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-rw-r--r--arch/x86/include/asm/debugreg.h156
1 files changed, 156 insertions, 0 deletions
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
new file mode 100644
index 000000000..9ed8343c9
--- /dev/null
+++ b/arch/x86/include/asm/debugreg.h
@@ -0,0 +1,156 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_DEBUGREG_H
+#define _ASM_X86_DEBUGREG_H
+
+
+#include <linux/bug.h>
+#include <uapi/asm/debugreg.h>
+
+DECLARE_PER_CPU(unsigned long, cpu_dr7);
+
+#ifndef CONFIG_PARAVIRT_XXL
+/*
+ * These special macros can be used to get or set a debugging register
+ */
+#define get_debugreg(var, register) \
+ (var) = native_get_debugreg(register)
+#define set_debugreg(value, register) \
+ native_set_debugreg(register, value)
+#endif
+
+static __always_inline unsigned long native_get_debugreg(int regno)
+{
+ unsigned long val = 0; /* Damn you, gcc! */
+
+ switch (regno) {
+ case 0:
+ asm("mov %%db0, %0" :"=r" (val));
+ break;
+ case 1:
+ asm("mov %%db1, %0" :"=r" (val));
+ break;
+ case 2:
+ asm("mov %%db2, %0" :"=r" (val));
+ break;
+ case 3:
+ asm("mov %%db3, %0" :"=r" (val));
+ break;
+ case 6:
+ asm("mov %%db6, %0" :"=r" (val));
+ break;
+ case 7:
+ /*
+ * Apply __FORCE_ORDER to DR7 reads to forbid re-ordering them
+ * with other code.
+ *
+ * This is needed because a DR7 access can cause a #VC exception
+ * when running under SEV-ES. Taking a #VC exception is not a
+ * safe thing to do just anywhere in the entry code and
+ * re-ordering might place the access into an unsafe location.
+ *
+ * This happened in the NMI handler, where the DR7 read was
+ * re-ordered to happen before the call to sev_es_ist_enter(),
+ * causing stack recursion.
+ */
+ asm volatile("mov %%db7, %0" : "=r" (val) : __FORCE_ORDER);
+ break;
+ default:
+ BUG();
+ }
+ return val;
+}
+
+static __always_inline void native_set_debugreg(int regno, unsigned long value)
+{
+ switch (regno) {
+ case 0:
+ asm("mov %0, %%db0" ::"r" (value));
+ break;
+ case 1:
+ asm("mov %0, %%db1" ::"r" (value));
+ break;
+ case 2:
+ asm("mov %0, %%db2" ::"r" (value));
+ break;
+ case 3:
+ asm("mov %0, %%db3" ::"r" (value));
+ break;
+ case 6:
+ asm("mov %0, %%db6" ::"r" (value));
+ break;
+ case 7:
+ /*
+ * Apply __FORCE_ORDER to DR7 writes to forbid re-ordering them
+ * with other code.
+ *
+ * While is didn't happen with a DR7 write (see the DR7 read
+ * comment above which explains where it happened), add the
+ * __FORCE_ORDER here too to avoid similar problems in the
+ * future.
+ */
+ asm volatile("mov %0, %%db7" ::"r" (value), __FORCE_ORDER);
+ break;
+ default:
+ BUG();
+ }
+}
+
+static inline void hw_breakpoint_disable(void)
+{
+ /* Zero the control register for HW Breakpoint */
+ set_debugreg(0UL, 7);
+
+ /* Zero-out the individual HW breakpoint address registers */
+ set_debugreg(0UL, 0);
+ set_debugreg(0UL, 1);
+ set_debugreg(0UL, 2);
+ set_debugreg(0UL, 3);
+}
+
+static __always_inline bool hw_breakpoint_active(void)
+{
+ return __this_cpu_read(cpu_dr7) & DR_GLOBAL_ENABLE_MASK;
+}
+
+extern void hw_breakpoint_restore(void);
+
+static __always_inline unsigned long local_db_save(void)
+{
+ unsigned long dr7;
+
+ if (static_cpu_has(X86_FEATURE_HYPERVISOR) && !hw_breakpoint_active())
+ return 0;
+
+ get_debugreg(dr7, 7);
+ dr7 &= ~0x400; /* architecturally set bit */
+ if (dr7)
+ set_debugreg(0, 7);
+ /*
+ * Ensure the compiler doesn't lower the above statements into
+ * the critical section; disabling breakpoints late would not
+ * be good.
+ */
+ barrier();
+
+ return dr7;
+}
+
+static __always_inline void local_db_restore(unsigned long dr7)
+{
+ /*
+ * Ensure the compiler doesn't raise this statement into
+ * the critical section; enabling breakpoints early would
+ * not be good.
+ */
+ barrier();
+ if (dr7)
+ set_debugreg(dr7, 7);
+}
+
+#ifdef CONFIG_CPU_SUP_AMD
+extern void set_dr_addr_mask(unsigned long mask, int dr);
+#else
+static inline void set_dr_addr_mask(unsigned long mask, int dr) { }
+#endif
+
+#endif /* _ASM_X86_DEBUGREG_H */