ptrace compile failure with gcc-8.2 on 32-bit powerpc

From: Meelis Roos <mroos@linux.ee>
To: linux-powerpc@vger.kernel.org,
	Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: ptrace compile failure with gcc-8.2 on 32-bit powerpc
Date: Thu, 16 Aug 2018 10:44:56 +0300 (EEST)	[thread overview]
Message-ID: <alpine.LRH.2.21.1808161041350.16413@math.ut.ee> (raw)

After upgrading my distro compiler to gcc-8.2, Linux fails to compile on=20
32-bit powerpc (tested with 4.17, 4.18 and v4.18-7873-gf91e654474d4).

  CC      arch/powerpc/kernel/ptrace.o
In file included from ./include/linux/bitmap.h:9,
                 from ./include/linux/cpumask.h:12,
                 from ./include/linux/rcupdate.h:44,
                 from ./include/linux/rculist.h:11,
                 from ./include/linux/pid.h:5,
                 from ./include/linux/sched.h:14,
                 from arch/powerpc/kernel/ptrace.c:19:
In function =A1memcpy=A2,
    inlined from =A1user_regset_copyin=A2 at ./include/linux/regset.h:295=
:4,
    inlined from =A1vr_set=A2 at arch/powerpc/kernel/ptrace.c:619:9:
./include/linux/string.h:345:9: error: =A1__builtin_memcpy=A2 offset [-52=
7, -529] is out of the bounds [0, 16] of object =A1vrsave=A2 with type =A1=
union <anonymous>=A2 [-Werror=3Darray-bounds]
  return __builtin_memcpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/kernel/ptrace.c: In function =A1vr_set=A2:
arch/powerpc/kernel/ptrace.c:614:5: note: =A1vrsave=A2 declared here
   } vrsave;
     ^~~~~~
In file included from ./include/linux/bitmap.h:9,
                 from ./include/linux/cpumask.h:12,
                 from ./include/linux/rcupdate.h:44,
                 from ./include/linux/rculist.h:11,
                 from ./include/linux/pid.h:5,
                 from ./include/linux/sched.h:14,
                 from arch/powerpc/kernel/ptrace.c:19:
In function =A1memcpy=A2,
    inlined from =A1user_regset_copyout=A2 at ./include/linux/regset.h:27=
0:4,
    inlined from =A1vr_get=A2 at arch/powerpc/kernel/ptrace.c:572:9:
./include/linux/string.h:345:9: error: =A1__builtin_memcpy=A2 offset [-52=
7, -529] is out of the bounds [0, 16] of object =A1vrsave=A2 with type =A1=
union <anonymous>=A2 [-Werror=3Darray-bounds]
  return __builtin_memcpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/kernel/ptrace.c: In function =A1vr_get=A2:
arch/powerpc/kernel/ptrace.c:567:5: note: =A1vrsave=A2 declared here
   } vrsave;
     ^~~~~~
cc1: all warnings being treated as errors
make[1]: *** [scripts/Makefile.build:311: arch/powerpc/kernel/ptrace.o] E=
rror 1

--=20
Meelis Roos (mroos@linux.ee)