Update On-demand paging documentation

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2877 42af7a65-404d-4744-a932-0658087f49c3

3 files changed, 105 insertions, 77 deletions

diff --git a/nuttx/arch/arm/src/arm/pg_macros.h b/nuttx/arch/arm/src/arm/pg_macros.h
index 47abf10ab..73bbb93b3 100644
--- a/nuttx/arch/arm/src/arm/pg_macros.h
+++ b/nuttx/arch/arm/src/arm/pg_macros.h
@@ -292,46 +292,49 @@
 #ifdef __ASSEMBLY__
 
 /****************************************************************************
- * Name: pg_map
+ * Name: pg_l2map
  *
  * Description:
  *   Write several, contiguous L2 page table entries.  npages entries will be
  *   written. This macro is used when CONFIG_PAGING is enable.  This case,
  *   it is used asfollows:
  *
- *	ldr	r0, =PG_L2_BASE_PADDR
- *	ldr	r1, =PG_LOCKED_PBASE
- *	ldr	r2, =CONFIG_PAGING_NLOCKED
- *      ldr	r3, =MMUFLAGS
- *	pg_map r0, r1, r2, r3, r4
+ *	ldr	r0, =PG_L2_BASE_PADDR		<-- Address in L2 table
+ *	ldr	r1, =PG_LOCKED_PBASE		<-- Physical page memory address
+ *	ldr	r2, =CONFIG_PAGING_NLOCKED	<-- number of pages
+ *      ldr	r3, =MMUFLAGS			<-- L2 MMU flags
+ *	pg_l2map r0, r1, r2, r3, r4
  *
  * Inputs:
- *   l2 - Physical start address in the L2 page table (modified)
- *   paddr - The physical address of the start of the region to span. Must
- *            be aligned to 1Mb section boundaries (modified)
+ *   l2 - Physical or virtual start address in the L2 page table, depending
+ *        upon the context. (modified)
+ *   ppage - The physical address of the start of the region to span. Must
+ *           be aligned to 1Mb section boundaries (modified)
  *   npages - Number of pages to write in the section (modified)
  *   mmuflags - L2 MMU FLAGS
  *
  * Scratch registers (modified): tmp
- *   l2  - Physical address in the L2 page table.
+ *   l2  - Next address in the L2 page table.
+ *   ppage - Start of next physical page
+ *   npages - Loop counter
  *   tmp - scratch
  *
  * Assumptions:
  * - The MMU is not yet enabled
  * - The L2 page tables have been zeroed prior to calling this function
- * - pg_span has been called to initialize the L1 table.
+ * - pg_l1span has been called to initialize the L1 table.
  *
  ****************************************************************************/
 
 #ifdef CONFIG_PAGING
-	.macro	pg_map, paddr, npages, mmuflags, l2, tmp
+	.macro	pg_l2map, l2, ppage, npages, mmuflags, tmp
 	b	2f
 1:
-	/* Write the one L2 entries.  First,  get tmp = (paddr | mmuflags),
+	/* Write the one L2 entries.  First,  get tmp = (ppage | mmuflags),
 	 * the value to write into the L2 PTE
 	 */
 
-	orr	\tmp, \paddr, \mmuflags
+	orr	\tmp, \ppage, \mmuflags
 
 	/* Write value into table at the current table address */
 
@@ -341,7 +344,7 @@
 	 * table entry.
 	 */
 
-	add	\paddr, \paddr, #CONFIG_PAGING_PAGESIZE
+	add	\ppage, \ppage, #CONFIG_PAGING_PAGESIZE
 	add	\l2, \l2, #4
 
 	/* Decrement the number of pages written */
@@ -357,7 +360,7 @@
 #endif /* CONFIG_PAGING */
 
 /****************************************************************************
- * Name: pg_span
+ * Name: pg_l1span
  *
  * Description:
  *   Write several, contiguous unmapped coarse L1 page table entries.  As
@@ -365,24 +368,24 @@
  *   macro is used when CONFIG_PAGING is enable.  This case, it is used as
  *   follows:
  *
- *	ldr	r0, =PG_L2_BASE_PADDR
- *	ldr	r1, =PG_LOCKED_PBASE
- *	ldr	r2, =(CONFIG_PAGING_NLOCKED+CONFIG_PAGING_NPAGES)
- *      ldr	r3, =MMU_FLAGS
- *	pg_span r0, r1, r2, r3, r4
+ *	ldr	r0, =PGTABLE_BASE_PADDR		<-- Address in L1 table
+ *	ldr	r1, =PG_LOCKED_VBASE		<-- Virtual address of region
+ *	pg_l1addr r0, r1, r0
+ *	ldr	r1, =PG_LOCKED_PBASE		<-- Physical address of region 
+ *	ldr	r1, =(CONFIG_PAGING_NLOCKED+CONFIG_PAGING_NVPAGED) <-- number of pages
+ *      ldr	r3, =MMU_FLAGS			<-- L1 MMU flags
+ *	pg_l1span r0, r1, r2, r3, r4
  *
  * Inputs (unmodified unless noted):
+ *   l1 - Physical or virtual address in the L1 table to begin writing (modified)
  *   l2 - Physical start address in the L2 page table (modified)
- *   addr - The virtual address of the start of the region to span. Must
- *     be aligned to 1Mb section boundaries (modified)
  *   npages - Number of pages to required to span that memory region (modified)
  *   mmuflags - L1 MMU flags to use
  *
- * Scratch registers (modified):
- *   addr, npages, tmp
- *   l2 - L2 page table physical address
- *   addr - Physical address in the L1 page table.
- *   npages - The number of pages remaining to be accounted for
+ * Scratch registers (modified): l1, l2, npages, tmp
+ *   l1 - Next L1 table address
+ *   l2 - Physical start address of the next L2 page table
+ *   npages - Loop counter
  *   tmp - scratch
  *
  * Return:
@@ -395,32 +398,24 @@
  ****************************************************************************/
 
 #ifdef CONFIG_PAGING
-	.macro	pg_span, l2, addr, npages, mmuflags, tmp
-
-	/* Get addr = the L1 page table address coresponding to the virtual
-	 * address of the start of memory region to be mapped.
-	 */
-
-   	ldr	\tmp, =PGTABLE_BASE_PADDR
-	lsr	\addr, \addr, #20
-	add	\addr, \tmp, \addr, lsl #2
+	.macro	pg_l1span, l1, l2, npages, mmuflags, tmp
 	b	2f
 1:
 	/* Write the L1 table entry that refers to this (unmapped) coarse page
 	 * table.
 	 *
-	 * tmp = (paddr | mmuflags), the value to write into the page table
+	 * tmp = (l2table | mmuflags), the value to write into the page table
 	 */
 
 	orr	\tmp, \l2, \mmuflags
 
 	/* Write the value into the L1 table at the correct offset. */
 	
-	str	\tmp, [\addr], #4
+	str	\tmp, [\l1], #4
 
 	/* Update the L2 page table address for the next L1 table entry. */
 
-	add	\l2, \l2, #PT_SIZE  /* Next L2 page table start paddr */
+	add	\l2, \l2, #PT_SIZE  /* Next L2 page table start address */
 
 	/* Update the number of pages that we have account for (with
 	 * non-mappings
@@ -436,6 +431,45 @@
 	bgt	1b
 	.endm
 
+/****************************************************************************
+ * Name: pg_l1addr
+ *
+ * Description:
+ *   Given the start of an L1 table and a virtual address, return the offset
+ *   address into the L1 table for that address.
+ *
+ *	ldr	r0, =PGTABLE_BASE_PADDR
+ *	ldr	r1, =PG_LOCKED_VBASE
+ *	pg_l1addr r0, r1, r0
+ *
+ * Inputs (unmodified unless noted):
+ *   l1 - The physical or virtual address of the start of the L1 table
+ *   vaddr - The virtual address of the start of the region to span. Must
+ *     be aligned to 1Mb section boundaries (modified)
+ *   npages - Number of pages to required to span that memory region (modified)
+ *   mmuflags - L1 MMU flags to use
+ *
+ * Scratch registers (modified): vaddr
+ *
+ * Return:
+ *   The offset L1 table address is returned in result.
+ *
+ * Assumptions:
+ *   None
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_PAGING
+	.macro	pg_l1addr, l1, vaddr, result
+
+	/* Get result = the L1 table address coresponding to a virtual
+	 * address.
+	 */
+
+	lsr	\vaddr, \vaddr, #20
+	add	\result, \l1, \vaddr, lsl #2
+	.endm
+
 #endif /* CONFIG_PAGING */
 #endif /* __ASSEMBLY__ */
 
diff --git a/nuttx/arch/arm/src/arm/up_head.S b/nuttx/arch/arm/src/arm/up_head.S
index d6e2196fe..cca34eae7 100644
--- a/nuttx/arch/arm/src/arm/up_head.S
+++ b/nuttx/arch/arm/src/arm/up_head.S
@@ -185,34 +185,36 @@ __start:
 	 * effect.  First populate the L1 table for the locked and paged
 	 * text regions.
 	 *
-	 * We could probably make the the pg_span and pg_map macros into
+	 * We could probably make the the pg_l1span and pg_l2map macros into
 	 * call-able subroutines, but we would have to be carefully during
 	 * this phase while we are operating in a physical address space.
 	 */
 
 	adr	r0, .Ltxtspan
-	ldmia	r0, {r0, r1, r2, r3}
- 	pg_span r0, r1, r2, r3, r4
-
+	ldmia	r0, {r0, r1, r2, r3, r4}
+	pg_l1addr r0, r1, r0
+ 	pg_l1span r0, r2, r3, r4, r1
+ 
 	/* Then populate the L2 table for the locked text region only. */
 
 	adr	r0, .Ltxtmap
 	ldmia	r0, {r0, r1, r2, r3}
- 	pg_map r0, r1, r2, r3, r4
+ 	pg_l2map r0, r1, r2, r3, r4
 
 	/* Make sure that the page table is itself mapped and and read/write-able.
 	 * First, populate the L1 table:
 	 */
 
 	adr	r0, .Lptabspan
-	ldmia	r0, {r0, r1, r2, r3}
- 	pg_span r0, r1, r2, r3, r4
+	ldmia	r0, {r0, r1, r2, r3, r4}
+	pg_l1addr r0, r1, r0
+ 	pg_l1span r0, r2, r3, r4, r1
 
 	/* Then populate the L2 table. */
 
 	adr	r0, .Lptabmap
 	ldmia	r0, {r0, r1, r2, r3}
- 	pg_map r0, r1, r2, r3, r4
+ 	pg_l2map r0, r1, r2, r3, r4
 
 #else
 	/* Create a virtual single section mapping for the first MB of the .text
@@ -350,27 +352,29 @@ __start:
 
 #ifdef CONFIG_PAGING
 .Ltxtspan:
-	.long	PG_L2_TEXT_PADDR		/* Physical address of L2 table */
-	.long	PG_TEXT_VBASE			/* Virtual address of text base */
-	.long	PG_TEXT_NVPAGES			/* Total virtual text pages to be mapped */
+	.long	PGTABLE_BASE_PADDR		/* Physical address of L1 table */
+	.long	PG_L2_TEXT_VADDR		/* Virtual address of the L2 page table */
+	.long	PG_L2_TEXT_PADDR		/* Physical address of the L2 page table */
+	.long	PG_TEXT_NVPAGES			/* Total (virtual) text pages to be mapped */
 	.long	MMU_L1_TEXTFLAGS		/* L1 MMU flags to use */
 
 .Ltxtmap:
 	.long	PG_L2_LOCKED_PADDR		/* Physical address of L2 table */
-	.long	PG_LOCKED_PBASE			/* Physical address of locked base */
+	.long	PG_LOCKED_PBASE			/* Physical address of locked base memory */
 	.long	CONFIG_PAGING_NLOCKED		/* Number of pages in the locked region */
 	.long	MMU_L2_TEXTFLAGS		/* L2 MMU flags to use */
 
 .Lptabspan:
-	.long	PG_L2_PGTABLE_PADDR		/* Physical address of L2 table */
-	.long	PGTABLE_BASE_VADDR		/* Virtual address of the page table */
-	.long	PG_TEXT_NPAGES			/* Total mapped page table pages */
+	.long	PGTABLE_BASE_PADDR		/* Physical address of L1 table */
+	.long	PG_L2_PGTABLE_VADDR		/* Virtual address of the L2 page table */
+	.long	PG_L2_PGTABLE_PADDR		/* Physical address of the L2 page table */
+	.long	PG_PGTABLE_NPAGES		/* Total mapped page table pages */
 	.long	MMU_L1_PGTABFLAGS		/* L1 MMU flags to use */
 
 .Lptabmap:
 	.long	PG_L2_PGTABLE_PADDR		/* Physical address of L2 table */
-	.long	PGTABLE_BASE_PADDR		/* Physical address of the page table */
-	.long	CONFIG_PAGING_NLOCKED		/* Total mapped page table pages */
+	.long	PGTABLE_BASE_PADDR		/* Physical address of the page table memory */
+	.long	PG_PGTABLE_NPAGES		/* Total mapped page table pages */
 	.long	MMU_L2_PGTABFLAGS		/* L2 MMU flags to use */
 #endif
 	.size	_start, .-_start
@@ -403,14 +407,15 @@ __start:
 	/* Populate the L1 table for the data regions */
 
 	adr	r0, .Ldataspan
-	ldmia	r0, {r0, r1, r2, r3}
- 	pg_span r0, r1, r2, r3, r4
+	ldmia	r0, {r0, r1, r2, r3, r4}
+	pg_l1addr r0, r1, r0
+ 	pg_l1span r0, r2, r3, r4, r1
 
 	/* Populate the L2 table for the data region */
 
 	adr	r0, .Ldatamap
 	ldmia	r0, {r0, r1, r2, r3}
- 	pg_map r0, r1, r2, r3, r4
+ 	pg_l2map r0, r1, r2, r3, r4
 
 #elif defined(CONFIG_BOOT_RUNFROMFLASH)
 #  error "Logic not implemented"
@@ -508,14 +513,15 @@ __start:
 
 #ifdef CONFIG_PAGING
 .Ldataspan:
-	.long	PG_L2_DATA_PADDR	/* Physical address of L2 table */
-	.long	PG_DATA_PBASE		/* Physical address of data base */
+	.long	PGTABLE_BASE_VADDR	/* Virtual address of the L1 table */
+	.long	PG_L2_DATA_VADDR	/* Virtual address of the L2 page table */
+	.long	PG_L2_DATA_PADDR	/* Physical address of the L2 page table */
 	.long	PG_DATA_NPAGED		/* Number of pages in the data region */
 	.long	MMU_L1_DATAFLAGS	/* L1 MMU flags to use */
 
 .Ldatamap:
-	.long	PG_L2_DATA_PADDR	/* Physical address of L2 table */
-	.long	PG_DATA_VBASE		/* Virtual address of data base */
+	.long	PG_L2_DATA_VADDR	/* Virtual address of L2 table */
+	.long	PG_DATA_VBASE		/* Virtual address of data memory  */
 	.long	PG_DATA_NPAGED		/* Number of pages in the data region */
 	.long	MMU_L2_DATAFLAGS	/* L2 MMU flags to use */
 #endif
diff --git a/nuttx/arch/arm/src/arm/up_prefetchabort.c b/nuttx/arch/arm/src/arm/up_prefetchabort.c
index b3ea3cba3..824fa30e1 100644
--- a/nuttx/arch/arm/src/arm/up_prefetchabort.c
+++ b/nuttx/arch/arm/src/arm/up_prefetchabort.c
@@ -54,19 +54,7 @@
  * 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
+/* Debug ********************************************************************/
 
 /* Output debug info if stack dump is selected -- even if 
  * debug is not selected.