1/******************************************************************************
2 * hypercall.S
3 *
4 * Xen hypercall wrappers
5 *
6 * Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Citrix, 2012
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License version 2
10 * as published by the Free Software Foundation; or, when distributed
11 * separately from the Linux kernel or incorporated into other
12 * software packages, subject to the following license:
13 *
14 * Permission is hereby granted, free of charge, to any person obtaining a copy
15 * of this source file (the "Software"), to deal in the Software without
16 * restriction, including without limitation the rights to use, copy, modify,
17 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
18 * and to permit persons to whom the Software is furnished to do so, subject to
19 * the following conditions:
20 *
21 * The above copyright notice and this permission notice shall be included in
22 * all copies or substantial portions of the Software.
23 *
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
26 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
28 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
29 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
30 * IN THE SOFTWARE.
31 */
32
33/*
34 * The Xen hypercall calling convention is very similar to the procedure
35 * call standard for the ARM 64-bit architecture: the first parameter is
36 * passed in x0, the second in x1, the third in x2, the fourth in x3 and
37 * the fifth in x4.
38 *
39 * The hypercall number is passed in x16.
40 *
41 * The return value is in x0.
42 *
43 * The hvc ISS is required to be 0xEA1, that is the Xen specific ARM
44 * hypercall tag.
45 *
46 * Parameter structs passed to hypercalls are laid out according to
47 * the ARM 64-bit EABI standard.
48 */
49
50#include <linux/linkage.h>
51#include <asm/assembler.h>
52#include <asm/asm-uaccess.h>
53#include <xen/interface/xen.h>
54
55
56#define XEN_IMM 0xEA1
57
58#define HYPERCALL_SIMPLE(hypercall)		\
59SYM_FUNC_START(HYPERVISOR_##hypercall)		\
60	mov x16, #__HYPERVISOR_##hypercall;	\
61	hvc XEN_IMM;				\
62	ret;					\
63SYM_FUNC_END(HYPERVISOR_##hypercall)
64
65#define HYPERCALL0 HYPERCALL_SIMPLE
66#define HYPERCALL1 HYPERCALL_SIMPLE
67#define HYPERCALL2 HYPERCALL_SIMPLE
68#define HYPERCALL3 HYPERCALL_SIMPLE
69#define HYPERCALL4 HYPERCALL_SIMPLE
70#define HYPERCALL5 HYPERCALL_SIMPLE
71
72                .text
73
74HYPERCALL2(xen_version);
75HYPERCALL3(console_io);
76HYPERCALL3(grant_table_op);
77HYPERCALL2(sched_op);
78HYPERCALL2(event_channel_op);
79HYPERCALL2(hvm_op);
80HYPERCALL2(memory_op);
81HYPERCALL2(physdev_op);
82HYPERCALL3(vcpu_op);
83HYPERCALL1(platform_op_raw);
84HYPERCALL2(multicall);
85HYPERCALL2(vm_assist);
86HYPERCALL3(dm_op);
87
88SYM_FUNC_START(privcmd_call)
89	mov x16, x0
90	mov x0, x1
91	mov x1, x2
92	mov x2, x3
93	mov x3, x4
94	mov x4, x5
95	/*
96	 * Privcmd calls are issued by the userspace. The kernel needs to
97	 * enable access to TTBR0_EL1 as the hypervisor would issue stage 1
98	 * translations to user memory via AT instructions. Since AT
99	 * instructions are not affected by the PAN bit (ARMv8.1), we only
100	 * need the explicit uaccess_enable/disable if the TTBR0 PAN emulation
101	 * is enabled (it implies that hardware UAO and PAN disabled).
102	 */
103	uaccess_ttbr0_enable x6, x7, x8
104	hvc XEN_IMM
105
106	/*
107	 * Disable userspace access from kernel once the hyp call completed.
108	 */
109	uaccess_ttbr0_disable x6, x7
110	ret
111SYM_FUNC_END(privcmd_call);
112