1 files changed, 90 insertions, 1 deletions

diff --git a/arch/arm64/include/asm/gcs.h b/arch/arm64/include/asm/gcs.h
index 5bc432234d3a..8fa0707069e8 100644
--- a/arch/arm64/include/asm/gcs.h
+++ b/arch/arm64/include/asm/gcs.h
@@ -21,7 +21,7 @@ static inline void gcsstr(u64 *addr, u64 val)
 	register u64 *_addr __asm__ ("x0") = addr;
 	register long _val __asm__ ("x1") = val;
 
-	/* GCSSTTR x1, x0 */
+	/* GCSSTTR x1, [x0] */
 	asm volatile(
 		".inst 0xd91f1c01\n"
 		:
@@ -81,6 +81,82 @@ static inline int gcs_check_locked(struct task_struct *task,
 	return 0;
 }
 
+static inline int gcssttr(unsigned long __user *addr, unsigned long val)
+{
+	register unsigned long __user *_addr __asm__ ("x0") = addr;
+	register unsigned long _val __asm__ ("x1") = val;
+	int err = 0;
+
+	/* GCSSTTR x1, [x0] */
+	asm volatile(
+		"1: .inst 0xd91f1c01\n"
+		"2: \n"
+		_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0)
+		: "+r" (err)
+		: "rZ" (_val), "r" (_addr)
+		: "memory");
+
+	return err;
+}
+
+static inline void put_user_gcs(unsigned long val, unsigned long __user *addr,
+				int *err)
+{
+	int ret;
+
+	if (!access_ok((char __user *)addr, sizeof(u64))) {
+		*err = -EFAULT;
+		return;
+	}
+
+	uaccess_ttbr0_enable();
+	ret = gcssttr(addr, val);
+	if (ret != 0)
+		*err = ret;
+	uaccess_ttbr0_disable();
+}
+
+static inline void push_user_gcs(unsigned long val, int *err)
+{
+	u64 gcspr = read_sysreg_s(SYS_GCSPR_EL0);
+
+	gcspr -= sizeof(u64);
+	put_user_gcs(val, (unsigned long __user *)gcspr, err);
+	if (!*err)
+		write_sysreg_s(gcspr, SYS_GCSPR_EL0);
+}
+
+/*
+ * Unlike put/push_user_gcs() above, get/pop_user_gsc() doesn't
+ * validate the GCS permission is set on the page being read.  This
+ * differs from how the hardware works when it consumes data stored at
+ * GCSPR. Callers should ensure this is acceptable.
+ */
+static inline u64 get_user_gcs(unsigned long __user *addr, int *err)
+{
+	unsigned long ret;
+	u64 load = 0;
+
+	/* Ensure previous GCS operation are visible before we read the page */
+	gcsb_dsync();
+	ret = copy_from_user(&load, addr, sizeof(load));
+	if (ret != 0)
+		*err = ret;
+	return load;
+}
+
+static inline u64 pop_user_gcs(int *err)
+{
+	u64 gcspr = read_sysreg_s(SYS_GCSPR_EL0);
+	u64 read_val;
+
+	read_val = get_user_gcs((__force unsigned long __user *)gcspr, err);
+	if (!*err)
+		write_sysreg_s(gcspr + sizeof(u64), SYS_GCSPR_EL0);
+
+	return read_val;
+}
+
 #else
 
 static inline bool task_gcs_el0_enabled(struct task_struct *task)
@@ -91,6 +167,10 @@ static inline bool task_gcs_el0_enabled(struct task_struct *task)
 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 void put_user_gcs(unsigned long val, unsigned long __user *addr,
+				int *err) { }
+static inline void push_user_gcs(unsigned long val, int *err) { }
+
 static inline unsigned long gcs_alloc_thread_stack(struct task_struct *tsk,
 						   const struct kernel_clone_args *args)
 {
@@ -101,6 +181,15 @@ static inline int gcs_check_locked(struct task_struct *task,
 {
 	return 0;
 }
+static inline u64 get_user_gcs(unsigned long __user *addr, int *err)
+{
+	*err = -EFAULT;
+	return 0;
+}
+static inline u64 pop_user_gcs(int *err)
+{
+	return 0;
+}
 
 #endif