arch/arm/xen/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 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)             \
  58 ENTRY(HYPERVISOR_##hypercall)                   \
  59         mov r12, #__HYPERVISOR_##hypercall;     \
  60         __HVC(XEN_IMM);                                         \
  61         ret lr;                                 \
  62 ENDPROC(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)                   \
  71 ENTRY(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                                  \
  78 ENDPROC(HYPERVISOR_##hypercall)
  79
  80                 .text
  81
  82 HYPERCALL2(xen_version);
  83 HYPERCALL3(console_io);
  84 HYPERCALL3(grant_table_op);
  85 HYPERCALL2(sched_op);
  86 HYPERCALL2(event_channel_op);
  87 HYPERCALL2(hvm_op);
  88 HYPERCALL2(memory_op);
  89 HYPERCALL2(physdev_op);
  90 HYPERCALL3(vcpu_op);
  91 HYPERCALL1(tmem_op);
  92 HYPERCALL1(platform_op_raw);
  93 HYPERCALL2(multicall);
  94 HYPERCALL2(vm_assist);
  95
  96 ENTRY(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)/set_fs(get_ds()) is
 116          * called before.
 117          */
 118         uaccess_disable r4
 119
 120         ldm sp!, {r4}
 121         ret lr
 122 ENDPROC(privcmd_call);