Date: Sun, 8 Jan 2017 15:41:33 +0100 From: Roman Divacky <rdivacky@vlakno.cz> To: Mark Millard <markmi@dsl-only.net> Cc: FreeBSD Toolchain <freebsd-toolchain@freebsd.org>, Justin Hibbits <chmeeedalf@gmail.com>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org>, Ed Maste <emaste@freebsd.org>, Mark Linimon <linimon@lonesome.com> Subject: Re: clang 3.9.0 buildkernel on old powerpc64's vs. trying to build hwpmc_e500.o and the like. . . [Actually .__start code failure vs. working and R_PPC64_ADDR16_DS vs. R_PPC64_TOC16_DS] Message-ID: <20170108144133.GA19529@vlakno.cz> In-Reply-To: <A88C2D49-FAF2-4026-B9C1-A1D3C1E39287@dsl-only.net> References: <20161208221452.GA42380@vlakno.cz> <20161212210922.GA27403@vlakno.cz> <613BB28B-46F1-4959-B576-C8AD42A21200@dsl-only.net> <20170107085126.GA82107@vlakno.cz> <2B5FDD60-4D8B-4803-B59C-3C569BA36E68@dsl-only.net> <FB7F73D7-BF8F-4477-8057-1404D27622A8@dsl-only.net> <45C94BFE-4F93-4897-A767-518DACB5D28B@dsl-only.net> <20170108090307.GA3140@vlakno.cz> <1BBC8304-F9E8-4181-A287-11DD8E73B31F@dsl-only.net> <A88C2D49-FAF2-4026-B9C1-A1D3C1E39287@dsl-only.net>
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Mark,
Would you be interested in trying lld? It has some support for ppc/ppc64, w=
hich
is probably quite incomplete but it would be nice to know what exactly is
missing.
We also have some people (emaste@, davide@) that have non-trivial lld knowl=
edge
so perhaps progress can be achieved on this side easily?
Roman
On Sun, Jan 08, 2017 at 02:57:11AM -0800, Mark Millard wrote:
> [I forgot to indicate that I still can not use the system bootstrapped
> ld command and so there is a reason that I used devel/powerpc64-binutils.]
>=20
> On 2017-Jan-8, at 2:24 AM, Mark Millard <markmi at dsl-only.net> wrote:
>=20
> > On 2017-Jan-8, at 1:03 AM, Roman Divacky <rdivacky at vlakno.cz> wrote:
> >=20
> >> I think we should add the @toc notations to all the places where it's =
needed.
> >> Can you submit such a patch (perhaps with the one for adding 0 to the =
cmp
> >> instruction) so they can be committed to FreeBSD repo?
> >=20
> > In order to test I added @toc to each of the 10 instructions instead
> > of adjusting the macros so that instructions would automatically
> > get the notation but other (what are now) TOC_REF(...) usage would
> > not that should not.
> >=20
> > I suspect Nathan and Justin might prefer a more automatic
> > alternative so that TOC_REF(...) in an instruction would
> > be sufficient without an explicit @toc in the instruction.
> >=20
> > I'll see about switching to such code before providing a
> > patch. I'd include the "0, " update to the cmp instruction.
> >=20
> > But adding @toc's in those instructions (with prior workarounds
> > as well) did allow me to build a bootable system based on using
> > devel/powerpc64-binutils and clang 3.9.1 for both buildworld
> > and buildkernel --still using clang's internal assembler.
> >=20
> > One issue is that clang does not support (or need) the
> > -mminmal-toc in sys/modules/zfs/Makefile but gcc 4.2.1
> > requires it. For sys/modules/zfs/Makefile my source
> > currently does not support gcc 4.2.1 without editing.
> > As I remember devel/powerpc64-gcc
> > (devel/powerpc64-xtoolchain-gcc) does not require the
> > -mminimal-toc either. But devel/powerpc64-gcc does
> > allow -mminimal-toc so it can be a clang vs. gcc based
> > choice.
> >=20
> > I might also deal with that before providing patches.
> >=20
> > Note: -mlongcall was also not needed nor used for clang.
> > (Still used for gcc.)
> >=20
> > sys/boot/powerpc/kboot/Makefile has a -mcpu=3Dpowerpc64
> > and -Wa,-mppc64bridge that I eliminated (they messed up
> > 32-bit powerpc builds) but I've no way to test kboot that
> > I know of. This patch might be rejected.
> >=20
> > Remember that I got this far in part by using your partial
> > e500-instructions patch. I can provide my variant that
> > is a diff with -r311147 instead of an older place in the
> > history. But it would be incomplete coverage of those 2
> > instructions in clang.
> >=20
> > Also I build with a workaround for PowerMac G5 boot
> > reliability since OpenFirmware and FreeBSD interact
> > badly at times on PowerMac G5's. This I would not
> > provide as it is PowerMac G5 specific.
> >=20
> >> If gnu as warns and llvm assembler does the wrong thing without @toc a=
nd both
> >> do the correct thing with @toc I think it's an obvious decision.
> >=20
> > My choice would be to supply the @toc notation in some way,
> > not necessarily the form I used for the initial test.
> >=20
> >> Also, with all these changes. Does clang compiled kernel boot?
> >=20
> > The PowerMac G5 so-called "Quad Core" that I currently have access
> > to is now running from buildworld and buildkernel based on
> > devel/powerpc64-binutils and clang 3.9.1 :
> >=20
> > Copyright (c) 1992-2017 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 #2 r311147M: Sat Jan 7 16:55:01 PST 2017
> > markmi@FreeBSDx64:/usr/obj/powerpc64vtsc_clang_altbinutils_kernel/pow=
erpc.powerpc64/usr/src/sys/GENERIC64vtsc-NODBG powerpc
> > FreeBSD clang version 3.9.1 (tags/RELEASE_391/final 289601) (based on L=
LVM 3.9.1)
> > . . .
> >=20
> > # uname -apKU
> > FreeBSD FBSDG5L 12.0-CURRENT FreeBSD 12.0-CURRENT #2 r311147M: Sat Jan =
7 16:55:01 PST 2017 markmi@FreeBSDx64:/usr/obj/powerpc64vtsc_clang_alt=
binutils_kernel/powerpc.powerpc64/usr/src/sys/GENERIC64vtsc-NODBG powerpc =
powerpc64 1200019 1200019
> >=20
> > I've built about a dozen ports on it after booting but I've not
> > done a self-hosted buildworld buildkernel yet.
> >=20
> > [Note: Anything dependent on throwing C++ exceptions in
> > code generated by clang++ 3.9.1 is broken.]
>=20
> I should have been explicit:
>=20
> I still can not use the system bootstrapped ld command
> and such binutils for buildkernel and so there is a
> reason that I used devel/powerpc64-binutils instead.
>=20
> Thus even with my patches clang 3.9.1 would not be ready
> for general use or for a default way of building. I
> have to have a tailored SRC_ENV_CONF file or the like
> still --and a port built and installed.
>=20
> [On a powerpc64 system devel/binutils could be used.]
>=20
> There is also the issue with throwing C++ exceptions
> in code when clang 3.9.1 was the code generator used.
>=20
> =3D=3D=3D
> Mark Millard
> markmi at dsl-only.net
>=20
> On Sat, Jan 07, 2017 at 04:28:48PM -0800, Mark Millard wrote:
> > [Top post about FreeBSD bugzilla 215819 and llvm bugzilla
> > 31574 submittals for the issue involved.]
> >=20
> > My guess is that FreeBSD will view this as a kernel
> > source code issue and not as a toolchain issue. But
> > it is only a guess on my part.
> >=20
> >=20
> > I have submitted llvm bugzilla 31574 for this issue. It
> > includes example .S file content that shows the "problem"
> > in the generated .o file (form FreeBSD's view point).
> > (I've no clue how llvm views its criteria relative to this
> > mismatch with gcc/binutils.)
> >=20
> > Because FreeBSD source code changes (being explicit about
> > @toc) avoid the distinction between clang and gcc/binutils
> > I've not added 31574 to the Depends on list for llvm 25780
> > (the FreeBSD system compiler issues META entry in llvm).
> >=20
> > Someone with official status for FreeBSD could add 31574 to
> > llvm's 25780 if FreeBSD wants to push llvm to match
> > gcc/binutils for "@toc notation missing".
> >=20
> > Otherwise this is a kernel source code issue (as I would
> > guess) and not a toolchain issue.
> >=20
> > Ed Maste or someone like that likely would make the final
> > decision.
> >=20
> >=20
> > I've added to FreeBSD Bugzilla 215819 the new information,
> > including the simple example .S file content that shows the
> > problem in the generated .o file. (Comments #3 and #4
> > have the new material.)
> >=20
> > My guess is that FreeBSD Bugzilla 215819 should no longer
> > be assigned to freebsd-toolchain@FreeBSD.org . Instead it
> > would be a powerpc64 kernel source code issue if I'm right.
> >=20
> > Ed Maste or someone like that likely would make this final
> > decision as well.
> >=20
> > =3D=3D=3D
> > Mark Millard
> > markmi at dsl-only.net
> >=20
> > On 2017-Jan-7, at 3:12 PM, Mark Millard <markmi at dsl-only.net> wrote:
> >=20
> >> [I've supplied a list of places that adding @toc notation should
> >> make clang 3.9.1 targeting powerpc64 do the right thing for
> >> this issue.]
> >>=20
> >> On 2017-Jan-7, at 2:07 PM, Mark Millard <markmi at dsl-only.net> wrote:
> >>=20
> >>> On 2017-Jan-7, at 12:51 AM, Roman Divacky <rdivacky at vlakno.cz> wro=
te:
> >>>=20
> >>>> That's a great progress. Can you produce minimal self contained test=
case that
> >>>> exhibits this bug? And submit it to llvm bugzilla?
> >>>>=20
> >>>> Also, clang3.9 defaults to using it's own internal asm, what happens=
if you
> >>>> add -no-integrated-as to CFLAGS and recompile the kernel? That shoul=
d remove
> >>>> this llvm assembly problem. Does it boot?
> >>>>=20
> >>>> Thanks Mark, really great progress.
> >>>>=20
> >>>> Roman
> >>>=20
> >>> In attempting this I found how to control the behavior based on
> >>> the assembler notation @toc being missing vs. being present.
> >>>=20
> >>> If llvm should change is strongly tied to llvm's criteria for
> >>> gcc compatibility relative to filling-in/defaulting omitted
> >>> @toc's in the assembler notation.
> >>>=20
> >>> FreeBSD has the option of always being explicit with @toc in order
> >>> to avoid differences in handling of omitted notation.
> >>>=20
> >>> So I've no clue if FreebSD wants to claim that a llvm change
> >>> is a requirement for using clang as the powerpc64 system compiler.
> >>>=20
> >>> [The issue of the distinction is submittable to llvm either way.]
> >>>=20
> >>> Details. . .
> >>>=20
> >>> For:
> >>>=20
> >>> .section ".toc","aw"
> >>> tmpstk.L: .tc tmpstk[TC],tmpstk
> >>> . . .
> >>> /* Set up the stack pointer */
> >>> ld %r1,tmpstk.L(%r2)
> >>>=20
> >>> using devel/powerpc64-gcc gets:
> >>>=20
> >>> # /usr/local/bin/powerpc64-unknown-freebsd12.0-gcc \ =
=
=
-c \ =
=
=
=
-x assembler-with-cpp \ =
=
=
=
-pipe \ =
=
=20
>=20
> >=20
> >>=20
> >>> =
locore64_simplified.S
> >>> locore64_simplified.S: Assembler messages:
> >>> locore64_simplified.S:80: Warning: assuming @toc on symbol
> >>>=20
> >>> and produces (with R_PPC64_TOC16_DS for .toc):
> >>>=20
> >>> # /usr/local/powerpc64-freebsd/bin/objdump -r locore64_simplified.o
> >>>=20
> >>> locore64_simplified.o: file format elf64-powerpc-freebsd
> >>>=20
> >>> RELOCATION RECORDS FOR [.text]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000028 R_PPC64_REL64 __tocbase+0x0000000000008000
> >>> 0000000000000046 R_PPC64_TOC16_DS .toc
> >>>=20
> >>>=20
> >>> RELOCATION RECORDS FOR [.toc]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000000 R_PPC64_ADDR64 tmpstk
> >>>=20
> >>>=20
> >>> RELOCATION RECORDS FOR [.opd]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000000 R_PPC64_ADDR64 .__start
> >>> 0000000000000008 R_PPC64_TOC *ABS*
> >>>=20
> >>>=20
> >>> By contrast clang is silent (cross compiler used):
> >>>=20
> >>> # /usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp/u=
sr/bin/cc \ =
=
-target powerpc64-unk=
nown-freebsd12.0 \ =
=
=
--sysroot=3D/usr/obj/powerpc64vtsc_clang_kernel/=
powerpc.powerpc64/usr/src/tmp \ =
=
=
-B/usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp/usr/b=
in \ =
=20
>=20
> >=20
> >>=20
> >>> =
-c \ =
=
=
-x as=
sembler-with-cpp \ =
=
=
-pipe \ =
=
=
=
locore64_simplified.S
> >>>=20
> >>> and produces code with R_PPC64_ADDR16_DS for the .toc instead:
> >>>=20
> >>> # /usr/local/powerpc64-freebsd/bin/objdump -r locore64_simplified.o |=
more =
=
=20
> >>> locore64_simplified.o: file format elf64-powerpc-freebsd
> >>>=20
> >>> RELOCATION RECORDS FOR [.text]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000028 R_PPC64_REL64 __tocbase+0x0000000000008000
> >>> 0000000000000046 R_PPC64_ADDR16_DS .toc
> >>>=20
> >>>=20
> >>> RELOCATION RECORDS FOR [.toc]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000000 R_PPC64_ADDR64 tmpstk
> >>>=20
> >>>=20
> >>> RELOCATION RECORDS FOR [.opd]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000000 R_PPC64_ADDR64 .__start
> >>> 0000000000000008 R_PPC64_TOC *ABS*
> >>>=20
> >>>=20
> >>>=20
> >>> But for:
> >>>=20
> >>> .section ".toc","aw"
> >>> tmpstk.L: .tc tmpstk[TC],tmpstk
> >>> . . .
> >>> /* Set up the stack pointer */
> >>> ld %r1,tmpstk.L@toc(%r2)
> >>>=20
> >>> (note the @toc notation) both compilers agree and use
> >>> R_PPC64_TOC16_DS for the .toc:
> >>>=20
> >>> # /usr/local/bin/powerpc64-unknown-freebsd12.0-gcc \ =
=
=
-c \ =
=
=
=
-x assembler-with-cpp \ =
=
=
=
-pipe \ =
=
=20
>=20
> >=20
> >>=20
> >>> =
locore64_simplified.S
> >>>=20
> >>> # /usr/local/powerpc64-freebsd/bin/objdump -r locore64_simplified.o |=
more =
=
=20
> >>> locore64_simplified.o: file format elf64-powerpc-freebsd
> >>>=20
> >>> RELOCATION RECORDS FOR [.text]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000028 R_PPC64_REL64 __tocbase+0x0000000000008000
> >>> 0000000000000046 R_PPC64_TOC16_DS .toc
> >>>=20
> >>>=20
> >>> RELOCATION RECORDS FOR [.toc]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000000 R_PPC64_ADDR64 tmpstk
> >>>=20
> >>>=20
> >>> RELOCATION RECORDS FOR [.opd]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000000 R_PPC64_ADDR64 .__start
> >>> 0000000000000008 R_PPC64_TOC *ABS*
> >>>=20
> >>>=20
> >>> # /usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp/u=
sr/bin/cc \ =
=
-target powerpc64-unk=
nown-freebsd12.0 \ =
=
=
--sysroot=3D/usr/obj/powerpc64vtsc_clang_kernel/=
powerpc.powerpc64/usr/src/tmp \ =
=
=
-B/usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp/usr/b=
in \ =
=20
>=20
> >=20
> >>=20
> >>> =
-c \ =
=
=
-x as=
sembler-with-cpp \ =
=
=
-pipe \ =
=
=
=
locore64_simplified.S
> >>>=20
> >>> # /usr/local/powerpc64-freebsd/bin/objdump -r locore64_simplified.o |=
more =
=
=20
> >>> locore64_simplified.o: file format elf64-powerpc-freebsd
> >>>=20
> >>> RELOCATION RECORDS FOR [.text]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000028 R_PPC64_REL64 __tocbase+0x0000000000008000
> >>> 0000000000000046 R_PPC64_TOC16_DS .toc
> >>>=20
> >>>=20
> >>> RELOCATION RECORDS FOR [.toc]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000000 R_PPC64_ADDR64 tmpstk
> >>>=20
> >>>=20
> >>> RELOCATION RECORDS FOR [.opd]:
> >>> OFFSET TYPE VALUE=20
> >>> 0000000000000000 R_PPC64_ADDR64 .__start
> >>> 0000000000000008 R_PPC64_TOC *ABS*
> >>>=20
> >>>=20
> >>>=20
> >>> I omitted "-f -gdwarf-2" to simplify things but with such
> >>> clang complains about:
> >>>=20
> >>> locore64_simplified.S:36:2: warning: DWARF2 only supports one section=
per compilation unit
> >>> .section ".toc","aw"
> >>> ^
> >>> locore64_simplified.S:47:2: warning: DWARF2 only supports one section=
per compilation unit
> >>> .section ".opd","aw"
> >>> ^
> >>>=20
> >>> (buildkernel gets such messages.)
> >>>=20
> >>>=20
> >>> I expect I can simplify the .S code more than I have so far but
> >>> I figured I'd report the discovery of the choice FreeBSD needs
> >>> to make for powerpc64 for if llvm changes are to be required
> >>> vs. not.
> >>=20
> >> The following should be a list of the places that adding @toc usage
> >> would fix some things for using clang 3.9.1 to target powerpc64:
> >>=20
> >> # grep "@toc[^b]" /root/sys_typescripts/typescript_make_powerpc64vtsc_=
nodebug_incl_clang_xtoolchain_kernel-amd64-host-2017-01-03:23:48:41 | more
> >> /usr/src/sys/powerpc/aim/locore64.S:102: Warning: assuming @toc on sym=
bol
> >> /usr/src/sys/powerpc/aim/trap_subr64.S:320: Warning: assuming @toc on =
symbol
> >> /usr/src/sys/powerpc/aim/trap_subr64.S:797: Warning: assuming @toc on =
symbol
> >> /usr/src/sys/powerpc/ofw/ofwcall64.S:104: Warning: assuming @toc on sy=
mbol
> >> /usr/src/sys/powerpc/ofw/ofwcall64.S:108: Warning: assuming @toc on sy=
mbol
> >> /usr/src/sys/powerpc/ofw/ofwcall64.S:116: Warning: assuming @toc on sy=
mbol
> >> /usr/src/sys/powerpc/ofw/ofwcall64.S:226: Warning: assuming @toc on sy=
mbol
> >> /usr/src/sys/powerpc/ofw/ofwcall64.S:228: Warning: assuming @toc on sy=
mbol
> >> /usr/src/sys/powerpc/ofw/ofwcall64.S:235: Warning: assuming @toc on sy=
mbol
> >> /usr/src/sys/powerpc/powerpc/swtch64.S:153: Warning: assuming @toc on =
symbol
> >>=20
> >> devel/powerpc64-gcc and devel/powerpc64-binutils together happens to r=
eport
> >> on missing @toc 's.
> >>=20
> >> But, of course, if some sections of code are conditionally compiled and
> >> excluded above they would not be listed.
> >>=20
> >> =3D=3D=3D
> >> Mark Millard
> >> markmi at dsl-only.net
> >=20
> > _______________________________________________
> > freebsd-toolchain@freebsd.org mailing list
> > https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain
> > To unsubscribe, send any mail to "freebsd-toolchain-unsubscribe@freebsd=
=2Eorg"
>=20
> _______________________________________________
> freebsd-toolchain@freebsd.org mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain
> To unsubscribe, send any mail to "freebsd-toolchain-unsubscribe@freebsd.o=
rg"
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