Added kernel_pointer()/set_kernel_pointer() tapset functions.

* tapset/conversions.stp (kernel_pointer): New function.
* tapset/conversions-guru.stp (set_kernel_pointer): Ditto.
* testsuite/buildok/conversions-embedded.stp: Added kernel_pointer() test.
* testsuite/buildok/conversions.stp: Ditto.
* testsuite/buildok/set_kernel.stp: Added set_kernel_pointer() test.
* tapset/nfs.stp: Removed __d_loff_t() function.  Uses new
  kernel_pointer() function instead.
* testsuite/buildok/nfs-embedded.stp: Removed __d_loff_t() test.

3 files changed, 38 insertions, 12 deletions

diff --git a/tapset/conversions-guru.stp b/tapset/conversions-guru.stp
index f914bb31..9d662ce3 100644
--- a/tapset/conversions-guru.stp
+++ b/tapset/conversions-guru.stp
@@ -115,3 +115,21 @@ deref_fault: /* branched to from kwrite() */
     CONTEXT->last_error = CONTEXT->error_buffer;
   }
 %}
+
+/**
+ * sfunction set_kernel_pointer - Writes a pointer value to kernel memory.
+ * @addr: The kernel address to write the pointer to.
+ * @val: The pointer which is to be written.
+ *
+ * Description: Writes the pointer value to a given kernel memory address.
+ * Reports an error when writing to the given address fails.
+ */
+function set_kernel_pointer (addr:long, val:long) %{ /* guru */
+  kwrite((void **) (intptr_t) THIS->addr, THIS->val);
+  if (0) {
+deref_fault: /* branched to from kwrite() */
+    snprintf (CONTEXT->error_buffer, sizeof(CONTEXT->error_buffer),
+        "kernel pointer copy fault at 0x%p", (void *) (uintptr_t) THIS->addr);
+    CONTEXT->last_error = CONTEXT->error_buffer;
+  }
+%}
diff --git a/tapset/conversions.stp b/tapset/conversions.stp
index 3bbbb725..fbaba6e4 100644
--- a/tapset/conversions.stp
+++ b/tapset/conversions.stp
@@ -1,5 +1,5 @@
 // conversions tapset
-// Copyright (C) 2005-2009 Red Hat Inc.
+// Copyright (C) 2005-2010 Red Hat Inc.
 // Copyright (C) 2007 Intel Corporation.
 //
 // This file is part of systemtap, and is free software.  You can
@@ -113,6 +113,24 @@ deref_fault: /* branched to from kread() */
   }
 %}
 
+/**
+ * sfunction kernel_pointer - Retrieves a pointer value stored in
+ * kernel memory.
+ * @addr: The kernel address to retrieve the pointer from.
+ *
+ * Description: Returns the pointer value from a given kernel memory
+ * address. Reports an error when reading from the given address
+ * fails.
+ */
+function kernel_pointer:long (addr:long) %{ /* pure */
+  THIS->__retvalue = (int64_t) kread((void **) (intptr_t) THIS->addr);
+  if (0) {
+deref_fault: /* branched to from kread() */
+    snprintf (CONTEXT->error_buffer, sizeof(CONTEXT->error_buffer),
+        "kernel pointer copy fault at 0x%p", (void *) (uintptr_t) THIS->addr);
+    CONTEXT->last_error = CONTEXT->error_buffer;
+  }
+%}
 
 /**
  * sfunction user_string - Retrieves string from user space.
diff --git a/tapset/nfs.stp b/tapset/nfs.stp
index 2fc05128..e80ba0de 100644
--- a/tapset/nfs.stp
+++ b/tapset/nfs.stp
@@ -134,16 +134,6 @@ function __p2sb_flag:long (page:long)
     return @cast(i_sb, "super_block", "kernel:nfs")->s_flags
 }
 
-function __d_loff_t :long (ppos :long) %{ /* pure */
-    loff_t *ppos = (loff_t *)((long)THIS->ppos);
-
-    if (ppos == NULL)
-        THIS->__retvalue = -1;
-    else
-        THIS->__retvalue = kread(ppos);
-    CATCH_DEREF_FAULT();
-%}
-
 function __file_inode:long (file:long)
 {
 %( kernel_v >= "2.6.20" %?
@@ -718,7 +708,7 @@ probe nfs.fop.sendfile = kernel.function("nfs_file_sendfile") !,
 	devname = kernel_string(s_id)
 
         count = $count
-        ppos  = __d_loff_t($ppos)
+        ppos  = $ppos ? kernel_pointer($ppos) : -1
 
         cache_valid = __nfsi_cache_valid(__file_inode($filp))
         cache_time  = __nfsi_rcache_time(__file_inode($filp))