x86-64, vdso: Fix vDSO build breakage due to empty .rela.dyn

jbeulich · H. Peter Anvin · commit 9f88b906b445 · 2014-07-10T15:59:56.000-07:00
Certain ld versions (observed with 2.20.0) put an empty .rela.dyn section into shared object files, breaking the assumption on the number of sections to be copied to the final output. Simply discard any empty SHT_REL and SHT_RELA sections to address this. Signed-off-by: Jan Beulich <jbeulich@suse.com> Link: http://lkml.kernel.org/r/53B5861E02000078000204D1@mail.emea.novell.com Acked-by: Andy Lutomirski <luto@amacapital.net> Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Tested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
@@ -93,6 +93,9 @@ static void BITSFUNC(copy_section)(struct BITSFUNC(fake_sections) *out,
 	uint64_t flags = GET_LE(&in->sh_flags);
 
 	bool copy = flags & SHF_ALLOC &&
+		(GET_LE(&in->sh_size) ||
+		 (GET_LE(&in->sh_type) != SHT_RELA &&
+		  GET_LE(&in->sh_type) != SHT_REL)) &&
 		strcmp(name, ".altinstructions") &&
 		strcmp(name, ".altinstr_replacement");
 
