Commit 72a20e22 authored by Russell King's avatar Russell King
Browse files

ARM: P2V: eliminate head.S use of PHYS_OFFSET for !XIP_KERNEL 



head.S makes use of PHYS_OFFSET.  When it becomes a variable, the
assembler won't understand this.  Compute PHYS_OFFSET by the following
method.  This code is linked at its virtual address, but run at before
the MMU is enabled, so at his physical address.

1:	.long	.
	.long	PAGE_OFFSET

	adr	r0, 1b		@ r0 = physical ','
	ldmia	r0, {r1, r2}	@ r1 = virtual '.', r2 = PAGE_OFFSET
	sub	r1, r0, r1	@ r1 = physical-virtual
	add	r2, r2, r1	@ r2 = PAGE_OFFSET + physical-virtual
				@    := PHYS_OFFSET.

Switch XIP users of PHYS_OFFSET to use PLAT_PHYS_OFFSET - we can't
use this method for XIP kernels as the code doesn't execute in RAM.

Tested-by: default avatarTony Lindgren <tony@atomide.com>
Reviewed-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent b75c178a

arch/arm/kernel/head.S

+22 −22
Original line number Diff line number Diff line
@@ -26,14 +26,6 @@ 
#include <mach/debug-macro.S>

#endif



#if (PHYS_OFFSET & 0x001fffff)

#error "PHYS_OFFSET must be at an even 2MiB boundary!"

#endif



#define KERNEL_RAM_VADDR	(PAGE_OFFSET + TEXT_OFFSET)

#define KERNEL_RAM_PADDR	(PHYS_OFFSET + TEXT_OFFSET)





/*

 * swapper_pg_dir is the virtual address of the initial page table.

 * We place the page tables 16K below KERNEL_RAM_VADDR.  Therefore, we must
@@ -41,6 +33,7 @@ 
 * the least significant 16 bits to be 0x8000, but we could probably

 * relax this restriction to KERNEL_RAM_VADDR >= PAGE_OFFSET + 0x4000.

 */

#define KERNEL_RAM_VADDR	(PAGE_OFFSET + TEXT_OFFSET)

#if (KERNEL_RAM_VADDR & 0xffff) != 0x8000

#error KERNEL_RAM_VADDR must start at 0xXXXX8000

#endif
@@ -48,8 +41,8 @@ 
	.globl	swapper_pg_dir

	.equ	swapper_pg_dir, KERNEL_RAM_VADDR - 0x4000



	.macro	pgtbl, rd

	ldr	\rd, =(KERNEL_RAM_PADDR - 0x4000)

	.macro	pgtbl, rd, phys

	add	\rd, \phys, #TEXT_OFFSET - 0x4000

	.endm



#ifdef CONFIG_XIP_KERNEL
@@ -88,9 +81,18 @@ ENTRY(stext) 
 THUMB( it	eq )		@ force fixup-able long branch encoding

	beq	__error_p			@ yes, error 'p'



#ifndef CONFIG_XIP_KERNEL

	adr	r3, 2f

	ldmia	r3, {r4, r8}

	sub	r4, r3, r4			@ (PHYS_OFFSET - PAGE_OFFSET)

	add	r8, r8, r4			@ PHYS_OFFSET

#else

	ldr	r8, =PLAT_PHYS_OFFSET

#endif



	/*

	 * r1 = machine no, r2 = atags,

	 * r9 = cpuid, r10 = procinfo

	 * r8 = phys_offset, r9 = cpuid, r10 = procinfo

	 */

	bl	__vet_atags

#ifdef CONFIG_SMP_ON_UP
@@ -114,21 +116,24 @@ ENTRY(stext) 
1:	b	__enable_mmu

ENDPROC(stext)

	.ltorg

#ifndef CONFIG_XIP_KERNEL

2:	.long	.

	.long	PAGE_OFFSET

#endif



/*

 * Setup the initial page tables.  We only setup the barest

 * amount which are required to get the kernel running, which

 * generally means mapping in the kernel code.

 *

 * r9  = cpuid

 * r10 = procinfo

 * r8 = phys_offset, r9 = cpuid, r10 = procinfo

 *

 * Returns:

 *  r0, r3, r5-r7 corrupted

 *  r4 = physical page table address

 */

__create_page_tables:

	pgtbl	r4				@ page table address

	pgtbl	r4, r8				@ page table address



	/*

	 * Clear the 16K level 1 swapper page table
@@ -184,10 +189,8 @@ __create_page_tables: 
	/*

	 * Map some ram to cover our .data and .bss areas.

	 */

	orr	r3, r7, #(KERNEL_RAM_PADDR & 0xff000000)

	.if	(KERNEL_RAM_PADDR & 0x00f00000)

	orr	r3, r3, #(KERNEL_RAM_PADDR & 0x00f00000)

	.endif

	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]!

	ldr	r6, =(_end - 1)
@@ -203,10 +206,7 @@ __create_page_tables: 
	 * Then map first 1MB of ram in case it contains our boot params.

	 */

	add	r0, r4, #PAGE_OFFSET >> 18

	orr	r6, r7, #(PHYS_OFFSET & 0xff000000)

	.if	(PHYS_OFFSET & 0x00f00000)

	orr	r6, r6, #(PHYS_OFFSET & 0x00f00000)

	.endif

	orr	r6, r7, r8

	str	r6, [r0]



#ifdef CONFIG_DEBUG_LL

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