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: Alexander van Heukelum <heukelum@fastmail.fm>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Alexander van Heukelum 2008-04-08 12:54:30 +02:00 committed by Ingo Molnar
parent 4c8337ac42
commit 7c53976404
4 changed files with 31 additions and 22 deletions

View file

@ -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:

View file

@ -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 */
.balign 4
user_stack:
.fill 4096,4,0
user_stack_end:
.bss
/* Stack and heap for uncompression */
.balign 4
boot_heap:
.fill BOOT_HEAP_SIZE, 1, 0
boot_stack:
.fill BOOT_STACK_SIZE, 1, 0
boot_stack_end:

View file

@ -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;

View file

@ -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 */