arm/xen/hypercall.S

0001 /******************************************************************************
0002  * hypercall.S
0003  *
0004  * Xen hypercall wrappers
0005  *
0006  * Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Citrix, 2012
0007  *
0008  * This program is free software; you can redistribute it and/or
0009  * modify it under the terms of the GNU General Public License version 2
0010  * as published by the Free Software Foundation; or, when distributed
0011  * separately from the Linux kernel or incorporated into other
0012  * software packages, subject to the following license:
0013  *
0014  * Permission is hereby granted, free of charge, to any person obtaining a copy
0015  * of this source file (the "Software"), to deal in the Software without
0016  * restriction, including without limitation the rights to use, copy, modify,
0017  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
0018  * and to permit persons to whom the Software is furnished to do so, subject to
0019  * the following conditions:
0020  *
0021  * The above copyright notice and this permission notice shall be included in
0022  * all copies or substantial portions of the Software.
0023  *
0024  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
0025  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
0026  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
0027  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
0028  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
0029  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
0030  * IN THE SOFTWARE.
0031  */
0032
0033 /*
0034  * The Xen hypercall calling convention is very similar to the ARM
0035  * procedure calling convention: the first paramter is passed in r0, the
0036  * second in r1, the third in r2 and the fourth in r3. Considering that
0037  * Xen hypercalls have 5 arguments at most, the fifth paramter is passed
0038  * in r4, differently from the procedure calling convention of using the
0039  * stack for that case.
0040  *
0041  * The hypercall number is passed in r12.
0042  *
0043  * The return value is in r0.
0044  *
0045  * The hvc ISS is required to be 0xEA1, that is the Xen specific ARM
0046  * hypercall tag.
0047  */
0048
0049 #include <linux/linkage.h>
0050 #include <asm/assembler.h>
0051 #include <asm/opcodes-virt.h>
0052 #include <xen/interface/xen.h>
0053
0054
0055 #define XEN_IMM 0xEA1
0056
0057 #define HYPERCALL_SIMPLE(hypercall)     \
0058 ENTRY(HYPERVISOR_##hypercall)           \
0059     mov r12, #__HYPERVISOR_##hypercall; \
0060     __HVC(XEN_IMM);                     \
0061     ret lr;                 \
0062 ENDPROC(HYPERVISOR_##hypercall)
0063
0064 #define HYPERCALL0 HYPERCALL_SIMPLE
0065 #define HYPERCALL1 HYPERCALL_SIMPLE
0066 #define HYPERCALL2 HYPERCALL_SIMPLE
0067 #define HYPERCALL3 HYPERCALL_SIMPLE
0068 #define HYPERCALL4 HYPERCALL_SIMPLE
0069
0070 #define HYPERCALL5(hypercall)           \
0071 ENTRY(HYPERVISOR_##hypercall)           \
0072     stmdb sp!, {r4}                     \
0073     ldr r4, [sp, #4]                    \
0074     mov r12, #__HYPERVISOR_##hypercall; \
0075     __HVC(XEN_IMM);                     \
0076     ldm sp!, {r4}                       \
0077     ret lr                  \
0078 ENDPROC(HYPERVISOR_##hypercall)
0079
0080                 .text
0081
0082 HYPERCALL2(xen_version);
0083 HYPERCALL3(console_io);
0084 HYPERCALL3(grant_table_op);
0085 HYPERCALL2(sched_op);
0086 HYPERCALL2(event_channel_op);
0087 HYPERCALL2(hvm_op);
0088 HYPERCALL2(memory_op);
0089 HYPERCALL2(physdev_op);
0090 HYPERCALL3(vcpu_op);
0091 HYPERCALL1(platform_op_raw);
0092 HYPERCALL2(multicall);
0093 HYPERCALL2(vm_assist);
0094 HYPERCALL3(dm_op);
0095
0096 ENTRY(privcmd_call)
0097     stmdb sp!, {r4}
0098     mov r12, r0
0099     mov r0, r1
0100     mov r1, r2
0101     mov r2, r3
0102     ldr r3, [sp, #8]
0103     /*
0104      * Privcmd calls are issued by the userspace. We need to allow the
0105      * kernel to access the userspace memory before issuing the hypercall.
0106      */
0107     uaccess_enable r4
0108
0109     /* r4 is loaded now as we use it as scratch register before */
0110     ldr r4, [sp, #4]
0111     __HVC(XEN_IMM)
0112
0113     /*
0114      * Disable userspace access from kernel. This is fine to do it
0115      * unconditionally as no set_fs(KERNEL_DS) is called before.
0116      */
0117     uaccess_disable r4
0118
0119     ldm sp!, {r4}
0120     ret lr
0121 ENDPROC(privcmd_call);