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 17 static uint64_t *reset_psw = 0, save_psw, ipl_continue; 18 19 void write_reset_psw(uint64_t psw) 20 { 21 *reset_psw = psw; 22 } 23 24 static 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 35 void 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 1,1\n\t" 68 "diag 1,1,0x308\n\t" 69 : : : "1", "memory"); 70 panic("\n! IPL returns !\n"); 71 } 72 73 void 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 *)0x10008, "S390EP", 6)) { 82 jump_to_IPL_code(KERN_IMAGE_START); 83 } 84 85 /* Trying to get PSW at zero address */ 86 if (*((uint64_t *)0) & 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