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Message-ID: <87tvlnzegi.fsf@concordia.ellerman.id.au>
Date: Mon, 15 Oct 2018 21:33:49 +1100
From: Michael Ellerman <mpe@...erman.id.au>
To: Meelis Roos <mroos@...ux.ee>, linux-kernel@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org
Subject: Re: 32-bit poweroc compile failure in v4.19-rc7-166-g7ec21823634d
Meelis Roos <mroos@...ux.ee> writes:
> I tried to test the fix to 32-bit poweroc boot hang but found that current git does not compile on 32bit poweroc at all for me:
That's GCC 8 I think?
I have seen that but couldn't work out what the hell GCC is thinking.
I don't think there's an actual bug, the size of the copy is bounded by
the count parameter, which *doesn't* come from user space, it's hard
coded.
I suspect the logic is just to convoluted for GCC.
We should fix it somehow, but I haven't worked out what's the best option.
cheers
> 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;
> ^~~~~~
> 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_copyout’ at ./include/linux/regset.h:270:4,
> inlined from ‘vr_get’ at arch/powerpc/kernel/ptrace.c:572:9:
> ./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_get’:
> arch/powerpc/kernel/ptrace.c:567:5: note: ‘vrsave’ declared here
> } vrsave;
> ^~~~~~
> cc1: all warnings being treated as errors
> make[1]: *** [scripts/Makefile.build:306: arch/powerpc/kernel/ptrace.o] Error 1
> make: *** [Makefile:1052: arch/powerpc/kernel] Error 2
>
> --
> Meelis Roos <mroos@...ux.ee>
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