[glibc] x86/cet: Add -fcf-protection=none before -fcf-protection=branch

[glibc] x86/cet: Add -fcf-protection=none before -fcf-protection=branch

[H.J. Lu]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b5dcccfb12385ee492eb074f6beb9ead56b5e5fd

commit b5dcccfb12385ee492eb074f6beb9ead56b5e5fd
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Mon Jan 1 07:55:18 2024 -0800

    x86/cet: Add -fcf-protection=none before -fcf-protection=branch
    
    When shadow stack is enabled, some CET tests failed when compiled with
    GCC 14:
    
    FAIL: elf/tst-cet-legacy-4
    FAIL: elf/tst-cet-legacy-5a
    FAIL: elf/tst-cet-legacy-6a
    
    which are caused by
    
    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113039
    
    These tests use -fcf-protection -fcf-protection=branch and assume that
    -fcf-protection=branch will override -fcf-protection.  But this GCC 14
    commit:
    
    https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=1c6231c05bdcca
    
    changed the -fcf-protection behavior such that
    
    -fcf-protection -fcf-protection=branch
    
    is treated the same as
    
    -fcf-protection
    
    Use
    
    -fcf-protection -fcf-protection=none -fcf-protection=branch
    
    as the workaround.  This fixes BZ #31187.
    
    Tested with GCC 13 and GCC 14 on Intel Tiger Lake.
    Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

Diff:
---
 sysdeps/x86/Makefile | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index a49b13c595..5c8ab64c4d 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -215,12 +215,12 @@ modules-names += \
   tst-cet-legacy-mod-6c \
 # modules-names
 
-CFLAGS-tst-cet-legacy-2.c += -fcf-protection=branch
+CFLAGS-tst-cet-legacy-2.c += -fcf-protection=none -fcf-protection=branch
 CFLAGS-tst-cet-legacy-2a.c += -fcf-protection
 CFLAGS-tst-cet-legacy-mod-1.c += -fcf-protection=none
 CFLAGS-tst-cet-legacy-mod-2.c += -fcf-protection=none
 CFLAGS-tst-cet-legacy-3.c += -fcf-protection=none
-CFLAGS-tst-cet-legacy-4.c += -fcf-protection=branch
+CFLAGS-tst-cet-legacy-4.c += -fcf-protection=none -fcf-protection=branch
 CPPFLAGS-tst-cet-legacy-4a.c += -DCET_IS_PERMISSIVE=1
 CFLAGS-tst-cet-legacy-4a.c += -fcf-protection
 CFLAGS-tst-cet-legacy-4b.c += -fcf-protection
@@ -231,7 +231,7 @@ CPPFLAGS-tst-cet-legacy-5a.c += -DCET_IS_PERMISSIVE=1
 endif
 CFLAGS-tst-cet-legacy-5b.c += -fcf-protection -mshstk
 CPPFLAGS-tst-cet-legacy-5b.c += -DCET_DISABLED_BY_ENV=1
-CFLAGS-tst-cet-legacy-mod-5a.c += -fcf-protection=branch
+CFLAGS-tst-cet-legacy-mod-5a.c += -fcf-protection=none -fcf-protection=branch
 CFLAGS-tst-cet-legacy-mod-5b.c += -fcf-protection
 CFLAGS-tst-cet-legacy-mod-5c.c += -fcf-protection
 CFLAGS-tst-cet-legacy-6a.c += -fcf-protection -mshstk
@@ -240,7 +240,7 @@ CPPFLAGS-tst-cet-legacy-6a.c += -DCET_IS_PERMISSIVE=1
 endif
 CFLAGS-tst-cet-legacy-6b.c += -fcf-protection -mshstk
 CPPFLAGS-tst-cet-legacy-6b.c += -DCET_DISABLED_BY_ENV=1
-CFLAGS-tst-cet-legacy-mod-6a.c += -fcf-protection=branch
+CFLAGS-tst-cet-legacy-mod-6a.c += -fcf-protection=none -fcf-protection=branch
 CFLAGS-tst-cet-legacy-mod-6b.c += -fcf-protection
 CFLAGS-tst-cet-legacy-mod-6c.c += -fcf-protection
 CFLAGS-tst-cet-legacy-7.c += -fcf-protection=none