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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Nick Desaulniers <ndesaulniers@google.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com,
	Kees Cook <keescook@chromium.org>,
	Fangrui Song <maskray@google.com>
Subject: Re: [PATCH 2/2] powerpc/vdso32: link vdso64 with linker
Date: Wed, 2 Sep 2020 10:16:35 +0000	[thread overview]
Message-ID: <dea7ef74-821f-0a1c-07dc-54e0c0d739aa@csgroup.eu> (raw)
In-Reply-To: <20200901222523.1941988-3-ndesaulniers@google.com>



On 9/1/20 10:25 PM, Nick Desaulniers wrote:
> Rather than invoke the compiler as the driver, use the linker. That way
> we can check --orphan-handling=warn support correctly, as cc-ldoption
> was removed in
> commit 055efab3120b ("kbuild: drop support for cc-ldoption").
> 
> Requires dropping the .got section.  I couldn't find how it was used in
> the vdso32.
> 
> Fixes: commit f2af201002a8 ("powerpc/build: vdso linker warning for orphan sections")
> Link: https://lore.kernel.org/lkml/CAKwvOdnn3wxYdJomvnveyD_njwRku3fABWT_bS92duihhywLJQ@mail.gmail.com/
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> Not sure removing .got is a good idea or not.  Otherwise I observe the
> following link error:
> powerpc-linux-gnu-ld: warning: orphan section `.got' from `arch/powerpc/kernel/vdso32/sigtramp.o' being placed in section `.got'
> powerpc-linux-gnu-ld: _GLOBAL_OFFSET_TABLE_ not defined in linker created .got
> powerpc-linux-gnu-ld: final link failed: bad value

Finally I spotted it I think:

	make arch/powerpc/kernel/vdso32/ V=1

powerpc64-linux-ld  -EB -m elf64ppc -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 -o 
arch/powerpc/kernel/vdso32/vdso32.so.dbg



If I do the same manually but with -m elf32ppc instead of -m elf64ppc, 
there is no failure.

Adding -m elf32ppc to ldflags-y also works, allthough I don't like too 
much having "-m elf64ppc -m elf32ppc" on the line.

Christophe

  parent reply	other threads:[~2020-09-02 10:17 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-01 22:25 [PATCH 0/2] link vdso with linker Nick Desaulniers
2020-09-01 22:25 ` [PATCH 1/2] powerpc/vdso64: link vdso64 " Nick Desaulniers
2020-09-02 12:14   ` Michael Ellerman
2020-09-02 17:41     ` Nick Desaulniers
2020-09-02 18:02       ` Christophe Leroy
2021-04-22 22:44         ` Nick Desaulniers
2021-04-23  7:40           ` Christophe Leroy
2021-04-23 17:18           ` Christophe Leroy
2022-03-02 16:48   ` Christophe Leroy
2020-09-01 22:25 ` [PATCH 2/2] powerpc/vdso32: " Nick Desaulniers
2020-09-02  2:58   ` Kees Cook
2020-09-02  6:46   ` Christophe Leroy
2020-09-02 14:14     ` Segher Boessenkool
2020-09-02 15:43       ` Christophe Leroy
2020-09-02 16:57         ` Segher Boessenkool
2020-09-02  7:56   ` Christophe Leroy
2020-09-02 10:16   ` Christophe Leroy [this message]
2020-09-02  5:21 ` [PATCH 0/2] link vdso " Nathan Chancellor

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