linux-kernel - Re: [PATCH v7 03/16] ARM: LPAE: Use PMD_(SHIFT|SIZE|MASK) instead of PGDIR

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Date:	Mon, 15 Aug 2011 17:48:42 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Cc:	Russell King - ARM Linux <linux@....linux.org.uk>
Subject: Re: [PATCH v7 03/16] ARM: LPAE: Use PMD_(SHIFT|SIZE|MASK) instead
 of PGDIR_*

On Wed, Aug 10, 2011 at 04:03:26PM +0100, Catalin Marinas wrote:
> PGDIR_SHIFT and PMD_SHIFT for the classic 2-level page table format have
> the same value (21). This patch converts the PGDIR_* uses in the kernel
> to the PMD_* equivalent so that LPAE builds can reuse the same code.
> 
> Signed-off-by: Catalin Marinas <catalin.marinas@....com>

Following Russell's advice to split the MMU setup patch, the diff below
will be folded into this patch for easier reviewing (and the commit will
be changed slightly to reflect this):

8<-----------------------

>From 98b3fe02dd44b6e9fabd05123135e77a794f2ebc Mon Sep 17 00:00:00 2001
From: Catalin Marinas <catalin.marinas@....com>
Date: Mon, 15 Aug 2011 17:34:52 +0100
Subject: [PATCH 1/1] fixup! ARM: LPAE: Use PMD_(SHIFT|SIZE|MASK) instead of PGDIR_*

Convert the hard-coded shift and mask values in head.S and mmu.c to
SECTION_SHIFT and PMD_ORDER for easier integration of the LPAE support.

Signed-off-by: Catalin Marinas <catalin.marinas@....com>
---
 arch/arm/kernel/head.S |   74 +++++++++++++++++++++++++----------------------
 arch/arm/mm/mmu.c      |    4 ++-
 2 files changed, 42 insertions(+), 36 deletions(-)

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index d8231b2..45e5e60 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -21,6 +21,7 @@
 #include <asm/memory.h>
 #include <asm/thread_info.h>
 #include <asm/system.h>
+#include <asm/pgtable.h>
 
 #ifdef CONFIG_DEBUG_LL
 #include <mach/debug-macro.S>
@@ -38,11 +39,14 @@
 #error KERNEL_RAM_VADDR must start at 0xXXXX8000
 #endif
 
+#define PG_DIR_SIZE	0x4000
+#define PMD_ORDER	2
+
 	.globl	swapper_pg_dir
-	.equ	swapper_pg_dir, KERNEL_RAM_VADDR - 0x4000
+	.equ	swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE
 
 	.macro	pgtbl, rd, phys
-	add	\rd, \phys, #TEXT_OFFSET - 0x4000
+	add	\rd, \phys, #TEXT_OFFSET - PG_DIR_SIZE
 	.endm
 
 #ifdef CONFIG_XIP_KERNEL
@@ -148,11 +152,11 @@ __create_page_tables:
 	pgtbl	r4, r8				@ page table address
 
 	/*
-	 * Clear the 16K level 1 swapper page table
+	 * Clear the swapper page table
 	 */
 	mov	r0, r4
 	mov	r3, #0
-	add	r6, r0, #0x4000
+	add	r6, r0, #PG_DIR_SIZE
 1:	str	r3, [r0], #4
 	str	r3, [r0], #4
 	str	r3, [r0], #4
@@ -171,30 +175,30 @@ __create_page_tables:
 	sub	r0, r0, r3			@ virt->phys offset
 	add	r5, r5, r0			@ phys __enable_mmu
 	add	r6, r6, r0			@ phys __enable_mmu_end
-	mov	r5, r5, lsr #20
-	mov	r6, r6, lsr #20
+	mov	r5, r5, lsr #SECTION_SHIFT
+	mov	r6, r6, lsr #SECTION_SHIFT
 
-1:	orr	r3, r7, r5, lsl #20		@ flags + kernel base
-	str	r3, [r4, r5, lsl #2]		@ identity mapping
-	teq	r5, r6
-	addne	r5, r5, #1			@ next section
-	bne	1b
+1:	orr	r3, r7, r5, lsl #SECTION_SHIFT	@ flags + kernel base
+	str	r3, [r4, r5, lsl #PMD_ORDER]	@ identity mapping
+	cmp	r5, r6
+	addlo	r5, r5, #1			@ next section
+	blo	1b
 
 	/*
 	 * Now setup the pagetables for our kernel direct
 	 * mapped region.
 	 */
 	mov	r3, pc
-	mov	r3, r3, lsr #20
-	orr	r3, r7, r3, lsl #20
-	add	r0, r4,  #(KERNEL_START & 0xff000000) >> 18
-	str	r3, [r0, #(KERNEL_START & 0x00f00000) >> 18]!
+	mov	r3, r3, lsr #SECTION_SHIFT
+	orr	r3, r7, r3, lsl #SECTION_SHIFT
+	add	r0, r4,  #(KERNEL_START & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER)
+	str	r3, [r0, #((KERNEL_START & 0x00f00000) >> SECTION_SHIFT) << PMD_ORDER]!
 	ldr	r6, =(KERNEL_END - 1)
-	add	r0, r0, #4
-	add	r6, r4, r6, lsr #18
+	add	r0, r0, #1 << PMD_ORDER
+	add	r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
 1:	cmp	r0, r6
-	add	r3, r3, #1 << 20
-	strls	r3, [r0], #4
+	add	r3, r3, #1 << SECTION_SHIFT
+	strls	r3, [r0], #1 << PMD_ORDER
 	bls	1b
 
 #ifdef CONFIG_XIP_KERNEL
@@ -203,11 +207,11 @@ __create_page_tables:
 	 */
 	add	r3, r8, #TEXT_OFFSET
 	orr	r3, r3, r7
-	add	r0, r4,  #(KERNEL_RAM_VADDR & 0xff000000) >> 18
-	str	r3, [r0, #(KERNEL_RAM_VADDR & 0x00f00000) >> 18]!
+	add	r0, r4,  #(KERNEL_RAM_VADDR & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER)
+	str	r3, [r0, #(KERNEL_RAM_VADDR & 0x00f00000) >> (SECTION_SHIFT - PMD_ORDER)]!
 	ldr	r6, =(_end - 1)
 	add	r0, r0, #4
-	add	r6, r4, r6, lsr #18
+	add	r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
 1:	cmp	r0, r6
 	add	r3, r3, #1 << 20
 	strls	r3, [r0], #4
@@ -218,12 +222,12 @@ __create_page_tables:
 	 * Then map boot params address in r2 or
 	 * the first 1MB of ram if boot params address is not specified.
 	 */
-	mov	r0, r2, lsr #20
-	movs	r0, r0, lsl #20
+	mov	r0, r2, lsr #SECTION_SHIFT
+	movs	r0, r0, lsl #SECTION_SHIFT
 	moveq	r0, r8
 	sub	r3, r0, r8
 	add	r3, r3, #PAGE_OFFSET
-	add	r3, r4, r3, lsr #18
+	add	r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
 	orr	r6, r7, r0
 	str	r6, [r3]
 
@@ -236,21 +240,21 @@ __create_page_tables:
 	 */
 	addruart r7, r3
 
-	mov	r3, r3, lsr #20
-	mov	r3, r3, lsl #2
+	mov	r3, r3, lsr #SECTION_SHIFT
+	mov	r3, r3, lsl #PMD_ORDER
 
 	add	r0, r4, r3
 	rsb	r3, r3, #0x4000			@ PTRS_PER_PGD*sizeof(long)
 	cmp	r3, #0x0800			@ limit to 512MB
 	movhi	r3, #0x0800
 	add	r6, r0, r3
-	mov	r3, r7, lsr #20
+	mov	r3, r7, lsr #SECTION_SHIFT
 	ldr	r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
-	orr	r3, r7, r3, lsl #20
+	orr	r3, r7, r3, lsl #SECTION_SHIFT
 1:	str	r3, [r0], #4
-	add	r3, r3, #1 << 20
-	teq	r0, r6
-	bne	1b
+	add	r3, r3, #1 << SECTION_SHIFT
+	cmp	r0, r6
+	blo	1b
 
 #else /* CONFIG_DEBUG_ICEDCC */
 	/* we don't need any serial debugging mappings for ICEDCC */
@@ -262,7 +266,7 @@ __create_page_tables:
 	 * If we're using the NetWinder or CATS, we also need to map
 	 * in the 16550-type serial port for the debug messages
 	 */
-	add	r0, r4, #0xff000000 >> 18
+	add	r0, r4, #0xff000000 >> (SECTION_SHIFT - PMD_ORDER)
 	orr	r3, r7, #0x7c000000
 	str	r3, [r0]
 #endif
@@ -272,10 +276,10 @@ __create_page_tables:
 	 * Similar reasons here - for debug.  This is
 	 * only for Acorn RiscPC architectures.
 	 */
-	add	r0, r4, #0x02000000 >> 18
+	add	r0, r4, #0x02000000 >> (SECTION_SHIFT - PMD_ORDER)
 	orr	r3, r7, #0x02000000
 	str	r3, [r0]
-	add	r0, r4, #0xd8000000 >> 18
+	add	r0, r4, #0xd8000000 >> (SECTION_SHIFT - PMD_ORDER)
 	str	r3, [r0]
 #endif
 #endif
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index dc26858..36e983d 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -889,6 +889,8 @@ static inline void prepare_page_table(void)
 		pmd_clear(pmd_off_k(addr));
 }
 
+#define SWAPPER_PG_DIR_SIZE	(PTRS_PER_PGD * sizeof(pgd_t))
+
 /*
  * Reserve the special regions of memory
  */
@@ -898,7 +900,7 @@ void __init arm_mm_memblock_reserve(void)
 	 * Reserve the page tables.  These are already in use,
 	 * and can only be in node 0.
 	 */
-	memblock_reserve(__pa(swapper_pg_dir), PTRS_PER_PGD * sizeof(pgd_t));
+	memblock_reserve(__pa(swapper_pg_dir), SWAPPER_PG_DIR_SIZE);
 
 #ifdef CONFIG_SA1111
 	/*

-- 
Catalin
--
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