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SubjectRe: [patch V4 part 4 15/24] x86/db: Split out dr6/7 handling
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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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