Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | [PATCH] ACPI: preserve the ebx value in acpi_copy_wakeup_routine | Date | Sun, 3 Jun 2007 00:11:42 +0200 |
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From: Tian Kevin <kevin.tian@intel.com>
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> --- 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-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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