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#include "s390-arch.h"
  12
  13#define KERN_IMAGE_START 0x010000UL
  14#define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_64)
  15#define RESET_PSW ((uint64_t)&jump_to_IPL_addr | RESET_PSW_MASK)
  16
  17static uint64_t *reset_psw = 0, save_psw, ipl_continue;
  18
  19void write_reset_psw(uint64_t psw)
  20{
  21    *reset_psw = psw;
  22}
  23
  24static void jump_to_IPL_addr(void)
  25{
  26    __attribute__((noreturn)) void (*ipl)(void) = (void *)ipl_continue;
  27
  28    /* Restore reset PSW */
  29    write_reset_psw(save_psw);
  30
  31    ipl();
  32    /* should not return */
  33}
  34
  35void jump_to_IPL_code(uint64_t address)
  36{
  37    /* store the subsystem information _after_ the bootmap was loaded */
  38    write_subsystem_identification();
  39    write_iplb_location();
  40
  41    /* prevent unknown IPL types in the guest */
  42    if (iplb.pbt == S390_IPL_TYPE_QEMU_SCSI) {
  43        iplb.pbt = S390_IPL_TYPE_CCW;
  44        set_iplb(&iplb);
  45    }
  46
  47    /*
  48     * The IPL PSW is at address 0. We also must not overwrite the
  49     * content of non-BIOS memory after we loaded the guest, so we
  50     * save the original content and restore it in jump_to_IPL_2.
  51     */
  52    if (address) {
  53        save_psw = *reset_psw;
  54        write_reset_psw(RESET_PSW);
  55        ipl_continue = address;
  56    }
  57    debug_print_int("set IPL addr to", address ?: *reset_psw & PSW_MASK_SHORT_ADDR);
  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 %%r1,1\n\t"
  68                 "diag %%r1,%%r1,0x308\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 *)S390EP, "S390EP", 6)) {
  82        jump_to_IPL_code(KERN_IMAGE_START);
  83    }
  84
  85    /* Trying to get PSW at zero address (pointed to by reset_psw) */
  86    if (*reset_psw & RESET_PSW_MASK) {
  87        /*
  88         * Surely nobody will try running directly from lowcore, so
  89         * let's use 0 as an indication that we want to load the reset
  90         * psw at 0x0 and not jump to the entry.
  91         */
  92        jump_to_IPL_code(0);
  93    }
  94
  95    /* No other option left, so use the Linux kernel start address */
  96    jump_to_IPL_code(KERN_IMAGE_START);
  97}
  98