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
  39    /* prevent unknown IPL types in the guest */
  40    if (iplb.pbt == S390_IPL_TYPE_QEMU_SCSI) {
  41        iplb.pbt = S390_IPL_TYPE_CCW;
  42        set_iplb(&iplb);
  43    }
  44
  45    /*
  46     * The IPL PSW is at address 0. We also must not overwrite the
  47     * content of non-BIOS memory after we loaded the guest, so we
  48     * save the original content and restore it in jump_to_IPL_2.
  49     */
  50    ResetInfo *current = 0;
  51
  52    save = *current;
  53    current->ipl_addr = (uint32_t) (uint64_t) &jump_to_IPL_2;
  54    current->ipl_continue = address & 0x7fffffff;
  55
  56    debug_print_int("set IPL addr to", current->ipl_continue);
  57
  58    /* Ensure the guest output starts fresh */
  59    sclp_print("\n");
  60
  61    /*
  62     * HACK ALERT.
  63     * We use the load normal reset to keep r15 unchanged. jump_to_IPL_2
  64     * can then use r15 as its stack pointer.
  65     */
  66    asm volatile("lghi 1,1\n\t"
  67                 "diag 1,1,0x308\n\t"
  68                 : : : "1", "memory");
  69    panic("\n! IPL returns !\n");
  70}
  71
  72void jump_to_low_kernel(void)
  73{
  74    /*
  75     * If it looks like a Linux binary, i.e. there is the "S390EP" magic from
  76     * arch/s390/kernel/head.S here, then let's jump to the well-known Linux
  77     * kernel start address (when jumping to the PSW-at-zero address instead,
  78     * the kernel startup code fails when we booted from a network device).
  79     */
  80    if (!memcmp((char *)0x10008, "S390EP", 6)) {
  81        jump_to_IPL_code(KERN_IMAGE_START);
  82    }
  83
  84    /* Trying to get PSW at zero address */
  85    if (*((uint64_t *)0) & IPL_PSW_MASK) {
  86        jump_to_IPL_code((*((uint64_t *)0)) & 0x7fffffff);
  87    }
  88
  89    /* No other option left, so use the Linux kernel start address */
  90    jump_to_IPL_code(KERN_IMAGE_START);
  91}
  92