From: Fangrui Song <maskray@google.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Christophe Leroy <christophe.leroy@c-s.fr>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com,
Fangrui Song <maskray@google.com>
Subject: [PATCH] powerpc/vdso32: mark __kernel_datapage_offset as STV_PROTECTED
Date: Tue, 4 Feb 2020 16:50:54 -0800 [thread overview]
Message-ID: <20200205005054.k72fuikf6rwrgfe4@google.com> (raw)
A PC-relative relocation (R_PPC_REL16_LO in this case) referencing a
preemptible symbol in a -shared link is not allowed. GNU ld's powerpc
port is permissive and allows it [1], but lld will report an error after
https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id=ec0895f08f99515194e9fcfe1338becf6f759d38
Make the symbol protected so that it is non-preemptible but still
exported.
[1]: https://sourceware.org/bugzilla/show_bug.cgi?id=25500
Link: https://github.com/ClangBuiltLinux/linux/issues/851
Signed-off-by: Fangrui Song <maskray@google.com>
---
arch/powerpc/kernel/vdso32/datapage.S | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/vdso32/datapage.S b/arch/powerpc/kernel/vdso32/datapage.S
index 217bb630f8f9..2831a8676365 100644
--- a/arch/powerpc/kernel/vdso32/datapage.S
+++ b/arch/powerpc/kernel/vdso32/datapage.S
@@ -13,7 +13,8 @@
#include <asm/vdso_datapage.h>
.text
- .global __kernel_datapage_offset;
+ .global __kernel_datapage_offset
+ .protected __kernel_datapage_offset
__kernel_datapage_offset:
.long 0
--
2.25.0.341.g760bfbb309-goog
next reply other threads:[~2020-02-05 0:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-05 0:50 Fangrui Song [this message]
2020-02-05 6:25 ` Christophe Leroy
2020-02-07 6:42 ` Nathan Chancellor
2020-06-03 23:50 ` Nick Desaulniers
2020-02-10 11:01 ` Michael Ellerman
2020-02-10 18:41 ` Fāng-ruì Sòng
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