Date: Sat, 17 Sep 2011 12:02:39 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Jason Harmening <jason.harmening@gmail.com> Cc: freebsd-current@freebsd.org Subject: Re: Crashes in world built w/ clang: FP registers? Message-ID: <20110917090239.GM1511@deviant.kiev.zoral.com.ua> In-Reply-To: <CAM=8qan5K6025J5oBT25s4fz9YgT15mp5SpNsEdzR0Fw%2BHVwig@mail.gmail.com> References: <CAM=8qan5K6025J5oBT25s4fz9YgT15mp5SpNsEdzR0Fw%2BHVwig@mail.gmail.com>
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On Fri, Sep 16, 2011 at 10:34:40PM -0500, Jason Harmening wrote:
> Hi everyone,
>=20
> Using clang as the default compiler, the kernel and drivers will work
> fine, but a lot of programs in the base system and ports will crash w/
> SIGBUS. In fact, so much of the stuff in the chroot'ed world will
> crash (everything from csh to gcc) that it's basically unusable. I
> finally got around to building w/ debug symbols, and ran gdb on a
> coredump generated while I was trying to use tab completion in csh:
>=20
> (gdb) bt
> #0 tw_collect (command=3Ddwarf2_read_address: Corrupted DWARF expression=
.)
> at /usr/src/bin/csh/../../contrib/tcsh/tw.parse.c:1308
> #1 0x000000000042777b in t_search (word=3DUnhandled dwarf expression opc=
ode 0x0)
> at /usr/src/bin/csh/../../contrib/tcsh/tw.parse.c:1725
> #2 0x0000000000426829 in tenematch (inputline=3DVariable "inputline" is
> not avail able.)
> at /usr/src/bin/csh/../../contrib/tcsh/tw.parse.c:301
> #3 0x000000000043545d in Inputl ()
> at /usr/src/bin/csh/../../contrib/tcsh/ed.inputl.c:415
> #4 0x0000000000417a90 in readc (wanteof=3DVariable "wanteof" is not avai=
lable.)
> at /usr/src/bin/csh/../../contrib/tcsh/sh.lex.c:1653
> #5 0x0000000000416f37 in lex (hp=3DVariable "hp" is not available.)
> at /usr/src/bin/csh/../../contrib/tcsh/sh.lex.c:162
> #6 0x0000000000405afb in process (catch=3DUnhandled dwarf expression opc=
ode 0x0)
> at /usr/src/bin/csh/../../contrib/tcsh/sh.c:1922
> #7 0x0000000000404b51 in main (argc=3DVariable "argc" is not available.)
> at /usr/src/bin/csh/../../contrib/tcsh/sh.c:1289
>=20
> gdb) disas
> Dump of assembler code for function tw_collect:
> 0x00000000004288b0 <tw_collect+0>: push %rbp
> 0x00000000004288b1 <tw_collect+1>: mov %rsp,%rbp
> 0x00000000004288b4 <tw_collect+4>: push %r15
> 0x00000000004288b6 <tw_collect+6>: push %r14
> 0x00000000004288b8 <tw_collect+8>: push %r13
> 0x00000000004288ba <tw_collect+10>: push %r12
> 0x00000000004288bc <tw_collect+12>: push %rbx
> 0x00000000004288bd <tw_collect+13>: sub $0x2e8,%rsp
> 0x00000000004288c4 <tw_collect+20>: mov %r9,-0x308(%rbp)
> 0x00000000004288cb <tw_collect+27>: mov %r8,-0x300(%rbp)
> 0x00000000004288d2 <tw_collect+34>: mov %rcx,-0x2f8(%rbp)
> 0x00000000004288d9 <tw_collect+41>: mov %rdx,-0x2f0(%rbp)
> 0x00000000004288e0 <tw_collect+48>: mov %esi,-0x2e8(%rbp)
> 0x00000000004288e6 <tw_collect+54>: mov %edi,-0x2e4(%rbp)
> 0x00000000004288ec <tw_collect+60>: movl $0x0,-0x1d4(%rbp)
> 0x00000000004288f6 <tw_collect+70>: movaps 0x23115b(%rip),%xmm0
> # 0x6 59a58
> <reslab+48>
This is actually 0x659a58 <reslab+48>
movaps tried to load %xmm0 from the unaligned address, which is forbidden
and causes #GP.
I have no idea why clang generates unaligned loads.
> 0x00000000004288fd <tw_collect+77>: lea -0x2(%rdi),%eax
> 0x0000000000428900 <tw_collect+80>: mov %eax,-0x2e0(%rbp)
> 0x0000000000428906 <tw_collect+86>: test %edi,%edi
> 0x0000000000428908 <tw_collect+88>: movaps %xmm0,-0x210(%rbp)
> 0x000000000042890f <tw_collect+95>: sete %al
> ---Type <return> to continue, or q <return> to quit---q
> Quit
> (gdb) info line tw.parse.c:1308
> Line 1308 of "/usr/src/bin/csh/../../contrib/tcsh/tw.parse.c"
> starts at address 0x4288f6 <tw_collect+70>
> and ends at 0x4288fd <tw_collect+77>.
>=20
>=20
> Looks like it's crashing as soon as it tries to use the XMM registers.
> I'm not sure if all of the crashes I'm getting are like this one, but
> I was surprised to see FP registers in code like this.
>=20
> I'm using march=3Dcorei7 and -O2 for both world and kernel, but using
> march=3Dnocona or just leaving out CPUTYPE has no effect (actual CPU is
> Nehalem Xeon 5520)
> Here's the relevant part of make.conf for completeness:
>=20
> .if !defined(CC) || ${CC} =3D=3D "cc"
> CC=3Dclang
> .endif
> .if !defined(CXX) || ${CXX} =3D=3D "c++"
> CXX=3Dclang++
> .endif
> .if !defined(CPP) || ${CPP} =3D=3D "cpp"
> CPP=3Dclang -E
> .endif
> NO_WERROR=3D
> WERROR=3D
> NO_FSCHG=3D
> CPUTYPE?=3Dcorei7
> CFLAGS=3D -O2 -pipe
> COPTFLAGS=3D -O2 -pipe
>=20
> Any thoughts? Is there some simple fix for this I'm missing?
>=20
> Thanks,
> Jason
> _______________________________________________
> freebsd-current@freebsd.org mailing list
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