LXR qemu/pc-bios/s390-ccw/jump2ipl.c

   1/*
   2 * QEMU s390-ccw firmware - jump to IPL code
   3 *
   4 * This work is licensed under the terms of the GNU GPL, version 2 or (at
   5 * your option) any later version. See the COPYING file in the top-level
   6 * directory.
   7 */
   8
   9#include "libc.h"
  10#include "s390-ccw.h"
  11
  12#define KERN_IMAGE_START 0x010000UL
  13#define PSW_MASK_64 0x0000000100000000ULL
  14#define PSW_MASK_32 0x0000000080000000ULL
  15#define IPL_PSW_MASK (PSW_MASK_32 | PSW_MASK_64)
  16
  17typedef struct ResetInfo {
  18    uint32_t ipl_mask;
  19    uint32_t ipl_addr;
  20    uint32_t ipl_continue;
  21} ResetInfo;
  22
  23static ResetInfo save;
  24
  25static void jump_to_IPL_2(void)
  26{
  27    ResetInfo *current = 0;
  28
  29    void (*ipl)(void) = (void *) (uint64_t) current->ipl_continue;
  30    *current = save;
  31    ipl(); /* should not return */
  32}
  33
  34void jump_to_IPL_code(uint64_t address)
  35{
  36    /* store the subsystem information _after_ the bootmap was loaded */
  37    write_subsystem_identification();
  38    write_iplb_location();
  39
  40    /* prevent unknown IPL types in the guest */
  41    if (iplb.pbt == S390_IPL_TYPE_QEMU_SCSI) {
  42        iplb.pbt = S390_IPL_TYPE_CCW;
  43        set_iplb(&iplb);
  44    }
  45
  46    /*
  47     * The IPL PSW is at address 0. We also must not overwrite the
  48     * content of non-BIOS memory after we loaded the guest, so we
  49     * save the original content and restore it in jump_to_IPL_2.
  50     */
  51    ResetInfo *current = 0;
  52
  53    save = *current;
  54    current->ipl_addr = (uint32_t) (uint64_t) &jump_to_IPL_2;
  55    current->ipl_continue = address & 0x7fffffff;
  56
  57    debug_print_int("set IPL addr to", current->ipl_continue);
  58
  59    /* Ensure the guest output starts fresh */
  60    sclp_print("\n");
  61
  62    /*
  63     * HACK ALERT.
  64     * We use the load normal reset to keep r15 unchanged. jump_to_IPL_2
  65     * can then use r15 as its stack pointer.
  66     */
  67    asm volatile("lghi 1,1\n\t"
  68                 "diag 1,1,0x308\n\t"
  69                 : : : "1", "memory");
  70    panic("\n! IPL returns !\n");
  71}
  72
  73void jump_to_low_kernel(void)
  74{
  75    /*
  76     * If it looks like a Linux binary, i.e. there is the "S390EP" magic from
  77     * arch/s390/kernel/head.S here, then let's jump to the well-known Linux
  78     * kernel start address (when jumping to the PSW-at-zero address instead,
  79     * the kernel startup code fails when we booted from a network device).
  80     */
  81    if (!memcmp((char *)0x10008, "S390EP", 6)) {
  82        jump_to_IPL_code(KERN_IMAGE_START);
  83    }
  84
  85    /* Trying to get PSW at zero address */
  86    if (*((uint64_t *)0) & IPL_PSW_MASK) {
  87        jump_to_IPL_code((*((uint64_t *)0)) & 0x7fffffff);
  88    }
  89
  90    /* No other option left, so use the Linux kernel start address */
  91    jump_to_IPL_code(KERN_IMAGE_START);
  92}
  93