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authorkib <kib@FreeBSD.org>2010-05-12 10:29:35 +0000
committerkib <kib@FreeBSD.org>2010-05-12 10:29:35 +0000
commit7c190c1c89d45ca83db4120a8a5fe107a8a52050 (patch)
treeeecf228988f4249cfce539021a39a53ebe7b9b01 /usr.bin
parent7b04e359b060fb4d6869ca817495df9327ef6090 (diff)
downloadFreeBSD-src-7c190c1c89d45ca83db4120a8a5fe107a8a52050.zip
FreeBSD-src-7c190c1c89d45ca83db4120a8a5fe107a8a52050.tar.gz
Route all returns from the interrupts and faults through the doreti_iret
labeled iretq instruction. Suppose that multithreaded process executes two threads, currently scheduled on different processors. Let assume that thread A executes using %cs or %ss pointing into the descriptor from LDT. If IPI comes which handler does not return by jump to doreti, and meantime thread B invalidates descriptor pointed to by %cs or %ss, then iretq from IPI handler could fault. Routing the return by doreti_iret allows kernel to catch the situation and recover from it by sending signal to the usermode. Tested by: pho MFC after: 1 week
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