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
  17 typedef struct ResetInfo {
  18     uint32_t ipl_mask;
  19     uint32_t ipl_addr;
  20     uint32_t ipl_continue;
  21 } ResetInfo;
  22
  23 static ResetInfo save;
  24
  25 static 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
  34 void 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
  72 void 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 }