diff options
Diffstat (limited to 'arch/i386/boot/compressed/head.S')
| -rw-r--r-- | arch/i386/boot/compressed/head.S | 185 |
1 files changed, 118 insertions, 67 deletions
diff --git a/arch/i386/boot/compressed/head.S b/arch/i386/boot/compressed/head.S index b5893e4..f395a4b 100644 --- a/arch/i386/boot/compressed/head.S +++ b/arch/i386/boot/compressed/head.S @@ -26,9 +26,11 @@ #include <linux/linkage.h> #include <asm/segment.h> #include <asm/page.h> +#include <asm/boot.h> +.section ".text.head" .globl startup_32 - + startup_32: cld cli @@ -37,93 +39,142 @@ startup_32: movl %eax,%es movl %eax,%fs movl %eax,%gs + movl %eax,%ss - lss stack_start,%esp - xorl %eax,%eax -1: incl %eax # check that A20 really IS enabled - movl %eax,0x000000 # loop forever if it isn't - cmpl %eax,0x100000 - je 1b +/* 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 0x34-0x3f are used as the stack for this calculation. + * Only 4 bytes are needed. + */ + leal 0x40(%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 + addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebx + andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx +#else + movl $LOAD_PHYSICAL_ADDR, %ebx +#endif + + /* Replace the compressed data size with the uncompressed size */ + subl input_len(%ebp), %ebx + movl output_len(%ebp), %eax + addl %eax, %ebx + /* Add 8 bytes for every 32K input block */ + shrl $12, %eax + addl %eax, %ebx + /* Add 32K + 18 bytes of extra slack */ + addl $(32768 + 18), %ebx + /* Align on a 4K boundary */ + addl $4095, %ebx + andl $~4095, %ebx + +/* Copy the compressed kernel to the end of our buffer + * where decompression in place becomes safe. + */ + pushl %esi + leal _end(%ebp), %esi + leal _end(%ebx), %edi + movl $(_end - startup_32), %ecx + std + rep + movsb + cld + popl %esi + +/* Compute the kernel start address. + */ +#ifdef CONFIG_RELOCATABLE + addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebp + andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebp +#else + movl $LOAD_PHYSICAL_ADDR, %ebp +#endif /* - * Initialize eflags. Some BIOS's leave bits like NT set. This would - * confuse the debugger if this code is traced. - * XXX - best to initialize before switching to protected mode. + * Jump to the relocated address. */ - pushl $0 - popfl + leal relocated(%ebx), %eax + jmp *%eax +.section ".text" +relocated: + /* * Clear BSS */ xorl %eax,%eax - movl $_edata,%edi - movl $_end,%ecx + leal _edata(%ebx),%edi + leal _end(%ebx), %ecx subl %edi,%ecx cld rep stosb + +/* + * Setup the stack for the decompressor + */ + leal stack_end(%ebx), %esp + /* * Do the decompression, and jump to the new kernel.. */ - subl $16,%esp # place for structure on the stack - movl %esp,%eax + movl output_len(%ebx), %eax + pushl %eax + pushl %ebp # output address + movl input_len(%ebx), %eax + pushl %eax # input_len + leal input_data(%ebx), %eax + pushl %eax # input_data + leal _end(%ebx), %eax + pushl %eax # end of the image as third argument pushl %esi # real mode pointer as second arg - pushl %eax # address of structure as first arg call decompress_kernel - orl %eax,%eax - jnz 3f - popl %esi # discard address - popl %esi # real mode pointer - xorl %ebx,%ebx - ljmp $(__BOOT_CS), $__PHYSICAL_START + addl $20, %esp + popl %ecx +#if CONFIG_RELOCATABLE +/* Find the address of the relocations. + */ + movl %ebp, %edi + addl %ecx, %edi + +/* Calculate the delta between where vmlinux was compiled to run + * and where it was actually loaded. + */ + movl %ebp, %ebx + subl $LOAD_PHYSICAL_ADDR, %ebx + jz 2f /* Nothing to be done if loaded at compiled addr. */ /* - * We come here, if we were loaded high. - * We need to move the move-in-place routine down to 0x1000 - * and then start it with the buffer addresses in registers, - * which we got from the stack. + * Process relocations. */ -3: - movl $move_routine_start,%esi - movl $0x1000,%edi - movl $move_routine_end,%ecx - subl %esi,%ecx - addl $3,%ecx - shrl $2,%ecx - cld - rep - movsl - - popl %esi # discard the address - popl %ebx # real mode pointer - popl %esi # low_buffer_start - popl %ecx # lcount - popl %edx # high_buffer_start - popl %eax # hcount - movl $__PHYSICAL_START,%edi - cli # make sure we don't get interrupted - ljmp $(__BOOT_CS), $0x1000 # and jump to the move routine + +1: subl $4, %edi + movl 0(%edi), %ecx + testl %ecx, %ecx + jz 2f + addl %ebx, -__PAGE_OFFSET(%ebx, %ecx) + jmp 1b +2: +#endif /* - * Routine (template) for moving the decompressed kernel in place, - * if we were high loaded. This _must_ PIC-code ! + * Jump to the decompressed kernel. */ -move_routine_start: - movl %ecx,%ebp - shrl $2,%ecx - rep - movsl - movl %ebp,%ecx - andl $3,%ecx - rep - movsb - movl %edx,%esi - movl %eax,%ecx # NOTE: rep movsb won't move if %ecx == 0 - addl $3,%ecx - shrl $2,%ecx - rep - movsl - movl %ebx,%esi # Restore setup pointer xorl %ebx,%ebx - ljmp $(__BOOT_CS), $__PHYSICAL_START -move_routine_end: + jmp *%ebp + +.bss +.balign 4 +stack: + .fill 4096, 1, 0 +stack_end: |
