From: Tian Kevin Date: Sun, 24 Jun 2007 00:16:52 +0000 (-0700) Subject: ACPI: preserve the ebx value in acpi_copy_wakeup_routine X-Git-Tag: v2.6.22-rc6~3 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c8cbee61c9d53ee28473ad33bbb54f6a88f5e3af;p=linux-2.6 ACPI: preserve the ebx value in acpi_copy_wakeup_routine 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 Looks-okay-to: Pavel Machek Signed-off-by: Rafael J. Wysocki Cc: Len Brown Acked-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/acpi/wakeup.S b/arch/i386/kernel/acpi/wakeup.S index b781b38131..a2295a34b2 100644 --- a/arch/i386/kernel/acpi/wakeup.S +++ b/arch/i386/kernel/acpi/wakeup.S @@ -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: