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

[Kevin Buettner <kevinb@redhat.com>]

On Fri, 13 Feb 2004 14:06:54 -0800
David Mosberger <davidm@napali.hpl.hp.com> wrote:

> 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.

I've committed the above via the following patch.  Please let me know
if I've missed anything.

	* ia64-tdep.h (ia64_write_pc, ia64_linux_write_pc): Declare.
	* ia64-tdep.c (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 (regcache.h): Include.
	(ia64_linux_write_pc): New function.

Index: ia64-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/ia64-linux-tdep.c,v
retrieving revision 1.6
diff -u -p -r1.6 ia64-linux-tdep.c
--- ia64-linux-tdep.c	17 Feb 2004 16:23:23 -0000	1.6
+++ ia64-linux-tdep.c	23 Feb 2004 21:06:43 -0000
@@ -23,6 +23,7 @@
 #include "ia64-tdep.h"
 #include "arch-utils.h"
 #include "gdbcore.h"
+#include "regcache.h"
 
 /* The sigtramp code is in a non-readable (executable-only) region
    of memory called the ``gate page''.  The addresses in question
@@ -93,4 +94,21 @@ ia64_linux_sigcontext_register_address (
       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_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 1.116
diff -u -p -r1.116 ia64-tdep.c
--- ia64-tdep.c	17 Feb 2004 16:23:23 -0000	1.116
+++ ia64-tdep.c	23 Feb 2004 21:06:44 -0000
@@ -628,7 +628,7 @@ ia64_read_pc (ptid_t ptid)
   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;
@@ -3338,7 +3338,10 @@ ia64_gdbarch_init (struct gdbarch_info i
   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);
Index: ia64-tdep.h
===================================================================
RCS file: /cvs/src/src/gdb/ia64-tdep.h,v
retrieving revision 1.1
diff -u -p -r1.1 ia64-tdep.h
--- ia64-tdep.h	17 Feb 2004 16:23:23 -0000	1.1
+++ ia64-tdep.h	23 Feb 2004 21:06:44 -0000
@@ -25,5 +25,7 @@
 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_write_pc (CORE_ADDR, ptid_t);
+extern void ia64_linux_write_pc (CORE_ADDR, ptid_t);
 
 #endif /* IA64_TDEP_H */