Re: [Xen-devel] [PATCH for-4.5] xen/arm: Correct the opcode for BUG_INSTR on arm32

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Konrad,

On 04/12/2014 19:34, Konrad Rzeszutek Wilk wrote:
> On Thu, Dec 04, 2014 at 07:26:55PM +0000, Julien Grall wrote:
> > A 0 was forgotten when the arm32 BUG instruction opcode has been added in commit
> > 3e802c6ca1fb9a9549258c2855a57cad483f3cbd "xen/arm: Correctly support WARN_ON".
> >
> > This will result to use a valid instruction (mcreq 0, 3, r0, cr15, cr0, {7}),
> > and inhibit usage of BUG/WARN_ON and co.
> >
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> >
> > ---
> >
> > Not sure, why I dropped the 0 when I implemented the patch...
> > This is a bug fixed for Xen 4.5. This is only affected ARM32 where the
> > BUG opcode was malformed.
> >
> > With the malformed opcode, the ASSERT/BUG_ON is skipped and the
> > processor may execute another patch (because the compiler has optimized
> s/patch/path/ ?
Yes.

> > due the unreachable in both macro).
> >
> > The code modified is only executed when Xen is in bad state.
> Release-Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Thanks!

Regards,



--
Julien Grall

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