The code in entry-common.c runs at exception entry and return
boundaries, where portions of the kernel environment aren't available.
For example, RCU may not be watching, and lockdep state may be
out-of-sync with the hardware. Due to this, it is not sound to
instrument this code.

We generally avoid instrumentation by marking the entry functions as
`noinstr`, but currently this doesn't inhibit KCOV instrumentation.
Prevent this by disabling KCOV for the entire compilation unit.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-20-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Now that we only call arm64_enter_nmi() and arm64_exit_nmi() from within
entry-common.c, let's make these static to ensure this remains the case.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-19-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

We'd like to keep all the entry sequencing in entry-common.c, as this
will allow us to ensure this is consistent, and free from any unsound
instrumentation.

Currently __sdei_handler() performs the NMI entry/exit sequences in
sdei.c. Let's split the low-level entry sequence from the event
handling, moving the former to entry-common.c and keeping the latter in
sdei.c. The event handling function is renamed to do_sdei_event(),
matching the do_${FOO}() pattern used for other exception handlers.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-18-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

We'd like to keep all the entry sequencing in entry-common.c, as this
will allow us to ensure this is consistent, and free from any unsound
instrumentation.

Currently handle_bad_stack() performs the NMI entry sequence in traps.c.
Let's split the low-level entry sequence from the reporting, moving the
former to entry-common.c and keeping the latter in traps.c. To make it
clear that reporting function never returns, it is renamed to
panic_bad_stack().
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-17-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

An unexpected synchronous exception from EL1h could happen at any time,
and for robustness we should treat this as an NMI, making minimal
assumptions about the context the exception was taken from.

Currently el1_inv() assumes we can use enter_from_kernel_mode(), and
also assumes that we should inherit the original DAIF value. Neither of
these are desireable when we take an unexpected exception. Further,
after el1_inv() calls __panic_unhandled(), the remainder of the function
is unreachable, and therefore superfluous.

Let's address this and simplify things by having el1h_64_sync_handler()
call __panic_unhandled() directly, without any of the redundant logic.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reported-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-16-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

We have 16 architectural exception vectors, and depending on kernel
configuration we handle 8 or 12 of these with C code, with the remaining
8 or 4 of these handled as special cases in the entry assembly.

It would be nicer if the entry assembly were uniform for all exceptions,
and we deferred any specific handling of the exceptions to C code. This
way the entry assembly can be more easily templated without ifdeffery or
special cases, and it's easier to modify the handling of these cases in
future (e.g. to dump additional registers other context).

This patch reworks the entry code so that we always have a C handler for
every architectural exception vector, with the entry assembly being
completely uniform. We now have to handle exceptions from EL1t and EL1h,
and also have to handle exceptions from AArch32 even when the kernel is
built without CONFIG_COMPAT. To make this clear and to simplify
templating, we rename the top-level exception handlers with a consistent
naming scheme:

  asm: <el+sp>_<regsize>_<type>
  c:   <el+sp>_<regsize>_<type>_handler

.. where:

  <el+sp> is `el1t`, `el1h`, or `el0t`
  <regsize> is `64` or `32`
  <type> is `sync`, `irq`, `fiq`, or `error`

... e.g.

  asm: el1h_64_sync
  c:   el1h_64_sync_handler

... with lower-level handlers simply using "el1" and "compat" as today.

For unexpected exceptions, this information is passed to
__panic_unhandled(), so it can report the specific vector an unexpected
exception was taken from, e.g.

| Unhandled 64-bit el1t sync exception

For vectors we never expect to enter legitimately, the C code is
generated using a macro to avoid code duplication. The exceptions are
handled via __panic_unhandled(), replacing bad_mode() (which is
removed).

The `kernel_ventry` and `entry_handler` assembly macros are updated to
handle the new naming scheme. In theory it should be possible to
generate the entry functions at the same time as the vectors using a
single table, but this will require reworking the linker script to split
the two into separate sections, so for now we have separate tables.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-15-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Now that the majority of the exception triage logic has been converted
to C, the entry assembly functions all have a uniform structure.

Let's generate them all with an assembly macro to reduce the amount of
code and to ensure they all remain in sync if we make changes in future.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-14-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Our use of bad_mode() has a few rough edges:

* AArch64 doesn't use the term "mode", and refers to "Execution
  states", "Exception levels", and "Selected stack pointer".

* We log the exception type (SYNC/IRQ/FIQ/SError), but not the actual
  "mode" (though this can be decoded from the SPSR value).

* We use bad_mode() as a second-level handler for unexpected synchronous
  exceptions, where the "mode" is legitimate, but the specific exception
  is not.

* We dump the ESR value, but call this "code", and so it's not clear to
  all readers that this is the ESR.

... and all of this can be somewhat opaque to those who aren't extremely
familiar with the code.

Let's make this a bit clearer by having bad_mode() log "Unhandled
${TYPE} exception" rather than "Bad mode in ${TYPE} handler", using
"ESR" rather than "code", and having the final panic() log "Unhandled
exception" rather than "Bad mode".

In future we'd like to log the specific architectural vector rather than
just the type of exception, so we also split the core of bad_mode() out
into a helper called __panic_unhandled(), which takes the vector as a
string argument.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-13-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

In subsequent patches we'll rework the way bad_mode() is called by
exception entry code. In preparation for this, let's move bad_mode()
itself into entry-common.c.

Let's also mark it as noinstr (e.g. to prevent it being kprobed), and
let's also make the `handler` array a local variable, as this is only
use by bad_mode(), and will be removed entirely in a subsequent patch.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-12-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Following the example of ret_to_user, let's consolidate all the EL1
return paths with a ret_to_kernel helper, rather than each entry point
having its own copy of the return code.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-11-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

In subsequent patches we'll rename the entry handlers based on their
original EL, register width, and exception class. To do so, we need to
make all 3 mandatory arguments to the `kernel_ventry` macro, and
distinguish EL1h from EL1t.

In preparation for this, let's make the current set of arguments
mandatory, and move the `regsize` column before the branch label suffix,
making the vectors easier to read column-wise.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-10-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

In entry.S we have two comments which distinguish EL0 and EL1 exception
handlers, but the code isn't actually laid out to match, and there are a
few other inconsistencies that would be good to clear up.

This patch organizes the entry handers consistently:

* The handlers are laid out in order of the vectors, to make them easier
  to navigate.

* The inconsistently-applied alignment is removed

* The handlers are consistently marked with SYM_CODE_START_LOCAL()
  rather than SYM_CODE_START_LOCAL_NOALIGN(), giving them the same
  default alignment as other assembly code snippets.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-9-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

For various reasons we'd like to convert the bulk of arm64's exception
triage logic to C. As a step towards that, this patch converts the EL1
and EL0 IRQ+FIQ triage logic to C.

Separate C functions are added for the native and compat cases so that
in subsequent patches we can handle native/compat differences in C.

Since the triage functions can now call arm64_apply_bp_hardening()
directly, the do_el0_irq_bp_hardening() wrapper function is removed.

Since the user_exit_irqoff macro is now unused, it is removed. The
user_enter_irqoff macro is still used by the ret_to_user code, and
cannot be removed at this time.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-8-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

When handling IRQ/FIQ exceptions the entry assembly may transition from
a task's stack to a CPU's IRQ stack (and IRQ shadow call stack).

In subsequent patches we want to migrate the IRQ/FIQ triage logic to C,
and as we want to perform some actions on the task stack (e.g. EL1
preemption), we need to switch stacks within the C handler. So that we
can do so, this patch adds a helper to call a function on a CPU's IRQ
stack (and shadow stack as appropriate).

Subsequent patches will make use of the new helper function.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-7-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Currently portions of our preempt logic are written in C while other
parts are written in assembly. Let's clean this up a little bit by
moving the NMI preempt checks to C. For now, the preempt count (and
need_resched) checking is left in assembly, and will be converted
with the body of the IRQ handler in subsequent patches.

Other than the increased lockdep coverage there should be no functional
change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-6-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Subsequent patches will pull more of the IRQ entry handling into C. To
keep this in one place, let's move arm64_preempt_schedule_irq() into
entry-common.c along with the other entry management functions.

We no longer need to include <linux/lockdep.h> in process.c, so the
include directive is removed.

There should be no functional change as a result of this patch.

Reviewed-by Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-5-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

For various reasons we'd like to convert the bulk of arm64's exception
triage logic to C. As a step towards that, this patch converts the EL1
and EL0 SError triage logic to C.

Separate C functions are added for the native and compat cases so that
in subsequent patches we can handle native/compat differences in C.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-4-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

For non-fatal exceptions taken from EL0, we expect that at some point
during exception handling it is possible to return to a regular process
context with all exceptions unmasked (e.g. as we do in
do_notify_resume()), and we generally aim to unmask exceptions wherever
possible.

While handling SError and debug exceptions from EL0, we need to leave
some exceptions masked during handling. Handling SError requires us to
mask SError (which also requires masking IRQ+FIQ), and handing debug
exceptions requires us to mask debug (which also requires masking
SError+IRQ+FIQ).

Once do_serror() or do_debug_exception() has returned, we no longer need
to mask exceptions, and can unmask them all, which is what we did prior
to commit:

  9034f625 ("arm64: Do not enable IRQs for ct_user_exit")

... where we had to mask IRQs as for context_tracking_user_exit()
expected IRQs to be masked.

Since then, we realised that our context tracking wasn't entirely
correct, and reworked the entry code to fix this. As of commit:

  23529049 ("arm64: entry: fix non-NMI user<->kernel transitions")

... we replaced the call to context_tracking_user_exit() with a call to
user_exit_irqoff() as part of enter_from_user_mode(), which occurs
earlier, before we run the body of the handler and unmask exceptions in
DAIF.

When we return to userspace, we go via ret_to_user(), which masks
exceptions in DAIF prior to calling user_enter_irqoff() as part of
exit_to_user_mode().

Thus, there's no longer a reason to leave IRQs or FIQs masked at the end
of the EL0 debug or error handlers, as neither the user exit context
tracking nor the user entry context tracking requires this. Let's bring
these into line with other EL0 exception handlers and ensure that IRQ
and FIQ are unmasked in DAIF at some point during the handler.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-3-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Upon taking an exception, the CPU sets all the DAIF bits. We never
clear any of these bits prior to calling bad_mode(), and bad_mode()
itself never clears any of these bits, so there's no need to call
local_daif_mask().

This patch removes the redundant call.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-2-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Pull perf fixes from Thomas Gleixner:
 "Two perf fixes:

   - Do not check the LBR_TOS MSR when setting up unrelated LBR MSRs as
     this can cause malfunction when TOS is not supported

   - Allocate the LBR XSAVE buffers along with the DS buffers upfront
     because allocating them when adding an event can deadlock"

* tag 'perf-urgent-2021-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/lbr: Remove cpuc->lbr_xsave allocation from atomic context
  perf/x86: Avoid touching LBR_TOS MSR for Arch LBR

Pull locking fixes from Thomas Gleixner:
 "Two locking fixes:

   - Invoke the lockdep tracepoints in the correct place so the ordering
     is correct again

   - Don't leave the mutex WAITER bit stale when the last waiter is
     dropping out early due to a signal as that forces all subsequent
     lock operations needlessly into the slowpath until it's cleaned up
     again"

* tag 'locking-urgent-2021-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal
  locking/lockdep: Correct calling tracepoints

Pull irq fixes from Thomas Gleixner:
 "A few fixes for irqchip drivers:

   - Allocate interrupt descriptors correctly on Mainstone PXA when
     SPARSE_IRQ is enabled; otherwise the interrupt association fails

   - Make the APPLE AIC chip driver depend on APPLE

   - Remove redundant error output on devm_ioremap_resource() failure"

* tag 'irq-urgent-2021-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip: Remove redundant error printing
  irqchip/apple-aic: APPLE_AIC should depend on ARCH_APPLE
  ARM: PXA: Fix cplds irqdesc allocation when using legacy mode

Pull x86 fixes from Borislav Petkov:

 - Fix how SEV handles MMIO accesses by forwarding potential page faults
   instead of killing the machine and by using the accessors with the
   exact functionality needed when accessing memory.

 - Fix a confusion with Clang LTO compiler switches passed to the it

 - Handle the case gracefully when VMGEXIT has been executed in
   userspace

* tag 'x86_urgent_for_v5.13_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sev-es: Use __put_user()/__get_user() for data accesses
  x86/sev-es: Forward page-faults which happen during emulation
  x86/sev-es: Don't return NULL from sev_es_get_ghcb()
  x86/build: Fix location of '-plugin-opt=' flags
  x86/sev-es: Invalidate the GHCB after completing VMGEXIT
  x86/sev-es: Move sev_es_put_ghcb() in prep for follow on patch

Pull powerpc fixes from Michael Ellerman:

 - Fix breakage of strace (and other ptracers etc.) when using the new
   scv ABI (Power9 or later with glibc >= 2.33).

 - Fix early_ioremap() on 64-bit, which broke booting on some machines.

Thanks to Dmitry V. Levin, Nicholas Piggin, Alexey Kardashevskiy, and
Christophe Leroy.

* tag 'powerpc-5.13-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64s/syscall: Fix ptrace syscall info with scv syscalls
  powerpc/64s/syscall: Use pt_regs.trap to distinguish syscall ABI difference between sc and scv syscalls
  powerpc: Fix early setup to make early_ioremap() work

Merge tag 'kbuild-fixes-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix short log indentation for tools builds

 - Fix dummy-tools to adjust to the latest stackprotector check

* tag 'kbuild-fixes-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: dummy-tools: adjust to stricter stackprotector check
  scripts/jobserver-exec: Fix a typo ("envirnoment")
  tools build: Fix quiet cmd indentation

Merge misc fixes from Andrew Morton:
 "10 patches.

  Subsystems affected by this patch series: mm (pagealloc, gup, kasan,
  and userfaultfd), ipc, selftests, watchdog, bitmap, procfs, and lib"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  userfaultfd: hugetlbfs: fix new flag usage in error path
  lib: kunit: suppress a compilation warning of frame size
  proc: remove Alexey from MAINTAINERS
  linux/bits.h: fix compilation error with GENMASK
  watchdog: reliable handling of timestamps
  kasan: slab: always reset the tag in get_freepointer_safe()
  tools/testing/selftests/exec: fix link error
  ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry
  Revert "mm/gup: check page posion status for coredump."
  mm/shuffle: fix section mismatch warning

In commit d6995da3 ("hugetlb: use page.private for hugetlb specific
page flags") the use of PagePrivate to indicate a reservation count
should be restored at free time was changed to the hugetlb specific flag
HPageRestoreReserve.  Changes to a userfaultfd error path as well as a
VM_BUG_ON() in remove_inode_hugepages() were overlooked.

Users could see incorrect hugetlb reserve counts if they experience an
error with a UFFDIO_COPY operation.  Specifically, this would be the
result of an unlikely copy_huge_page_from_user error.  There is not an
increased chance of hitting the VM_BUG_ON.

Link: https://lkml.kernel.org/r/20210521233952.236434-1-mike.kravetz@oracle.com
Fixes: d6995da3 ("hugetlb: use page.private for hugetlb specific page flags")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Mina Almasry <almasry.mina@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/bitfield_kunit.c: In function `test_bitfields_constants':
lib/bitfield_kunit.c:93:1: warning: the frame size of 7456 bytes is larger than 2048 bytes [-Wframe-larger-than=]
 }
 ^

As the description of BITFIELD_KUNIT in lib/Kconfig.debug, it "Only useful
for kernel devs running the KUnit test harness, and not intended for
inclusion into a production build".  Therefore, it is not worth modifying
variable 'test_bitfields_constants' to clear this warning.  Just suppress
it.

Link: https://lkml.kernel.org/r/20210518094533.7652-1-thunder.leizhen@huawei.comSigned-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Vitor Massaru Iha <vitor@massaru.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

People Cc me and I don't have time.

Link: https://lkml.kernel.org/r/YKarMxHJBIhMHQIh@localhost.localdomainSigned-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

GENMASK() has an input check which uses __builtin_choose_expr() to
enable a compile time sanity check of its inputs if they are known at
compile time.

However, it turns out that __builtin_constant_p() does not always return
a compile time constant [0].  It was thought this problem was fixed with
gcc 4.9 [1], but apparently this is not the case [2].

Switch to use __is_constexpr() instead which always returns a compile time
constant, regardless of its inputs.

Link: https://lore.kernel.org/lkml/42b4342b-aefc-a16a-0d43-9f9c0d63ba7a@rasmusvillemoes.dk [0]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449 [1]
Link: https://lore.kernel.org/lkml/1ac7bbc2-45d9-26ed-0b33-bf382b8d858b@I-love.SAKURA.ne.jp [2]
Link: https://lkml.kernel.org/r/20210511203716.117010-1-rikard.falkeborn@gmail.comSigned-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 9bf3bc94 ("watchdog: cleanup handling of false positives")
tried to handle a virtual host stopped by the host a more
straightforward and cleaner way.

But it introduced a risk of false softlockup reports.  The virtual host
might be stopped at any time, for example between
kvm_check_and_clear_guest_paused() and is_softlockup().  As a result,
is_softlockup() might read the updated jiffies and detects a softlockup.

A solution might be to put back kvm_check_and_clear_guest_paused() after
is_softlockup() and detect it.  But it would put back the cycle that
complicates the logic.

In fact, the handling of all the timestamps is not reliable.  The code
does not guarantee when and how many times the timestamps are read.  For
example, "period_ts" might be touched anytime also from NMI and re-read in
is_softlockup().  It works just by chance.

Fix all the problems by making the code even more explicit.

1. Make sure that "now" and "period_ts" timestamps are read only once.
   They might be changed at anytime by NMI or when the virtual guest is
   stopped by the host.  Note that "now" timestamp does this implicitly
   because "jiffies" is marked volatile.

2. "now" time must be read first.  The state of "period_ts" will
   decide whether it will be used or the period will get restarted.

3. kvm_check_and_clear_guest_paused() must be called before reading
   "period_ts".  It touches the variable when the guest was stopped.

As a result, "now" timestamp is used only when the watchdog was not
touched and the guest not stopped in the meantime.  "period_ts" is
restarted in all other situations.

Link: https://lkml.kernel.org/r/YKT55gw+RZfyoFf7@alley
Fixes: 9bf3bc94 ("watchdog: cleanup handling of false positives")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reported-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

With CONFIG_DEBUG_PAGEALLOC enabled, the kernel should also untag the
object pointer, as done in get_freepointer().

Failing to do so reportedly leads to SLUB freelist corruptions that
manifest as boot-time crashes.

Link: https://lkml.kernel.org/r/20210514072228.534418-1-glider@google.comSigned-off-by: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Elliot Berman <eberman@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fix the link error by adding '-static':

  gcc -Wall  -Wl,-z,max-page-size=0x1000 -pie load_address.c -o /home/yang/linux/tools/testing/selftests/exec/load_address_4096
  /usr/bin/ld: /tmp/ccopEGun.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `stderr@@GLIBC_2.17' which may bind externally can not be used when making a shared object; recompile with -fPIC
  /usr/bin/ld: /tmp/ccopEGun.o(.text+0x158): unresolvable R_AARCH64_ADR_PREL_PG_HI21 relocation against symbol `stderr@@GLIBC_2.17'
  /usr/bin/ld: final link failed: bad value
  collect2: error: ld returned 1 exit status
  make: *** [Makefile:25: tools/testing/selftests/exec/load_address_4096] Error 1

Link: https://lkml.kernel.org/r/20210514092422.2367367-1-yangyingliang@huawei.com
Fixes: 206e22f0 ("tools/testing/selftests: add self-test for verifying load alignment")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Cc: Chris Kennelly <ckennelly@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

do_mq_timedreceive calls wq_sleep with a stack local address.  The
sender (do_mq_timedsend) uses this address to later call pipelined_send.

This leads to a very hard to trigger race where a do_mq_timedreceive
call might return and leave do_mq_timedsend to rely on an invalid
address, causing the following crash:

  RIP: 0010:wake_q_add_safe+0x13/0x60
  Call Trace:
   __x64_sys_mq_timedsend+0x2a9/0x490
   do_syscall_64+0x80/0x680
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f5928e40343

The race occurs as:

1. do_mq_timedreceive calls wq_sleep with the address of `struct
   ext_wait_queue` on function stack (aliased as `ewq_addr` here) - it
   holds a valid `struct ext_wait_queue *` as long as the stack has not
   been overwritten.

2. `ewq_addr` gets added to info->e_wait_q[RECV].list in wq_add, and
   do_mq_timedsend receives it via wq_get_first_waiter(info, RECV) to call
   __pipelined_op.

3. Sender calls __pipelined_op::smp_store_release(&this->state,
   STATE_READY).  Here is where the race window begins.  (`this` is
   `ewq_addr`.)

4. If the receiver wakes up now in do_mq_timedreceive::wq_sleep, it
   will see `state == STATE_READY` and break.

5. do_mq_timedreceive returns, and `ewq_addr` is no longer guaranteed
   to be a `struct ext_wait_queue *` since it was on do_mq_timedreceive's
   stack.  (Although the address may not get overwritten until another
   function happens to touch it, which means it can persist around for an
   indefinite time.)

6. do_mq_timedsend::__pipelined_op() still believes `ewq_addr` is a
   `struct ext_wait_queue *`, and uses it to find a task_struct to pass to
   the wake_q_add_safe call.  In the lucky case where nothing has
   overwritten `ewq_addr` yet, `ewq_addr->task` is the right task_struct.
   In the unlucky case, __pipelined_op::wake_q_add_safe gets handed a
   bogus address as the receiver's task_struct causing the crash.

do_mq_timedsend::__pipelined_op() should not dereference `this` after
setting STATE_READY, as the receiver counterpart is now free to return.
Change __pipelined_op to call wake_q_add_safe on the receiver's
task_struct returned by get_task_struct, instead of dereferencing `this`
which sits on the receiver's stack.

As Manfred pointed out, the race potentially also exists in
ipc/msg.c::expunge_all and ipc/sem.c::wake_up_sem_queue_prepare.  Fix
those in the same way.

Link: https://lkml.kernel.org/r/20210510102950.12551-1-varad.gautam@suse.com
Fixes: c5b2cbdb ("ipc/mqueue.c: update/document memory barriers")
Fixes: 8116b54e ("ipc/sem.c: document and update memory barriers")
Fixes: 0d97a82b ("ipc/msg.c: update and document memory barriers")
Signed-off-by: Varad Gautam <varad.gautam@suse.com>
Reported-by: Matthias von Faber <matthias.vonfaber@aox-tech.de>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

While reviewing [1] I came across commit d3378e86 ("mm/gup: check
page posion status for coredump.") and noticed that this patch is broken
in two ways.  First it doesn't really prevent hwpoison pages from being
dumped because hwpoison pages can be marked asynchornously at any time
after the check.  Secondly, and more importantly, the patch introduces a
ref count leak because get_dump_page takes a reference on the page which
is not released.

It also seems that the patch was merged incorrectly because there were
follow up changes not included as well as discussions on how to address
the underlying problem [2]

Therefore revert the original patch.

Link: http://lkml.kernel.org/r/20210429122519.15183-4-david@redhat.com [1]
Link: http://lkml.kernel.org/r/57ac524c-b49a-99ec-c1e4-ef5027bfb61b@redhat.com [2]
Link: https://lkml.kernel.org/r/20210505135407.31590-1-mhocko@kernel.org
Fixes: d3378e86 ("mm/gup: check page posion status for coredump.")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Aili Yao <yaoaili@kingsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

clang sometimes decides not to inline shuffle_zone(), but it calls a
__meminit function.  Without the extra __meminit annotation we get this
warning:

  WARNING: modpost: vmlinux.o(.text+0x2a86d4): Section mismatch in reference from the function shuffle_zone() to the function .meminit.text:__shuffle_zone()
  The function shuffle_zone() references
  the function __meminit __shuffle_zone().
  This is often because shuffle_zone lacks a __meminit
  annotation or the annotation of __shuffle_zone is wrong.

shuffle_free_memory() did not show the same problem in my tests, but it
could happen in theory as well, so mark both as __meminit.

Link: https://lkml.kernel.org/r/20210514135952.2928094-1-arnd@kernel.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull block fixes from Jens Axboe:

 - Fix BLKRRPART and deletion race (Gulam, Christoph)

 - NVMe pull request (Christoph):
      - nvme-tcp corruption and timeout fixes (Sagi Grimberg, Keith
        Busch)
      - nvme-fc teardown fix (James Smart)
      - nvmet/nvme-loop memory leak fixes (Wu Bo)"

* tag 'block-5.13-2021-05-22' of git://git.kernel.dk/linux-block:
  block: fix a race between del_gendisk and BLKRRPART
  block: prevent block device lookups at the beginning of del_gendisk
  nvme-fc: clear q_live at beginning of association teardown
  nvme-tcp: rerun io_work if req_list is not empty
  nvme-tcp: fix possible use-after-completion
  nvme-loop: fix memory leak in nvme_loop_create_ctrl()
  nvmet: fix memory leak in nvmet_alloc_ctrl()

Pull io_uring fixes from Jens Axboe:
 "One fix for a regression with poll in this merge window, and another
  just hardens the io-wq exit path a bit"

* tag 'io_uring-5.13-2021-05-22' of git://git.kernel.dk/linux-block:
  io_uring: fortify tctx/io_wq cleanup
  io_uring: don't modify req->poll for rw

Pull xen fixes from Juergen Gross:

 - a fix for a boot regression when running as PV guest on hardware
   without NX support

 - a small series fixing a bug in the Xen pciback driver when
   configuring a PCI card with multiple virtual functions

* tag 'for-linus-5.13b-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen-pciback: reconfigure also from backend watch handler
  xen-pciback: redo VF placement in the virtual topology
  x86/Xen: swap NX determination and GDT setup on BSP