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Kernel: Support loading the kernel at almost arbitrary virtual addresses

This enables further work on implementing KASLR by adding relocation
support to the pre-kernel and updating the kernel to be less dependent
on specific virtual memory layouts.
This commit is contained in:
Gunnar Beutner 2021-07-26 15:10:51 +02:00 committed by Andreas Kling
parent e3d2ca6bd2
commit 57417a3d6e
20 changed files with 123 additions and 87 deletions

View file

@ -2,39 +2,37 @@
ENTRY(init)
#if ARCH(I386)
# define KERNEL_BASE 0xc0000000
#else
# define KERNEL_BASE 0x2000000000
#endif
#define PF_X 0x1
#define PF_W 0x2
#define PF_R 0x4
KERNEL_VIRTUAL_BASE = KERNEL_BASE;
PHDRS
{
elf_headers PT_LOAD FILEHDR PHDRS FLAGS(PF_R) ;
super_pages PT_LOAD FLAGS(PF_R | PF_W) ;
text PT_LOAD FLAGS(PF_R | PF_X) ;
data PT_LOAD FLAGS(PF_R | PF_W) ;
bss PT_LOAD FLAGS(PF_R | PF_W) ;
dynamic_segment PT_LOAD FLAGS(PF_R | PF_W) ;
dynamic PT_DYNAMIC FLAGS(PF_R | PF_W) ;
ksyms PT_LOAD FLAGS(PF_R) ;
}
SECTIONS
{
. = KERNEL_VIRTUAL_BASE + 0x00200000;
start_of_kernel_image = .;
.super_pages ALIGN(4K) (NOLOAD) : AT (ADDR(.super_pages) - KERNEL_VIRTUAL_BASE)
.elf_headers (SIZEOF_HEADERS) : AT (ADDR(.elf_headers) + SIZEOF_HEADERS)
{
start_of_elf_headers = .;
} :elf_headers
.super_pages ALIGN(4K) (NOLOAD) : AT (ADDR(.super_pages))
{
*(.super_pages)
} :super_pages
.text ALIGN(4K) : AT (ADDR(.text) - KERNEL_VIRTUAL_BASE)
.text ALIGN(4K) : AT (ADDR(.text))
{
start_of_kernel_text = .;
@ -48,7 +46,7 @@ SECTIONS
*(.text*)
} :text
.unmap_after_init ALIGN(4K) : AT (ADDR(.unmap_after_init) - KERNEL_VIRTUAL_BASE)
.unmap_after_init ALIGN(4K) : AT (ADDR(.unmap_after_init))
{
start_of_unmap_after_init = .;
*(.unmap_after_init*);
@ -57,7 +55,7 @@ SECTIONS
end_of_kernel_text = .;
} :text
.rodata ALIGN(4K) : AT (ADDR(.rodata) - KERNEL_VIRTUAL_BASE)
.rodata ALIGN(4K) : AT (ADDR(.rodata))
{
start_heap_ctors = .;
*libkernel_heap.a:*(.ctors)
@ -70,21 +68,21 @@ SECTIONS
*(.rodata*)
} :data
.data ALIGN(4K) : AT (ADDR(.data) - KERNEL_VIRTUAL_BASE)
.data ALIGN(4K) : AT (ADDR(.data))
{
start_of_kernel_data = .;
*(.data*)
end_of_kernel_data = .;
} :data
.ro_after_init ALIGN(4K) (NOLOAD) : AT(ADDR(.ro_after_init) - KERNEL_VIRTUAL_BASE)
.ro_after_init ALIGN(4K) (NOLOAD) : AT(ADDR(.ro_after_init))
{
start_of_ro_after_init = .;
*(.ro_after_init);
end_of_ro_after_init = .;
} :data
.bss ALIGN(4K) (NOLOAD) : AT (ADDR(.bss) - KERNEL_VIRTUAL_BASE)
.bss ALIGN(4K) (NOLOAD) : AT (ADDR(.bss))
{
start_of_kernel_bss = .;
*(page_tables)
@ -96,8 +94,12 @@ SECTIONS
*(.heap)
} :bss
.dynamic ALIGN(4K) : AT (ADDR(.dynamic))
{
*(.dynamic)
} :dynamic_segment :dynamic
.ksyms ALIGN(4K) : AT (ADDR(.ksyms) - KERNEL_VIRTUAL_BASE)
.ksyms ALIGN(4K) : AT (ADDR(.ksyms))
{
start_of_kernel_ksyms = .;
*(.kernel_symbols)