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Date:      Mon, 23 Sep 2019 14:14:43 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r352623 - in head/sys: amd64/amd64 kern
Message-ID:  <201909231414.x8NEEh9e040728@repo.freebsd.org>
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Author: markj
Date: Mon Sep 23 14:14:43 2019
New Revision: 352623
URL: https://svnweb.freebsd.org/changeset/base/352623

Log:
  Use elf_relocaddr() when handling R_X86_64_RELATIVE relocations.
  
  This is required for DPCPU and VNET data variable definitions to work when
  KLDs are linked as DSOs.  R_X86_64_RELATIVE relocations should not appear
  in object files, so assert this in elf_relocaddr().
  
  Reviewed by:	kib
  MFC after:	1 month
  Sponsored by:	Netflix
  Differential Revision:	https://reviews.freebsd.org/D21755

Modified:
  head/sys/amd64/amd64/elf_machdep.c
  head/sys/kern/link_elf.c

Modified: head/sys/amd64/amd64/elf_machdep.c
==============================================================================
--- head/sys/amd64/amd64/elf_machdep.c	Mon Sep 23 14:11:59 2019	(r352622)
+++ head/sys/amd64/amd64/elf_machdep.c	Mon Sep 23 14:14:43 2019	(r352623)
@@ -267,7 +267,6 @@ elf_reloc_internal(linker_file_t lf, Elf_Addr relocbas
 			 */
 			printf("kldload: unexpected R_COPY relocation\n");
 			return (-1);
-			break;
 
 		case R_X86_64_GLOB_DAT:	/* S */
 		case R_X86_64_JMP_SLOT:	/* XXX need addend + offset */
@@ -279,7 +278,7 @@ elf_reloc_internal(linker_file_t lf, Elf_Addr relocbas
 			break;
 
 		case R_X86_64_RELATIVE:	/* B + A */
-			addr = relocbase + addend;
+			addr = elf_relocaddr(lf, relocbase + addend);
 			val = addr;
 			if (*where != val)
 				*where = val;

Modified: head/sys/kern/link_elf.c
==============================================================================
--- head/sys/kern/link_elf.c	Mon Sep 23 14:11:59 2019	(r352622)
+++ head/sys/kern/link_elf.c	Mon Sep 23 14:14:43 2019	(r352623)
@@ -1162,6 +1162,9 @@ elf_relocaddr(linker_file_t lf, Elf_Addr x)
 {
 	elf_file_t ef;
 
+	KASSERT(lf->ops->cls == (kobj_class_t)&link_elf_class,
+	    ("elf_relocaddr: unexpected linker file %p", lf));
+
 	ef = (elf_file_t)lf;
 	if (x >= ef->pcpu_start && x < ef->pcpu_stop)
 		return ((x - ef->pcpu_start) + ef->pcpu_base);

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