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Subject[PATCH v3 0/5] ARM64: disable irq between breakpoint and step exception
v2 -> v3
- Moved step_needed from uapi structure to kernel only structure
- Re-enable interrupt if stepped instruction faults
- Modified register_wide_hw_breakpoint() to accept step_needed arg
v2 was here:

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)
v1 was here:

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.
Since, it also takes care of SW breakpoint, so I hope kgdb should also be
fine. However, I have not tested that.
@Takahiro: Will it be possible to test these patches for kgdb.


Pratyush Anand (5):
hw_breakpoint: Add step_needed event attribute
arm64: use hw_breakpoint_needs_single_step() to decide if step is
register_wide_hw_breakpoint(): modify to accept step_needed arg
arm64: disable irq between breakpoint and step exception
arm64: fault: re-enable irq if it was disabled for single stepping

arch/arm64/kernel/debug-monitors.c | 3 +++
arch/arm64/kernel/hw_breakpoint.c | 10 +++++-----
arch/arm64/mm/fault.c | 28 ++++++++++++++++++++++++----
arch/x86/kernel/kgdb.c | 2 +-
include/linux/hw_breakpoint.h | 10 ++++++++--
include/linux/perf_event.h | 6 ++++++
kernel/events/core.c | 2 ++
kernel/events/hw_breakpoint.c | 4 +++-
samples/hw_breakpoint/data_breakpoint.c | 3 ++-
9 files changed, 54 insertions(+), 14 deletions(-)


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