[RFC] problem in solib-svr4/enable_break

[Michael Snyder <msnyder@vmware.com>]

[-- Attachment #1: Type: text/plain, Size: 933 bytes --]

The attached patch isn't for submission, but just to help
illustrate the problem.  It fixes a symptom but seems kludgy
to me (and not well understood).

Here's the problem.  I have a kernel image which is statically
linked and PIE.  When it gets to enable_break, it succeeds in
finding "debug_base", but "debug_base" is in the text section
of the main executable (ie. not in the dynamic loader, which is
not actually present).

Therefore we compute info->interp_text_sect_low and
info->interp_text_sect_high as the start and end of the text
section of the main executable.  And therefore whenever we
call in_solib_dynsym_resolve_code(), it returns TRUE, and
therefore source level stepping won't work.


This simple patch just checks to see whether "tmp_bfd" (which
is supposed to be the dynamic loader) matches exec_bfd, and
if so, lets interp_text_sect_low and interp_text_sect_high
remain zero.

Anybody got a better suggestion?


[-- Attachment #2: svr4.txt --]
[-- Type: text/plain, Size: 706 bytes --]

Index: solib-svr4.c
===================================================================
RCS file: /cvs/src/src/gdb/solib-svr4.c,v
retrieving revision 1.110
diff -u -p -r1.110 solib-svr4.c
--- solib-svr4.c	8 Jan 2010 22:52:03 -0000	1.110
+++ solib-svr4.c	14 Jan 2010 21:57:37 -0000
@@ -1312,7 +1312,10 @@ enable_break (struct svr4_info *info, in
 				os->objfile->sect_index_text);
 
 	  interp_sect = bfd_get_section_by_name (tmp_bfd, ".text");
-	  if (interp_sect)
+
+	  /* Skip if tmp_bfd points to main executable.  */
+	  if (interp_sect
+	      && strcmp (tmp_bfd->filename, exec_bfd->filename) != 0)
 	    {
 	      info->interp_text_sect_low =
 		bfd_section_vma (tmp_bfd, interp_sect) + load_addr;