Live-lock issues in memory allocator.

    * Debug tool for PageManager.
    * Support PageMgr allocations of non-2^k size.
    * Switch page-allocation to always be in kernel-mode.

    While investigating issue 44511, I noticed two problesm with the
    memory page allocator (PageManager).  First, the allocator did
    not support allocations of pages which were not a power of 2,
    which would result in pages appearing to "leak".  Second, in
    situations where a large allocation was requested and there was
    not a large chunk available, the allocation would enter a
    live-lock condition where coalescing would never occur.

    Switched the PageManager so that all allocations happen in
    kernel space.  This allows us to force memory-release operations
    on the syscall path when we are out of memory and also put in
    place a task_yield call which will allow coalescing to eventually
    occur.  Issue 44523 is suppose to fully resolve any of these
    live-lock paths.

RTC: 44511
Change-Id: Ifefd5d0996ee6914e291c862fac0c7b76980717f
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/1330
Tested-by: Jenkins Server
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Reviewed-by: A. Patrick Williams III <iawillia@us.ibm.com>

1 files changed, 41 insertions, 22 deletions

diff --git a/src/include/kernel/misc.H b/src/include/kernel/misc.H
index f04439748..ebec9cc48 100644
--- a/src/include/kernel/misc.H
+++ b/src/include/kernel/misc.H
@@ -1,25 +1,26 @@
-//  IBM_PROLOG_BEGIN_TAG
-//  This is an automatically generated prolog.
-//
-//  $Source: src/include/kernel/misc.H $
-//
-//  IBM CONFIDENTIAL
-//
-//  COPYRIGHT International Business Machines Corp. 2011
-//
-//  p1
-//
-//  Object Code Only (OCO) source materials
-//  Licensed Internal Code Source Materials
-//  IBM HostBoot Licensed Internal Code
-//
-//  The source code for this program is not published or other-
-//  wise divested of its trade secrets, irrespective of what has
-//  been deposited with the U.S. Copyright Office.
-//
-//  Origin: 30
-//
-//  IBM_PROLOG_END
+/*  IBM_PROLOG_BEGIN_TAG
+ *  This is an automatically generated prolog.
+ *
+ *  $Source: src/include/kernel/misc.H $
+ *
+ *  IBM CONFIDENTIAL
+ *
+ *  COPYRIGHT International Business Machines Corp. 2011-2012
+ *
+ *  p1
+ *
+ *  Object Code Only (OCO) source materials
+ *  Licensed Internal Code Source Materials
+ *  IBM HostBoot Licensed Internal Code
+ *
+ *  The source code for this program is not published or other-
+ *  wise divested of its trade secrets, irrespective of what has
+ *  been deposited with the U.S. Copyright Office.
+ *
+ *  Origin: 30
+ *
+ *  IBM_PROLOG_END_TAG
+ */
 /** @file misc.H
  *  @brief Misc. Kernel functions and utilities.
  */
@@ -28,6 +29,7 @@
 #define __KERNEL_MISC_H
 
 #include <stdint.h>
+#include <usr/vmmconst.h>
 
 namespace KernelMisc
 {
@@ -40,5 +42,22 @@ namespace KernelMisc
     extern uint64_t g_payload_base;
     /** @brief Address from base of payload entry-point. */
     extern uint64_t g_payload_entry;
+
+    /** @fn in_kernel_mode
+     *  @brief Determine if the code is currently in kernel mode or not.
+     *
+     *  @return [true | false]
+     */
+    inline bool in_kernel_mode()
+    {
+        uint64_t stack = 0;
+        asm volatile("mr %0, 1" : "=r"(stack));
+        if((stack >= VMM_VADDR_STACK_SEGMENT) &&
+           (stack < (VMM_VADDR_STACK_SEGMENT + VMM_SEGMENT_SIZE)))
+        {
+            return false;
+        }
+        return true;
+    }
 };
 #endif