[PATCH V2 0/4] ARM64: Fix irq generation between breakpoint and step exception

[Pratyush Anand <panand@redhat.com>]

v1 was here http://marc.info/?l=linux-arm-kernel&m=149910958418708&w=2

v1 -> v2:
- patch 1 of v1 has been modified to patch 1-3 of v2.
- Introduced a new event attribute step_needed and implemented
  hw_breakpoint_needs_single_step() (patch 1)
- Replaced usage of is_default_overflow_handler() with
  hw_breakpoint_needs_single_step(). (patch 2)
- Modified sample test to set set step_needed bit field (patch 3)

samples/hw_breakpoint/data_breakpoint.c passes with x86_64 but fails with
ARM64. Even though it has been NAKed previously on upstream [1, 2], I have
tried to come up with patches which can resolve it for ARM64 as well.

I noticed that even perf step exception can go into an infinite loop if CPU
receives an interrupt while executing breakpoint/watchpoint handler. So,
event though we are not concerned about above test, we will have to find a
solution for the perf issue.

This patchset attempts to resolve both the issue. Please review.

[1] http://marc.info/?l=linux-arm-kernel&m=149580777524910&w=2
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-April/425266.html

Pratyush Anand (4):
  hw_breakpoint: Add step_needed event attribute
  arm64: use hw_breakpoint_needs_single_step() to decide if step is
    needed
  hw-breakpoint: sample test: set step_needed bit field
  arm64: disable irq between breakpoint and step exception

 arch/arm64/kernel/debug-monitors.c      |  3 +++
 arch/arm64/kernel/hw_breakpoint.c       | 10 +++++-----
 arch/arm64/mm/fault.c                   | 22 ++++++++++++++++++----
 include/linux/hw_breakpoint.h           |  6 ++++++
 include/uapi/linux/perf_event.h         |  3 ++-
 kernel/events/core.c                    |  2 ++
 samples/hw_breakpoint/data_breakpoint.c |  1 +
 tools/include/uapi/linux/perf_event.h   |  3 ++-
 8 files changed, 39 insertions(+), 11 deletions(-)

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2.9.3