Re: [PATCH] ARM: hw_breakpoint: Handle inexact watchpoint addresses

Hi,

On Thu, Aug 6, 2020 at 8:45 AM Doug Anderson [off-list ref] wrote:

Hi,

On Thu, Aug 6, 2020 at 8:41 AM Russell King - ARM Linux admin
[off-list ref] wrote:

quoted

On Thu, Aug 06, 2020 at 08:05:10AM -0700, Doug Anderson wrote:

quoted

Hi,

On Mon, Dec 2, 2019 at 8:36 AM Doug Anderson [off-list ref] wrote:

quoted

Hi,

On Wed, Nov 20, 2019 at 11:18 AM Will Deacon [off-list ref] wrote:

quoted

On Sat, Oct 19, 2019 at 11:12:26AM -0700, Douglas Anderson wrote:

quoted

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.

quoted

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

Oddly, I found that if I go visit that page now I see:

quoted

- - - Note 2 submitted by Russell King on 17 Jan 2020 11:16:34 (UTC) - - -
Moved to applied

Applied to git-curr (misc branch).

Yet if I go check mainline the patch is not there.  This came to my
attention since we had my patch picked to the Chrome OS 4.19 tree and
suddenly recently got a stable merge conflict with "ARM: 8986/1:
hw_breakpoint: Don't invoke overflow handler on uaccess watchpoints".

Anyone know what happened here?

Yes.  Stephen Rothwell raised a complaint against it, which you were
copied with:

Was a mailing list copied?  If so, do you have a lore.kernel.org link?
 I certainly don't see the email so I can only assume it made it to
spam.  That's unfortunate.

quoted

quoted

Hi all,

Commit

  116375be0461 ("ARM: 8944/1: hw_breakpoint: Handle inexact watchpoint addresses")

is missing a Signed-off-by from its author.

My reply to Stephen's email was:

quoted

Thanks Stephen, patch dropped.

It looks like Doug used his "m.disordat.com" address to submit the
patch through the web interface, and there was no From: in the patch
itself, so that was used as the patch author.  However, as you spotted,
it was signed off using Doug's "chromium.org" address.

I think it's time to make the patch system a bit more strict, checking
that the submission address is mentioned in a signed-off-by tag
somewhere in the commit message.

Doug, the patch system does have your "chromium.org" address, if that's
the one you want to use as the author, please submit using that instead.
Thanks.

Russell.

Neither email got a response from you, so the patch was dropped and
nothing further happened.

OK, I guess I'll have to rebase and resend.

Let's hope this one works:

https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=8997/1

I re-tested it and it also matches how the conflict was resolved in
the Chrome OS tree which means that (once the stable merge lands in
our tree) this conflict resolution will get a bit of testing, though
the vast majority of devices running this code have since stopped
receiving auto updates.

-Doug

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