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From: Pedro Alves <pedro@codesourcery.com>
To: gdb-patches@sourceware.org
Subject: Re: [rfc] Fix PowerPC displaced stepping regression
Date: Mon, 28 Sep 2009 19:41:00 -0000
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Cc: "Ulrich Weigand" <uweigand@de.ibm.com>,  Julian Brown <julian@codesourcery.com>,  Daniel Jacobowitz <drow@false.org>
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On Sunday 27 September 2009 22:47:13, Ulrich Weigand wrote:
> + # the the displaced instruction identified by CLOSURE.  If false,

Double "the".

> + /* Always use hardware single-stepping to execute the
> + =A0 =A0displaced instruction. =A0*/
> + static int
> + ppc_displaced_step_hw_singlestep (struct gdbarch *gdbarch,
> + =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0 =A0struct displaced_step_closure *closure)
> + {
> + =A0 return 1;
> + }
> +

Hmmm, does this mean that a breakpoint at the start of an
atomic sequence instruction wouldn't be displaced stepped properly,
as in, you'd trip on the same issue that happens when stepping over
an atomic sequence without displaced stepping?
(If broken, this was already broken before your patch and even
before the regression your patch fixes)

( A nice stress test of the displaced stepping support is to run the
whole testsuite with "set displaced-stepping on". )

I've now read through the patch carefully, and didn't spot
anything wrong.  I think this would be safe for 7.0 as well.

--=20
Pedro Alves