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>

6 files changed, 88 insertions, 69 deletions

diff --git a/src/include/kernel/devicesegment.H b/src/include/kernel/devicesegment.H
index c300eedde..2b87c9161 100644
--- a/src/include/kernel/devicesegment.H
+++ b/src/include/kernel/devicesegment.H
@@ -1,25 +1,26 @@
-//  IBM_PROLOG_BEGIN_TAG
-//  This is an automatically generated prolog.
-//
-//  $Source: src/include/kernel/devicesegment.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/devicesegment.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
+ */
 #ifndef __KERNEL_DEVICESEGMENT_H
 #define __KERNEL_DEVICESEGMENT_H
 
@@ -41,7 +42,7 @@ class DeviceSegment : public Segment
          *
          * Associates itself with the SegmentManager.
          */
-        explicit DeviceSegment(size_t segId) : Segment(segId * TERABYTE)
+        explicit DeviceSegment(size_t segId) : Segment(segId * VMM_SEGMENT_SIZE)
                 { init(segId); };
 
         /**
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
diff --git a/src/include/kernel/pagemgr.H b/src/include/kernel/pagemgr.H
index 6676a469c..93cd82bb5 100644
--- a/src/include/kernel/pagemgr.H
+++ b/src/include/kernel/pagemgr.H
@@ -54,7 +54,7 @@ class PageManagerCore
         /**
          * Default Constructor
          */
-        PageManagerCore() 
+        PageManagerCore()
             : iv_available(0) {}
 
         /**
@@ -76,7 +76,7 @@ class PageManagerCore
          * @return a pointer to the requested allocation | NULL
          * if the request could not be satisfied.
          */
-        page_t  * allocatePage( size_t i_pageCount );
+        page_t * allocatePage( size_t i_pageCount );
 
         /**
          * Return page allocations to the page manager
@@ -136,9 +136,10 @@ class PageManager
         /**
          * Allocate pages
          * @param[in] n, Requested allocation in pages
+         * @param[in] userspace - Request to allocate came from userspace
          * @return pointer to requested memory
          */
-        static void* allocatePage(size_t n = 1);
+        static void* allocatePage(size_t n = 1, bool userspace = false);
 
         /**
          * Return pages to the pagemanager
@@ -170,6 +171,9 @@ class PageManager
         {
             MEMLEN = VmmManager::MBOX_DMA_ADDR,
             RESERVED_PAGES = 4,
+
+            LOWMEM_NORM_LIMIT = 16,
+            LOWMEM_CRIT_LIMIT = 5,
         };
 
         static size_t cv_coalesce_count;        //!< running coalesced counter
@@ -182,15 +186,9 @@ class PageManager
 
     private:
 
-        void* _allocatePage(size_t);    //!< see allocatePage()
-        void _freePage(void*, size_t);  //!< see freePage()
-        void _coalesce( void );         //!< see coalesce()
-
-        /**
-         * Query if in kernel mode
-         * @return [true | false]
-         */
-        bool queryKernelMode() const;
+        void* _allocatePage(size_t,bool);    //!< see allocatePage()
+        void _freePage(void*, size_t);       //!< see freePage()
+        void _coalesce( void );              //!< see coalesce()
 
         /** see queryAvail() */
         ALWAYS_INLINE uint64_t _queryAvail() const
diff --git a/src/include/kernel/syscalls.H b/src/include/kernel/syscalls.H
index 20cfd4e65..a46fde703 100644
--- a/src/include/kernel/syscalls.H
+++ b/src/include/kernel/syscalls.H
@@ -97,8 +97,8 @@ namespace Systemcalls
            /** mm_set_permission() */
         MM_SET_PERMISSION,
 
-           /** mm_flush_pages() */
-        MM_FLUSH_PAGES,
+           /** mm_alloc_pages() */
+        MM_ALLOC_PAGES,
 
 	SYSCALL_MAX
     };
diff --git a/src/include/sys/mm.h b/src/include/sys/mm.h
index 105b145be..d9b5536a1 100644
--- a/src/include/sys/mm.h
+++ b/src/include/sys/mm.h
@@ -97,12 +97,6 @@ int mm_remove_pages(PAGE_REMOVAL_OPS i_op, void* i_vaddr, uint64_t i_size);
  */
 int mm_set_permission(void* va, uint64_t size, uint64_t access_type);
 
-/** @fn mm_flush_pages()
- * @brief  System call to flush pages
- * @param[in] i_sev - [VmmManager::NORMAL | VmmManager::CRITIAL]
- */
-void mm_flush_pages(uint64_t i_sev);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/include/usr/vmmconst.h b/src/include/usr/vmmconst.h
index a43a70a7a..1997b9276 100644
--- a/src/include/usr/vmmconst.h
+++ b/src/include/usr/vmmconst.h
@@ -35,14 +35,21 @@
  * Segments
  */
 
+/** Stacks are all 1TB in size. */
+#define VMM_SEGMENT_SIZE (1 * TERABYTE)
+
+/** Base Segment is at 0 TB */
+#define VMM_VADDR_BASE_SEGMENT  (0 * TERABYTE)
+
 /** Stack Segment is at 1 TB */
-#define VMM_VADDR_STACK_SEGMENT  (1 * TERABYTE)
+#define VMM_VADDR_STACK_SEGMENT  (VMM_VADDR_BASE_SEGMENT + VMM_SEGMENT_SIZE)
 
 /** Device Segments are at 2 TB - 10 TB */
-#define VMM_VADDR_DEVICE_SEGMENT_FIRST  (2 * TERABYTE)
-#define VMM_VADDR_DEVICE_SEGMENT_LAST   (VMM_VADDR_DEVICE_SEGMENT_FIRST + \
-                                         (8 * TERABYTE))
+#define VMM_VADDR_DEVICE_SEGMENT_FIRST  \
+            (VMM_VADDR_STACK_SEGMENT + VMM_SEGMENT_SIZE)
 
+#define VMM_VADDR_DEVICE_SEGMENT_LAST  \
+            (VMM_VADDR_DEVICE_SEGMENT_FIRST + (8 * VMM_SEGMENT_SIZE))
 
 /**
  * Resource Providers