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Message-ID: <4afd73392c4a31916e7aaad7767d5e945a40ddb9.camel@linux.ibm.com>
Subject: Re: [PATCH v2 3/6] powerpc/module: Optimise nearby branches in ELF
 V2 ABI stub
From: Benjamin Gray <bgray@linux.ibm.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>,
        "linuxppc-dev@lists.ozlabs.org"
	 <linuxppc-dev@lists.ozlabs.org>
Date: Tue, 27 Sep 2022 13:12:18 +1000
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On Mon, 2022-09-26 at 14:49 +0000, Christophe Leroy wrote:
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/* Replace indirect branch s=
equence with direct branch
> > where possible */
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (!create_branch(&direct, =
jump_seq_addr, addr, 0))
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0if (patch_instruction(jump_seq_addr, direct))
>=20
> Why not use patch_branch() ?

I didn't think of it at the time. To get the same abort-if-patch-failed
semantics then the following should work

  int err;
  ...

  /* Replace indirect branch sequence with direct branch where=C2=A0
   * possible=C2=A0
   */
  err =3D patch_branch(&entry->jump[PPC64_STUB_MTCTR_OFFSET], addr, 0);
  if (err && err !=3D -ERANGE)
      return 0;
>=20