Broken cast in linux-thread-db

[Andreas Schwab]

Daniel Jacobowitz <drow@false.org> writes:

> Well presumably it honors POINTERS_EXTEND_UNSIGNED.

No.

http://gcc.gnu.org/onlinedocs/gcc/Arrays-and-pointers-implementation.html#Arrays-and-pointers-implementation

>> If notify.u.bptaddr has the high bit set it will be sign extended, but the
>> breakpoint address when the thread event breakpoint is hit will be zero
>> extended, so they don't match and the breakpoint is not recognized.
>
> Then this will break thread debugging on MIPS, where the breakpoint
> address will be sign extended.

Note that CORE_ADDR is always unsigned, even on MIPS.

> We'll only be in linux-thread-db.c if we have enough symbols to load
> shared libraries; maybe bfd_get_sign_extend_vma (exec_bfd) and assert
> that exec_bfd is provided?

Like this?

2005-10-12  Andreas Schwab  <schwab@suse.de>

	* Makefile.in (linux-thread-db.o): Depend on $(gdbcore_h).

	* linux-thread-db.c (enable_thread_event): Extend pointer value as
	specified by target.
	(thread_db_get_thread_local_address): Likewise.

Index: gdb/Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.755
diff -u -a -p -u -p -a -r1.755 gdb/Makefile.in
--- gdb/Makefile.in	28 Sep 2005 02:55:41 -0000	1.755
+++ gdb/Makefile.in	12 Oct 2005 15:11:48 -0000
@@ -2182,7 +2182,7 @@ linux-nat.o: linux-nat.c $(defs_h) $(inf
 linux-thread-db.o: linux-thread-db.c $(defs_h) $(gdb_assert_h) \
 	$(gdb_proc_service_h) $(gdb_thread_db_h) $(bfd_h) $(exceptions_h) \
 	$(gdbthread_h) $(inferior_h) $(symfile_h) $(objfiles_h) $(target_h) \
-	$(regcache_h) $(solib_svr4_h)
+	$(regcache_h) $(solib_svr4_h) $(gdbcore_h)
 lynx-nat.o: lynx-nat.c $(defs_h) $(frame_h) $(inferior_h) $(target_h) \
 	$(gdbcore_h) $(regcache_h)
 m2-exp.o: m2-exp.c $(defs_h) $(gdb_string_h) $(expression_h) $(language_h) \
--- gdb/linux-thread-db.c	12 Sep 2005 11:04:57 +0200	1.10
+++ gdb/linux-thread-db.c	12 Okt 2005 15:11:31 +0200	
@@ -36,6 +36,7 @@
 #include "target.h"
 #include "regcache.h"
 #include "solib-svr4.h"
+#include "gdbcore.h"
 
 #ifdef HAVE_GNU_LIBC_VERSION_H
 #include <gnu/libc-version.h>
@@ -505,9 +506,14 @@ enable_thread_event (td_thragent_t *thre
     return err;
 
   /* Set up the breakpoint.  */
-  (*bp) = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
-					      (CORE_ADDR) notify.u.bptaddr,
-					      &current_target);
+  gdb_assert (exec_bfd);
+  (*bp) = (gdbarch_convert_from_func_ptr_addr
+	   (current_gdbarch,
+	    /* Do proper sign extension for the target.  */
+	    (bfd_get_sign_extend_vma (exec_bfd) > 0
+	     ? (CORE_ADDR) (intptr_t) notify.u.bptaddr
+	     : (CORE_ADDR) (uintptr_t) notify.u.bptaddr),
+	    &current_target));
   create_thread_event_breakpoint ((*bp));
 
   return TD_OK;
@@ -1277,7 +1283,11 @@ thread_db_get_thread_local_address (ptid
                      (("%s")), thread_db_err_str (err));
 
       /* Cast assuming host == target.  Joy.  */
-      return (CORE_ADDR) address;
+      /* Do proper sign extension for the target.  */
+      gdb_assert (exec_bfd);
+      return (bfd_get_sign_extend_vma (exec_bfd) > 0
+	      ? (CORE_ADDR) (intptr_t) address
+	      : (CORE_ADDR) (uintptr_t) address);
     }
 
   if (target_beneath->to_get_thread_local_address)

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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