter Zijlstra suppressing KCOV instrumentation in
  noinstr sections.

  Peter Zijlstra says:
    "Address KCOV vs noinstr. There is no function attribute to
     selectively suppress KCOV instrumentation, instead teach objtool
     to NOP out the calls in noinstr functions"

  This cures a bunch of KCOV crashes (as used by syzcaller)"

* tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix noinstr vs KCOV
  objtool: Provide elf_write_{insn,reloc}()
  objtool: Clean up elf_write() condition

Pull x86 entry fixes from Borislav Petkov:
 "This is the x86/entry urgent pile which has accumulated since the
  merge window.

  It is not the smallest but considering the almost complete entry core
  rewrite, the amount of fixes to follow is somewhat higher than usual,
  which is to be expected.

  Peter Zijlstra says:
   'These patches address a number of instrumentation issues that were
    found after the x86/entry overhaul. When combined with rcu/urgent
    and objtool/urgent, these patches make UBSAN/KASAN/KCSAN happy
    again.

    Part of making this all work is bumping the minimum GCC version for
    KASAN builds to gcc-8.3, the reason for this is that the
    __no_sanitize_address function attribute is broken in GCC releases
    before that.

    No known GCC version has a working __no_sanitize_undefined, however
    because the only noinstr violation that results from this happens
    when an UB is found, we treat it like WARN. That is, we allow it to
    violate the noinstr rules in order to get the warning out'"

* tag 'x86_entry_for_5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/entry: Fix #UD vs WARN more
  x86/entry: Increase entry_stack size to a full page
  x86/entry: Fixup bad_iret vs noinstr
  objtool: Don't consider vmlinux a C-file
  kasan: Fix required compiler version
  compiler_attributes.h: Support no_sanitize_undefined check with GCC 4
  x86/entry, bug: Comment the instrumentation_begin() usage for WARN()
  x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*()
  x86/entry, cpumask: Provide non-instrumented variant of cpu_is_offline()
  compiler_types.h: Add __no_sanitize_{address,undefined} to noinstr
  kasan: Bump required compiler version
  x86, kcsan: Add __no_kcsan to noinstr
  kcsan: Remove __no_kcsan_or_inline
  x86, kcsan: Remove __no_kcsan_or_inline usage

Some performance regression on reaim benchmark have been raised with
  commit 070f5e86 ("sched/fair: Take into account runnable_avg to classify group")

The problem comes from the init value of runnable_avg which is initialized
with max value. This can be a problem if the newly forked task is finally
a short task because the group of CPUs is wrongly set to overloaded and
tasks are pulled less agressively.

Set initial value of runnable_avg equals to util_avg to reflect that there
is no waiting time so far.

Fixes: 070f5e86 ("sched/fair: Take into account runnable_avg to classify group")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200624154422.29166-1-vincent.guittot@linaro.org

Instead of relying on BUG_ON() to ensure the various data structures
line up, use a bunch of horrible unions to make it all automatic.

Much of the union magic is to ensure irq_work and smp_call_function do
not (yet) see the members of their respective data structures change
name.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20200622100825.844455025@infradead.org

Use a better name for this poorly named flag, to avoid confusion...
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lkml.kernel.org/r/20200622100825.785115830@infradead.org

Paul reported rcutorture occasionally hitting a NULL deref:

  sched_ttwu_pending()
    ttwu_do_wakeup()
      check_preempt_curr() := check_preempt_wakeup()
        find_matching_se()
          is_same_group()
            if (se->cfs_rq == pse->cfs_rq) <-- *BOOM*

Debugging showed that this only appears to happen when we take the new
code-path from commit:

  2ebb1771 ("sched/core: Offload wakee task activation if it the wakee is descheduling")

and only when @cpu == smp_processor_id(). Something which should not
be possible, because p->on_cpu can only be true for remote tasks.
Similarly, without the new code-path from commit:

  c6e7bd7a ("sched/core: Optimize ttwu() spinning on p->on_cpu")

this would've unconditionally hit:

  smp_cond_load_acquire(&p->on_cpu, !VAL);

and if: 'cpu == smp_processor_id() && p->on_cpu' is possible, this
would result in an instant live-lock (with IRQs disabled), something
that hasn't been reported.

The NULL deref can be explained however if the task_cpu(p) load at the
beginning of try_to_wake_up() returns an old value, and this old value
happens to be smp_processor_id(). Further assume that the p->on_cpu
load accurately returns 1, it really is still running, just not here.

Then, when we enqueue the task locally, we can crash in exactly the
observed manner because p->se.cfs_rq != rq->cfs_rq, because p's cfs_rq
is from the wrong CPU, therefore we'll iterate into the non-existant
parents and NULL deref.

The closest semi-plausible scenario I've managed to contrive is
somewhat elaborate (then again, actual reproduction takes many CPU
hours of rcutorture, so it can't be anything obvious):

					X->cpu = 1
					rq(1)->curr = X

	CPU0				CPU1				CPU2

					// switch away from X
					LOCK rq(1)->lock
					smp_mb__after_spinlock
					dequeue_task(X)
					  X->on_rq = 9
					switch_to(Z)
					  X->on_cpu = 0
					UNLOCK rq(1)->lock

									// migrate X to cpu 0
									LOCK rq(1)->lock
									dequeue_task(X)
									set_task_cpu(X, 0)
									  X->cpu = 0
									UNLOCK rq(1)->lock

									LOCK rq(0)->lock
									enqueue_task(X)
									  X->on_rq = 1
									UNLOCK rq(0)->lock

	// switch to X
	LOCK rq(0)->lock
	smp_mb__after_spinlock
	switch_to(X)
	  X->on_cpu = 1
	UNLOCK rq(0)->lock

	// X goes sleep
	X->state = TASK_UNINTERRUPTIBLE
	smp_mb();			// wake X
					ttwu()
					  LOCK X->pi_lock
					  smp_mb__after_spinlock

					  if (p->state)

					  cpu = X->cpu; // =? 1

					  smp_rmb()

	// X calls schedule()
	LOCK rq(0)->lock
	smp_mb__after_spinlock
	dequeue_task(X)
	  X->on_rq = 0

					  if (p->on_rq)

					  smp_rmb();

					  if (p->on_cpu && ttwu_queue_wakelist(..)) [*]

					  smp_cond_load_acquire(&p->on_cpu, !VAL)

					  cpu = select_task_rq(X, X->wake_cpu, ...)
					  if (X->cpu != cpu)
	switch_to(Y)
	  X->on_cpu = 0
	UNLOCK rq(0)->lock

However I'm having trouble convincing myself that's actually possible
on x86_64 -- after all, every LOCK implies an smp_mb() there, so if ttwu
observes ->state != RUNNING, it must also observe ->cpu != 1.

(Most of the previous ttwu() races were found on very large PowerPC)

Nevertheless, this fully explains the observed failure case.

Fix it by ordering the task_cpu(p) load after the p->on_cpu load,
which is easy since nothing actually uses @cpu before this.

Fixes: c6e7bd7a ("sched/core: Optimize ttwu() spinning on p->on_cpu")
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200622125649.GC576871@hirez.programming.kicks-ass.net

syzbot reported the following warning:

 WARNING: CPU: 1 PID: 6351 at kernel/sched/deadline.c:628
 enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504

At deadline.c:628 we have:

 623 static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
 624 {
 625 	struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
 626 	struct rq *rq = rq_of_dl_rq(dl_rq);
 627
 628 	WARN_ON(dl_se->dl_boosted);
 629 	WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
        [...]
     }

Which means that setup_new_dl_entity() has been called on a task
currently boosted. This shouldn't happen though, as setup_new_dl_entity()
is only called when the 'dynamic' deadline of the new entity
is in the past w.r.t. rq_clock and boosted tasks shouldn't verify this
condition.

Digging through the PI code I noticed that what above might in fact happen
if an RT tasks blocks on an rt_mutex hold by a DEADLINE task. In the
first branch of boosting conditions we check only if a pi_task 'dynamic'
deadline is earlier than mutex holder's and in this case we set mutex
holder to be dl_boosted. However, since RT 'dynamic' deadlines are only
initialized if such tasks get boosted at some point (or if they become
DEADLINE of course), in general RT 'dynamic' deadlines are usually equal
to 0 and this verifies the aforementioned condition.

Fix it by checking that the potential donor task is actually (even if
temporary because in turn boosted) running at DEADLINE priority before
using its 'dynamic' deadline value.

Fixes: 2d3d891d ("sched/deadline: Add SCHED_DEADLINE inheritance logic")
Reported-by: syzbot+119ba87189432ead09b4@syzkaller.appspotmail.com
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Tested-by: Daniel Wagner <dwagner@suse.de>
Link: https://lkml.kernel.org/r/20181119153201.GB2119@localhost.localdomain

syzbot reported the following warning triggered via SYSC_sched_setattr():

  WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 setup_new_dl_entity /kernel/sched/deadline.c:594 [inline]
  WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 enqueue_dl_entity /kernel/sched/deadline.c:1370 [inline]
  WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 enqueue_task_dl+0x1c17/0x2ba0 /kernel/sched/deadline.c:1441

This happens because the ->dl_boosted flag is currently not initialized by
__dl_clear_params() (unlike the other flags) and setup_new_dl_entity()
rightfully complains about it.

Initialize dl_boosted to 0.

Fixes: 2d3d891d ("sched/deadline: Add SCHED_DEADLINE inheritance logic")
Reported-by: syzbot+5ac8bac25f95e8b221e7@syzkaller.appspotmail.com
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Daniel Wagner <dwagner@suse.de>
Link: https://lkml.kernel.org/r/20200617072919.818409-1-juri.lelli@redhat.com

This function is concerned with the long-term CPU mask, not the
transitory mask the task might have while migrate disabled.  Before
this patch, if a task was migrate-disabled at the time
__set_cpus_allowed_ptr() was called, and the new mask happened to be
equal to the CPU that the task was running on, then the mask update
would be lost.
Signed-off-by: Scott Wood <swood@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200617121742.cpxppyi7twxmpin7@linutronix.de

As a temporary build fix, the proper cleanup needs more work.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Eric Biggers <ebiggers@kernel.org>
Suggested-by: Eric Biggers <ebiggers@kernel.org>
Suggested-by: Kees Cook <keescook@chromium.org>
Fixes: a1488664 ("sched: Replace rq::wake_list")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge tag 'imx-fixes-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux into arm/fixes

i.MX fixes for 5.8:

- Fix LDO1 and LDO2 voltage range for a couple of i.MX8M board device
  trees.
- Fix i.MX8MP UID fuse offset in i.MX8M SoC driver.
- Fix watchdog configuration in imx6ul-kontron device tree.
- Fix one build warning seen on building soc-imx8m driver with
  x86_64-randconfig.
- Add missing put_device() call for a couple of mach-imx PM functions.

* tag 'imx-fixes-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux:
  soc: imx8m: fix build warning
  ARM: imx6: add missing put_device() call in imx6q_suspend_init()
  ARM: imx5: add missing put_device() call in imx_suspend_alloc_ocram()
  soc: imx8m: Correct i.MX8MP UID fuse offset
  ARM: dts: imx6ul-kontron: Change WDOG_ANY signal from push-pull to open-drain
  ARM: dts: imx6ul-kontron: Move watchdog from Kontron i.MX6UL/ULL board to SoM
  arm64: dts: imx8mm-beacon: Fix voltages on LDO1 and LDO2
  arm64: dts: imx8mn-ddr4-evk: correct ldo1/ldo2 voltage range
  arm64: dts: imx8mm-evk: correct ldo1/ldo2 voltage range

Link: https://lore.kernel.org/r/20200624111725.GA24312@dragonSigned-off-by: Arnd Bergmann <arnd@arndb.de>

This pull request contains Broadcom ARM/ARM64/MIPS SoCs drivers fixes
for 5.8, please pull the following:

- Andy provides a fix for the Raspberry Pi firmware driver to print the
  correct time upon boot. This is a fallout from a converstion to use
  the ptT format

* tag 'arm-soc/for-5.8/drivers-fixes' of https://github.com/Broadcom/stblinux:
  ARM: bcm2835: Fix integer overflow in rpi_firmware_print_firmware_revision()

Link: https://lore.kernel.org/r/20200619202250.19029-2-f.fainelli@gmail.comSigned-off-by: Arnd Bergmann <arnd@arndb.de>

This pull request contains Broadcom ARM-based SoCs machine/Kconfig fixes
for 5.8, please pull the following:

- Matthew adds a missing select to permit the use of the standard ARM
  SP804 timers on Norsthstar Plus (NSP)

* tag 'arm-soc/for-5.8/soc-fixes' of https://github.com/Broadcom/stblinux:
  ARM: bcm: Select ARM_TIMER_SP804 for ARCH_BCM_NSP

Link: https://lore.kernel.org/r/20200619202250.19029-3-f.fainelli@gmail.comSigned-off-by: Arnd Bergmann <arnd@arndb.de>

This pull request contains Broadcom ARM-based SoCs Device Tree fixes for
5.8, please pull the following:

- Rafal adds a missing 'device_type' property to the Luxul XWC-2000
  required for the memory nodes to be correctly parsed by Linux

- Matthew provides two fixes for the NSP SoCs, one to disable the PL330
  DMA controller by default since it can be left in reset by the
  bootloader and the second to correct the flow accelerator mailbox node

* tag 'arm-soc/for-5.8/devicetree-fixes' of https://github.com/Broadcom/stblinux:
  ARM: dts: NSP: Correct FA2 mailbox node
  ARM: dts: NSP: Disable PL330 by default, add dma-coherent property
  ARM: dts: BCM5301X: Add missing memory "device_type" for Luxul XWC-2000

Link: https://lore.kernel.org/r/20200619202250.19029-1-f.fainelli@gmail.comSigned-off-by: Arnd Bergmann <arnd@arndb.de>

This reverts commit 7b8e0188.

Initially, STiH410-B2260 was supposed to be secured, that's why
l2c_write_sec was stubbed to avoid secure register access from
non secure world.

But by default, STiH410-B2260 is running in non secure mode,
so L2 cache register accesses are authorized, l2c_write_sec stub
is not needed.

With this patch, L2 cache is configured and performance are enhanced.

Link: https://lore.kernel.org/r/20200618172456.29475-1-patrice.chotard@st.comSigned-off-by: Patrice Chotard <patrice.chotard@st.com>
Cc: Alain Volmat <alain.volmat@st.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Merge tag 'omap-for-v5.8/fixes-rc1-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into arm/omap-fixes

Few dts fixes for omaps for v5.8

Few fixes for various devices:

- Prevent pocketgeagle header line signal from accidentally setting
  micro-SD write protection signal by removing the default mux

- Fix NFSroot flakeyness after resume for duover by switching the
  smsc911x gpio interrupt to back to level sensitive

- Fix regression for omap4 clockevent source after recent system
  timer changes

- Yet another ethernet regression fix for the "rgmii" vs "rgmii-rxid"
  phy-mode

* tag 'omap-for-v5.8/fixes-rc1-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  ARM: dts: am5729: beaglebone-ai: fix rgmii phy-mode
  ARM: dts: Fix omap4 system timer source clocks
  ARM: dts: Fix duovero smsc interrupt for suspend
  ARM: dts: am335x-pocketbeagle: Fix mmc0 Write Protect

Link: https://lore.kernel.org/r/pull-1592499282-121092@atomide.comSigned-off-by: Arnd Bergmann <arnd@arndb.de>

Merge tag 'omap-for-v5.8/dt-missed-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into arm/omap-fixes

Missed sdhci patch for am3 and am4

I forgot to send a pull request earlier for converting am3 and am4 to
use sdhci-omap driver instead of the old omap_hsmmc driver.

There was a display subsystem related suspend and resume regression found
recently and looks like I forgot to send a pull request for this patch
while debugging the regression. This patch has been tested without the
display subsystem, and has been in Linux next for several weeks now, so
would be good to have merged for v5.8.

* tag 'omap-for-v5.8/dt-missed-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  ARM: dts: Move am33xx and am43xx mmc nodes to sdhci-omap driver

Link: https://lore.kernel.org/r/pull-1591637467-607254@atomide.comSigned-off-by: Arnd Bergmann <arnd@arndb.de>

Change the TEE mailing list in MAINTAINERS

* tag 'tee-ml-for-v5.8' of git://git.linaro.org/people/jens.wiklander/linux-tee:
  MAINTAINERS: change tee mailing list

Link: https://lore.kernel.org/r/20200616075948.GA2288211@jadeSigned-off-by: Arnd Bergmann <arnd@arndb.de>

Merge tag 'omap-for-v5.8/fixes-merge-window-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into arm/fixes

Fixes for omaps for v5.8

The recent display subsystem (DSS) related platform data changes caused
display related regressions for suspend and resume. Looks like I only
tested suspend and resume before dropping the legacy platform data, and
forgot to test it after dropping it. Turns out the main issue was that
we no longer have platform code calling pm_runtime_suspend for DSS like
we did for the legacy platform data case, and that fix is still being
discussed on the dri-devel list and will get merged separately. The DSS
related testing exposed a pile other other display related issues that
also need fixing though:

- Fix ti-sysc optional clock handling and reset status checks
  for devices that reset automatically in idle like DSS

- Ignore ti-sysc clockactivity bit unless separately requested
  to avoid unexpected performance issues

- Init ti-sysc framedonetv_irq to true and disable for am4

- Avoid duplicate DSS reset for legacy mode with dts data

- Remove LCD timings for am4 as they cause warnings now that we're
  using generic panels

Then there is a pile of other fixes not related to the DSS:

- Fix omap_prm reset deassert as we still have drivers setting the
  pm_runtime_irq_safe() flag

- Flush posted write for ti-sysc enable and disable

- Fix droid4 spi related errors with spi flags

- Fix am335x USB range and a typo for softreset

- Fix dra7 timer nodes for clocks for IPU and DSP

- Drop duplicate mailboxes after mismerge for dra7

* tag 'omap-for-v5.8/fixes-merge-window-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  Revert "bus: ti-sysc: Increase max softreset wait"
  ARM: dts: am437x-epos-evm: remove lcd timings
  ARM: dts: am437x-gp-evm: remove lcd timings
  ARM: dts: am437x-sk-evm: remove lcd timings
  ARM: dts: dra7-evm-common: Fix duplicate mailbox nodes
  ARM: dts: dra7: Fix timer nodes properly for timer_sys_ck clocks
  ARM: dts: Fix am33xx.dtsi ti,sysc-mask wrong softreset flag
  ARM: dts: Fix am33xx.dtsi USB ranges length
  bus: ti-sysc: Increase max softreset wait
  ARM: OMAP2+: Fix legacy mode dss_reset
  bus: ti-sysc: Fix uninitialized framedonetv_irq
  bus: ti-sysc: Ignore clockactivity unless specified as a quirk
  bus: ti-sysc: Use optional clocks on for enable and wait for softreset bit
  ARM: dts: omap4-droid4: Fix spi configuration and increase rate
  bus: ti-sysc: Flush posted write on enable and disable
  soc: ti: omap-prm: use atomic iopoll instead of sleeping one

Link: https://lore.kernel.org/r/pull-1591889257-410830@atomide.comSigned-off-by: Arnd Bergmann <arnd@arndb.de>

The cell name stored in the afs_cell struct is a 64-char + NUL buffer -
when it needs to be able to handle up to AFS_MAXCELLNAME (256 chars) + NUL.

Fix this by changing the array to a pointer and allocating the string.

Found using Coverity.

Fixes: 989782dc ("afs: Overhaul cell database management")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull cifs fixes from Steve French:
 "Six cifs/smb3 fixes, three of them for stable.

  Fixes xfstests 451, 313 and 316"

* tag '5.8-rc2-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: misc: Use array_size() in if-statement controlling expression
  cifs: update ctime and mtime during truncate
  cifs/smb3: Fix data inconsistent when punch hole
  cifs/smb3: Fix data inconsistent when zero file range
  cifs: Fix double add page to memcg when cifs_readpages
  cifs: Fix cached_fid refcnt leak in open_shroot