From: Tian Kevin <[email protected]>
Register %ebx serves as the "global offset table base register"
for position-independent code. For absolute code, %ebx serves
as a local register and has no specified role in the function
calling sequence. In either case, a function must preserve the
register value for the caller.
acpi_copy_wakeup_routine overrides %ebx without saving it,
this may corrupt the called data.
Kevin found that most time the value of Sx is saved in %esi,
however sometimes compiler also uses %ebx. When this happens,
suspends fails since sleep value in ebx is changed by
acpi_copy_wakeup_routine.
The same funtion in X86_64 doesn't have this problem.
Signed-off-by: Zhang Rui <[email protected]>
Looks-okay-to: Pavel Machek <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
---
arch/i386/kernel/acpi/wakeup.S | 2 ++
1 files changed, 2 insertions(+)
Index: linux-2.6.22-rc3/arch/i386/kernel/acpi/wakeup.S
===================================================================
--- linux-2.6.22-rc3.orig/arch/i386/kernel/acpi/wakeup.S 2007-05-31 17:23:56.000000000 +0800
+++ linux-2.6.22-rc3/arch/i386/kernel/acpi/wakeup.S 2007-05-31 17:24:08.000000000 +0800
@@ -230,6 +230,7 @@ bogus_magic:
#
ENTRY(acpi_copy_wakeup_routine)
+ pushl %ebx
sgdt saved_gdt
sidt saved_idt
sldt saved_ldt
@@ -263,6 +264,7 @@ ENTRY(acpi_copy_wakeup_routine)
movl %edx, video_flags - wakeup_start (%eax)
movl $0x12345678, real_magic - wakeup_start (%eax)
movl $0x12345678, saved_magic
+ popl %ebx
ret
save_registers:
-
-
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