Commit 8ef44be3 authored by Arvind Sankar's avatar Arvind Sankar Committed by Ingo Molnar
Browse files

x86/boot/compressed/32: Save the output address instead of recalculating it 



In preparation for being able to decompress into a buffer starting at a
different address than startup_32, save the calculated output address
instead of recalculating it later.

We now keep track of three addresses:

	%edx: startup_32 as we were loaded by bootloader
	%ebx: new location of compressed kernel
	%ebp: start of decompression buffer

Signed-off-by: default avatarArvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200303221205.4048668-2-nivedita@alum.mit.edu
Link: https://lore.kernel.org/r/20200308080859.21568-16-ardb@kernel.org
parent f3fa0efc

arch/x86/boot/compressed/head_32.S

+12 −13
Original line number Diff line number Diff line
@@ -75,11 +75,11 @@ SYM_FUNC_START(startup_32) 
 */

	leal	(BP_scratch+4)(%esi), %esp

	call	1f

1:	popl	%ebp

	subl	$1b, %ebp

1:	popl	%edx

	subl	$1b, %edx



	/* Load new GDT */

	leal	gdt(%ebp), %eax

	leal	gdt(%edx), %eax

	movl	%eax, 2(%eax)

	lgdt	(%eax)
@@ -92,13 +92,14 @@ SYM_FUNC_START(startup_32) 
	movl	%eax, %ss



/*

 * %ebp contains the address we are loaded at by the boot loader and %ebx

 * %edx 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.

 * for safe in-place decompression. %ebp contains the address that the kernel

 * will be decompressed to.

 */



#ifdef CONFIG_RELOCATABLE

	movl	%ebp, %ebx

	movl	%edx, %ebx

	movl	BP_kernel_alignment(%esi), %eax

	decl	%eax

	addl    %eax, %ebx
@@ -110,10 +111,10 @@ SYM_FUNC_START(startup_32) 
	movl	$LOAD_PHYSICAL_ADDR, %ebx

1:



	movl	%ebx, %ebp	// Save the output address for later

	/* Target address to relocate to for decompression */

	movl    BP_init_size(%esi), %eax

	subl    $_end, %eax

	addl    %eax, %ebx

	addl    BP_init_size(%esi), %ebx

	subl    $_end, %ebx



	/* Set up the stack */

	leal	boot_stack_end(%ebx), %esp
@@ -127,7 +128,7 @@ SYM_FUNC_START(startup_32) 
 * where decompression in place becomes safe.

 */

	pushl	%esi

	leal	(_bss-4)(%ebp), %esi

	leal	(_bss-4)(%edx), %esi

	leal	(_bss-4)(%ebx), %edi

	movl	$(_bss - startup_32), %ecx

	shrl	$2, %ecx
@@ -196,9 +197,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) 
				/* push arguments for extract_kernel: */

	pushl	$z_output_len	/* decompressed length, end of relocs */



	leal	_end(%ebx), %eax

	subl    BP_init_size(%esi), %eax

	pushl	%eax		/* output address */

	pushl	%ebp		/* output address */



	pushl	$z_input_len	/* input_len */

	leal	input_data(%ebx), %eax

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