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>
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 036e635..ba7736c 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -130,7 +130,7 @@
/*
* 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 @@
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 @@
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:
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index e8657b9..7a212a6 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -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 @@
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 @@
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 @@
*/
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 @@
.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:
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index dad4e699..90456ce 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -217,12 +217,6 @@
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 @@
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;
diff --git a/include/asm-x86/boot.h b/include/asm-x86/boot.h
index ed8affb..2faed7e 100644
--- a/include/asm-x86/boot.h
+++ b/include/asm-x86/boot.h
@@ -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 */