Re: [PULL 24/27] accel/tcg: Move breakpoint recognition outside translation

[Richard Henderson]

On 8/17/21 5:39 AM, Richard Henderson wrote:
> Hmm, you're correct that we get this wrong.
>
> > We probably didn't do these in the right priority
> > order before this series, though, and I dunno whether
> > we get the insn-abort vs swstep ordering right either...
>
> And you're correct that we got it wrong beforehand.  The reorg did not alter the 
> recognized ordering of the exceptions.
>
> I'm a bit surprised that insn-abort comes higher than breakpoint.

That would be because I mis-remembered the language.

Going back to the list,

  4 - software step
  6 - pc alignment fault
  7 - instruction abort (address translation!)
  8 - breakpoint exceptions
  9 - illegal execution state
 10 - software breakpoint (brk)
 11 - BTI exceptions
 12 - el2 traps
 13 - undefined exceptions

I thought "insn-abort" was #13, but it's really #7.

Well, behaviour is unchanged, since we check for address match before calling 
arm_ldl_code, before and after the reorg.

So: we need to suppress breakpoints (#8) for any higher-priority condition.  For #7, that 
might require some extra generic work.  I should have a look at the other targets that use 
architectural breakpoints to see what happens for a breakpoint on an unmapped page.

I'll work something out.


r~