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| author | Peter Zijlstra <peterz@infradead.org> | 2014-01-10 21:06:03 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-01-16 09:19:48 +0100 |
| commit | c026b3591e4f2a4993df773183704bb31634e0bd (patch) | |
| tree | 2115229bf8310f0f66d7d924e01865bee4af6911 | |
| parent | Merge branches 'sched-urgent-for-linus' and 'timers-urgent-for-linus' of git:... (diff) | |
| download | linux-c026b3591e4f2a4993df773183704bb31634e0bd.tar.xz linux-c026b3591e4f2a4993df773183704bb31634e0bd.zip | |
x86, mm, perf: Allow recursive faults from interrupts
Waiman managed to trigger a PMI while in a emulate_vsyscall() fault,
the PMI in turn managed to trigger a fault while obtaining a stack
trace. This triggered the sig_on_uaccess_error recursive fault logic
and killed the process dead.
Fix this by explicitly excluding interrupts from the recursive fault
logic.
Reported-and-Tested-by: Waiman Long <waiman.long@hp.com>
Fixes: e00b12e64be9 ("perf/x86: Further optimize copy_from_user_nmi()")
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140110200603.GJ7572@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/mm/fault.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 9ff85bb8dd69..9d591c895803 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -641,6 +641,20 @@ no_context(struct pt_regs *regs, unsigned long error_code, /* Are we prepared to handle this kernel fault? */ if (fixup_exception(regs)) { + /* + * Any interrupt that takes a fault gets the fixup. This makes + * the below recursive fault logic only apply to a faults from + * task context. + */ + if (in_interrupt()) + return; + + /* + * Per the above we're !in_interrupt(), aka. task context. + * + * In this case we need to make sure we're not recursively + * faulting through the emulate_vsyscall() logic. + */ if (current_thread_info()->sig_on_uaccess_error && signal) { tsk->thread.trap_nr = X86_TRAP_PF; tsk->thread.error_code = error_code | PF_USER; @@ -649,6 +663,10 @@ no_context(struct pt_regs *regs, unsigned long error_code, /* XXX: hwpoison faults will set the wrong code. */ force_sig_info_fault(signal, si_code, address, tsk, 0); } + + /* + * Barring that, we can do the fixup and be happy. + */ return; } |