Messages in this thread | | | From | Doug Anderson <> | Date | Mon, 2 Dec 2019 08:36:19 -0800 | Subject | Re: [PATCH] ARM: hw_breakpoint: Handle inexact watchpoint addresses |
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Hi,
On Wed, Nov 20, 2019 at 11:18 AM Will Deacon <will@kernel.org> wrote: > > On Sat, Oct 19, 2019 at 11:12:26AM -0700, Douglas Anderson wrote: > > This is commit fdfeff0f9e3d ("arm64: hw_breakpoint: Handle inexact > > watchpoint addresses") but ported to arm32, which has the same > > problem. > > > > This problem was found by Android CTS tests, notably the > > "watchpoint_imprecise" test [1]. I tested locally against a copycat > > (simplified) version of the test though. > > > > [1] https://android.googlesource.com/platform/bionic/+/master/tests/sys_ptrace_test.cpp > > > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > > --- > > > > arch/arm/kernel/hw_breakpoint.c | 96 ++++++++++++++++++++++++--------- > > 1 file changed, 70 insertions(+), 26 deletions(-) > > Sorry for taking so long to look at this. After wrapping my head around the > logic again
Yeah. It was a little weird and (unfortunately) arbitrarily different in some places compared to the arm64 code.
> I think it looks fine, so please put it into the patch system > with my Ack: > > Acked-by: Will Deacon <will@kernel.org>
Thanks! Submitted as:
https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8944/1
> One interesting difference between the implementation here and the arm64 > code is that I think if you have multiple watchpoints, all of which fire > with a distance != 0, then arm32 will actually report them all whereas > you'd only get one on arm64.
Are you sure about that? The "/* No exact match found. */" code is outside the for loop so it should only be able to trigger for exactly one breakpoint, no?
-Doug
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