diff options
Diffstat (limited to 'kernel/arch/x86/boot/compressed/head_32.S')
| -rw-r--r-- | kernel/arch/x86/boot/compressed/head_32.S | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/kernel/arch/x86/boot/compressed/head_32.S b/kernel/arch/x86/boot/compressed/head_32.S new file mode 100644 index 000000000..8ef964ddc --- /dev/null +++ b/kernel/arch/x86/boot/compressed/head_32.S @@ -0,0 +1,248 @@ +/* + * linux/boot/head.S + * + * Copyright (C) 1991, 1992, 1993 Linus Torvalds + */ + +/* + * head.S contains the 32-bit startup code. + * + * NOTE!!! Startup happens at absolute address 0x00001000, which is also where + * the page directory will exist. The startup code will be overwritten by + * the page directory. [According to comments etc elsewhere on a compressed + * kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC] + * + * Page 0 is deliberately kept safe, since System Management Mode code in + * laptops may need to access the BIOS data stored there. This is also + * useful for future device drivers that either access the BIOS via VM86 + * mode. + */ + +/* + * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 + */ + .text + +#include <linux/init.h> +#include <linux/linkage.h> +#include <asm/segment.h> +#include <asm/page_types.h> +#include <asm/boot.h> +#include <asm/asm-offsets.h> +#include <asm/bootparam.h> + + __HEAD +ENTRY(startup_32) +#ifdef CONFIG_EFI_STUB + jmp preferred_addr + + /* + * We don't need the return address, so set up the stack so + * efi_main() can find its arguments. + */ +ENTRY(efi_pe_entry) + add $0x4, %esp + + call 1f +1: popl %esi + subl $1b, %esi + + popl %ecx + movl %ecx, efi32_config(%esi) /* Handle */ + popl %ecx + movl %ecx, efi32_config+8(%esi) /* EFI System table pointer */ + + /* Relocate efi_config->call() */ + leal efi32_config(%esi), %eax + add %esi, 88(%eax) + pushl %eax + + call make_boot_params + cmpl $0, %eax + je fail + movl %esi, BP_code32_start(%eax) + popl %ecx + pushl %eax + pushl %ecx + jmp 2f /* Skip efi_config initialization */ + +ENTRY(efi32_stub_entry) + add $0x4, %esp + popl %ecx + popl %edx + + call 1f +1: popl %esi + subl $1b, %esi + + movl %ecx, efi32_config(%esi) /* Handle */ + movl %edx, efi32_config+8(%esi) /* EFI System table pointer */ + + /* Relocate efi_config->call() */ + leal efi32_config(%esi), %eax + add %esi, 88(%eax) + pushl %eax +2: + call efi_main + cmpl $0, %eax + movl %eax, %esi + jne 2f +fail: + /* EFI init failed, so hang. */ + hlt + jmp fail +2: + movl BP_code32_start(%esi), %eax + leal preferred_addr(%eax), %eax + jmp *%eax + +preferred_addr: +#endif + cld + /* + * Test KEEP_SEGMENTS flag to see if the bootloader is asking + * us to not reload segments + */ + testb $KEEP_SEGMENTS, BP_loadflags(%esi) + jnz 1f + + cli + movl $__BOOT_DS, %eax + movl %eax, %ds + movl %eax, %es + movl %eax, %fs + movl %eax, %gs + movl %eax, %ss +1: + +/* + * Calculate the delta between where we were compiled to run + * at and where we were actually loaded at. This can only be done + * with a short local call on x86. Nothing else will tell us what + * address we are running at. The reserved chunk of the real-mode + * data at 0x1e4 (defined as a scratch field) are used as the stack + * for this calculation. Only 4 bytes are needed. + */ + leal (BP_scratch+4)(%esi), %esp + call 1f +1: popl %ebp + subl $1b, %ebp + +/* + * %ebp contains the address we are loaded at by the boot loader and %ebx + * contains the address where we should move the kernel image temporarily + * for safe in-place decompression. + */ + +#ifdef CONFIG_RELOCATABLE + movl %ebp, %ebx + movl BP_kernel_alignment(%esi), %eax + decl %eax + addl %eax, %ebx + notl %eax + andl %eax, %ebx + cmpl $LOAD_PHYSICAL_ADDR, %ebx + jge 1f +#endif + movl $LOAD_PHYSICAL_ADDR, %ebx +1: + + /* Target address to relocate to for decompression */ + addl $z_extract_offset, %ebx + + /* Set up the stack */ + leal boot_stack_end(%ebx), %esp + + /* Zero EFLAGS */ + pushl $0 + popfl + +/* + * Copy the compressed kernel to the end of our buffer + * where decompression in place becomes safe. + */ + pushl %esi + leal (_bss-4)(%ebp), %esi + leal (_bss-4)(%ebx), %edi + movl $(_bss - startup_32), %ecx + shrl $2, %ecx + std + rep movsl + cld + popl %esi + +/* + * Jump to the relocated address. + */ + leal relocated(%ebx), %eax + jmp *%eax +ENDPROC(startup_32) + + .text +relocated: + +/* + * Clear BSS (stack is currently empty) + */ + xorl %eax, %eax + leal _bss(%ebx), %edi + leal _ebss(%ebx), %ecx + subl %edi, %ecx + shrl $2, %ecx + rep stosl + +/* + * Adjust our own GOT + */ + leal _got(%ebx), %edx + leal _egot(%ebx), %ecx +1: + cmpl %ecx, %edx + jae 2f + addl %ebx, (%edx) + addl $4, %edx + jmp 1b +2: + +/* + * Do the decompression, and jump to the new kernel.. + */ + /* push arguments for decompress_kernel: */ + pushl $z_run_size /* size of kernel with .bss and .brk */ + pushl $z_output_len /* decompressed length, end of relocs */ + leal z_extract_offset_negative(%ebx), %ebp + pushl %ebp /* output address */ + pushl $z_input_len /* input_len */ + leal input_data(%ebx), %eax + pushl %eax /* input_data */ + leal boot_heap(%ebx), %eax + pushl %eax /* heap area */ + pushl %esi /* real mode pointer */ + call decompress_kernel /* returns kernel location in %eax */ + addl $28, %esp + +/* + * Jump to the decompressed kernel. + */ + xorl %ebx, %ebx + jmp *%eax + +#ifdef CONFIG_EFI_STUB + .data +efi32_config: + .fill 11,8,0 + .long efi_call_phys + .long 0 + .byte 0 +#endif + +/* + * Stack and heap for uncompression + */ + .bss + .balign 4 +boot_heap: + .fill BOOT_HEAP_SIZE, 1, 0 +boot_stack: + .fill BOOT_STACK_SIZE, 1, 0 +boot_stack_end: |