Messages in this thread Patch in this message | | | From | Michael Ellerman <> | Subject | Re: ptrace compile failure with gcc-8.2 on 32-bit powerpc | Date | Thu, 16 Aug 2018 22:06:41 +1000 |
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Meelis Roos <mroos@linux.ee> writes: > After upgrading my distro compiler to gcc-8.2, Linux fails to compile on > 32-bit powerpc (tested with 4.17, 4.18 and v4.18-7873-gf91e654474d4).
Yeah I noticed this just yesterday.
> 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 ‘memcpy’, > inlined from ‘user_regset_copyin’ at ./include/linux/regset.h:295:4, > inlined from ‘vr_set’ at arch/powerpc/kernel/ptrace.c:619:9: > ./include/linux/string.h:345:9: error: ‘__builtin_memcpy’ offset [-527, -529] is out of the bounds [0, 16] of object ‘vrsave’ with type ‘union <anonymous>’ [-Werror=array-bounds] > return __builtin_memcpy(p, q, size); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > arch/powerpc/kernel/ptrace.c: In function ‘vr_set’: > arch/powerpc/kernel/ptrace.c:614:5: note: ‘vrsave’ declared here > } vrsave; > ^~~~~~
I couldn't actually work out how GCC has decided this is definitely happening, possibly it just thinks it _could_ happen. I think it's wrong, but admittedly the code is not easy to follow.
The patch below should fix the build error, but I haven't had time to test it actually works at runtime:
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index 9667666eb18e..607273067d3f 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -570,7 +570,8 @@ static int vr_get(struct task_struct *target, const struct user_regset *regset, vrsave.word = target->thread.vrsave; ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &vrsave, - 33 * sizeof(vector128), -1); + 33 * sizeof(vector128), + 34 * sizeof(vector128)); } return ret; @@ -617,7 +618,8 @@ static int vr_set(struct task_struct *target, const struct user_regset *regset, vrsave.word = target->thread.vrsave; ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &vrsave, - 33 * sizeof(vector128), -1); + 33 * sizeof(vector128), + 34 * sizeof(vector128)); if (!ret) target->thread.vrsave = vrsave.word; }
cheers
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