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Re: [Qemu-arm] [Qemu-devel] [PATCH for-4.1?] target/arm: Deliver BKPT/BR

From: Peter Maydell
Subject: Re: [Qemu-arm] [Qemu-devel] [PATCH for-4.1?] target/arm: Deliver BKPT/BRK exceptions to correct exception level
Date: Tue, 30 Jul 2019 17:41:52 +0100

On Tue, 30 Jul 2019 at 16:31, Philippe Mathieu-Daudé <address@hidden> wrote:
> On 7/30/19 3:25 PM, Peter Maydell wrote:
> > Most Arm architectural debug exceptions (eg watchpoints) are ignored
> > if the configured "debug exception level" is below the current
> > exception level (so for example EL1 can't arrange to get debug exceptions
> > for EL2 execution). Exceptions generated by the BRK or BPKT instructions
> > are a special case -- they must always cause an exception, so if
> > we're executing above the debug exception level then we
> > must take them to the current exception level.
> >
> > This fixes a bug where executing BRK at EL2 could result in an
> > exception being taken at EL1 (which is strictly forbidden by the
> > architecture).
> >
> > Fixes: https://bugs.launchpad.net/qemu/+bug/1838277
> > Signed-off-by: Peter Maydell <address@hidden>
> > ---
> > At this point in the release cycle I'm not sure we should put this
> > into 4.1 -- it is definitely a bug but it's not a regression as
> > we've been wrong like this for multiple releases, pretty much
> > since we put in the debug handling code I suspect.
> The fix is quite trivial, and the user reported using a release, so
> having it in the next release would be nice.
> Or as usual, wait for 'last-minute-bugfix-that-postpone-another-rc' and
> squeeze this fix in.
> Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

OK, people seem to think it's worth putting in, so I've applied
it to master.

-- PMM

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