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authorPeter Zijlstra <peterz@infradead.org>2014-01-10 21:06:03 +0100
committerIngo Molnar <mingo@kernel.org>2014-01-16 09:19:48 +0100
commitc026b3591e4f2a4993df773183704bb31634e0bd (patch)
tree2115229bf8310f0f66d7d924e01865bee4af6911
parent85ce70fdf48aa290b4845311c2dd815d7f8d1fa5 (diff)
downloadlinux-c026b3591e4f2a4993df773183704bb31634e0bd.tar.gz
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.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 9ff85bb8dd6..9d591c89580 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;
}