1 files changed, 50 insertions, 0 deletions
diff --git a/arch/x86/um/stub_64.S b/arch/x86/um/stub_64.S
new file mode 100644
index 000000000..f34046401
--- /dev/null
+++ b/arch/x86/um/stub_64.S
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <as-layout.h>
+
+.section .__syscall_stub, "ax"
+	.globl batch_syscall_stub
+batch_syscall_stub:
+	/* %rsp has the pointer to first operation */
+	mov	%rsp, %rbx
+	add	$0x10, %rsp
+again:
+	/* load length of additional data */
+	mov	0x0(%rsp), %rax
+
+	/* if(length == 0) : end of list */
+	/* write possible 0 to header */
+	mov	%rax, 8(%rbx)
+	cmp	$0, %rax
+	jz	done
+
+	/* save current pointer */
+	mov	%rsp, 8(%rbx)
+
+	/* skip additional data */
+	add	%rax, %rsp
+
+	/* load syscall-# */
+	pop	%rax
+
+	/* load syscall params */
+	pop	%rdi
+	pop	%rsi
+	pop	%rdx
+	pop	%r10
+ 	pop	%r8
+	pop	%r9
+
+	/* execute syscall */
+	syscall
+
+	/* check return value */
+	pop	%rcx
+	cmp	%rcx, %rax
+	je	again
+
+done:
+	/* save return value */
+	mov	%rax, (%rbx)
+
+	/* stop */
+	int3