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); ?
alex.
