elf: Get the real kept section

When mixing linkonce and comdat sections, we need to keep searching to
get the real kept section.

bfd/

	PR ld/26936
	* elflink.c (_bfd_elf_check_kept_section): Get the real kept
	section.

ld/

	PR ld/26936
	* testsuite/ld-elf/pr26936.d: New file.
	* testsuite/ld-elf/pr26936a.s: Likewise.
	* testsuite/ld-elf/pr26936b.s: Likewise.
	* testsuite/ld-elf/pr26936c.s: Likewise.

7 files changed, 64 insertions, 4 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index d47d518..eeb0b81 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+2020-11-25  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/26936
+	* elflink.c (_bfd_elf_check_kept_section): Get the real kept
+	section.
+
 2020-11-23  Nick Clifton  <nickc@redhat.com>
 
 	PR 26931
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 7ba667a..0fbebca 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -10698,10 +10698,21 @@ _bfd_elf_check_kept_section (asection *sec, struct bfd_link_info *info)
     {
       if ((kept->flags & SEC_GROUP) != 0)
 	kept = match_group_member (sec, kept, info);
-      if (kept != NULL
-	  && ((sec->rawsize != 0 ? sec->rawsize : sec->size)
-	      != (kept->rawsize != 0 ? kept->rawsize : kept->size)))
-	kept = NULL;
+      if (kept != NULL)
+	{
+	  if ((sec->rawsize != 0 ? sec->rawsize : sec->size)
+	      != (kept->rawsize != 0 ? kept->rawsize : kept->size))
+	    kept = NULL;
+	  else
+	    {
+	      /* Get the real kept section.  */
+	      asection *next;
+	      for (next = kept->kept_section;
+		   next != NULL;
+		   next = next->kept_section)
+		kept = next;
+	    }
+	}
       sec->kept_section = kept;
     }
   return kept;
diff --git a/ld/ChangeLog b/ld/ChangeLog
index d7280ef..005d54e 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,11 @@
+2020-11-25  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/26936
+	* testsuite/ld-elf/pr26936.d: New file.
+	* testsuite/ld-elf/pr26936a.s: Likewise.
+	* testsuite/ld-elf/pr26936b.s: Likewise.
+	* testsuite/ld-elf/pr26936c.s: Likewise.
+
 2020-11-25  Alan Modra  <amodra@gmail.com>
 
 	* ldlang.c (lang_output_section_statement_lookup): Change "create"
diff --git a/ld/testsuite/ld-elf/pr26936.d b/ld/testsuite/ld-elf/pr26936.d
new file mode 100644
index 0000000..b007e83
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr26936.d
@@ -0,0 +1,12 @@
+#source: pr26936a.s
+#source: pr26936b.s
+#source: pr26936c.s
+#as: -g
+#ld: -z noseparate-code -Ttext-segment 0x10000 -z max-page-size=0x1000
+#readelf: -wL
+
+#...
+CU: .*/pr26936c.s:
+File name +Line number +Starting address +View +Stmt
+pr26936c.s +6 +0x10[0-9a-f][0-9a-f][0-9a-f] +x
+#pass
diff --git a/ld/testsuite/ld-elf/pr26936a.s b/ld/testsuite/ld-elf/pr26936a.s
new file mode 100644
index 0000000..24b90da
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr26936a.s
@@ -0,0 +1,6 @@
+	.section .gnu.linkonce.t.__x86.get_pc_thunk.bx,"ax",%progbits
+	.globl  __x86.get_pc_thunk.bx
+	.hidden __x86.get_pc_thunk.bx
+	.type   __x86.get_pc_thunk.bx, %function
+__x86.get_pc_thunk.bx:
+	.nop
diff --git a/ld/testsuite/ld-elf/pr26936b.s b/ld/testsuite/ld-elf/pr26936b.s
new file mode 100644
index 0000000..433528c
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr26936b.s
@@ -0,0 +1,11 @@
+	.text
+	.globl _start
+_start:
+	.type   _start, %function
+	.nop
+	.section .text.__x86.get_pc_thunk.bx,"axG",%progbits,__x86.get_pc_thunk.bx,comdat
+	.globl  __x86.get_pc_thunk.bx
+	.hidden __x86.get_pc_thunk.bx
+	.type   __x86.get_pc_thunk.bx, %function
+__x86.get_pc_thunk.bx:
+	.nop
diff --git a/ld/testsuite/ld-elf/pr26936c.s b/ld/testsuite/ld-elf/pr26936c.s
new file mode 100644
index 0000000..379cb71
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr26936c.s
@@ -0,0 +1,6 @@
+	.section .text.__x86.get_pc_thunk.bx,"axG",%progbits,__x86.get_pc_thunk.bx,comdat
+	.globl  __x86.get_pc_thunk.bx
+	.hidden __x86.get_pc_thunk.bx
+	.type   __x86.get_pc_thunk.bx, %function
+__x86.get_pc_thunk.bx:
+	.nop