From cadaf1336332ca7bcdfe4a400776e5782a20e26d Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 28 Oct 2015 07:49:44 -0700
Subject: [PATCH] Keep only ELF_RTYPE_CLASS_{PLT|COPY} bits for prelink

prelink runs ld.so with the environment variable LD_TRACE_PRELINKING
set to dump the relocation type class from _dl_debug_bindings.  prelink
has the following relocation type classes:

 #define RTYPE_CLASS_VALID       8
 #define RTYPE_CLASS_PLT         (8|1)
 #define RTYPE_CLASS_COPY        (8|2)
 #define RTYPE_CLASS_TLS         (8|4)

where ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA has a conflict with
RTYPE_CLASS_TLS.

Since prelink only uses ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY
bits, we should clear the other bits when the DL_DEBUG_PRELINK bit is
set.

	[BZ #19178]
	* elf/dl-lookup.c (RTYPE_CLASS_VALID): New.
	(RTYPE_CLASS_PLT): Likewise.
	(RTYPE_CLASS_COPY): Likewise.
	(RTYPE_CLASS_TLS): Likewise.
	(_dl_debug_bindings): Use RTYPE_CLASS_TLS and RTYPE_CLASS_VALID
	to set relocation type class for DL_DEBUG_PRELINK.  Keep only
	ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY bits for
	DL_DEBUG_PRELINK.

Upstream-Status: submitted (https://sourceware.org/bugzilla/show_bug.cgi?id=19178)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
---
 elf/dl-lookup.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 581fb20..6ae6cc3 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -1016,6 +1016,18 @@ _dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
 #ifdef SHARED
   if (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK)
     {
+/* ELF_RTYPE_CLASS_XXX must match RTYPE_CLASS_XXX used by prelink with
+   LD_TRACE_PRELINKING.  */
+#define RTYPE_CLASS_VALID	8
+#define RTYPE_CLASS_PLT		(8|1)
+#define RTYPE_CLASS_COPY	(8|2)
+#define RTYPE_CLASS_TLS		(8|4)
+#if ELF_RTYPE_CLASS_PLT != 0 && ELF_RTYPE_CLASS_PLT != 1
+# error ELF_RTYPE_CLASS_PLT must be 0 or 1!
+#endif
+#if ELF_RTYPE_CLASS_COPY != 0 && ELF_RTYPE_CLASS_COPY != 2
+# error ELF_RTYPE_CLASS_COPY must be 0 or 2!
+#endif
       int conflict = 0;
       struct sym_val val = { NULL, NULL };
 
@@ -1071,12 +1083,17 @@ _dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
 
       if (value->s)
 	{
+	  /* Keep only ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY
+	     bits since since prelink only uses them.  */
+	  type_class &= ELF_RTYPE_CLASS_PLT | ELF_RTYPE_CLASS_COPY;
 	  if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info)
 				== STT_TLS))
-	    type_class = 4;
+	    /* Clear the RTYPE_CLASS_VALID bit in RTYPE_CLASS_TLS.  */
+	    type_class = RTYPE_CLASS_TLS & ~RTYPE_CLASS_VALID;
 	  else if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info)
 				     == STT_GNU_IFUNC))
-	    type_class |= 8;
+	    /* Set the RTYPE_CLASS_VALID bit.  */
+	    type_class |= RTYPE_CLASS_VALID;
 	}
 
       if (conflict
-- 
1.9.3