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
This commit is contained in:
Linus Torvalds 2007-10-26 13:56:01 -07:00
commit 26adc0d585
5 changed files with 51 additions and 25 deletions

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@ -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 @@ static inline int isdigit(int ch)
}
/* 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 @@ static inline char *__get_heap(size_t s, size_t a, size_t n)
#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 */

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@ -173,7 +173,8 @@ ramdisk_size: .long 0 # its size in bytes
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 @@ start_of_setup:
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

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@ -79,7 +79,7 @@ static int bios_probe(void)
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))

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@ -57,7 +57,7 @@ static int vesa_probe(void)
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)

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@ -371,7 +371,7 @@ static void save_screen(void)
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);