Re: [PATCH 1/3] x86, acpi: Eliminate saved_eip
From: Denys Vlasenko
Date: Tue Jun 16 2015 - 08:46:29 EST
On 06/16/2015 12:05 PM, Pavel Machek wrote:
>> diff --git a/arch/x86/kernel/acpi/wakeup_32.S b/arch/x86/kernel/acpi/wakeup_32.S
>> index 665c6b7..eef2bd3 100644
>> --- a/arch/x86/kernel/acpi/wakeup_32.S
>> +++ b/arch/x86/kernel/acpi/wakeup_32.S
>> @@ -31,17 +31,11 @@ wakeup_pmode_return:
>> movl %cs:saved_magic, %eax
>> cmpl $0x12345678, %eax
>> - jne bogus_magic
>> - # jump to place where we left off
>> - movl saved_eip, %eax
>> - jmp *%eax
>> + je ret_point
> Longjump is supposed to flush the prefetch, but hopefully nothing
> depends on that detail... ...
> longjump is supposed to be there. Sorry about that. I guess indirect
> jump is not neccessary, and we should add a comment there.
What "long jump"? It's not a far (segment:offset) jump, it's a near
jump (one which only changes the offset), indirect one through a register.
And we aren't switching to or from protected mode here.
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