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 empty? */
  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
  29 loop:
  30         xc      0(256,%r1),0(%r1)
  31         la      %r1,256(%r1)
  32         brctg   %r4,loop
  33 remainder:
  34         larl    %r2,memsetxc
  35         ex      %r3,0(%r2)
  36 done:
  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
  42 memsetxc:
  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
  52 disabled_wait:
  53         larl    %r1,disabled_wait_psw
  54         lpswe   0(%r1)
  55 1:      j       1b
  56
  57
  58 /*
  59  * void consume_sclp_int(void)
  60  *
  61  * eats one sclp interrupt
  62  */
  63         .globl consume_sclp_int
  64 consume_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
  84 consume_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
  98 external_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
 105 io_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
 113 disabled_wait_psw:
 114         .quad   0x0002000180000000,0x0000000000000000
 115 enabled_wait_psw:
 116         .quad   0x0302000180000000,0x0000000000000000
 117 external_new_mask:
 118         .quad   0x0000000180000000
 119 io_new_mask:
 120         .quad   0x0000000180000000