xref: /openbmc/linux/arch/x86/um/stub_64.S (revision 0545810f)
1/* SPDX-License-Identifier: GPL-2.0 */
2#include <as-layout.h>
3
4.section .__syscall_stub, "ax"
5	.globl batch_syscall_stub
6batch_syscall_stub:
7	/* %rsp has the pointer to first operation */
8	mov	%rsp, %rbx
9	add	$0x10, %rsp
10again:
11	/* load length of additional data */
12	mov	0x0(%rsp), %rax
13
14	/* if(length == 0) : end of list */
15	/* write possible 0 to header */
16	mov	%rax, 8(%rbx)
17	cmp	$0, %rax
18	jz	done
19
20	/* save current pointer */
21	mov	%rsp, 8(%rbx)
22
23	/* skip additional data */
24	add	%rax, %rsp
25
26	/* load syscall-# */
27	pop	%rax
28
29	/* load syscall params */
30	pop	%rdi
31	pop	%rsi
32	pop	%rdx
33	pop	%r10
34 	pop	%r8
35	pop	%r9
36
37	/* execute syscall */
38	syscall
39
40	/* check return value */
41	pop	%rcx
42	cmp	%rcx, %rax
43	je	again
44
45done:
46	/* save return value */
47	mov	%rax, (%rbx)
48
49	/* stop */
50	int3
51