Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | Re: avoid infinite loop in x86_64 interrupt return | Date | Wed, 4 May 2005 11:00:32 +0200 |
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Hi,
On Wednesday, 4 of May 2005 07:01, Andrea Arcangeli wrote: > Hello, > > A few minutes ago I've got an unkillable task in R state with vanilla > 2.6.12-rc3 on x86_64, luckily system was still up with the other cpu (on > the desktop, so I had no kgdb environment set). Debugging revelaed rdi > corrupt when entering retint_signal (not set to $_TIF_WORK_MASK as > expected). This lead the rdx&rdi to return 0x20000 -> infinite loop. > Precisely rdi is set to ffff810030923f58 instead of $_TIF_WORK_MASK. So > it was the combination of ...2xxxx as rsp with TIF_IA32 in the task > flags. After noticing the rdi screwup the bug was quite clear: rdi was > set to pt_regs instead of $_TIF_WORK_MASK. Of course rsp is set to > ffff810030923f58 too (which also means do_notify_resume didn't clobber > rdi even if it could). > > The below should fix the problem, I've no idea how to reproduce the > problem but it works on basic testing. The task looping was java (32bit, > that's where the 0x20000 come from), but it wasn't me starting java, it > must have been some random website (java was hanging around with 100% > system time for half an hour once I noticed it). > > Signed-off-by: Andrea Arcangeli <andrea@suse.de> > > --- 2.6.12-rc3/arch/x86_64/kernel/entry.S.orig 2005-05-04 06:47:02.000000000 +0200 > +++ 2.6.12-rc3/arch/x86_64/kernel/entry.S 2005-05-04 06:50:34.000000000 +0200 > @@ -489,6 +489,7 @@ retint_signal: > movq %rsp,%rdi # &pt_regs > call do_notify_resume > RESTORE_REST > + movl $_TIF_WORK_MASK,%edi > cli > GET_THREAD_INFO(%rcx) > jmp retint_check > -
You also need to add two missing clis. Please have a look at the attached patch from Andi.
Greets, Rafael
-- - Would you tell me, please, which way I ought to go from here? - That depends a good deal on where you want to get to. -- Lewis Carroll "Alice's Adventures in Wonderland" Signed-off-by: Andi Kleen <ak@suse.de>
diff -u linux-2.6.12rc3/arch/x86_64/kernel/entry.S-o linux-2.6.12rc3/arch/x86_64/kernel/entry.S --- linux-2.6.12rc3/arch/x86_64/kernel/entry.S-o 2005-04-22 12:48:11.000000000 +0200 +++ linux-2.6.12rc3/arch/x86_64/kernel/entry.S 2005-04-27 15:52:49.305183345 +0200 @@ -296,6 +296,7 @@ call syscall_trace_leave popq %rdi andl $~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edi + cli jmp int_restore_rest int_signal: @@ -307,6 +308,7 @@ 1: movl $_TIF_NEED_RESCHED,%edi int_restore_rest: RESTORE_REST + cli jmp int_with_check CFI_ENDPROC @@ -490,7 +492,8 @@ call do_notify_resume RESTORE_REST cli - GET_THREAD_INFO(%rcx) + GET_THREAD_INFO(%rcx) + movl $_TIF_WORK_MASK,%edi jmp retint_check #ifdef CONFIG_PREEMPT
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