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-rw-r--r--arch/x86/um/stub_64.S50
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