From 2d25eac7bc3966ea8cb5e00bdbf175adcff18aab Mon Sep 17 00:00:00 2001
From: patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3>
Date: Tue, 17 Aug 2010 01:37:39 +0000
Subject: [PATCH] Add on-demand paging support to ARM9 prefetch abort handler

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2860 42af7a65-404d-4744-a932-0658087f49c3
---
 Documentation/NuttxPortingGuide.html | 22 +++++++++-
 arch/arm/include/arm/irq.h           |  2 +-
 arch/arm/src/arm/up_prefetchabort.c  | 60 ++++++++++++++++++++++++++--
 arch/arm/src/arm/up_vectors.S        | 33 +++++++--------
 configs/README.txt                   | 18 +++++++--
 include/nuttx/page.h                 | 37 +++++++++++++++++
 sched/os_start.c                     |  7 +++-
 7 files changed, 152 insertions(+), 27 deletions(-)

diff --git a/Documentation/NuttxPortingGuide.html b/Documentation/NuttxPortingGuide.html
index 6150823fb10..13a4775ef39 100644
--- a/Documentation/NuttxPortingGuide.html
+++ b/Documentation/NuttxPortingGuide.html
@@ -12,7 +12,7 @@
       <h1><big><font color="#3c34ec">
         <i>NuttX RTOS Porting Guide</i>
       </font></big></h1>
-      <p>Last Updated: August 14, 2010</p>
+      <p>Last Updated: August 16, 2010</p>
     </td>
   </tr>
 </table>
@@ -2390,6 +2390,26 @@ extern void up_ledoff(int led);
   If CONFIG_PAGING is selected, then the following also apply:
 </p>
 <ul>
+  </li>
+  <li>
+    <code>CONFIG_PAGING_PAGESIZE</code>:
+    The size of one managed page.
+    This must be a value supported by the processor's memory management unit.
+  </li>
+  <li>
+    <code>CONFIG_PAGING_NLOCKED</code>:
+    This is the number of locked pages in the memory map.
+    The locked address region will then be from <code>CONFIG_DRAM_VSTART</code> through
+    (<code>CONFIG_DRAM_VSTART</code> + <code>CONFIG_PAGING_PAGESIZE</code>*<code>CONFIG_PAGING_NLOCKED</code>)
+  </li>
+  <li>
+    <code>CONFIG_PAGING_NPAGES</code>:
+    The number of pages in the paged region of the memory map. 
+    This paged region then begins at
+    (<code>CONFIG_DRAM_VSTART</code> + <code>CONFIG_PAGING_PAGESIZE</code>*<code>CONFIG_PAGING_NLOCKED</code>)
+    and continues until (<code>CONFIG_DRAM_VSTART</code> +
+    <code>CONFIG_PAGING_PAGESIZE</code>*(<code>CONFIG_PAGING_NLOCKED</code> + <code>CONFIG_PAGING_NPAGES</code>)
+  </li>
   <li>
     <code>CONFIG_PAGING_DEFPRIO</code>:
     The default, minimum priority of the page fill worker thread.
diff --git a/arch/arm/include/arm/irq.h b/arch/arm/include/arm/irq.h
index 38ea2055363..6e361d4f6b8 100644
--- a/arch/arm/include/arm/irq.h
+++ b/arch/arm/include/arm/irq.h
@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/arm/include/arm/irq.h
  *
- *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009-2010 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
  *
  * Redistribution and use in source and binary forms, with or without
diff --git a/arch/arm/src/arm/up_prefetchabort.c b/arch/arm/src/arm/up_prefetchabort.c
index 3d6f5b8d82c..13d4f5a070e 100644
--- a/arch/arm/src/arm/up_prefetchabort.c
+++ b/arch/arm/src/arm/up_prefetchabort.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  *  arch/arm/src/src/up_prefetchabort.c
  *
- *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2010 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -41,7 +41,11 @@
 
 #include <stdint.h>
 #include <debug.h>
+
 #include <nuttx/irq.h>
+#ifdef CONFIG_PAGING
+#  include <nuttx/page.h>
+#endif
 
 #include "os_internal.h"
 #include "up_internal.h"
@@ -50,6 +54,20 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
+/* Configuration ************************************************************/
+
+#ifdef CONFIG_PAGING
+#  ifndef CONFIG_PAGING_PAGESIZE
+#    error "CONFIG_PAGING_PAGESIZE is not defined in your .config file"
+#  endif
+#  ifndef CONFIG_PAGING_NLOCKED
+#    error "CONFIG_PAGING_NLOCKED is not defined in your .config file"
+#  endif
+#  ifndef CONFIG_PAGING_NPAGES
+#    error "CONFIG_PAGING_NPAGES is not defined in your .config file"
+#  endif
+#endif
+
 /* Output debug info if stack dump is selected -- even if 
  * debug is not selected.
  */
@@ -77,7 +95,43 @@
 
 void up_prefetchabort(uint32_t *regs)
 {
-  lldbg("Prefetch abort at 0x%x\n", regs[REG_PC]);
+  /* Save the saved processor context in current_regs where it can be accessed
+   * for register dumps and possibly context switching.
+   */
+
   current_regs = regs;
-  PANIC(OSERR_ERREXCEPTION);
+
+#ifdef CONFIG_PAGING
+  /* Get the (virtual) address of instruction that caused the prefetch abort.
+   * When the exception occurred, this address was provide in the lr register
+   * and this value was saved in the context save area as the PC at the
+   * REG_R15 index.
+   *
+   * Check to see if this miss address is within the configured range of
+   * virtual addresses.
+   */
+
+  if (regs[REG_R15] >= CONFIG_PAGING_PAGEDBASE &&
+      regs[REG_R15] <  CONFIG_PAGING_PAGEDEND)
+    {
+      /* Call pg_miss() to schedule the page fill.  A consequences of this
+       * call are:
+       *
+       * (1) The currently executing task will be blocked and saved on
+       *     on the g_waitingforfill task list.
+       * (2) An interrupt-level context switch will occur so that when
+       *     this function returns, it will return to a different task,
+       *     most likely the page fill worker thread.
+       * (3) The page fill worker task has been signalled and should
+       *     execute immediately when we return from this exception.
+       */
+
+      pg_miss();
+    }
+  else
+#endif
+    {
+      lldbg("Prefetch abort at 0x%x\n", regs[REG_PC]);
+      PANIC(OSERR_ERREXCEPTION);
+    }
 }
diff --git a/arch/arm/src/arm/up_vectors.S b/arch/arm/src/arm/up_vectors.S
index 987b875ce14..6072e63875b 100644
--- a/arch/arm/src/arm/up_vectors.S
+++ b/arch/arm/src/arm/up_vectors.S
@@ -1,7 +1,7 @@
 /************************************************************************************
  * arch/arm/src/arm/up_vectors.S
  *
- *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2010 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -82,8 +82,8 @@ g_aborttmp:
  * Name: up_vectorirq
  *
  * Description:
- *   Interrupt excetpion. Entered in IRQ mode with spsr = SVC
- *   CPSR, lr = SVC PC
+ *   Interrupt excetpion. Entered in IRQ mode with spsr = SVC CPSR, lr = SVC PC
+ *
  ************************************************************************************/
 
 	.globl	up_vectorirq
@@ -91,7 +91,6 @@ g_aborttmp:
 up_vectorirq:
 	/* On entry, we are in IRQ mode.  We are free to use
 	 * the IRQ mode r13 and r14.
-         *
 	 */
 
 	ldr	r13, .Lirqtmp
@@ -159,7 +158,8 @@ up_vectorirq:
  * Function: up_vectorswi
  * 
  * Description:
- *   SWI interrupt. We enter the SWI in SVC mode
+ *   SWI interrupt. We enter the SWI in SVC mode.
+ *
  ************************************************************************************/
 
 	.globl	up_vectorswi
@@ -205,9 +205,10 @@ up_vectorswi:
  * Name: up_vectordata
  *
  * Description:
- *   Data abort Exception dispatcher. Give control to data
- *   abort handler.  This function is entered in ABORT mode
- *   with spsr = SVC CPSR, lr = SVC PC
+ *   This is the data abort exception dispatcher. The ARM data abort exception occurs
+ *   when a memory fault is detected during a data transfer.  This handler saves the
+ *   current processor state and gives control to data abort handler.  This function
+ *   is entered in ABORT mode with spsr = SVC CPSR, lr = SVC PC
  *
  ************************************************************************************/
 	
@@ -274,8 +275,11 @@ up_vectordata:
  * Name: up_vectorprefetch
  *
  * Description:
- *    Prefetch abort exception.  Entered in ABT mode with
- *    spsr = SVC CPSR, lr = SVC PC
+ *   This is the prefetch abort exception dispatcher. The ARM prefetch abort exception
+ *   occurs when a memory fault is detected during an an instruction fetch.  This
+ *   handler saves the current processor state and gives control to prefetch abort
+ *   handler.  This function is entered in ABT mode with spsr = SVC CPSR, lr = SVC PC.
+ *
  ************************************************************************************/
 	
 	.globl	up_vectorprefetch
@@ -341,8 +345,8 @@ up_vectorprefetch:
  * Name: up_vectorundefinsn
  *
  * Description:
- *   Undefined instruction entry exception.  Entered in
- *   UND mode, spsr = SVC  CPSR, lr = SVC PC
+ *   Undefined instruction entry exception.  Entered in UND mode, spsr = SVC  CPSR,
+ *   lr = SVC PC
  *
  ************************************************************************************/
 	
@@ -409,6 +413,7 @@ up_vectorundefinsn:
  *
  * Description:
  *   Shouldn't happen
+ *
  ************************************************************************************/
 
 	.globl	up_vectorfiq
@@ -419,10 +424,6 @@ up_vectorfiq:
 
 /************************************************************************************
  *  Name: up_interruptstack/g_userstack
- *
- * Description:
- *   Shouldn't happen
- *
  ************************************************************************************/
 
 #if CONFIG_ARCH_INTERRUPTSTACK > 3
diff --git a/configs/README.txt b/configs/README.txt
index 23ea00bd310..335ee04681f 100644
--- a/configs/README.txt
+++ b/configs/README.txt
@@ -264,13 +264,23 @@ defconfig -- This is a configuration file similar to the Linux
 
     OS setup related to on-demand paging:
 
-
 		CONFIG_PAGING - If set =y in your configation file, this setting will
-          enable the on-demand paging feature as described in
-          http://www.nuttx.org/NuttXDemandPaging.html.
+		  enable the on-demand paging feature as described in
+		  http://www.nuttx.org/NuttXDemandPaging.html.
 
     If CONFIG_PAGING is selected, then the following also apply:
 
+		CONFIG_PAGING_PAGESIZE - The size of one managed page.  This must
+		  be a value supported by the processor's memory management unit.
+                CONFIG_PAGING_NLOCKED - This is the number of locked pages in the
+		  memory map.  The locked address region will then be from
+		  CONFIG_DRAM_VSTART through (CONFIG_DRAM_VSTART +
+		  CONFIG_PAGING_PAGESIZE*CONFIG_PAGING_NLOCKED)
+		CONFIG_PAGING_NPAGES - The number of pages in the paged region of
+		  the memory map.  This paged region then begins at (CONFIG_DRAM_VSTART +
+		  CONFIG_PAGING_PAGESIZE*CONFIG_PAGING_NLOCKED) and continues until
+		  (CONFIG_DRAM_VSTART + CONFIG_PAGING_PAGESIZE*(CONFIG_PAGING_NLOCKED +
+		  CONFIG_PAGING_NPAGES)
 		CONFIG_PAGING_DEFPRIO - The default, minimum priority of the page fill
 		  worker thread.  The priority of the page fill work thread will be boosted
 		  boosted dynmically so that it matches the priority of the task on behalf
@@ -285,7 +295,7 @@ defconfig -- This is a configuration file similar to the Linux
 		CONFIG_PAGING_TIMEOUT_TICKS - If defined, the implementation will monitor
  		  the (asynchronous) page fill logic.  If the fill takes longer than this
 		  number if microseconds, then a fatal error will be declared.
-          Default: No timeouts monitored.
+		  Default: No timeouts monitored.
 
 	The following can be used to disable categories of APIs supported
 	by the OS.  If the compiler supports weak functions, then it
diff --git a/include/nuttx/page.h b/include/nuttx/page.h
index fc8ec989d8d..1e5ed444940 100755
--- a/include/nuttx/page.h
+++ b/include/nuttx/page.h
@@ -44,6 +44,7 @@
 #include <nuttx/config.h>
 
 #include <stdbool.h>
+#include <nuttx/sched.h>
 
 #ifdef CONFIG_PAGING
 
@@ -51,6 +52,42 @@
  * Pre-Processor Definitions
  ****************************************************************************/
 
+/* Configuration ************************************************************/
+/* CONFIG_PAGING_PAGESIZE - The size of one managed page.  This must be a
+ *   value supported by the processor's memory management unit.
+ * CONFIG_PAGING_NLOCKED - This is the number of locked pages in the memory
+ *   map.  The locked address region will then be from:
+ */
+
+#define CONFIG_PAGING_LOCKEDBASE CONFIG_DRAM_VSTART
+#define CONFIG_PAGING_LOCKEDSIZE (CONFIG_PAGING_PAGESIZE*CONFIG_PAGING_NLOCKED)
+#define CONFIG_PAGING_LOCKEDEND  (CONFIG_PAGING_LOCKEDBASE + CONFIG_PAGING_LOCKEDSIZE)
+
+/* CONFIG_PAGING_NPAGES - The number of pages in the paged region of the
+ *   memory map.  This paged region then begins and ends at:
+ */
+
+#define CONFIG_PAGING_PAGEDBASE CONFIG_PAGING_LOCKEDEND
+#define CONFIG_PAGING_PAGEDSIZE (CONFIG_PAGING_PAGESIZE*CONFIG_PAGING_NPAGES)
+#define CONFIG_PAGING_PAGEDEND  (CONFIG_PAGING_PAGEDBASE + CONFIG_PAGING_PAGEDSIZE)
+
+/* CONFIG_PAGING_DEFPRIO - The default, minimum priority of the page fill
+ *   worker thread.  The priority of the page fill work thread will be boosted
+ *   boosted dynmically so that it matches the priority of the task on behalf
+ *   of which it peforms the fill.  This defines the minimum priority that
+ *   will be used. Default: 50.
+ * CONFIG_PAGING_STACKSIZE - Defines the size of the allocated stack
+ *   for the page fill worker thread. Default: 1024.
+ * CONFIG_PAGING_BLOCKINGFILL - The architecture specific up_fillpage()
+ *   function may be blocking or non-blocking.  If defined, this setting
+ *   indicates that the up_fillpage() implementation will block until the
+ *   transfer is completed. Default:  Undefined (non-blocking).
+ * CONFIG_PAGING_TIMEOUT_TICKS - If defined, the implementation will monitor
+ *   the (asynchronous) page fill logic.  If the fill takes longer than this
+ *   number if microseconds, then a fatal error will be declared.
+ *   Default: No timeouts monitored.
+ */
+
 /****************************************************************************
  * Public Data
  ****************************************************************************/
diff --git a/sched/os_start.c b/sched/os_start.c
index 9e299a94672..6ca865fbc3a 100644
--- a/sched/os_start.c
+++ b/sched/os_start.c
@@ -189,15 +189,18 @@ const tasklist_t g_tasklisttable[NUM_TASK_STATES] =
   { &g_readytorun,           true  },  /* TSTATE_TASK_READYTORUN */
   { &g_readytorun,           true  },  /* TSTATE_TASK_RUNNING */
   { &g_inactivetasks,        false },  /* TSTATE_TASK_INACTIVE */
-  { &g_waitingforsemaphore,  true  },  /* TSTATE_WAIT_SEM */
+  { &g_waitingforsemaphore,  true  }   /* TSTATE_WAIT_SEM */
 #ifndef CONFIG_DISABLE_SIGNALS
-  { &g_waitingforsignal,     false },  /* TSTATE_WAIT_SIG */
+  ,
+  { &g_waitingforsignal,     false }  /* TSTATE_WAIT_SIG */
 #endif
 #ifndef CONFIG_DISABLE_MQUEUE
+  ,
   { &g_waitingformqnotempty, true  },  /* TSTATE_WAIT_MQNOTEMPTY */
   { &g_waitingformqnotfull,  true  }   /* TSTATE_WAIT_MQNOTFULL */
 #endif
 #ifdef CONFIG_PAGING
+  ,
   { &g_waitingforfill,       true  }   /* TSTATE_WAIT_PAGEFILL */
 #endif
 };