From owner-freebsd-arm@freebsd.org Fri Dec 25 14:25:00 2015 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id D4650A510C2 for ; Fri, 25 Dec 2015 14:25:00 +0000 (UTC) (envelope-from markmi@dsl-only.net) Received: from asp.reflexion.net (outbound-mail-211-151.reflexion.net [208.70.211.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 99CA117E1 for ; Fri, 25 Dec 2015 14:25:00 +0000 (UTC) (envelope-from markmi@dsl-only.net) Received: (qmail 4731 invoked from network); 25 Dec 2015 14:24:58 -0000 Received: from unknown (HELO mail-cs-01.app.dca.reflexion.local) (10.81.19.1) by 0 (rfx-qmail) with SMTP; 25 Dec 2015 14:24:58 -0000 Received: by mail-cs-01.app.dca.reflexion.local (Reflexion email security v7.80.0) with SMTP; Fri, 25 Dec 2015 09:25:04 -0500 (EST) Received: (qmail 9553 invoked from network); 25 Dec 2015 14:25:03 -0000 Received: from unknown (HELO iron2.pdx.net) (69.64.224.71) by 0 (rfx-qmail) with SMTP; 25 Dec 2015 14:25:03 -0000 X-No-Relay: not in my network X-No-Relay: not in my network Received: from [192.168.1.8] (c-76-115-7-162.hsd1.or.comcast.net [76.115.7.162]) by iron2.pdx.net (Postfix) with ESMTPSA id 0EA50B1E001; Fri, 25 Dec 2015 06:24:56 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Subject: Re: 11.0-CURRENT (r292413) on a rpi2b: arm-gnueabi-freebsd/bin/ar, _fseeko, and memset vs memory alignment (SCTRL bit[1]=1?): Explains the Bus error? From: Mark Millard In-Reply-To: Date: Fri, 25 Dec 2015 06:24:57 -0800 Content-Transfer-Encoding: quoted-printable Message-Id: References: <4CC6220D-72FB-45AD-AE70-5EB4EF0BCF5C@dsl-only.net> To: freebsd-arm@freebsd.org, FreeBSD Toolchain X-Mailer: Apple Mail (2.2104) X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 25 Dec 2015 14:25:00 -0000 [Good News Summary: Rebuilding buildworld/buildkernel for rpi2 = 11.0-CURRENT 292413 from amd64 based on adding -fmax-type-align=3D4 has = so far removed the crashes during the toolchain activity: no more = misaligned accesses in libc's _fseeko or elsewhere.] On 2015-Dec-25, at 12:31 AM, Mark Millard wrote: > On 2015-Dec-24, at 10:39 PM, Mark Millard wrote: >=20 >> [I do not know if this partial crash analysis related to on-arm = clang-associated activity is good enough and appropriate to submit or = not.] >>=20 >> The /usr/local/arm-gnueabi-freebsd/bin/ar on the rpi2b involved below = came from pkg install activity instead of port building. Used as-is. >>=20 >> When I just tried my first from-rpi2b builds (ports for a rpi2b), = /usr/local/arm-gnueabi-freebsd/bin/ar crashed. I believe that the = following suggests an alignment error for the type of instructions that = memset for 128 bytes was translated to (sizeof(mbstate_t)) in the code = used by /usr/local/arm-gnueabi-freebsd/bin/ar. (But I do not know how to = check SCTLR bit[1] to be directly sure that alignment was being = enforced.) >>=20 >> The crash was a Bus error in /usr/local/arm-gnueabi-freebsd/bin/ar : >>=20 >>> libtool: link: /usr/local/arm-gnueabi-freebsd/bin/ar cru = .libs/libgnuintl.a bindtextdom.o dcgettext.o dgettext.o gettext.o = finddomain.o hash-string.o loadmsgcat.o localealias.o textdomain.o = l10nflist.o explodename.o dcigettext.o dcngettext.o dngettext.o = ngettext.o pluralx.o plural-exp.o localcharset.o threadlib.o lock.o = relocatable.o langprefs.o localename.o log.o printf.o setlocale.o = version.o xsize.o osdep.o intl-compat.o >>> Bus error (core dumped) >>> *** [libgnuintl.la] Error code 138 >>=20 >> It failed in _fseeko doing a memset that turned into uses of "vst1.64 = {d16-d17}, [r0]" instructions, for an address in register r0 that ended = in 0xa4, so was not aligned to 8 byte boundaries. =46rom what I read = such "VSTn (multiple n-element structures)" that have .64 require 8 byte = alignment. The evidence of the code and register value follow. >>=20 >>> # gdb /usr/local/arm-gnueabi-freebsd/bin/ar = /usr/obj/portswork/usr/ports/devel/gettext-tools/work/gettext-0.19.6/gette= xt-tools/intl/ar.core >>> . . . >>> #0 0x2033adcc in _fseeko (fp=3D0x20651dcc, offset=3D, whence=3D, ltest=3D) at /usr/src/lib/libc/stdio/fseek.c:299 >>> 299 memset(&fp->_mbstate, 0, sizeof(mbstate_t)); >>> . . . >>> (gdb) x/24i 0x2033adb0 >>> 0x2033adb0 <_fseeko+836>: vmov.i32 q8, #0 ; 0x00000000 >>> 0x2033adb4 <_fseeko+840>: movw r1, #65503 ; 0xffdf >>> 0x2033adb8 <_fseeko+844>: stm r4, {r0, r7} >>> 0x2033adbc <_fseeko+848>: ldrh r0, [r4, #12] >>> 0x2033adc0 <_fseeko+852>: and r0, r0, r1 >>> 0x2033adc4 <_fseeko+856>: strh r0, [r4, #12] >>> 0x2033adc8 <_fseeko+860>: add r0, r4, #216 ; 0xd8 >>> 0x2033adcc <_fseeko+864>: vst1.64 {d16-d17}, [r0] >>> 0x2033add0 <_fseeko+868>: add r0, r4, #200 ; 0xc8 >>> 0x2033add4 <_fseeko+872>: vst1.64 {d16-d17}, [r0] >>> 0x2033add8 <_fseeko+876>: add r0, r4, #184 ; 0xb8 >>> 0x2033addc <_fseeko+880>: vst1.64 {d16-d17}, [r0] >>> 0x2033ade0 <_fseeko+884>: add r0, r4, #168 ; 0xa8 >>> 0x2033ade4 <_fseeko+888>: vst1.64 {d16-d17}, [r0] >>> 0x2033ade8 <_fseeko+892>: add r0, r4, #152 ; 0x98 >>> 0x2033adec <_fseeko+896>: vst1.64 {d16-d17}, [r0] >>> 0x2033adf0 <_fseeko+900>: add r0, r4, #136 ; 0x88 >>> 0x2033adf4 <_fseeko+904>: vst1.64 {d16-d17}, [r0] >>> 0x2033adf8 <_fseeko+908>: add r0, r4, #120 ; 0x78 >>> 0x2033adfc <_fseeko+912>: vst1.64 {d16-d17}, [r0] >>> 0x2033ae00 <_fseeko+916>: add r0, r4, #104 ; 0x68 >>> 0x2033ae04 <_fseeko+920>: vst1.64 {d16-d17}, [r0] >>> 0x2033ae08 <_fseeko+924>: b 0x2033b070 <_fseeko+1540> >>> 0x2033ae0c <_fseeko+928>: cmp r5, #0 ; 0x0 >>> (gdb) info all-registers >>> r0 0x20651ea4 543497892 >>> r1 0xffdf 65503 >>> r2 0x0 0 >>> r3 0x0 0 >>> r4 0x20651dcc 543497676 >>> r5 0x0 0 >>> r6 0x0 0 >>> r7 0x0 0 >>> r8 0x20359df4 540384756 >>> r9 0x0 0 >>> r10 0x0 0 >>> r11 0xbfbfb948 -1077954232 >>> r12 0x2037b208 540520968 >>> sp 0xbfbfb898 -1077954408 >>> lr 0x2035a004 540385284 >>> pc 0x2033adcc 540257740 >>> f0 0 (raw 0x000000000000000000000000) >>> f1 0 (raw 0x000000000000000000000000) >>> f2 0 (raw 0x000000000000000000000000) >>> f3 0 (raw 0x000000000000000000000000) >>> f4 0 (raw 0x000000000000000000000000) >>> f5 0 (raw 0x000000000000000000000000) >>> f6 0 (raw 0x000000000000000000000000) >>> f7 0 (raw 0x000000000000000000000000) >>> fps 0x0 0 >>> cpsr 0x60000010 1610612752 >>=20 >> The syntax in use for vst1.64 instructions does not explicitly have = the alignment notation. Presuming that the decoding is correct then from = what I read the following applies: >>=20 >>> Home > NEON and VFP Programming > NEON load and store element and = structure instructions > Alignment restrictions in load and store, = element and structure instructions >>>=20 >>> . . . When the alignment is not specified in the instruction, the = alignment restriction is controlled by the A bit (SCTLR bit[1]): >>> =E2=80=A2 if the A bit is 0, there are no alignment = restrictions (except for strongly ordered or device memory, where = accesses must be element aligned or the result is unpredictable) >>> =E2=80=A2 if the A bit is 1, accesses must be element = aligned. >>> If an address is not correctly aligned, an alignment fault occurs. >>=20 >> So if at the time the "A bit" (SCTLR bit[1]) is 1 then the Bus error = would have the context to happen because of the mis-alignment. >>=20 >> The following shows the make.conf context that explains how = /usr/local/arm-gnueabi-freebsd/bin/ar came to be invoked: >>=20 >>> # more /etc/make.conf=20 >>> WRKDIRPREFIX=3D/usr/obj/portswork >>> WITH_DEBUG=3D >>> WITH_DEBUG_FILES=3D >>> MALLOC_PRODUCTION=3D >>> # >>> TO_TYPE=3Darmv6 >>> TOOLS_TO_TYPE=3Darm-gnueabi >>> CROSS_BINUTILS_PREFIX=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ >>> .if ${.MAKE.LEVEL} =3D=3D 0 >>> CC=3D/usr/bin/clang -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a >>> CXX=3D/usr/bin/clang++ -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a >>> CPP=3D/usr/bin/clang-cpp -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a >>> .export CC >>> .export CXX >>> .export CPP >>> AS=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/as >>> AR=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ar >>> LD=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ld >>> NM=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/nm >>> OBJCOPY=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/objcopy >>> OBJDUMP=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/objdump >>> RANLIB=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ranlib >>> SIZE=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/size >>> #NO-SUCH: STRINGS=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/strings >>> STRINGS=3D/usr/local/bin/${TOOLS_TO_TYPE}-freebsd-strings >>> .export AS >>> .export AR >>> .export LD >>> .export NM >>> .export OBJCOPY >>> .export OBJDUMP >>> .export RANLIB >>> .export SIZE >>> .export STRINGS >>> .endif >>=20 >>=20 >> Other context: >>=20 >>> # freebsd-version -ku; uname -aKU >>> 11.0-CURRENT >>> 11.0-CURRENT >>> FreeBSD rpi2 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r292413M: Tue Dec = 22 22:02:21 PST 2015 = root@FreeBSDx64:/usr/obj/clang/arm.armv6/usr/src/sys/RPI2-NODBG arm = 1100091 1100091 >>=20 >>=20 >>=20 >> I will note that world and kernel are my own build of -r292413 = (earlier experiment) --a build made from an amd64 host context and put = in place via DESTDIR=3D. My expectation would be that the amd64 context = would not be likely to have similar alignment restrictions involved in = its ar activity (or other activity). That would explain how I got this = far using such a clang 3.7 related toolchain for targeting an rpi2 = before finding such a problem. >=20 >=20 > I realized re-reading the all above that it seems to suggest that the = _fseeko code involved is from /usr/local/arm-gnueabi-freebsd/bin/ar but = that was not my intent. >=20 > libc.so.7 is from my buildworld, including the fseeko implementation: >=20 > 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 >=20 >=20 > head/sys/sys/_types.h has: >=20 > /* > * mbstate_t is an opaque object to keep conversion state during = multibyte > * stream conversions. > */ > typedef union { > char __mbstate8[128]; > __int64_t _mbstateL; /* for alignment */ > } __mbstate_t; >=20 > suggesting an implicit alignment of the union to whatever the = implementation defines for __int64_t --which need not be 8 byte = alignment (in the abstract, general case). But 8 byte alignment is a = possibility as well (in the abstract). >=20 > But printing *fp in gdb for the fp argument to _fseeko reports the = same not-8-byte aligned address for __mbstate8 that was in r0: >=20 >> (gdb) bt >> #0 0x2033adcc in _fseeko (fp=3D0x20651dcc, offset=3D, whence=3D, ltest=3D) at = /usr/src/lib/libc/stdio/fseek.c:299 >> #1 0x2033b108 in fseeko (fp=3D0x20651dcc, offset=3D18571438587904, = whence=3D0) at /usr/src/lib/libc/stdio/fseek.c:82 >> #2 0x00016138 in ?? () >> (gdb) print fp >> $2 =3D (FILE *) 0x20651dcc >> (gdb) print *fp >> $3 =3D {_p =3D 0x2069a240 "", _r =3D 0, _w =3D 0, _flags =3D 5264, = _file =3D 36, _bf =3D {_base =3D 0x2069a240 "", _size =3D 32768}, = _lbfsize =3D 0, _cookie =3D 0x20651dcc, _close =3D 0x20359dfc = <__sclose>,=20 >> _read =3D 0x20359de4 <__sread>, _seek =3D 0x20359df4 <__sseek>, = _write =3D 0x20359dec <__swrite>, _ub =3D {_base =3D 0x0, _size =3D 0}, = _up =3D 0x0, _ur =3D 0, _ubuf =3D 0x20651e0c "", _nbuf =3D 0x20651e0f = "", _lb =3D { >> _base =3D 0x0, _size =3D 0}, _blksize =3D 32768, _offset =3D 0, = _fl_mutex =3D 0x0, _fl_owner =3D 0x0, _fl_count =3D 0, _orientation =3D = 0, _mbstate =3D {__mbstate8 =3D 0x20651e34 "", _mbstateL =3D 0}, _flags2 = =3D 0} >=20 > The overall FILE struct containing the _mbstate field is also not = 8-byte aligned. But the offset from the start of the FILE struct to = __mbstate8 is a multiple of 8 bytes. >=20 > It is my interpretation that there is nothing here to justify the = memset implementation combination: >=20 > SCTLR bit[1]=3D=3D1 >=20 > mixed with >=20 > vst1.64 instructions >=20 > I.e.: one or both needs to change unless some way for forcing 8-byte = alignment is introduced. >=20 > I have not managed to track down anything that would indicate = FreeBSD's intent for SCTLR bit[1]. I do not even know if it is required = by the design to be constant (once initialized). I have (so far) removed the build tool crashes based on adding = -fmax-type-align=3D4 to avoid the misaligned accesses. Details follow. src.conf on amd64 for the rpi2 targeting buildworld/buildkernel now = looks like: > # more ~/src.configs/src.conf.rpi2-clang.amd64-host > TO_TYPE=3Darmv6 > TOOLS_TO_TYPE=3Darm-gnueabi > FROM_TYPE=3Damd64 > TOOLS_FROM_TYPE=3Dx86_64 > VERSION_CONTEXT=3D11.0 > # > KERNCONF=3DRPI2-NODBG > TARGET=3Darm > .if ${.MAKE.LEVEL} =3D=3D 0 > TARGET_ARCH=3D${TO_TYPE} > .export TARGET_ARCH > .endif > # > WITHOUT_CROSS_COMPILER=3D > # > # For WITH_BOOT=3D . . . > # arm-gnueabi-freebsd/bin/ld reports bootinfo.o: relocation = R_ARM_MOVW_ABS_NC against `a local symbol' can not be used when making a = shared object; recompile with -fPIC=20 > WITHOUT_BOOT=3D > # > WITH_FAST_DEPEND=3D > WITH_LIBCPLUSPLUS=3D > WITH_CLANG=3D > WITH_CLANG_IS_CC=3D > WITH_CLANG_FULL=3D > WITH_LLDB=3D > WITH_CLANG_EXTRAS=3D > # > WITHOUT_LIB32=3D > WITHOUT_GCC=3D > WITHOUT_GNUCXX=3D > # > NO_WERROR=3D > MALLOC_PRODUCTION=3D > #CFLAGS+=3D -DELF_VERBOSE > # > WITH_DEBUG=3D > WITH_DEBUG_FILES=3D > # > # TOOLS_TO_TYPE based on ${TO_TYPE}-xtoolchain-gcc related = bintutils... > # > #CROSS_TOOLCHAIN=3D${TO_TYPE}-gcc > X_COMPILER_TYPE=3Dclang > CROSS_BINUTILS_PREFIX=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ > .if ${.MAKE.LEVEL} =3D=3D 0 > XCC=3D/usr/bin/clang -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a -fmax-type-align=3D4 > XCXX=3D/usr/bin/clang++ -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a -fmax-type-align=3D4 > XCPP=3D/usr/bin/clang-cpp -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a -fmax-type-align=3D4 > .export XCC > .export XCXX > .export XCPP > XAS=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/as > XAR=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ar > XLD=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ld > XNM=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/nm > XOBJCOPY=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/objcopy > XOBJDUMP=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/objdump > XRANLIB=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ranlib > XSIZE=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/size > #NO-SUCH: XSTRINGS=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/strings > XSTRINGS=3D/usr/local/bin/${TOOLS_TO_TYPE}-freebsd-strings > .export XAS > .export XAR > .export XLD > .export XNM > .export XOBJCOPY > .export XOBJDUMP > .export XRANLIB > .export XSIZE > .export XSTRINGS > .endif > # > # Host compiler stuff: > .if ${.MAKE.LEVEL} =3D=3D 0 > CC=3D/usr/bin/clang -B/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin > CXX=3D/usr/bin/clang++ -B/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin > CPP=3D/usr/bin/clang-cpp -B/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin > .export CC > .export CXX > .export CPP > AS=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/as > AR=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/ar > LD=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/ld > NM=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/nm > OBJCOPY=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/objcopy > OBJDUMP=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/objdump > RANLIB=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/ranlib > SIZE=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/size > #NO-SUCH: STRINGS=3D/usr/local/${TOOLS_FROM_TYPE}-freebsd/bin/strings > STRINGS=3D/usr/local/bin/${TOOLS_FROM_TYPE}-freebsd-strings > .export AS > .export AR > .export LD > .export NM > .export OBJCOPY > .export OBJDUMP > .export RANLIB > .export SIZE > .export STRINGS > .endif make.conf for during the on-rpi2 port builds now looks like: > $ more /etc/make.conf=20 > WRKDIRPREFIX=3D/usr/obj/portswork > WITH_DEBUG=3D > WITH_DEBUG_FILES=3D > MALLOC_PRODUCTION=3D > # > TO_TYPE=3Darmv6 > TOOLS_TO_TYPE=3Darm-gnueabi > CROSS_BINUTILS_PREFIX=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ > .if ${.MAKE.LEVEL} =3D=3D 0 > CC=3D/usr/bin/clang -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a -fmax-type-align=3D4 > CXX=3D/usr/bin/clang++ -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a -fmax-type-align=3D4 > CPP=3D/usr/bin/clang-cpp -target ${TO_TYPE}--freebsd11.0-gnueabi = -march=3Darmv7a -fmax-type-align=3D4 > .export CC > .export CXX > .export CPP > AS=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/as > AR=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ar > LD=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ld > NM=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/nm > OBJCOPY=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/objcopy > OBJDUMP=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/objdump > RANLIB=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ranlib > SIZE=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/size > #NO-SUCH: STRINGS=3D/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/strings > STRINGS=3D/usr/local/bin/${TOOLS_TO_TYPE}-freebsd-strings > .export AS > .export AR > .export LD > .export NM > .export OBJCOPY > .export OBJDUMP > .export RANLIB > .export SIZE > .export STRINGS > .endif =3D=3D=3D Mark Millard markmi at dsl-only.net