/******************************************************************************
 * hypercall.S
 *
 * Xen hypercall wrappers
 *
 * Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Citrix, 2012
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

/*
 * The Xen hypercall calling convention is very similar to the ARM
 * procedure calling convention: the first paramter is passed in r0, the
 * second in r1, the third in r2 and the fourth in r3. Considering that
 * Xen hypercalls have 5 arguments at most, the fifth paramter is passed
 * in r4, differently from the procedure calling convention of using the
 * stack for that case.
 *
 * The hypercall number is passed in r12.
 *
 * The return value is in r0.
 *
 * The hvc ISS is required to be 0xEA1, that is the Xen specific ARM
 * hypercall tag.
 */

#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/opcodes-virt.h>
#include <xen/interface/xen.h>


#define XEN_IMM 0xEA1

#define HYPERCALL_SIMPLE(hypercall)             \
ENTRY(HYPERVISOR_##hypercall)                   \
        mov r12, #__HYPERVISOR_##hypercall;     \
        __HVC(XEN_IMM);                                         \
        ret lr;                                 \
ENDPROC(HYPERVISOR_##hypercall)

#define HYPERCALL0 HYPERCALL_SIMPLE
#define HYPERCALL1 HYPERCALL_SIMPLE
#define HYPERCALL2 HYPERCALL_SIMPLE
#define HYPERCALL3 HYPERCALL_SIMPLE
#define HYPERCALL4 HYPERCALL_SIMPLE

#define HYPERCALL5(hypercall)                   \
ENTRY(HYPERVISOR_##hypercall)                   \
        stmdb sp!, {r4}                                         \
        ldr r4, [sp, #4]                                        \
        mov r12, #__HYPERVISOR_##hypercall;     \
        __HVC(XEN_IMM);                                         \
        ldm sp!, {r4}                                           \
        ret lr                                  \
ENDPROC(HYPERVISOR_##hypercall)

                .text

HYPERCALL2(xen_version);
HYPERCALL3(console_io);
HYPERCALL3(grant_table_op);
HYPERCALL2(sched_op);
HYPERCALL2(event_channel_op);
HYPERCALL2(hvm_op);
HYPERCALL2(memory_op);
HYPERCALL2(physdev_op);
HYPERCALL3(vcpu_op);
HYPERCALL1(platform_op_raw);
HYPERCALL2(multicall);
HYPERCALL2(vm_assist);
HYPERCALL3(dm_op);

ENTRY(privcmd_call)
        stmdb sp!, {r4}
        mov r12, r0
        mov r0, r1
        mov r1, r2
        mov r2, r3
        ldr r3, [sp, #8]
        /*
         * Privcmd calls are issued by the userspace. We need to allow the
         * kernel to access the userspace memory before issuing the hypercall.
         */
        uaccess_enable r4

        /* r4 is loaded now as we use it as scratch register before */
        ldr r4, [sp, #4]
        __HVC(XEN_IMM)

        /*
         * Disable userspace access from kernel. This is fine to do it
         * unconditionally as no set_fs(KERNEL_DS) is called before.
         */
        uaccess_disable r4

        ldm sp!, {r4}
        ret lr
ENDPROC(privcmd_call);