clang 3.9.0 vs. TARGET_ARCH=powerpc: fsck_ufs and "df -m" are example failures: __floatdidf gets SIGSEGV's in both of them.
Mark Millard
markmi at dsl-only.net
Sun Nov 27 00:41:10 UTC 2016
[Summary: Looking around with gdb at fsck_ufs I found two __floatdidf routines
with different code. df has the same.]
On 2016-Nov-26, at 3:39 PM, Mark Millard <markmi at dsl-only.net> wrote:
> I updated to head -r309197 (with a work around for -r309144 breaking the build).
>
> This was on amd64, then used it to try to cross buildworld using clang 3.9.0 for
> TARGET_ARCH=powerpc . The build completed. (I've been using clang 3.8.0 this way
> for a long time.)
>
> [The kernel here was cross built via gcc 4.2.1, as has been my normal procedure.
> The kernel still has my "red zone for signal delivery" hack that was a workaround
> for clang 3.8.0 stack-handling ABI violations.]
>
> Booting, however, had problems because of fsck_ufs getting signal 11 and ended up
> initially in single user mode.
>
> Exiting single user did finish the boot. But "df -m" core dumps. (I've not
> explored much else.)
>
> Turns out that both fsck_ufs and "df -m" fail in the same routine for a SIGSEGV:
> __floatdidf
>
>
> The details. . .
>
> First the boot and fsck_ufs:
>
>> Copyright (c) 1992-2016 The FreeBSD Project.
>> Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
>> The Regents of the University of California. All rights reserved.
>> FreeBSD is a registered trademark of The FreeBSD Foundation.
>> FreeBSD 12.0-CURRENT #9 r309179M: Sat Nov 26 12:53:11 PST 2016
>> markmi at FreeBSDx64:/usr/obj/powerpcvtsc_clang_gcc421_kernel/powerpc.powerpc/usr/src/sys/GENERICvtsc-NODBG powerpc
>> gcc version 4.2.1 20070831 patched [FreeBSD]
>> cpu0: IBM PowerPC 970MP revision 1.1, 18446744071914.91 MHz
>> cpu0: Features dc000000<PPC32,PPC64,ALTIVEC,FPU,MMU>
>> cpu0: HID0 1511081<DEEPNAP,NAP,DPM,NHR,TBEN,ENATTN>
>> real memory = 2118565888 (2020 MB)
>> avail memory = 2014863360 (1921 MB)
>> FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
>> . . .
>> Trying to mount root from ufs:/dev/ufs/FBSDG4Srootfs [rw,noatime]...
>> . . .
>> pid 53 (fsck_ufs), uid 0: exited on signal 11
>
>
> Manually running fsck later gets a segmentation fault core file in /var/crash/
> and I used this too see a point of failure (__floatdidf):
>
>> # fsck /
>> ** /dev/ufs/FBSDG4Srootfs (NO WRITE)
>> ** Last Mounted on /
>> ** Root file system
>> ** Phase 1 - Check Blocks and Sizes
>> INCORRECT BLOCK COUNT I=11538459 (8 should be 0)
>> CORRECT? no
>>
>> ** Phase 2 - Check Pathnames
>> ** Phase 3 - Check Connectivity
>> ** Phase 4 - Check Reference Counts
>> LINK COUNT FILE I=10016041 OWNER=operator MODE=100400
>> SIZE=4096 MTIME=Nov 26 14:44 2016 COUNT 2 SHOULD BE 1
>> ADJUST? no
>>
>> LINK COUNT FILE I=10016049 OWNER=operator MODE=100400
>> SIZE=4096 MTIME=Nov 26 14:55 2016 COUNT 2 SHOULD BE 1
>> ADJUST? no
>>
>> LINK COUNT FILE I=10016089 OWNER=operator MODE=100400
>> SIZE=4096 MTIME=Nov 26 15:00 2016 COUNT 2 SHOULD BE 1
>> ADJUST? no
>>
>> UNREF FILE I=11538459 OWNER=root MODE=100600
>> SIZE=0 MTIME=Nov 26 15:11 2016
>> RECONNECT? no
>>
>>
>> CLEAR? no
>>
>> ** Phase 5 - Check Cyl groups
>> FREE BLK COUNT(S) WRONG IN SUPERBLK
>> SALVAGE? no
>>
>> SUMMARY INFORMATION BAD
>> SALVAGE? no
>>
>> BLK(S) MISSING IN BIT MAPS
>> SALVAGE? no
>>
>> fsck: /dev/ufs/FBSDG4Srootfs: Segmentation fault
>
>
>> # gdb fsck_ufs /var/crash/fsck_ufs.1129.core
>> GNU gdb 6.1.1 [FreeBSD]
>> Copyright 2004 Free Software Foundation, Inc.
>> GDB is free software, covered by the GNU General Public License, and you are
>> welcome to change it and/or distribute copies of it under certain conditions.
>> Type "show copying" to see the conditions.
>> There is absolutely no warranty for GDB. Type "show warranty" for details.
>> This GDB was configured as "powerpc-marcel-freebsd"...
>> Core was generated by `fsck_ufs /dev/ufs/FBSDG4Srootfs'.
>> Program terminated with signal 11, Segmentation fault.
>> Reading symbols from /lib/libufs.so.6...Reading symbols from /usr/lib/debug//lib/libufs.so.6.debug...done.
>> done.
>> Loaded symbols for /lib/libufs.so.6
>> Reading symbols from /lib/libc.so.7...Reading symbols from /usr/lib/debug//lib/libc.so.7.debug...done.
>> done.
>> Loaded symbols for /lib/libc.so.7
>> Reading symbols from /libexec/ld-elf.so.1...Reading symbols from /usr/lib/debug//libexec/ld-elf.so.1.debug...done.
>> done.
>> Loaded symbols for /libexec/ld-elf.so.1
>> #0 0x0181b024 in __floatdidf ()
>> (gdb) bt
>> #0 0x0181b024 in __floatdidf ()
>> #1 0x0180a8e0 in main (argc=<value optimized out>, argv=<value optimized out>) at /usr/src/sbin/fsck_ffs/main.c:519
>> #2 0x01801664 in _start ()
>> #3 0x418303a0 in .text () at /usr/src/libexec/rtld-elf/powerpc/rtld_start.S:112
>
> main.c's line 519 is part of:
>
>> printf("(%ju frags, %ju blocks, %.1f%% fragmentation)\n",
>> (uintmax_t)n_ffree, (uintmax_t)n_bfree,
>> n_ffree * 100.0 / sblock.fs_dsize);
>
>
>
> As for "df -m" --it failed in __floatdidf as well:
>
>> # gdb df /var/crash/df.1056.core GNU gdb 6.1.1 [FreeBSD]
>> Copyright 2004 Free Software Foundation, Inc.
>> GDB is free software, covered by the GNU General Public License, and you are
>> welcome to change it and/or distribute copies of it under certain conditions.
>> Type "show copying" to see the conditions.
>> There is absolutely no warranty for GDB. Type "show warranty" for details.
>> This GDB was configured as "powerpc-marcel-freebsd"...
>> Core was generated by `df -m'.
>> Program terminated with signal 11, Segmentation fault.
>> Reading symbols from /lib/libxo.so.0...Reading symbols from /usr/lib/debug//lib/libxo.so.0.debug...done.
>> done.
>> Loaded symbols for /lib/libxo.so.0
>> Reading symbols from /lib/libutil.so.9...Reading symbols from /usr/lib/debug//lib/libutil.so.9.debug...done.
>> done.
>> Loaded symbols for /lib/libutil.so.9
>> Reading symbols from /lib/libc.so.7...Reading symbols from /usr/lib/debug//lib/libc.so.7.debug...done.
>> done.
>> Loaded symbols for /lib/libc.so.7
>> Reading symbols from /libexec/ld-elf.so.1...Reading symbols from /usr/lib/debug//libexec/ld-elf.so.1.debug...done.
>> done.
>> Loaded symbols for /libexec/ld-elf.so.1
>> #0 0x01802a18 in __floatdidf ()
>> (gdb) bt
>> #0 0x01802a18 in __floatdidf ()
>> #1 0x01802538 in prtstat (sfsp=0x41e24000, mwp=0xffffd930) at /usr/src/bin/df/df.c:503
>> #2 0x01801df0 in main (argc=<value optimized out>, argv=<value optimized out>) at /usr/src/bin/df/df.c:308
>> #3 0x01800cdc in _start ()
>> #4 0x418153a0 in .text () at /usr/src/libexec/rtld-elf/powerpc/rtld_start.S:112
>
> df.c's line 503 was part of:
>
>> xo_emit(" {:used-percent/%5.0f}{U:%%}",
>> availblks == 0 ? 100.0 : (double)used / (double)availblks * 100.0);
>
>
>
> Context details:
>
>> # head ~/sys_typescripts/typescript_make_powerpcvtsc_nodebug_clang_bootstrap_world-amd64-host-2016-11-26:11:38:36
>> Script started on Sat Nov 26 11:38:36 2016
>> Command: env __MAKE_CONF=/root/src.configs/make.conf SRCCONF=/dev/null SRC_ENV_CONF=/root/src.configs/src.conf.powerpc-clang-bootstrap.amd64-host WITH_META_MODE=yes MAKEOBJDIRPREFIX=/usr/obj/powerpcvtsc_clang_world make -j 5 buildworld
>> --- buildworld ---
>
> . . .
>
>
>> # more ~/src.configs/src.conf.powerpc-clang-bootstrap.amd64-host
>> TO_TYPE=powerpc
>> #
>> KERNCONF=GENERICvtsc-NODBG
>> TARGET=${TO_TYPE}
>> .if ${.MAKE.LEVEL} == 0
>> TARGET_ARCH=${TO_TYPE}
>> .export TARGET_ARCH
>> .endif
>> #
>> WITH_CROSS_COMPILER=
>> WITHOUT_SYSTEM_COMPILER=
>> #
>> WITH_LIBCPLUSPLUS=
>> WITH_BINUTILS_BOOTSTRAP=
>> WITH_CLANG_BOOTSTRAP=
>> WITH_CLANG=
>> WITH_CLANG_IS_CC=
>> WITH_CLANG_FULL=
>> WITH_CLANG_EXTRAS=
>> # lldb requires missing atomic 8-byte operations for powerpc (non-64)
>> WITHOUT_LLDB=
>> #
>> WITH_BOOT=
>> WITHOUT_LIB32=
>> #
>> WITHOUT_ELFTOOLCHAIN_BOOTSTRAP=
>> WITHOUT_GCC_BOOTSTRAP=
>> WITHOUT_GCC=
>> WITHOUT_GCC_IS_CC=
>> WITHOUT_GNUCXX=
>> #
>> NO_WERROR=
>> #WERROR=
>> MALLOC_PRODUCTION=
>> #
>> WITH_DEBUG_FILES=
>
>
>> # more ~/src.configs/make.conf
>> CFLAGS.gcc+= -v
Looking around in gdb there seem to be two __floatdidf routines with differing code.
First showing the one that was used and failed:
(gdb) x/50i 0x0181afc0
. . .
0x181afcc <__floatdidf>: mflr r0
0x181afd0 <__floatdidf+4>: stw r0,4(r1)
0x181afd4 <__floatdidf+8>: stwu r1,-32(r1)
0x181afd8 <__floatdidf+12>: stw r31,28(r1)
0x181afdc <__floatdidf+16>: stw r30,24(r1)
0x181afe0 <__floatdidf+20>: bl 0x182e96c <.got+20>
0x181afe4 <__floatdidf+24>: mr r31,r1
0x181afe8 <__floatdidf+28>: xoris r3,r3,32768
0x181afec <__floatdidf+32>: lis r5,17200
0x181aff0 <__floatdidf+36>: mflr r30
0x181aff4 <__floatdidf+40>: stw r3,12(r31)
0x181aff8 <__floatdidf+44>: stw r5,8(r31)
0x181affc <__floatdidf+48>: lwz r3,-16(r30)
0x181b000 <__floatdidf+52>: lwz r6,-20(r30)
0x181b004 <__floatdidf+56>: lfd f1,8(r31)
0x181b008 <__floatdidf+60>: stw r4,20(r31)
0x181b00c <__floatdidf+64>: stw r5,16(r31)
0x181b010 <__floatdidf+68>: lfd f13,16(r31)
0x181b014 <__floatdidf+72>: lwz r0,36(r1)
0x181b018 <__floatdidf+76>: lwz r31,28(r1)
0x181b01c <__floatdidf+80>: lwz r30,24(r1)
0x181b020 <__floatdidf+84>: lfs f2,0(r3)
0x181b024 <__floatdidf+88>: lwz r3,-12(r30)
0x181b028 <__floatdidf+92>: lfs f0,0(r6)
0x181b02c <__floatdidf+96>: lfs f12,0(r3)
0x181b030 <__floatdidf+100>: fsub f0,f1,f0
0x181b034 <__floatdidf+104>: fmul f0,f0,f2
0x181b038 <__floatdidf+108>: fadd f0,f0,f12
0x181b03c <__floatdidf+112>: fadd f1,f13,f0
0x181b040 <__floatdidf+116>: addi r1,r1,32
0x181b044 <__floatdidf+120>: mtlr r0
0x181b048 <__floatdidf+124>: blr
. . .
Then showing the one that was not used that I found:
(gdb) disass __floatdidf
Dump of assembler code for function __floatdidf:
0x4199fc8c <__floatdidf+0>: mflr r0
0x4199fc90 <__floatdidf+4>: stw r0,4(r1)
0x4199fc94 <__floatdidf+8>: stwu r1,-32(r1)
0x4199fc98 <__floatdidf+12>: stw r31,28(r1)
0x4199fc9c <__floatdidf+16>: stw r30,24(r1)
0x4199fca0 <__floatdidf+20>: mr r31,r1
0x4199fca4 <__floatdidf+24>: srawi r5,r3,31
0x4199fca8 <__floatdidf+28>: bl 0x41a0a288 <.got+14428>
0x4199fcac <__floatdidf+32>: cmpwi r3,0
0x4199fcb0 <__floatdidf+36>: addc r6,r4,r5
0x4199fcb4 <__floatdidf+40>: adde r6,r3,r5
0x4199fcb8 <__floatdidf+44>: lis r3,17200
0x4199fcbc <__floatdidf+48>: xor r5,r6,r5
0x4199fcc0 <__floatdidf+52>: mflr r30
0x4199fcc4 <__floatdidf+56>: bge- 0x4199fccc <__floatdidf+64>
0x4199fcc8 <__floatdidf+60>: neg r4,r4
0x4199fccc <__floatdidf+64>: lwz r12,-3124(r30)
0x4199fcd0 <__floatdidf+68>: stw r5,20(r31)
0x4199fcd4 <__floatdidf+72>: stw r4,12(r31)
0x4199fcd8 <__floatdidf+76>: lwz r4,-3120(r30)
0x4199fcdc <__floatdidf+80>: stw r3,16(r31)
0x4199fce0 <__floatdidf+84>: stw r3,8(r31)
0x4199fce4 <__floatdidf+88>: lfd f1,16(r31)
0x4199fce8 <__floatdidf+92>: lfd f3,8(r31)
0x4199fcec <__floatdidf+96>: lfs f0,0(r12)
0x4199fcf0 <__floatdidf+100>: lfs f2,0(r4)
0x4199fcf4 <__floatdidf+104>: fsub f1,f1,f0
0x4199fcf8 <__floatdidf+108>: fsub f0,f3,f0
0x4199fcfc <__floatdidf+112>: fmul f1,f1,f2
0x4199fd00 <__floatdidf+116>: fadd f1,f0,f1
0x4199fd04 <__floatdidf+120>: bge- 0x4199fd0c <__floatdidf+128>
0x4199fd08 <__floatdidf+124>: fneg f1,f1
0x4199fd0c <__floatdidf+128>: lwz r0,36(r1)
0x4199fd10 <__floatdidf+132>: lwz r31,28(r1)
0x4199fd14 <__floatdidf+136>: lwz r30,24(r1)
0x4199fd18 <__floatdidf+140>: addi r1,r1,32
0x4199fd1c <__floatdidf+144>: mtlr r0
0x4199fd20 <__floatdidf+148>: blr
End of assembler dump.
===
Mark Millard
markmi at dsl-only.net
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