1 files changed, 50 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/vdso/getrandom.h b/arch/arm64/include/asm/vdso/getrandom.h
new file mode 100644
index 000000000000..342f807e2044
--- /dev/null
+++ b/arch/arm64/include/asm/vdso/getrandom.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_VDSO_GETRANDOM_H
+#define __ASM_VDSO_GETRANDOM_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/unistd.h>
+#include <asm/vdso/vsyscall.h>
+#include <vdso/datapage.h>
+
+/**
+ * getrandom_syscall - Invoke the getrandom() syscall.
+ * @buffer:	Destination buffer to fill with random bytes.
+ * @len:	Size of @buffer in bytes.
+ * @flags:	Zero or more GRND_* flags.
+ * Returns:	The number of random bytes written to @buffer, or a negative value indicating an error.
+ */
+static __always_inline ssize_t getrandom_syscall(void *_buffer, size_t _len, unsigned int _flags)
+{
+	register void *buffer asm ("x0") = _buffer;
+	register size_t len asm ("x1") = _len;
+	register unsigned int flags asm ("x2") = _flags;
+	register long ret asm ("x0");
+	register long nr asm ("x8") = __NR_getrandom;
+
+	asm volatile(
+	"       svc #0\n"
+	: "=r" (ret)
+	: "r" (buffer), "r" (len), "r" (flags), "r" (nr)
+	: "memory");
+
+	return ret;
+}
+
+static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)
+{
+	/*
+	 * The RNG data is in the real VVAR data page, but if a task belongs to a time namespace
+	 * then VVAR_DATA_PAGE_OFFSET points to the namespace-specific VVAR page and VVAR_TIMENS_
+	 * PAGE_OFFSET points to the real VVAR page.
+	 */
+	if (IS_ENABLED(CONFIG_TIME_NS) && _vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS)
+		return (void *)&_vdso_rng_data + VVAR_TIMENS_PAGE_OFFSET * (1UL << CONFIG_PAGE_SHIFT);
+	return &_vdso_rng_data;
+}
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __ASM_VDSO_GETRANDOM_H */