hypercall.S

  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);
 86
 87SYM_FUNC_START(HYPERVISOR_dm_op)
 88	mov x16, #__HYPERVISOR_dm_op;	\
 89	/*
 90	 * dm_op hypercalls are issued by the userspace. The kernel needs to
 91	 * enable access to TTBR0_EL1 as the hypervisor would issue stage 1
 92	 * translations to user memory via AT instructions. Since AT
 93	 * instructions are not affected by the PAN bit (ARMv8.1), we only
 94	 * need the explicit uaccess_enable/disable if the TTBR0 PAN emulation
 95	 * is enabled (it implies that hardware UAO and PAN disabled).
 96	 */
 97	uaccess_ttbr0_enable x6, x7, x8
 98	hvc XEN_IMM
 99
100	/*
101	 * Disable userspace access from kernel once the hyp call completed.
102	 */
103	uaccess_ttbr0_disable x6, x7
104	ret
105SYM_FUNC_END(HYPERVISOR_dm_op);
106
107SYM_FUNC_START(privcmd_call)
108	mov x16, x0
109	mov x0, x1
110	mov x1, x2
111	mov x2, x3
112	mov x3, x4
113	mov x4, x5
114	/*
115	 * Privcmd calls are issued by the userspace. The kernel needs to
116	 * enable access to TTBR0_EL1 as the hypervisor would issue stage 1
117	 * translations to user memory via AT instructions. Since AT
118	 * instructions are not affected by the PAN bit (ARMv8.1), we only
119	 * need the explicit uaccess_enable/disable if the TTBR0 PAN emulation
120	 * is enabled (it implies that hardware UAO and PAN disabled).
121	 */
122	uaccess_ttbr0_enable x6, x7, x8
123	hvc XEN_IMM
124
125	/*
126	 * Disable userspace access from kernel once the hyp call completed.
127	 */
128	uaccess_ttbr0_disable x6, x7
129	ret
130SYM_FUNC_END(privcmd_call);