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ARM: 9088/1: Split KERNEL_OFFSET from PAGE_OFFSET

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We want to be able to compile the kernel into an address different
from PAGE_OFFSET (start of lowmem) + TEXT_OFFSET, so start to pry
apart the address of where the kernel is located from the address
where the lowmem is located by defining and using KERNEL_OFFSET in
a few key places.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Linus Walleij 2021-06-03 09:50:16 +01:00 committed by Russell King (Oracle)
parent 8b95a7d90c
commit b78f63f443
3 changed files with 9 additions and 4 deletions
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8
arch/arm/include/asm/memory.h
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@ -20,8 +20,14 @@
#endif
#include <asm/kasan_def.h>
/* PAGE_OFFSET - the virtual address of the start of the kernel image */
/*
* PAGE_OFFSET: the virtual address of the start of lowmem, memory above
* the virtual address range for userspace.
* KERNEL_OFFSET: the virtual address of the start of the kernel image.
* we may further offset this with TEXT_OFFSET in practice.
*/
#define PAGE_OFFSET UL(CONFIG_PAGE_OFFSET)
#define KERNEL_OFFSET (PAGE_OFFSET)
#ifdef CONFIG_MMU

3
arch/arm/kernel/head.S
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@ -23,7 +23,6 @@
#if defined(CONFIG_DEBUG_LL) && !defined(CONFIG_DEBUG_SEMIHOSTING)
#include CONFIG_DEBUG_LL_INCLUDE
#endif
/*
* 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
@ -31,7 +30,7 @@
* 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)
#define KERNEL_RAM_VADDR (KERNEL_OFFSET + TEXT_OFFSET)
#if (KERNEL_RAM_VADDR & 0xffff) != 0x8000
#error KERNEL_RAM_VADDR must start at 0xXXXX8000
#endif

2
arch/arm/kernel/vmlinux.lds.S
View File

@ -47,7 +47,7 @@ SECTIONS
#endif
}
. = PAGE_OFFSET + TEXT_OFFSET;
. = KERNEL_OFFSET + TEXT_OFFSET;
.head.text : {
_text = .;
HEAD_TEXT