On Fri, Feb 22, 2019 at 11:18 AM H.J. Lu <hjl.to...@gmail.com> wrote: > > On Fri, Dec 14, 2018 at 1:28 PM Jeff Law <l...@redhat.com> wrote: > > > > On 12/11/18 9:03 AM, H.J. Lu wrote: > > > On Mon, Dec 3, 2018 at 5:45 AM H.J. Lu <hjl.to...@gmail.com> wrote: > > >> On Mon, Jun 18, 2018 at 2:20 AM Richard Biener > > >> <richard.guent...@gmail.com> wrote: > > >>> On Fri, Jun 15, 2018 at 2:59 PM H.J. Lu <hongjiu...@intel.com> wrote: > > >>>> Currently GCC inserts ENDBR instruction at entries of all non-static > > >>>> functions, unless LTO compilation is used. Marking all functions, > > >>>> which are not called indirectly with nocf_check attribute, is not > > >>>> ideal since 99% of functions in a program may be of this kind. > > >>>> > > >>>> This patch adds -mmanual-endbr and cf_check function attribute. They > > >>>> can be used together with -fcf-protection such that ENDBR instruction > > >>>> is inserted only at entries of functions with cf_check attribute. It > > >>>> can limit number of ENDBR instructions to reduce program size. > > >>>> > > >>>> OK for trubk? > > >>> I wonder if the linker could assist with ENDBR creation by > > >>> redirecting all non-direct call relocs to a linker-generated > > >>> stub with ENBR and a direct branch? > > >>> > > >> The goal of this patch is to add as few as ENDBR as possible > > >> to reduce program size as much as possible. Also there is no > > >> relocation for indirect branch via register. > > >> > > > Hi Honza, Jakub, Jeff, Richard, > > > > > > Here is the rebased patch. Can you guys take a look? > > > > > > Thanks. > > > > > > > > > -- H.J. > > > > > > > > > 0001-i386-Add-mmanual-endbr-and-cf_check-function-attribu.patch > > > > > > From 5934c6be6495b2d6f278646e25f9e684f6610e2b Mon Sep 17 00:00:00 2001 > > > From: "H.J. Lu" <hjl.to...@gmail.com> > > > Date: Thu, 14 Jun 2018 09:19:27 -0700 > > > Subject: [PATCH] i386; Add -mmanual-endbr and cf_check function attribute > > > > > > Currently GCC inserts ENDBR instruction at entries of all non-static > > > functions, unless LTO compilation is used. Marking all functions, > > > which are not called indirectly with nocf_check attribute, is not > > > ideal since 99% of functions in a program may be of this kind. > > > > > > This patch adds -mmanual-endbr and cf_check function attribute. They > > > can be used together with -fcf-protection such that ENDBR instruction > > > is inserted only at entries of functions with cf_check attribute. It > > > can limit number of ENDBR instructions to reduce program size. > > > > > > gcc/ > > > > > > * config/i386/i386.c (rest_of_insert_endbranch): Insert ENDBR > > > at the function entry only when -mmanual-endbr isn't used or > > > there is cf_check function attribute. > > > (ix86_attribute_table): Add cf_check. > > > * config/i386/i386.opt: Add -mmanual-endbr. > > > * doc/extend.texi: Document cf_check attribute. > > > * doc/invoke.texi: Document -mmanual-endbr. > > > > > > gcc/testsuite/ > > > > > > * gcc.target/i386/cf_check-1.c: New test. > > > * gcc.target/i386/cf_check-2.c: Likewise. > > > * gcc.target/i386/cf_check-3.c: Likewise. > > > * gcc.target/i386/cf_check-4.c: Likewise. > > > * gcc.target/i386/cf_check-5.c: Likewise. > > OK. > > > > Though I'm not sure how valuable this is in practice. Yea, it saves > > some space at the start of functions, but I find myself wondering more > > and more if we should be pushing folks towards LTO for a variety of reasons. > > > > Hi Jeff, > > Here is an update for this new option to move -mmanual-endbr check to > pass_insert_endbranch::gate. I'd like to get it into GCC 9. > >
I withdraw this patch. It is covered by https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89355 -- H.J.
