Re: [PATCH 1/2] powerpc/vdso64: link vdso64 with linker

[Christophe Leroy]

Le 23/04/2021 à 00:44, Nick Desaulniers a écrit :
> On Wed, Sep 2, 2020 at 11:02 AM Christophe Leroy
> <christophe.leroy@xxxxxxxxxx> wrote:
> > Le 02/09/2020 à 19:41, Nick Desaulniers a écrit :
> > > On Wed, Sep 2, 2020 at 5:14 AM Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
> > > > Nick Desaulniers <ndesaulniers@xxxxxxxxxx> writes:
> > > > > Fixes: commit f2af201002a8 ("powerpc/build: vdso linker warning for orphan sections")
> > > >
> > > > I think I'll just revert that for v5.9 ?
> > >
> > > SGTM; you'll probably still want these changes with some modifications
> > > at some point; vdso32 did have at least one orphaned section, and will
> > > be important for hermetic builds.  Seeing crashes in supported
> > > versions of the tools ties our hands at the moment.
> >
> > Keeping the tool problem aside with binutils 2.26, do you have a way to
> > really link an elf32ppc object when  building vdso32 for PPC64 ?
>
> Sorry, I'm doing a bug scrub and found
> https://github.com/ClangBuiltLinux/linux/issues/774 still open (and my
> reply to this thread still in Drafts; never sent). With my patches
> rebased:
> $ file arch/powerpc/kernel/vdso32/vdso32.so
> arch/powerpc/kernel/vdso32/vdso32.so: ELF 32-bit MSB shared object,
> PowerPC or cisco 4500, version 1 (SYSV), dynamically linked, stripped
>
> Are you still using 2.26?

Yes, our production kernels and applications are built with gcc 5.5 and binutils 2.26

> I'm not able to repro Nathan's reported issue from
> https://lore.kernel.org/lkml/20200902052123.GA2687902@ubuntu-n2-xlarge-x86/,
> so I'm curious if I should resend the rebased patches as v2?

I can't remember what was all this discussion about.

I gave a try to your rebased patches.

Still an issue with binutils 2.26:

  VDSO32L arch/powerpc/kernel/vdso32/vdso32.so.dbg
ppc-linux-ld: warning: orphan section `.rela.got' from `arch/powerpc/kernel/vdso32/sigtramp.o' being 
placed in section `.rela.dyn'.
ppc-linux-ld: warning: orphan section `.rela.plt' from `arch/powerpc/kernel/vdso32/sigtramp.o' being 
placed in section `.rela.dyn'.
ppc-linux-ld: warning: orphan section `.glink' from `arch/powerpc/kernel/vdso32/sigtramp.o' being 
placed in section `.glink'.
ppc-linux-ld: warning: orphan section `.iplt' from `arch/powerpc/kernel/vdso32/sigtramp.o' being 
placed in section `.iplt'.
ppc-linux-ld: warning: orphan section `.rela.iplt' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.rela.dyn'.
ppc-linux-ld: warning: orphan section `.rela.text' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.rela.dyn'.
/bin/sh: line 1:  7850 Segmentation fault      (core dumped) ppc-linux-ld -EB -m elf32ppc -shared 
-soname linux-vdso32.so.1 --eh-frame-hdr --orphan-handling=warn -T 
arch/powerpc/kernel/vdso32/vdso32.lds arch/powerpc/kernel/vdso32/sigtramp.o 
arch/powerpc/kernel/vdso32/gettimeofday.o arch/powerpc/kernel/vdso32/datapage.o 
arch/powerpc/kernel/vdso32/cacheflush.o arch/powerpc/kernel/vdso32/note.o 
arch/powerpc/kernel/vdso32/getcpu.o arch/powerpc/kernel/vdso32/vgettimeofday.o -o 
arch/powerpc/kernel/vdso32/vdso32.so.dbg
make[2]: *** [arch/powerpc/kernel/vdso32/vdso32.so.dbg] Error 139
make[2]: *** Deleting file `arch/powerpc/kernel/vdso32/vdso32.so.dbg'



With gcc 10.1 and binutils 2.34 I get:

PPC32 build:

  VDSO32L arch/powerpc/kernel/vdso32/vdso32.so.dbg
powerpc64-linux-ld: warning: orphan section `.rela.got' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.plt' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.glink' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.glink'
powerpc64-linux-ld: warning: orphan section `.iplt' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.iplt'
powerpc64-linux-ld: warning: orphan section `.rela.iplt' from 
`arch/powerpc/kernel/vdso32/sigtramp.o' being placed in section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.branch_lt' from 
`arch/powerpc/kernel/vdso32/sigtramp.o' being placed in section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.text' from 
`arch/powerpc/kernel/vdso32/sigtramp.o' being placed in section `.rela.dyn'


PPC64 build:

  VDSO32L arch/powerpc/kernel/vdso32/vdso32.so.dbg
powerpc64-linux-ld: warning: orphan section `.rela.got' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.plt' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.glink' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.glink'
powerpc64-linux-ld: warning: orphan section `.iplt' from `arch/powerpc/kernel/vdso32/sigtramp.o' 
being placed in section `.iplt'
powerpc64-linux-ld: warning: orphan section `.rela.iplt' from 
`arch/powerpc/kernel/vdso32/sigtramp.o' being placed in section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.branch_lt' from 
`arch/powerpc/kernel/vdso32/sigtramp.o' being placed in section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.text' from 
`arch/powerpc/kernel/vdso32/sigtramp.o' being placed in section `.rela.dyn'
  VDSOSYM include/generated/vdso32-offsets.h
  VDSO64L arch/powerpc/kernel/vdso64/vdso64.so.dbg
powerpc64-linux-ld: warning: orphan section `.iplt' from `linker stubs' being placed in section `.iplt'
powerpc64-linux-ld: warning: orphan section `.rela.iplt' from `linker stubs' being placed in section 
`.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.branch_lt' from `linker stubs' being placed in 
section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.branch_lt' from `linker stubs' being placed in 
section `.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.plt' from `linker stubs' being placed in section `.plt'
powerpc64-linux-ld: warning: orphan section `.rela.plt' from `linker stubs' being placed in section 
`.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.got' from `linker stubs' being placed in section 
`.rela.dyn'
powerpc64-linux-ld: warning: orphan section `.rela.opd' from `linker stubs' being placed in section 
`.rela.dyn'


Christophe