1 files changed, 66 insertions, 0 deletions

diff --git a/arch/x86/um/stub_64.S b/arch/x86/um/stub_64.S
new file mode 100644
index 000000000000..20e4a96a6dcb
--- /dev/null
+++ b/arch/x86/um/stub_64.S
@@ -0,0 +1,66 @@
+#include "as-layout.h"
+
+        .globl syscall_stub
+.section .__syscall_stub, "ax"
+syscall_stub:
+        syscall
+        /* We don't have 64-bit constants, so this constructs the address
+         * we need.
+         */
+        movq    $(STUB_DATA >> 32), %rbx
+        salq    $32, %rbx
+        movq    $(STUB_DATA & 0xffffffff), %rcx
+        or      %rcx, %rbx
+        movq    %rax, (%rbx)
+        int3
+
+        .globl batch_syscall_stub
+batch_syscall_stub:
+        mov     $(STUB_DATA >> 32), %rbx
+        sal     $32, %rbx
+        mov     $(STUB_DATA & 0xffffffff), %rax
+        or      %rax, %rbx
+        /* load pointer to first operation */
+        mov     %rbx, %rsp
+        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