Re: make inferior calls work on ia64 even when syscall is pending

[David Mosberger <davidm@napali.hpl.hp.com>]

>>>>> On Thu, 1 Jan 2004 00:33:23 +0100 (CET), Mark Kettenis <kettenis@chello.nl> said:

  Mark>    From: David Mosberger <davidm@napali.hpl.hp.com> Date: Wed,
  Mark> 31 Dec 2003 12:19:20 -0800

  Mark>    If the gdb patch looks OK, please check it in.

  Mark> David, there are two issues with the patch:

  Mark> * I suspect that this approach is Linux-specific.  If so, you
  Mark> really shouldn't be adding this bit of code to the generic
  Mark> ia64_write_pc().  Instead you should create a Linux-specific
  Mark> ia64_linux_write_pc() and put it in ia64-linux-tdep.c; you'll
  Mark> probably want to call the generic ia64_write_pc() from there.
  Mark> Then you must hook in the Linux-specific version if the OSABI
  Mark> is GDB_OSABI_LINUX.

  Mark> * You should use write_register_pid() instead of
  Mark> write_register().

How about the attached patch?

	--david

ChangeLog

2004-02-12  David Mosberger  <davidm@hpl.hp.com>

	* ia64-tdep.c (ia64_linux_write_pc): Declare as extern.
	(ia64_write_pc): Make it a global function.
	(ia64_gdbarch_init): For Linux targets, use ia64_linux_write_pc()
	instead of ia64_write_pc().

	* ia64-linux-tdep.c (ia64_write_pc): Declare as extern.
	(ia64_linux_write_pc): New function.  Works like ia64_write_pc(),
	except that it also clears r10 afterwards to prevent the kernel
	from attempting to restart an interrupt system call.

Index: ia64-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/ia64-linux-tdep.c,v
retrieving revision 1.5
diff -u -r1.5 ia64-linux-tdep.c
--- ia64-linux-tdep.c	8 Jan 2004 16:46:27 -0000	1.5
+++ ia64-linux-tdep.c	13 Feb 2004 01:12:11 -0000
@@ -34,6 +34,8 @@
 /* Offset to sigcontext structure from frame of handler */
 #define IA64_LINUX_SIGCONTEXT_OFFSET 192
 
+extern void ia64_write_pc (CORE_ADDR, ptid_t);
+
 int
 ia64_linux_in_sigtramp (CORE_ADDR pc, char *func_name)
 {
@@ -92,4 +94,21 @@
       default :
 	return 0;
       }
+}
+
+void
+ia64_linux_write_pc (CORE_ADDR pc, ptid_t ptid)
+{
+  ia64_write_pc (pc, ptid);
+
+  /* We must be careful with modifying the instruction-pointer: if we
+     just interrupt a system call, the kernel would ordinarily try to
+     restart it when we resume the inferior, which typically results
+     in SIGSEGV or SIGILL.  We prevent this by clearing r10, which
+     will tell the kernel that r8 does NOT contain a valid error code
+     and hence it will skip system-call restart.
+
+     The clearing of r10 is safe as long as ia64_linux_write_pc() is only
+     called as part of setting up an inferior call.  */
+  write_register_pid (IA64_GR10_REGNUM, 0, ptid);
 }
Index: ia64-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/ia64-tdep.c,v
retrieving revision 1.112
diff -u -r1.112 ia64-tdep.c
--- ia64-tdep.c	10 Feb 2004 19:35:59 -0000	1.112
+++ ia64-tdep.c	13 Feb 2004 01:12:11 -0000
@@ -94,6 +94,7 @@
 extern CORE_ADDR ia64_linux_sigcontext_register_address (CORE_ADDR, int);
 extern CORE_ADDR ia64_aix_sigcontext_register_address (CORE_ADDR, int);
 extern unsigned long ia64_linux_getunwind_table (void *, size_t);
+extern void ia64_linux_write_pc (CORE_ADDR, ptid_t);
 
 static gdbarch_init_ftype ia64_gdbarch_init;
 
@@ -632,7 +633,7 @@
   return pc_value | (slot_num * SLOT_MULTIPLIER);
 }
 
-static void
+void
 ia64_write_pc (CORE_ADDR new_pc, ptid_t ptid)
 {
   int slot_num = (int) (new_pc & 0xf) / SLOT_MULTIPLIER;
@@ -3339,7 +3348,10 @@
   set_gdbarch_memory_remove_breakpoint (gdbarch, ia64_memory_remove_breakpoint);
   set_gdbarch_breakpoint_from_pc (gdbarch, ia64_breakpoint_from_pc);
   set_gdbarch_read_pc (gdbarch, ia64_read_pc);
-  set_gdbarch_write_pc (gdbarch, ia64_write_pc);
+  if (info.osabi == GDB_OSABI_LINUX)
+    set_gdbarch_write_pc (gdbarch, ia64_linux_write_pc);
+  else
+    set_gdbarch_write_pc (gdbarch, ia64_write_pc);
 
   /* Settings for calling functions in the inferior.  */
   set_gdbarch_push_dummy_call (gdbarch, ia64_push_dummy_call);