1 files changed, 107 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/gcs.h b/arch/arm64/include/asm/gcs.h
new file mode 100644
index 000000000000..f50660603ecf
--- /dev/null
+++ b/arch/arm64/include/asm/gcs.h
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2023 ARM Ltd.
+ */
+#ifndef __ASM_GCS_H
+#define __ASM_GCS_H
+
+#include <asm/types.h>
+#include <asm/uaccess.h>
+
+struct kernel_clone_args;
+struct ksignal;
+
+static inline void gcsb_dsync(void)
+{
+	asm volatile(".inst 0xd503227f" : : : "memory");
+}
+
+static inline void gcsstr(u64 *addr, u64 val)
+{
+	register u64 *_addr __asm__ ("x0") = addr;
+	register long _val __asm__ ("x1") = val;
+
+	/* GCSSTTR x1, x0 */
+	asm volatile(
+		".inst 0xd91f1c01\n"
+		:
+		: "rZ" (_val), "r" (_addr)
+		: "memory");
+}
+
+static inline void gcsss1(u64 Xt)
+{
+	asm volatile (
+		"sys #3, C7, C7, #2, %0\n"
+		:
+		: "rZ" (Xt)
+		: "memory");
+}
+
+static inline u64 gcsss2(void)
+{
+	u64 Xt;
+
+	asm volatile(
+		"SYSL %0, #3, C7, C7, #3\n"
+		: "=r" (Xt)
+		:
+		: "memory");
+
+	return Xt;
+}
+
+#define PR_SHADOW_STACK_SUPPORTED_STATUS_MASK \
+	(PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_WRITE | PR_SHADOW_STACK_PUSH)
+
+#ifdef CONFIG_ARM64_GCS
+
+static inline bool task_gcs_el0_enabled(struct task_struct *task)
+{
+	return current->thread.gcs_el0_mode & PR_SHADOW_STACK_ENABLE;
+}
+
+void gcs_set_el0_mode(struct task_struct *task);
+void gcs_free(struct task_struct *task);
+void gcs_preserve_current_state(void);
+unsigned long gcs_alloc_thread_stack(struct task_struct *tsk,
+				     const struct kernel_clone_args *args);
+
+static inline int gcs_check_locked(struct task_struct *task,
+				   unsigned long new_val)
+{
+	unsigned long cur_val = task->thread.gcs_el0_mode;
+
+	cur_val &= task->thread.gcs_el0_locked;
+	new_val &= task->thread.gcs_el0_locked;
+
+	if (cur_val != new_val)
+		return -EBUSY;
+
+	return 0;
+}
+
+#else
+
+static inline bool task_gcs_el0_enabled(struct task_struct *task)
+{
+	return false;
+}
+
+static inline void gcs_set_el0_mode(struct task_struct *task) { }
+static inline void gcs_free(struct task_struct *task) { }
+static inline void gcs_preserve_current_state(void) { }
+static inline unsigned long gcs_alloc_thread_stack(struct task_struct *tsk,
+						   const struct kernel_clone_args *args)
+{
+	return -ENOTSUPP;
+}
+static inline int gcs_check_locked(struct task_struct *task,
+				   unsigned long new_val)
+{
+	return 0;
+}
+
+#endif
+
+#endif