linux-stable.git/arch/powerpc/kernel/process.c, branch v5.2

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

powerpc/64: Don't trace code that runs with the soft irq mask unreconciled

2019-05-02T15:58:11+00:00

"Reconciling" in terms of interrupt handling, is to bring the soft irq
mask state in to synch with the hardware, after an interrupt causes
MSR[EE] to be cleared (while the soft mask may be enabled, and hard
irqs not marked disabled).

General kernel code should not be called while unreconciled, because
local_irq_disable, etc. manipulations can cause surprising irq traces,
and it's fragile because the soft irq code does not really expect to
be called in this situation.

When exiting from an interrupt, MSR[EE] is cleared to prevent races,
but soft irq state is enabled for the returned-to context, so this is
now an unreconciled state. restore_math is called in this state, and
that can be ftraced, and the ftrace subsystem disables local irqs.

Mark restore_math and its callees as notrace. Restore a sanity check
in the soft irq code that had to be disabled for this case, by commit
4da1f79227ad4 ("powerpc/64: Disable irq restore warning for now").

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman

powerpc/64s: Remove 'dummy_copy_buffer'

2019-05-01T02:08:44+00:00

In commit 2bf1071a8d50 ("powerpc/64s: Remove POWER9 DD1 support") the
function __switch_to remove usage for 'dummy_copy_buffer'. Since it is
not used anywhere else, remove it completely.

This remove the following warning:
  arch/powerpc/kernel/process.c:1156:17: error: 'dummy_copy_buffer' defined but not used

Suggested-by: Christophe Leroy 
Signed-off-by: Mathieu Malaterre 
Signed-off-by: Michael Ellerman

Merge branch 'topic/ppc-kvm' into next

2019-04-30T12:52:03+00:00

Merge our topic branch shared with KVM. In particular this includes the
rewrite of the idle code into C.

powerpc: Add force enable of DAWR on P9 option

2019-04-20T12:20:45+00:00

This adds a flag so that the DAWR can be enabled on P9 via:
  echo Y > /sys/kernel/debug/powerpc/dawr_enable_dangerous

The DAWR was previously force disabled on POWER9 in:
  9654153158 powerpc: Disable DAWR in the base POWER9 CPU features
Also see Documentation/powerpc/DAWR-POWER9.txt

This is a dangerous setting, USE AT YOUR OWN RISK.

Some users may not care about a bad user crashing their box
(ie. single user/desktop systems) and really want the DAWR.  This
allows them to force enable DAWR.

This flag can also be used to disable DAWR access. Once this is
cleared, all DAWR access should be cleared immediately and your
machine once again safe from crashing.

Userspace may get confused by toggling this. If DAWR is force
enabled/disabled between getting the number of breakpoints (via
PTRACE_GETHWDBGINFO) and setting the breakpoint, userspace will get an
inconsistent view of what's available. Similarly for guests.

For the DAWR to be enabled in a KVM guest, the DAWR needs to be force
enabled in the host AND the guest. For this reason, this won't work on
POWERVM as it doesn't allow the HCALL to work. Writes of 'Y' to the
dawr_enable_dangerous file will fail if the hypervisor doesn't support
writing the DAWR.

To double check the DAWR is working, run this kernel selftest:
  tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c
Any errors/failures/skips mean something is wrong.

Signed-off-by: Michael Neuling 
Signed-off-by: Michael Ellerman

powerpc/mm/radix: Don't do SLB preload when using the radix MMU

2019-04-20T12:02:26+00:00

Add radix_enabled() check to avoid SLB preload with radix translation.

Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc: regain entire stack space

2019-02-23T11:31:40+00:00

thread_info is not anymore in the stack, so the entire stack
can now be used.

There is also no risk anymore of corrupting task_cpu(p) with a
stack overflow so the patch removes the test.

When doing this, an explicit test for NULL stack pointer is
needed in validate_sp() as it is not anymore implicitely covered
by the sizeof(thread_info) gap.

In the meantime, with the previous patch all pointers to the stacks
are not anymore pointers to thread_info so this patch changes them
to void*

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman

powerpc: Activate CONFIG_THREAD_INFO_IN_TASK

2019-02-23T11:31:40+00:00

This patch activates CONFIG_THREAD_INFO_IN_TASK which
moves the thread_info into task_struct.

Moving thread_info into task_struct has the following advantages:
  - It protects thread_info from corruption in the case of stack
    overflows.
  - Its address is harder to determine if stack addresses are leaked,
    making a number of attacks more difficult.

This has the following consequences:
  - thread_info is now located at the beginning of task_struct.
  - The 'cpu' field is now in task_struct, and only exists when
    CONFIG_SMP is active.
  - thread_info doesn't have anymore the 'task' field.

This patch:
  - Removes all recopy of thread_info struct when the stack changes.
  - Changes the CURRENT_THREAD_INFO() macro to point to current.
  - Selects CONFIG_THREAD_INFO_IN_TASK.
  - Modifies raw_smp_processor_id() to get ->cpu from current without
    including linux/sched.h to avoid circular inclusion and without
    including asm/asm-offsets.h to avoid symbol names duplication
    between ASM constants and C constants.
  - Modifies klp_init_thread_info() to take a task_struct pointer
    argument.

Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
[mpe: Add task_stack.h to livepatch.h to fix build fails]
Signed-off-by: Michael Ellerman

powerpc: Replace current_thread_info()->task with current

2019-02-23T11:31:40+00:00

We have a few places that use current_thread_info()->task to access
current. This won't work with THREAD_INFO_IN_TASK so fix them now.

Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
[mpe: Split out of larger patch]
Signed-off-by: Michael Ellerman

powerpc: prep stack walkers for THREAD_INFO_IN_TASK

2019-02-23T11:31:40+00:00

[text copied from commit 9bbd4c56b0b6
("arm64: prep stack walkers for THREAD_INFO_IN_TASK")]

When CONFIG_THREAD_INFO_IN_TASK is selected, task stacks may be freed
before a task is destroyed. To account for this, the stacks are
refcounted, and when manipulating the stack of another task, it is
necessary to get/put the stack to ensure it isn't freed and/or re-used
while we do so.

This patch reworks the powerpc stack walking code to account for this.
When CONFIG_THREAD_INFO_IN_TASK is not selected these perform no
refcounting, and this should only be a structural change that does not
affect behaviour.

Acked-by: Mark Rutland 
Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
[mpe: Move try_get_task_stack() below tsk == NULL check in show_stack()]
Signed-off-by: Michael Ellerman