LXR qemu/pc-bios/s390-ccw/start.S

   1/*
   2 * First stage boot loader for virtio devices. The compiled output goes
   3 * into the pc-bios directory of qemu.
   4 *
   5 * Copyright (c) 2013 Alexander Graf <agraf@suse.de>
   6 * Copyright IBM Corp. 2013, 2017
   7 *
   8 * This work is licensed under the terms of the GNU GPL, version 2 or (at
   9 * your option) any later version. See the COPYING file in the top-level
  10 * directory.
  11 */
  12
  13        .globl _start
  14_start:
  15
  16        larl   %r15, stack + 0x8000     /* Set up stack */
  17
  18        /* clear bss */
  19        larl %r2, __bss_start
  20        larl %r3, _end
  21        slgr %r3, %r2           /* get sizeof bss */
  22        ltgr    %r3,%r3         /* bss emtpy? */
  23        jz      done
  24        aghi    %r3,-1
  25        srlg    %r4,%r3,8       /* how many 256 byte chunks? */
  26        ltgr    %r4,%r4
  27        lgr     %r1,%r2
  28        jz      remainder
  29loop:
  30        xc      0(256,%r1),0(%r1)
  31        la      %r1,256(%r1)
  32        brctg   %r4,loop
  33remainder:
  34        larl    %r2,memsetxc
  35        ex      %r3,0(%r2)
  36done:
  37        j      main             /* And call C */
  38
  39memsetxc:
  40        xc      0(1,%r1),0(%r1)
  41
  42
  43/*
  44 * void disabled_wait(void)
  45 *
  46 * stops the current guest cpu.
  47 */
  48        .globl disabled_wait
  49disabled_wait:
  50        larl %r1,disabled_wait_psw
  51        lpswe   0(%r1)
  52
  53
  54/*
  55 * void consume_sclp_int(void)
  56 *
  57 * eats one sclp interrupt
  58 */
  59        .globl consume_sclp_int
  60consume_sclp_int:
  61        /* enable service interrupts in cr0 */
  62        stctg 0,0,0(15)
  63        oi 6(15), 0x2
  64        lctlg 0,0,0(15)
  65        /* prepare external call handler */
  66        larl %r1, external_new_code
  67        stg %r1, 0x1b8
  68        larl %r1, external_new_mask
  69        mvc 0x1b0(8),0(%r1)
  70        /* load enabled wait PSW */
  71        larl %r1, enabled_wait_psw
  72        lpswe 0(%r1)
  73
  74external_new_code:
  75        /* disable service interrupts in cr0 */
  76        stctg 0,0,0(15)
  77        ni 6(15), 0xfd
  78        lctlg 0,0,0(15)
  79        br 14
  80
  81        .align  8
  82disabled_wait_psw:
  83        .quad   0x0002000180000000,0x0000000000000000
  84enabled_wait_psw:
  85        .quad   0x0302000180000000,0x0000000000000000
  86external_new_mask:
  87        .quad   0x0000000180000000
  88