Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hpa/linux-2.6-x86setup
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hpa/linux-2.6-x86setup:
x86 setup: sizeof() is unsigned, unbreak comparisons
x86 setup: handle boot loaders which set up the stack incorrectly
diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 5f9a2e7..d2b5adf 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -17,6 +17,8 @@
#ifndef BOOT_BOOT_H
#define BOOT_BOOT_H
+#define STACK_SIZE 512 /* Minimum number of bytes for stack */
+
#ifndef __ASSEMBLY__
#include <stdarg.h>
@@ -198,8 +200,6 @@
}
/* Heap -- available for dynamic lists. */
-#define STACK_SIZE 512 /* Minimum number of bytes for stack */
-
extern char _end[];
extern char *HEAP;
extern char *heap_end;
@@ -216,9 +216,9 @@
#define GET_HEAP(type, n) \
((type *)__get_heap(sizeof(type),__alignof__(type),(n)))
-static inline int heap_free(void)
+static inline bool heap_free(size_t n)
{
- return heap_end-HEAP;
+ return (int)(heap_end-HEAP) >= (int)n;
}
/* copy.S */
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 8353c81..6ef5a06 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -173,7 +173,8 @@
bootsect_kludge:
.long 0 # obsolete
-heap_end_ptr: .word _end+1024 # (Header version 0x0201 or later)
+heap_end_ptr: .word _end+STACK_SIZE-512
+ # (Header version 0x0201 or later)
# space from here (exclusive) down to
# end of setup code can be used by setup
# for local heap purposes.
@@ -230,28 +231,53 @@
int $0x13
#endif
-# We will have entered with %cs = %ds+0x20, normalize %cs so
-# it is on par with the other segments.
- pushw %ds
- pushw $setup2
- lretw
-
-setup2:
# Force %es = %ds
movw %ds, %ax
movw %ax, %es
cld
-# Stack paranoia: align the stack and make sure it is good
-# for both 16- and 32-bit references. In particular, if we
-# were meant to have been using the full 16-bit segment, the
-# caller might have set %sp to zero, which breaks %esp-based
-# references.
- andw $~3, %sp # dword align (might as well...)
- jnz 1f
- movw $0xfffc, %sp # Make sure we're not zero
-1: movzwl %sp, %esp # Clear upper half of %esp
- sti
+# Apparently some ancient versions of LILO invoked the kernel
+# with %ss != %ds, which happened to work by accident for the
+# old code. If the CAN_USE_HEAP flag is set in loadflags, or
+# %ss != %ds, then adjust the stack pointer.
+
+ # Smallest possible stack we can tolerate
+ movw $(_end+STACK_SIZE), %cx
+
+ movw heap_end_ptr, %dx
+ addw $512, %dx
+ jnc 1f
+ xorw %dx, %dx # Wraparound - whole segment available
+1: testb $CAN_USE_HEAP, loadflags
+ jnz 2f
+
+ # No CAN_USE_HEAP
+ movw %ss, %dx
+ cmpw %ax, %dx # %ds == %ss?
+ movw %sp, %dx
+ # If so, assume %sp is reasonably set, otherwise use
+ # the smallest possible stack.
+ jne 4f # -> Smallest possible stack...
+
+ # Make sure the stack is at least minimum size. Take a value
+ # of zero to mean "full segment."
+2:
+ andw $~3, %dx # dword align (might as well...)
+ jnz 3f
+ movw $0xfffc, %dx # Make sure we're not zero
+3: cmpw %cx, %dx
+ jnb 5f
+4: movw %cx, %dx # Minimum value we can possibly use
+5: movw %ax, %ss
+ movzwl %dx, %esp # Clear upper half of %esp
+ sti # Now we should have a working stack
+
+# We will have entered with %cs = %ds+0x20, normalize %cs so
+# it is on par with the other segments.
+ pushw %ds
+ pushw $6f
+ lretw
+6:
# Check signature at end of setup
cmpl $0x5a5aaa55, setup_sig
diff --git a/arch/x86/boot/video-bios.c b/arch/x86/boot/video-bios.c
index 68e65d9..ed0672a 100644
--- a/arch/x86/boot/video-bios.c
+++ b/arch/x86/boot/video-bios.c
@@ -79,7 +79,7 @@
video_bios.modes = GET_HEAP(struct mode_info, 0);
for (mode = 0x14; mode <= 0x7f; mode++) {
- if (heap_free() < sizeof(struct mode_info))
+ if (!heap_free(sizeof(struct mode_info)))
break;
if (mode_defined(VIDEO_FIRST_BIOS+mode))
diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
index 1921907..4716b9a 100644
--- a/arch/x86/boot/video-vesa.c
+++ b/arch/x86/boot/video-vesa.c
@@ -57,7 +57,7 @@
while ((mode = rdfs16(mode_ptr)) != 0xffff) {
mode_ptr += 2;
- if (heap_free() < sizeof(struct mode_info))
+ if (!heap_free(sizeof(struct mode_info)))
break; /* Heap full, can't save mode info */
if (mode & ~0x1ff)
diff --git a/arch/x86/boot/video.c b/arch/x86/boot/video.c
index e4ba897..ad9712f 100644
--- a/arch/x86/boot/video.c
+++ b/arch/x86/boot/video.c
@@ -371,7 +371,7 @@
saved.curx = boot_params.screen_info.orig_x;
saved.cury = boot_params.screen_info.orig_y;
- if (heap_free() < saved.x*saved.y*sizeof(u16)+512)
+ if (!heap_free(saved.x*saved.y*sizeof(u16)+512))
return; /* Not enough heap to save the screen */
saved.data = GET_HEAP(u16, saved.x*saved.y);