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ARM: 9089/1: Define kernel physical section start and end

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When we are mapping the initial sections in head.S we
know very well where the start and end of the kernel image
in physical memory is placed. Later on it gets hard
to determine this.

Save the information into two variables named
kernel_sec_start and kernel_sec_end for convenience
for later work involving the physical start and end
of the kernel. These variables are section-aligned
corresponding to the early section mappings set up
in head.S.

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 09:51:21 +01:00 committed by Russell King (Oracle)
parent b78f63f443
commit a91da54570
2 changed files with 31 additions and 3 deletions
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7
arch/arm/include/asm/memory.h
View file

@ -158,6 +158,13 @@ extern unsigned long vectors_base;
#ifndef __ASSEMBLY__
/*
* Physical start and end address of the kernel sections. These addresses are
* 2MB-aligned to match the section mappings placed over the kernel.
*/
extern phys_addr_t kernel_sec_start;
extern phys_addr_t kernel_sec_end;
/*
* Physical vs virtual RAM address space conversion. These are
* private definitions which should NOT be used outside memory.h

27
arch/arm/kernel/head.S
View file

@ -47,6 +47,20 @@
.globl swapper_pg_dir
.equ swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE
/*
* This needs to be assigned at runtime when the linker symbols are
* resolved.
*/
.pushsection .data
.align 2
.globl kernel_sec_start
.globl kernel_sec_end
kernel_sec_start:
.long 0
kernel_sec_end:
.long 0
.popsection
.macro pgtbl, rd, phys
add \rd, \phys, #TEXT_OFFSET
sub \rd, \rd, #PG_DIR_SIZE
@ -229,16 +243,23 @@ __create_page_tables:
blo 1b
/*
* Map our RAM from the start to the end of the kernel .bss section.
* The main matter: map in the kernel using section mappings, and
* set two variables to indicate the physical start and end of the
* kernel.
*/
add r0, r4, #PAGE_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
add r0, r4, #KERNEL_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
ldr r6, =(_end - 1)
orr r3, r8, r7
adr_l r5, kernel_sec_start @ _pa(kernel_sec_start)
str r8, [r5] @ Save physical start of kernel
orr r3, r8, r7 @ Add the MMU flags
add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
1: str r3, [r0], #1 << PMD_ORDER
add r3, r3, #1 << SECTION_SHIFT
cmp r0, r6
bls 1b
eor r3, r3, r7 @ Remove the MMU flags
adr_l r5, kernel_sec_end @ _pa(kernel_sec_end)
str r3, [r5] @ Save physical end of kernel
#ifdef CONFIG_XIP_KERNEL
/*