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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 ARM
35 * procedure calling convention: the first paramter is passed in r0, the
36 * second in r1, the third in r2 and the fourth in r3. Considering that
37 * Xen hypercalls have 5 arguments at most, the fifth paramter is passed
38 * in r4, differently from the procedure calling convention of using the
39 * stack for that case.
40 *
41 * The hypercall number is passed in r12.
42 *
43 * The return value is in r0.
44 *
45 * The hvc ISS is required to be 0xEA1, that is the Xen specific ARM
46 * hypercall tag.
47 */
48
49#include <linux/linkage.h>
50#include <asm/assembler.h>
51#include <asm/opcodes-virt.h>
52#include <xen/interface/xen.h>
53
54
55#define XEN_IMM 0xEA1
56
57#define HYPERCALL_SIMPLE(hypercall) \
58ENTRY(HYPERVISOR_##hypercall) \
59 mov r12, #__HYPERVISOR_##hypercall; \
60 __HVC(XEN_IMM); \
61 ret lr; \
62ENDPROC(HYPERVISOR_##hypercall)
63
64#define HYPERCALL0 HYPERCALL_SIMPLE
65#define HYPERCALL1 HYPERCALL_SIMPLE
66#define HYPERCALL2 HYPERCALL_SIMPLE
67#define HYPERCALL3 HYPERCALL_SIMPLE
68#define HYPERCALL4 HYPERCALL_SIMPLE
69
70#define HYPERCALL5(hypercall) \
71ENTRY(HYPERVISOR_##hypercall) \
72 stmdb sp!, {r4} \
73 ldr r4, [sp, #4] \
74 mov r12, #__HYPERVISOR_##hypercall; \
75 __HVC(XEN_IMM); \
76 ldm sp!, {r4} \
77 ret lr \
78ENDPROC(HYPERVISOR_##hypercall)
79
80 .text
81
82HYPERCALL2(xen_version);
83HYPERCALL3(console_io);
84HYPERCALL3(grant_table_op);
85HYPERCALL2(sched_op);
86HYPERCALL2(event_channel_op);
87HYPERCALL2(hvm_op);
88HYPERCALL2(memory_op);
89HYPERCALL2(physdev_op);
90HYPERCALL3(vcpu_op);
91HYPERCALL1(platform_op_raw);
92HYPERCALL2(multicall);
93HYPERCALL2(vm_assist);
94HYPERCALL3(dm_op);
95
96ENTRY(privcmd_call)
97 stmdb sp!, {r4}
98 mov r12, r0
99 mov r0, r1
100 mov r1, r2
101 mov r2, r3
102 ldr r3, [sp, #8]
103 /*
104 * Privcmd calls are issued by the userspace. We need to allow the
105 * kernel to access the userspace memory before issuing the hypercall.
106 */
107 uaccess_enable r4
108
109 /* r4 is loaded now as we use it as scratch register before */
110 ldr r4, [sp, #4]
111 __HVC(XEN_IMM)
112
113 /*
114 * Disable userspace access from kernel. This is fine to do it
115 * unconditionally as no set_fs(KERNEL_DS) is called before.
116 */
117 uaccess_disable r4
118
119 ldm sp!, {r4}
120 ret lr
121ENDPROC(privcmd_call);