linux-kernel - Re: [PATCH v4 2/3] powerpc/modules: Don't try to restore r2 after a sibling call

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Date:   Wed, 15 Nov 2017 19:26:28 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
Cc:     Balbir Singh <bsingharora@...il.com>,
        Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        live-patching@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH v4 2/3] powerpc/modules: Don't try to restore r2 after a
 sibling call

On Wed, Nov 15, 2017 at 02:58:33PM +0530, Naveen N. Rao wrote:
> > +int instr_is_link_branch(unsigned int instr)
> > +{
> > +	return (instr_is_branch_iform(instr) || instr_is_branch_bform(instr)) &&
> > +	       (instr & BRANCH_SET_LINK);
> > +}
> > +
> 
> Nitpicking here, but since we're not considering the other branch forms,
> perhaps this can be renamed to instr_is_link_relative_branch() (or maybe
> instr_is_relative_branch_link()), just so we're clear :)

My understanding is that the absolute/relative bit isn't a "form", but
rather a bit that can be set for either the b-form (conditional) or the
i-form (unconditional).  And the above function isn't checking the
absolute bit, so it isn't necessarily a relative branch.  Or did I miss
something?

-- 
Josh