Re: RFA: ia64 portion of libunwind patch

["J. Johnston" <jjohnstn at redhat dot com>]

I have chosen the first option to implement the syscall.  I have included a 
patch here regarding this mechanism.

Ok to commit?

-- Jeff J.

2003-11-04  Jeff Johnston  <jjohnstn@redhat.com>

	* config/ia64/nm-linux.h (CHILD_TO_XFER_PARTIAL): New macro to set up   		the 
ia64 linux native target to_xfer_partial method.
	(ia64_linux_xfer_partial): New prototype.
	* ia64-linux-nat.c (ia64_linux_xfer_partial): New function.
	* inftarg.c (init_child_ops)[CHILD_TO_XFER_PARTIAL]: Set up xfer partial 
method if one provided via macro.
	* target.c (init_dummy_target): Initialize to_xfer_partial to default.
	* target.h (target_object): Add new TARGET_OBJECT_UNWIND_TABLE enum.


Andrew Cagney wrote:
> > Nothing which involves a syscall is acceptable in a tdep file.  That's
> > what the t means - target support.
>
>
> ("tdep" mysteriously means "architecture vector support".  That "t" 
> really no longer makes sense :-()
>
> Yes, architecture vector shouldn't be directly making syscalls.  Instead 
> the architecture specific code should use the target vector to obtain 
> this system information.  Here I think the best option is to add another 
> TARGET_OBJECT_xxxx variant and then use the target_read() method to pull 
> in the data.
>
> As for the native target side, ia64-linux-nat should export something 
> like ia64_linux_child_read_partial that performs the syscall.  The 
> tricky [er messy] part is wiring it into child_ops, I see there are lots 
> of choices :-(
>
> - define a nm-*.c macro and have that enable the assignment (ex #define 
> NATIVE_TO_READ_PARTIAL ia64_linux_child?) (ref KILL_INFERIOR)
>
> - have a callback set the to_read_partial method in child_ops 
> (exec_set_find_memory_regions)
>
> - modify all the targets so that each implements the new method
>
> - others?
>
> Is this information available via /proc?  In a core file?
>
> Andrew
>
> PS: Note this pending patch.  Dependant on the timing you or I may need 
> to tweak the name.
> http://sources.redhat.com/ml/gdb-patches/2003-10/msg00795.html
Index: config/ia64/nm-linux.h
===================================================================
RCS file: /cvs/src/src/gdb/config/ia64/nm-linux.h,v
retrieving revision 1.10
diff -u -r1.10 nm-linux.h
--- config/ia64/nm-linux.h	20 Jun 2003 13:57:29 -0000	1.10
+++ config/ia64/nm-linux.h	4 Nov 2003 16:53:37 -0000
@@ -69,4 +69,13 @@
 extern int ia64_linux_remove_watchpoint (ptid_t ptid, CORE_ADDR addr,
                                          int len);
 
+#include "target.h"
+
+#define CHILD_TO_XFER_PARTIAL ia64_linux_xfer_partial
+extern LONGEST ia64_linux_xfer_partial (struct target_ops *ops, 
+					enum target_object object,
+					const char *annex, const void *writebuf,
+					void *readbuf,
+					ULONGEST offset, LONGEST len);
+
 #endif /* #ifndef NM_LINUX_H */
Index: ia64-linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/ia64-linux-nat.c,v
retrieving revision 1.20
diff -u -r1.20 ia64-linux-nat.c
--- ia64-linux-nat.c	2 Oct 2003 20:28:29 -0000	1.20
+++ ia64-linux-nat.c	4 Nov 2003 16:53:37 -0000
@@ -34,6 +34,7 @@
 #ifdef HAVE_SYS_REG_H
 #include <sys/reg.h>
 #endif
+#include <sys/syscall.h>
 #include <sys/user.h>
 
 #include <asm/ptrace_offsets.h>
@@ -644,4 +645,48 @@
   write_register_pid (IA64_PSR_REGNUM, psr, ptid);
 
   return (CORE_ADDR) siginfo.si_addr;
+}
+
+LONGEST 
+ia64_linux_xfer_partial (struct target_ops *ops,
+			 enum target_object object,
+			 const char *annex, const void *writebuf,
+			 void *readbuf,
+			 ULONGEST offset, LONGEST len)
+{
+  switch (object)
+    {
+    case TARGET_OBJECT_UNWIND_TABLE:
+      return syscall (__NR_getunwind, readbuf, len);
+    case TARGET_OBJECT_MEMORY:
+      if (ops->to_xfer_memory != NULL)
+	/* Fall back to the target's "to_xfer_memory" method.  */
+	{
+	  int xfered = -1;
+	  errno = 0;
+	  if (writebuf != NULL)
+	    {
+	      void *buffer = xmalloc (len);
+	      struct cleanup *cleanup = make_cleanup (xfree, buffer);
+	      memcpy (buffer, writebuf, len);
+	      xfered = ops->to_xfer_memory (offset, buffer, len, 1/*write*/, NULL,
+					    ops);
+	      do_cleanups (cleanup);
+	    }
+	  if (readbuf != NULL)
+	    xfered = ops->to_xfer_memory (offset, readbuf, len, 0/*read*/, NULL,
+					  ops);
+	  
+	  if (xfered > 0)
+	    return xfered;
+	  else if (xfered == 0 && errno == 0)
+	    /* "to_xfer_memory" uses 0, cross checked against ERRNO as one
+	       indication of an error.  */
+	    return 0;
+	  else
+	    return -1;
+	}
+    default:
+      return -1;
+    }
 }
Index: inftarg.c
===================================================================
RCS file: /cvs/src/src/gdb/inftarg.c,v
retrieving revision 1.18
diff -u -r1.18 inftarg.c
--- inftarg.c	21 Sep 2003 01:26:45 -0000	1.18
+++ inftarg.c	4 Nov 2003 16:53:37 -0000
@@ -609,6 +609,9 @@
   child_ops.to_get_current_exception_event = child_get_current_exception_event;
   child_ops.to_pid_to_exec_file = child_pid_to_exec_file;
   child_ops.to_stratum = process_stratum;
+#ifdef CHILD_TO_XFER_PARTIAL
+  child_ops.to_xfer_partial = CHILD_TO_XFER_PARTIAL;
+#endif
   child_ops.to_has_all_memory = 1;
   child_ops.to_has_memory = 1;
   child_ops.to_has_stack = 1;
Index: target.c
===================================================================
RCS file: /cvs/src/src/gdb/target.c,v
retrieving revision 1.64
diff -u -r1.64 target.c
--- target.c	31 Oct 2003 15:25:34 -0000	1.64
+++ target.c	4 Nov 2003 16:53:38 -0000
@@ -1644,6 +1644,7 @@
   dummy_target.to_stratum = dummy_stratum;
   dummy_target.to_find_memory_regions = dummy_find_memory_regions;
   dummy_target.to_make_corefile_notes = dummy_make_corefile_notes;
+  dummy_target.to_xfer_partial = default_xfer_partial;
   dummy_target.to_magic = OPS_MAGIC;
 }
 
Index: target.h
===================================================================
RCS file: /cvs/src/src/gdb/target.h,v
retrieving revision 1.51
diff -u -r1.51 target.h
--- target.h	31 Oct 2003 19:19:51 -0000	1.51
+++ target.h	4 Nov 2003 16:53:38 -0000
@@ -223,8 +223,10 @@
   /* AVR target specific transfer.  See "avr-tdep.c" and "remote.c".  */
   TARGET_OBJECT_AVR,
   /* Transfer up-to LEN bytes of memory starting at OFFSET.  */
-  TARGET_OBJECT_MEMORY
-  /* Possible future ojbects: TARGET_OJBECT_FILE, TARGET_OBJECT_PROC,
+  TARGET_OBJECT_MEMORY,
+  /* Kernel Unwind Table.  See "ia64-tdep.c".  */
+  TARGET_OBJECT_UNWIND_TABLE,
+  /* Possible future objects: TARGET_OBJECT_FILE, TARGET_OBJECT_PROC,
      TARGET_OBJECT_AUXV, ...  */
 };