x86: Rename variables for debugging
Rename variables for debugging to describe meaning of them precisely.
Also, introduce a generic way to switch IDT by checking a current state,
debug on/off.
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/51C323A8.7050905@hds.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 8bf1c06..af290b8 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -36,8 +36,8 @@
extern struct desc_ptr idt_descr;
extern gate_desc idt_table[];
-extern struct desc_ptr nmi_idt_descr;
-extern gate_desc nmi_idt_table[];
+extern struct desc_ptr debug_idt_descr;
+extern gate_desc debug_idt_table[];
struct gdt_page {
struct desc_struct gdt[GDT_ENTRIES];
@@ -316,7 +316,7 @@
gate_desc s;
pack_gate(&s, GATE_INTERRUPT, (unsigned long)addr, 0, 0, __KERNEL_CS);
- write_idt_entry(nmi_idt_table, gate, &s);
+ write_idt_entry(debug_idt_table, gate, &s);
}
#endif
@@ -405,4 +405,45 @@
_set_gate(n, GATE_INTERRUPT, addr, 0x3, ist, __KERNEL_CS);
}
+#ifdef CONFIG_X86_64
+DECLARE_PER_CPU(u32, debug_idt_ctr);
+static inline bool is_debug_idt_enabled(void)
+{
+ if (this_cpu_read(debug_idt_ctr))
+ return true;
+
+ return false;
+}
+
+static inline void load_debug_idt(void)
+{
+ load_idt((const struct desc_ptr *)&debug_idt_descr);
+}
+#else
+static inline bool is_debug_idt_enabled(void)
+{
+ return false;
+}
+
+static inline void load_debug_idt(void)
+{
+}
+#endif
+
+/*
+ * the load_current_idt() is called with interrupt disabled by local_irq_save()
+ * to avoid races. That way the IDT will always be set back to the expected
+ * descriptor.
+ */
+static inline void load_current_idt(void)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ if (is_debug_idt_enabled())
+ load_debug_idt();
+ else
+ load_idt((const struct desc_ptr *)&idt_descr);
+ local_irq_restore(flags);
+}
#endif /* _ASM_X86_DESC_H */
