Re: [PATCH v2 16/16] objtool/powerpc: Add --mcount specific implementation

From: Segher Boessenkool
Date: Mon Sep 05 2022 - 16:49:45 EST


Hi!

On Mon, Sep 05, 2022 at 04:15:07PM +0530, Naveen N. Rao wrote:
> Segher Boessenkool wrote:
> >>> + if ((insn & 3) == 1) {
> >>> + *type = INSN_CALL;
> >>> + *immediate = insn & 0x3fffffc;
> >>> + if (*immediate & 0x2000000)
> >>> + *immediate -= 0x4000000;
> >>> + }
> >>> + break;
> >>> + }
> >
> >Does this handle AA=1 correctly at all? That is valid both with and
> >without relocations, just like AA=0. Same for AA=1 LK=0 btw.
> >
> >If you only handle AA=0, the code should explicitly test for that.
>
> The code does test for AA=0 LK=1 with the if statement there?

Yes, but that is not what I said :-)

It may be fine to not *handle* AA=1 at all, but the code should at least
scream bloody murder when it encounters it anyway :-)


Segher