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        /* set up a pgm exception disabled wait psw */
  38        larl    %r2, disabled_wait_psw
  39        mvc     0x01d0(16), 0(%r2)
  40        j      main             /* And call C */
  41
  42memsetxc:
  43        xc      0(1,%r1),0(%r1)
  44
  45
  46/*
  47 * void disabled_wait(void)
  48 *
  49 * stops the current guest cpu.
  50 */
  51        .globl disabled_wait
  52disabled_wait:
  53        larl    %r1,disabled_wait_psw
  54        lpswe   0(%r1)
  551:      j       1b
  56
  57
  58/*
  59 * void consume_sclp_int(void)
  60 *
  61 * eats one sclp interrupt
  62 */
  63        .globl consume_sclp_int
  64consume_sclp_int:
  65        /* enable service interrupts in cr0 */
  66        stctg   %c0,%c0,0(%r15)
  67        oi      6(%r15),0x2
  68        lctlg   %c0,%c0,0(%r15)
  69        /* prepare external call handler */
  70        larl %r1, external_new_code
  71        stg %r1, 0x1b8
  72        larl %r1, external_new_mask
  73        mvc 0x1b0(8),0(%r1)
  74        /* load enabled wait PSW */
  75        larl %r1, enabled_wait_psw
  76        lpswe 0(%r1)
  77
  78/*
  79 * void consume_io_int(void)
  80 *
  81 * eats one I/O interrupt
  82 */
  83        .globl consume_io_int
  84consume_io_int:
  85        /* enable I/O interrupts in cr6 */
  86        stctg %c6,%c6,0(%r15)
  87        oi    4(%r15), 0xff
  88        lctlg %c6,%c6,0(%r15)
  89        /* prepare i/o call handler */
  90        larl  %r1, io_new_code
  91        stg   %r1, 0x1f8
  92        larl  %r1, io_new_mask
  93        mvc   0x1f0(8),0(%r1)
  94        /* load enabled wait PSW */
  95        larl  %r1, enabled_wait_psw
  96        lpswe 0(%r1)
  97
  98external_new_code:
  99        /* disable service interrupts in cr0 */
 100        stctg   %c0,%c0,0(%r15)
 101        ni      6(%r15),0xfd
 102        lctlg   %c0,%c0,0(%r15)
 103        br      %r14
 104
 105io_new_code:
 106        /* disable I/O interrupts in cr6 */
 107        stctg %c6,%c6,0(%r15)
 108        ni    4(%r15), 0x00
 109        lctlg %c6,%c6,0(%r15)
 110        br    %r14
 111
 112        .align  8
 113disabled_wait_psw:
 114        .quad   0x0002000180000000,0x0000000000000000
 115enabled_wait_psw:
 116        .quad   0x0302000180000000,0x0000000000000000
 117external_new_mask:
 118        .quad   0x0000000180000000
 119io_new_mask:
 120        .quad   0x0000000180000000
 121