On Mon, Jul 31, 2017 at 04:10:28PM +0530, Pratyush Anand wrote:
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: http://marc.info/?l=linux-arm-kernel&m=149942910730496&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)
v1 was here: http://marc.info/?l=linux-arm-kernel&m=149910958418708&w=2
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.
I have not yet understood the details of your patch, but
I gave it a try and didn't see any difference around the behavior
of kgdb's single stepping.
I also gave a try to James' patch, but again nothing different
as long as kgdb is concerned.
(I'm tackling some issue in single stepping at irq's kernel_exit,
in particular, 'eret'.)