On Sun, Mar 10, 2013 at 06:15:18PM +0100, Jiri Olsa wrote: > On Sun, Mar 03, 2013 at 11:43:21AM +0100, Jiri Olsa wrote: > > On Fri, Mar 01, 2013 at 10:57:50AM -0800, H. Peter Anvin wrote: > > > On 03/01/2013 10:11 AM, Jiri Olsa wrote: > > > > 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. > > > > > > > > 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 > > > > > > > > > > Makes sense. However, can you combine all the flags-clearing into one > > > statement while you are at it? > > Is there any other reason for this besides having just signal
s/signal/single/ ;-) jirka > instruction doing this update? > > It looks like gcc is smart enough to do that anyway: > > ... > andq $0xfffffffffffffaff,(%rdi) > ... > > > I need to send V2 anyway, since the patchset no longer > applies into latest tip. > > thanks, > jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
