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 } 92