acpi_wakeup.S: simplify logic

Pavel Machek (pavel@ucw.cz)
Wed, 4 Dec 2002 13:58:17 +0100


Hi!

This simplifies logic in acpi_wakeup.S by putting code and data into
same segment. Plus it kills off-by-3 bug and uses constant instead of
hardcoded value. Please apply,
Pavel

--- clean/arch/i386/kernel/acpi_wakeup.S 2002-11-19 16:45:58.000000000 +0100
+++ linux-swsusp/arch/i386/kernel/acpi_wakeup.S 2002-12-04 13:34:30.000000000 +0100
@@ -1,12 +1,21 @@
-
.text
#include <linux/linkage.h>
#include <asm/segment.h>
+#include <asm/page.h>

-# Do we need to deal with A20?
+#
+# wakeup_code runs in real mode, and at unknown address (determined at run-time).
+# Therefore it must only use relative jumps/calls.
+#
+# Do we need to deal with A20? It is okay: ACPI specs says A20 must be enabled
+#
+# If physical address of wakeup_code is 0x12345, BIOS should call us with
+# cs = 0x1234, eip = 0x05
+#

ALIGN
-wakeup_start:
+ .align 4096
+ENTRY(wakeup_start)
wakeup_code:
wakeup_code_start = .
.code16
@@ -14,49 +23,70 @@
movw $0xb800, %ax
movw %ax,%fs
movw $0x0e00 + 'L', %fs:(0x10)
+
cli
cld
-
+
# setup data segment
movw %cs, %ax
-
- addw $(wakeup_data - wakeup_code) >> 4, %ax
- movw %ax, %ds
+ movw %ax, %ds # Make ds:0 point to wakeup_start
movw %ax, %ss
- mov $(wakeup_stack - wakeup_data), %sp # Private stack is needed for ASUS board
- movw $0x0e00 + 'S', %fs:(0x12)
+ mov wakeup_stack - wakeup_code, %sp # Private stack is needed for ASUS board
+ movw $0x0e00 + 'S', %fs:(0x12)

- movl real_magic - wakeup_data, %eax
+ pushl $0 # Kill any dangerous flags
+ popfl
+
+ movl real_magic - wakeup_code, %eax
cmpl $0x12345678, %eax
jne bogus_real_magic

- mov video_mode - wakeup_data, %ax
+#if 1
+ lcall $0xc000,$3
+#endif
+#if 0
+ mov video_mode - wakeup_code, %ax
call mode_set
+#endif

# set up page table
- movl (real_save_cr3 - wakeup_data), %eax
+#if 1
+ movl $swapper_pg_dir-__PAGE_OFFSET, %eax
+#else
+ movl (real_save_cr3 - wakeup_data), %eax
+#endif
movl %eax, %cr3

# make sure %cr4 is set correctly (features, etc)
- movl (real_save_cr4 - wakeup_data), %eax
+ movl real_save_cr4 - wakeup_code, %eax
movl %eax, %cr4
movw $0xb800, %ax
movw %ax,%fs
movw $0x0e00 + 'i', %fs:(0x12)
-
+
# need a gdt
- lgdt real_save_gdt - wakeup_data
+ lgdt real_save_gdt - wakeup_code

- movl (real_save_cr0 - wakeup_data), %eax
+ movl real_save_cr0 - wakeup_code, %eax
movl %eax, %cr0
+ jmp 1f
+1:
movw $0x0e00 + 'n', %fs:(0x14)

- movl real_magic - wakeup_data, %eax
+ movl real_magic - wakeup_code, %eax
cmpl $0x12345678, %eax
jne bogus_real_magic

ljmpl $__KERNEL_CS,$wakeup_pmode_return

+real_save_gdt: .word 0
+ .long 0
+real_save_cr0: .long 0
+real_save_cr3: .long 0
+real_save_cr4: .long 0
+real_magic: .long 0
+video_mode: .long 0
+
bogus_real_magic:
movw $0x0e00 + 'B', %fs:(0x12)
jmp bogus_real_magic
@@ -129,20 +159,12 @@
.code32
ALIGN

-.org 0x300
-wakeup_data:
- .word 0
-real_save_gdt: .word 0
- .long 0
-real_save_cr0: .long 0
-real_save_cr3: .long 0
-real_save_cr4: .long 0
-real_magic: .long 0
-video_mode: .long 0

-.org 0x500
+.org 0x2000
wakeup_stack:
-wakeup_end:
+.org 0x3000
+ENTRY(wakeup_end)
+.org 0x4000

wakeup_pmode_return:
movl $__KERNEL_DS, %eax
@@ -205,7 +227,6 @@
movw $0x0e00 + '2', %ds:(0xb8018)
jmp bogus_magic2

-
##
# acpi_copy_wakeup_routine
#
@@ -228,7 +249,7 @@

movl %eax, %edi
leal wakeup_start, %esi
- movl $(wakeup_end - wakeup_start) >> 2, %ecx
+ movl $(wakeup_end - wakeup_start + 3) >> 2, %ecx

rep ; movsl

@@ -290,8 +311,8 @@
ret
.p2align 4,,7
.L1432:
- movl $104,%eax
- movw %eax, %ds
+ movl $__KERNEL_DS,%eax
+ movw %ax, %ds
movl saved_context_esp, %esp
movl saved_context_ebp, %ebp
movl saved_context_eax, %eax
@@ -310,5 +331,4 @@
saved_idt: .long 0,0
saved_ldt: .long 0
saved_tss: .long 0
-saved_cr0: .long 0

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