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 PSW_MASK_SHORTPSW 0x0008000000000000ULL
  16 #define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_32 | PSW_MASK_64)
  17
  18 typedef struct ResetInfo {
  19     uint64_t ipl_psw;
  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     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
  55     current->ipl_psw = (uint64_t) &jump_to_IPL_2;
  56     current->ipl_psw |= RESET_PSW_MASK;
  57     current->ipl_continue = address & 0x7fffffff;
  58
  59     debug_print_int("set IPL addr to", current->ipl_continue);
  60
  61     /* Ensure the guest output starts fresh */
  62     sclp_print("\n");
  63
  64     /*
  65      * HACK ALERT.
  66      * We use the load normal reset to keep r15 unchanged. jump_to_IPL_2
  67      * can then use r15 as its stack pointer.
  68      */
  69     asm volatile("lghi 1,1\n\t"
  70                  "diag 1,1,0x308\n\t"
  71                  : : : "1", "memory");
  72     panic("\n! IPL returns !\n");
  73 }
  74
  75 void jump_to_low_kernel(void)
  76 {
  77     /*
  78      * If it looks like a Linux binary, i.e. there is the "S390EP" magic from
  79      * arch/s390/kernel/head.S here, then let's jump to the well-known Linux
  80      * kernel start address (when jumping to the PSW-at-zero address instead,
  81      * the kernel startup code fails when we booted from a network device).
  82      */
  83     if (!memcmp((char *)0x10008, "S390EP", 6)) {
  84         jump_to_IPL_code(KERN_IMAGE_START);
  85     }
  86
  87     /* Trying to get PSW at zero address */
  88     if (*((uint64_t *)0) & RESET_PSW_MASK) {
  89         jump_to_IPL_code((*((uint64_t *)0)) & 0x7fffffff);
  90     }
  91
  92     /* No other option left, so use the Linux kernel start address */
  93     jump_to_IPL_code(KERN_IMAGE_START);
  94 }