Commit-ID: c026b3591e4f2a4993df773183704bb31634e0bd Gitweb: http://git.kernel.org/tip/c026b3591e4f2a4993df773183704bb31634e0bd Author: Peter Zijlstra <[email protected]> AuthorDate: Fri, 10 Jan 2014 21:06:03 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 16 Jan 2014 09:19:48 +0100
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 <[email protected]> Fixes: e00b12e64be9 ("perf/x86: Further optimize copy_from_user_nmi()") Cc: Aswin Chandramouleeswaran <[email protected]> Cc: Scott J Norton <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Andrew Morton <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/mm/fault.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 9ff85bb..9d591c8 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; } -- 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/
