m68k-linux: fix thread debugging

[Andreas Schwab <schwab@linux-m68k.org>]

2012-03-08  Andreas Schwab  <schwab@linux-m68k.org>

	* m68klinux-nat.c: Include "gdb_proc_service.h".
	(PTRACE_GET_THREAD_AREA): Define.
	(ps_get_thread_area): New function.

diff --git a/gdb/m68klinux-nat.c b/gdb/m68klinux-nat.c
index c7137c0..d4410e6 100644
--- a/gdb/m68klinux-nat.c
+++ b/gdb/m68klinux-nat.c
@@ -51,6 +51,13 @@
 
 /* Prototypes for supply_gregset etc.  */
 #include "gregset.h"
+
+/* Defines ps_err_e, struct ps_prochandle.  */
+#include "gdb_proc_service.h"
+
+#ifndef PTRACE_GET_THREAD_AREA
+#define PTRACE_GET_THREAD_AREA 25
+#endif
 \f
 /* This table must line up with gdbarch_register_name in "m68k-tdep.c".  */
 static const int regmap[] =
@@ -556,6 +563,24 @@ fetch_core_registers (struct regcache *regcache,
 }
 \f
 
+/* Fetch the thread-local storage pointer for libthread_db.  */
+
+ps_err_e
+ps_get_thread_area (const struct ps_prochandle *ph, 
+		    lwpid_t lwpid, int idx, void **base)
+{
+  if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) < 0)
+    return PS_ERR;
+
+  /* IDX is the bias from the thread pointer to the beginning of the
+     thread descriptor.  It has to be subtracted due to implementation
+     quirks in libthread_db.  */
+  *base = (char *) *base - idx;
+
+  return PS_OK;
+}
+\f
+
 /* Register that we are able to handle GNU/Linux ELF core file
    formats.  */
 
-- 
1.7.9.3


-- 
Andreas Schwab, schwab@linux-m68k.org
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