gdb/

	Fix libraries displacement if they change whether they were prelinked.
	* solib-svr4.c (LM_ADDR_CHECK): Set L_ADDR even if the DYNAMIC pointer
	does not match.  Comment why.

gdb/testsuite/
	* gdb.base/break-interp-lib.c (v, vptr): New variables.
	* gdb.base/break-interp.exp (test_attach): New comment.

5 files changed, 39 insertions, 5 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 9a862b1..2be27b5 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2011-04-17  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
+	Fix libraries displacement if they change whether they were prelinked.
+	* solib-svr4.c (LM_ADDR_CHECK): Set L_ADDR even if the DYNAMIC pointer
+	does not match.  Comment why.
+
+2011-04-17  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
 	* corelow.c: Include wrapper.h.
 	(core_open): Call now gdb_target_find_new_threads.
 	* wrapper.c: Include target.h.
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index 78c6b1c..b632dd0 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -237,11 +237,11 @@ LM_ADDR_CHECK (struct so_list *so, bfd *abfd)
 
 	     Even on PPC it must be zero-aligned at least for MINPAGESIZE.  */
 
+	  l_addr = l_dynaddr - dynaddr;
+
 	  if ((l_addr & (minpagesize - 1)) == 0
 	      && (l_addr & align) == ((l_dynaddr - dynaddr) & align))
 	    {
-	      l_addr = l_dynaddr - dynaddr;
-
 	      if (info_verbose)
 		printf_unfiltered (_("Using PIC (Position Independent Code) "
 				     "prelink displacement %s for \"%s\".\n"),
@@ -249,9 +249,20 @@ LM_ADDR_CHECK (struct so_list *so, bfd *abfd)
 				   so->so_name);
 	    }
 	  else
-	    warning (_(".dynamic section for \"%s\" "
-		       "is not at the expected address "
-		       "(wrong library or version mismatch?)"), so->so_name);
+	    {
+	      /* There is no way to verify the library file matches.  prelink
+		 can during prelinking of an unprelinked file (or unprelinking
+		 of a prelinked file) shift the DYNAMIC segment by arbitrary
+		 offset without any page size alignment.  There is no way to
+		 find out the ELF header and/or Program Headers for a limited
+		 verification if it they match.  One could do a verification
+		 of the DYNAMIC segment.  Still the found address is the best
+		 one GDB could find.  */
+
+	      warning (_(".dynamic section for \"%s\" "
+			 "is not at the expected address "
+			 "(wrong library or version mismatch?)"), so->so_name);
+	    }
 	}
 
     set_addr:
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 6a0d097..dc66c84 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2011-04-17  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
+	* gdb.base/break-interp-lib.c (v, vptr): New variables.
+	* gdb.base/break-interp.exp (test_attach): New comment.
+
+2011-04-17  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
 	* gdb.threads/gcore-thread.exp ($core0file): New variable.
 	(clear __stack_user.next, clear stack_used.next)
 	(save a zeroed-threads corefile): New test.
diff --git a/gdb/testsuite/gdb.base/break-interp-lib.c b/gdb/testsuite/gdb.base/break-interp-lib.c
index 50c5aad..aea27a6 100644
--- a/gdb/testsuite/gdb.base/break-interp-lib.c
+++ b/gdb/testsuite/gdb.base/break-interp-lib.c
@@ -20,6 +20,10 @@
 #include <assert.h>
 #include <stdio.h>
 
+/* Force REL->RELA conversion on i386, see "Prelink", March 4, 2004.  */
+volatile int v[2];
+volatile int *vptr = &v[1];
+
 void
 libfunc (const char *action)
 {
diff --git a/gdb/testsuite/gdb.base/break-interp.exp b/gdb/testsuite/gdb.base/break-interp.exp
index fe79cae..08a65cd 100644
--- a/gdb/testsuite/gdb.base/break-interp.exp
+++ b/gdb/testsuite/gdb.base/break-interp.exp
@@ -352,6 +352,14 @@ proc test_attach {file displacement {relink_args ""}} {
 	    # test simplicity, we merged this test and the test above by not
 	    # restoring $INTERP after $EXEC prelink.  $INTERP gets restored
 	    # later below.
+	    #
+	    # `(wrong library or version mismatch?)' messages are printed for
+	    # $binfile_lib on platforms converting REL->RELA relocations by
+	    # prelink (such as on i386).  There is no reliable way to verify
+	    # the library file matches the running library in such case but
+	    # GDB at least attempts to set the right displacement.  We test
+	    # `libfunc' is present in the backtrace and therefore the
+	    # displacement has been guessed right.
 
 	    if [prelink$relink $relink_args [file tail $exec]] {
 		# /proc/PID/exe cannot be loaded as it is "EXECNAME (deleted)".