| Subject | Re: [patch V4 part 4 15/24] x86/db: Split out dr6/7 handling | From | Alexandre Chartre <> | Date | Thu, 7 May 2020 19:18:45 +0200 |
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On 5/5/20 3:49 PM, Thomas Gleixner wrote: > From: Peter Zijlstra <peterz@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 <peterz@infradead.org> > Signed-off-by: Thomas Gleixner <tglx@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); ?
alex.
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