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x86/decompressor: Factor out kernel decompression and relocation

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Factor out the decompressor sequence that invokes the decompressor,
parses the ELF and applies the relocations so that it can be called
directly from the EFI stub.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230807162720.545787-21-ardb@kernel.org
This commit is contained in:
Ard Biesheuvel 2023-08-07 18:27:17 +02:00 committed by Borislav Petkov (AMD)
parent 24388292e2
commit 8338151935
2 changed files with 31 additions and 5 deletions
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28
arch/x86/boot/compressed/misc.c
View File

@ -330,11 +330,33 @@ static size_t parse_elf(void *output)
return ehdr.e_entry - LOAD_PHYSICAL_ADDR;
}
const unsigned long kernel_total_size = VO__end - VO__text;
static u8 boot_heap[BOOT_HEAP_SIZE] __aligned(4);
extern unsigned char input_data[];
extern unsigned int input_len, output_len;
unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr,
void (*error)(char *x))
{
unsigned long entry;
if (!free_mem_ptr) {
free_mem_ptr = (unsigned long)boot_heap;
free_mem_end_ptr = (unsigned long)boot_heap + sizeof(boot_heap);
}
if (__decompress(input_data, input_len, NULL, NULL, outbuf, output_len,
NULL, error) < 0)
return ULONG_MAX;
entry = parse_elf(outbuf);
handle_relocations(outbuf, output_len, virt_addr);
return entry;
}
/*
* The compressed kernel image (ZO), has been moved so that its position
* is against the end of the buffer used to hold the uncompressed kernel
@ -354,7 +376,6 @@ extern unsigned int input_len, output_len;
*/
asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output)
{
const unsigned long kernel_total_size = VO__end - VO__text;
unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
memptr heap = (memptr)boot_heap;
unsigned long needed_size;
@ -463,10 +484,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output)
accept_memory(__pa(output), __pa(output) + needed_size);
}
__decompress(input_data, input_len, NULL, NULL, output, output_len,
NULL, error);
entry_offset = parse_elf(output);
handle_relocations(output, output_len, virt_addr);
entry_offset = decompress_kernel(output, virt_addr, error);
debug_putstr("done.\nBooting the kernel (entry_offset: 0x");
debug_puthex(entry_offset);

8
arch/x86/include/asm/boot.h
View File

@ -62,4 +62,12 @@
# define BOOT_STACK_SIZE 0x1000
#endif
#ifndef __ASSEMBLY__
extern unsigned int output_len;
extern const unsigned long kernel_total_size;
unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr,
void (*error)(char *x));
#endif
#endif /* _ASM_X86_BOOT_H */