Clearing RF EFLAGS bit for signal handler. The reason is, that this flag is set by debug exception code to prevent the recursive exception entry.
Leaving it set for signal handler might prevent debug exception of the signal handler itself. Signed-off-by: Jiri Olsa <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Corey Ashford <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Vince Weaver <[email protected]> --- arch/x86/kernel/signal.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index b6fe116..e273571 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -726,6 +726,13 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, regs->flags &= ~X86_EFLAGS_DF; /* + * Clear RF when entering the signal handler, because + * it might disable possible debug exception from the + * signal handler. + */ + regs->flags &= ~X86_EFLAGS_RF; + + /* * Clear TF when entering the signal handler, but * notify any tracer that was single-stepping it. * The tracer may want to single-step inside the -- 1.7.11.7 -- 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/
