On Tue 2015-06-16 14:46:20, Denys Vlasenko wrote: > 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 > >> bogus_magic: > > > > Longjump is supposed to flush the prefetch, but hopefully nothing > > depends on that detail... ... > > > > no. > > > > https://en.wikibooks.org/wiki/X86_Assembly/Protected_Mode#Entering_Protected_Mode > > > > 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.
Yup, you are right, the ljmp is few instructions above that. > And we aren't switching to or from protected mode here. wakeup_pmode_return... that's just after switching to protected mode AFAICT. Anyway, Acked-by: Pavel Machek <[email protected]> Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
