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

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/ ?


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>



Julien Grall

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