Re: [Xen-devel] [PATCH v5 for 4.5] xen/arm: Correctly support WARN_ON

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Oct 01, 2014 at 01:18:20PM +0100, Ian Campbell wrote:
> On Tue, 2014-09-30 at 17:58 +0100, Julien Grall wrote:
> > Currently the hypervisor will hang if it hits a WARN_ON.
> > 
> > The implementation uses an undefined instruction, made ourself because ARM
> > don't provide one, to implement BUG/ASSERT/WARN_ON, and sets up the
> > different tables (one for each type) which contain useful information.
> > 
> > This is based on the x86 implementation (include/asm-x86/bug.h). 
> > Unfortunately
> > the structure can't be shared because many ARM{32,64} gcc versions doesn't
> > correctly support %c. The support for executing a function in an exception 
> > handler
> > is also keep unimplemented on ARM. Therefore, dump_execution_state is
> > implemented as WARN()
> > 
> > The current opcode used to go in exception mode may not be undefined on 
> > ARM64.
> > Use the instruction "brk" to generate a software debug exception.
> > 
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> 
> Acked...
> 
> > ---
> >     This is a bug fix for Xen 4.5. It make WARN_ON working correctly
> >     when it has been hit in the hypervisor.
> 
> ...and applied on that basis.

Excellent!
> 
> 

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