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ACPI: preserve the ebx value in acpi_copy_wakeup_routine

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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 <rui.zhang@intel.com>
Looks-okay-to: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tian Kevin 2007-06-23 17:16:52 -07:00 committed by Linus Torvalds
parent e5d2861f31
commit c8cbee61c9
1 changed files with 2 additions and 0 deletions
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2
arch/i386/kernel/acpi/wakeup.S
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@ -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: