arch/arm64/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 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)             \
  59 ENTRY(HYPERVISOR_##hypercall)                   \
  60         mov x16, #__HYPERVISOR_##hypercall;     \
  61         hvc XEN_IMM;                            \
  62         ret;                                    \
  63 ENDPROC(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
  74 HYPERCALL2(xen_version);
  75 HYPERCALL3(console_io);
  76 HYPERCALL3(grant_table_op);
  77 HYPERCALL2(sched_op);
  78 HYPERCALL2(event_channel_op);
  79 HYPERCALL2(hvm_op);
  80 HYPERCALL2(memory_op);
  81 HYPERCALL2(physdev_op);
  82 HYPERCALL3(vcpu_op);
  83 HYPERCALL1(tmem_op);
  84 HYPERCALL1(platform_op_raw);
  85 HYPERCALL2(multicall);
  86 HYPERCALL2(vm_assist);
  87 HYPERCALL3(dm_op);
  88
  89 ENTRY(privcmd_call)
  90         mov x16, x0
  91         mov x0, x1
  92         mov x1, x2
  93         mov x2, x3
  94         mov x3, x4
  95         mov x4, x5
  96         /*
  97          * Privcmd calls are issued by the userspace. The kernel needs to
  98          * enable access to TTBR0_EL1 as the hypervisor would issue stage 1
  99          * translations to user memory via AT instructions. Since AT
 100          * instructions are not affected by the PAN bit (ARMv8.1), we only
 101          * need the explicit uaccess_enable/disable if the TTBR0 PAN emulation
 102          * is enabled (it implies that hardware UAO and PAN disabled).
 103          */
 104         uaccess_ttbr0_enable x6, x7
 105         hvc XEN_IMM
 106
 107         /*
 108          * Disable userspace access from kernel once the hyp call completed.
 109          */
 110         uaccess_ttbr0_disable x6
 111         ret
 112 ENDPROC(privcmd_call);