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); 122