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
WARNING: multiple messages have this Message-ID (diff)
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: Joe Lawrence <joe.lawrence@redhat.com>,
Kees Cook <keescook@chromium.org>,
Fangrui Song <maskray@google.com>,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org
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
next prev parent reply other threads:[~2020-09-02 10:17 UTC|newest]
Thread overview: 35+ 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 ` Nick Desaulniers
2020-09-01 22:25 ` [PATCH 1/2] powerpc/vdso64: link vdso64 " Nick Desaulniers
2020-09-01 22:25 ` Nick Desaulniers
2020-09-02 12:14 ` Michael Ellerman
2020-09-02 12:14 ` Michael Ellerman
2020-09-02 17:41 ` Nick Desaulniers
2020-09-02 17:41 ` Nick Desaulniers
2020-09-02 18:02 ` Christophe Leroy
2021-04-22 22:44 ` Nick Desaulniers
2021-04-22 22:44 ` Nick Desaulniers
2021-04-23 7:40 ` Christophe Leroy
2021-04-23 7:40 ` Christophe Leroy
2021-04-23 17:18 ` 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
2020-09-01 22:25 ` Nick Desaulniers
2020-09-02 2:58 ` Kees Cook
2020-09-02 2:58 ` Kees Cook
2020-09-02 6:46 ` Christophe Leroy
2020-09-02 6:46 ` Christophe Leroy
2020-09-02 14:14 ` Segher Boessenkool
2020-09-02 14:14 ` Segher Boessenkool
2020-09-02 15:43 ` Christophe Leroy
2020-09-02 15:43 ` Christophe Leroy
2020-09-02 16:57 ` Segher Boessenkool
2020-09-02 16:57 ` Segher Boessenkool
2020-09-02 7:56 ` Christophe Leroy
2020-09-02 7:56 ` Christophe Leroy
2020-09-02 10:16 ` Christophe Leroy [this message]
2020-09-02 10:16 ` Christophe Leroy
2020-09-02 5:21 ` [PATCH 0/2] link vdso " Nathan Chancellor
2020-09-02 5:21 ` Nathan Chancellor
2020-09-02 9:14 [PATCH 2/2] powerpc/vdso32: link vdso64 " kernel test robot
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