Home
Reading
Searching
Subscribe
Sponsors
Statistics
Posting
Contact
Spam
Lists
Links
About
Hosting
Filtering
Features Download
Marketing
Archives
FAQ
Blog
 
Gmane
From: Zhang Rui <rui.zhang <at> intel.com>
Subject: [PATCH]: ACPI: preserve the ebx value in acpi_copy_wakeup_routine
Newsgroups: gmane.linux.acpi.devel
Date: Friday 1st June 2007 10:09:13 UTC (over 10 years ago)
From: Tian Kevin 

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 
---
 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:
-
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
 
CD: 4ms