Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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 */