[PATCH] powerpc/vdso32: mark __kernel_datapage_offset as STV_PROTECTED

[Fangrui Song]

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 at 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