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Commit 7c539764 authored by Alexander van Heukelum's avatar Alexander van Heukelum Committed by Ingo Molnar
Browse files

x86: cleanup boot-heap usage 



The kernel decompressor wrapper uses memory located beyond the
end of the image. This might lead to hard to debug problems,
but even if it can be proven to be safe, it is at the very
least unclean. I don't see any advantages either, unless you
count it not being zeroed out as an advantage. This patch
moves the boot-heap area to the bss segment.

Signed-off-by: default avatarAlexander van Heukelum <heukelum@fastmail.fm>

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 4c8337ac

arch/x86/boot/compressed/head_32.S

+9 −6
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ relocated: 
/*

 * Setup the stack for the decompressor

 */

	leal stack_end(%ebx), %esp

	leal boot_stack_end(%ebx), %esp



/*

 * Do the decompression, and jump to the new kernel..
@@ -142,8 +142,8 @@ relocated: 
	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

	leal boot_heap(%ebx), %eax

	pushl %eax	# heap area as third argument

	pushl %esi	# real mode pointer as second arg

	call decompress_kernel

	addl $20, %esp
@@ -181,7 +181,10 @@ relocated: 
	jmp *%ebp



.bss

/* Stack and heap for uncompression */

.balign 4

stack:

	.fill 4096, 1, 0

stack_end:
 
boot_heap:

	.fill BOOT_HEAP_SIZE, 1, 0

boot_stack:

	.fill BOOT_STACK_SIZE, 1, 0

boot_stack_end:

arch/x86/boot/compressed/head_64.S

+13 −9
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <asm/segment.h>

#include <asm/pgtable.h>

#include <asm/page.h>

#include <asm/boot.h>

#include <asm/msr.h>

#include <asm/asm-offsets.h>
@@ -62,7 +63,7 @@ startup_32: 
	subl	$1b, %ebp



/* setup a stack and make sure cpu supports long mode. */

	movl	$user_stack_end, %eax

	movl	$boot_stack_end, %eax

	addl	%ebp, %eax

	movl	%eax, %esp
@@ -274,7 +275,7 @@ relocated: 
	stosb



	/* Setup the stack */

	leaq	user_stack_end(%rip), %rsp

	leaq	boot_stack_end(%rip), %rsp



	/* zero EFLAGS after setting rsp */

	pushq	$0
@@ -285,7 +286,7 @@ relocated: 
 */

	pushq	%rsi			# Save the real mode argument

	movq	%rsi, %rdi		# real mode address

	leaq	_heap(%rip), %rsi	# _heap

	leaq	boot_heap(%rip), %rsi	# malloc area for uncompression

	leaq	input_data(%rip), %rdx  # input_data

	movl	input_len(%rip), %eax

	movq	%rax, %rcx		# input_len
@@ -310,9 +311,12 @@ gdt: 
	.quad	0x0080890000000000	/* TS descriptor */

	.quad   0x0000000000000000	/* TS continued */

gdt_end:



.bss

/* Stack for uncompression */

/* Stack and heap for uncompression */

.balign 4

user_stack:

	.fill 4096,4,0

user_stack_end:
 
boot_heap:

	.fill BOOT_HEAP_SIZE, 1, 0

boot_stack:

	.fill BOOT_STACK_SIZE, 1, 0

boot_stack_end:

arch/x86/boot/compressed/misc.c

+1 −7
Original line number Diff line number Diff line
@@ -217,12 +217,6 @@ static void putstr(const char *); 
static memptr free_mem_ptr;

static memptr free_mem_end_ptr;



#ifdef CONFIG_X86_64

#define HEAP_SIZE             0x7000

#else

#define HEAP_SIZE             0x4000

#endif



static char *vidmem;

static int vidport;

static int lines, cols;
@@ -449,7 +443,7 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap, 


	window = output;		/* Output buffer (Normally at 1M) */

	free_mem_ptr     = heap;	/* Heap */

	free_mem_end_ptr = heap + HEAP_SIZE;

	free_mem_end_ptr = heap + BOOT_HEAP_SIZE;

	inbuf  = input_data;		/* Input buffer */

	insize = input_len;

	inptr  = 0;

include/asm-x86/boot.h

+8 −0
Original line number Diff line number Diff line
@@ -17,4 +17,12 @@ 
				+ (CONFIG_PHYSICAL_ALIGN - 1)) \

				& ~(CONFIG_PHYSICAL_ALIGN - 1))



#ifdef CONFIG_X86_64

#define BOOT_HEAP_SIZE	0x7000

#define BOOT_STACK_SIZE	0x4000

#else

#define BOOT_HEAP_SIZE	0x4000

#define BOOT_STACK_SIZE	0x1000

#endif



#endif /* _ASM_BOOT_H */