On Thu, May 07, 2020 at 07:18:45PM +0200, Alexandre Chartre wrote:
>
> On 5/5/20 3:49 PM, Thomas Gleixner wrote:
> > From: Peter Zijlstra <pet...@infradead.org>
> >
> > DR6/7 should be handled before nmi_enter() is invoked and restore after
> > nmi_exit() to minimize the exposure.
> >
> > Split it out into helper inlines and bring it into the correct order.
> >
> > Signed-off-by: Peter Zijlstra <pet...@infradead.org>
> > Signed-off-by: Thomas Gleixner <t...@linutronix.de>
> > ---
> > arch/x86/kernel/hw_breakpoint.c | 6 ---
> > arch/x86/kernel/traps.c | 62
> > +++++++++++++++++++++++++++-------------
> > 2 files changed, 44 insertions(+), 24 deletions(-)
> >
> ...
> > --- a/arch/x86/kernel/traps.c
> > +++ b/arch/x86/kernel/traps.c
> > @@ -691,6 +691,44 @@ static bool is_sysenter_singlestep(struc
> > #endif
> > }
> > +static __always_inline void debug_enter(unsigned long *dr6, unsigned long
> > *dr7)
> > +{
> > + /*
> > + * Disable breakpoints during exception handling; recursive exceptions
> > + * are exceedingly 'fun'.
> > + *
> > + * Since this function is NOKPROBE, and that also applies to
> > + * HW_BREAKPOINT_X, we can't hit a breakpoint before this (XXX except a
> > + * HW_BREAKPOINT_W on our stack)
> > + *
> > + * Entry text is excluded for HW_BP_X and cpu_entry_area, which
> > + * includes the entry stack is excluded for everything.
> > + */
> > + get_debugreg(*dr7, 6);
>
> Do you mean get_debugreg(*dr7, 7); ?
Shees, I have to go buy a new stack of brown paper bags at this rate,
don't I :/
