| 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 <string.h> |
| 10 | #include <stdio.h> |
| 11 | #include "s390-ccw.h" |
| 12 | #include "s390-arch.h" |
| 13 | |
| 14 | #define KERN_IMAGE_START 0x010000UL |
| 15 | #define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_64) |
| 16 | #define RESET_PSW ((uint64_t)&jump_to_IPL_addr | RESET_PSW_MASK) |
| 17 | |
| 18 | static uint64_t *reset_psw = 0, save_psw, ipl_continue; |
| 19 | |
| 20 | void write_reset_psw(uint64_t psw) |
| 21 | { |
| 22 | *reset_psw = psw; |
| 23 | } |
| 24 | |
| 25 | static void jump_to_IPL_addr(void) |
| 26 | { |
| 27 | __attribute__((noreturn)) void (*ipl)(void) = (void *)ipl_continue; |
| 28 | |
| 29 | /* Restore reset PSW */ |
| 30 | write_reset_psw(save_psw); |
| 31 | |
| 32 | ipl(); |
| 33 | /* should not return */ |
| 34 | } |
| 35 | |
| 36 | int jump_to_IPL_code(uint64_t address) |
| 37 | { |
| 38 | /* store the subsystem information _after_ the bootmap was loaded */ |
| 39 | write_subsystem_identification(); |
| 40 | write_iplb_location(); |
| 41 | |
| 42 | /* |
| 43 | * The IPLB for QEMU SCSI type devices must be rebuilt during re-ipl. The |
| 44 | * iplb.devno is set to the boot position of the target SCSI device. |
| 45 | */ |
| 46 | if (iplb->pbt == S390_IPL_TYPE_QEMU_SCSI) { |
| 47 | iplb->devno = qipl.index; |
| 48 | } |
| 49 | |
| 50 | if (have_iplb && !set_iplb(iplb)) { |
| 51 | panic("Failed to set IPLB"); |
| 52 | } |
| 53 | |
| 54 | /* |
| 55 | * The IPL PSW is at address 0. We also must not overwrite the |
| 56 | * content of non-BIOS memory after we loaded the guest, so we |
| 57 | * save the original content and restore it in jump_to_IPL_2. |
| 58 | */ |
| 59 | if (address) { |
| 60 | save_psw = *reset_psw; |
| 61 | write_reset_psw(RESET_PSW); |
| 62 | ipl_continue = address; |
| 63 | } |
| 64 | debug_print_int("set IPL addr to", address ?: *reset_psw & PSW_MASK_SHORT_ADDR); |
| 65 | |
| 66 | /* Ensure the guest output starts fresh */ |
| 67 | printf("\n"); |
| 68 | |
| 69 | /* |
| 70 | * HACK ALERT. |
| 71 | * We use the load normal reset to keep r15 unchanged. jump_to_IPL_2 |
| 72 | * can then use r15 as its stack pointer. |
| 73 | */ |
| 74 | asm volatile("lghi %%r1,1\n\t" |
| 75 | "diag %%r1,%%r1,0x308\n\t" |
| 76 | : : : "1", "memory"); |
| 77 | puts("IPL code jump failed"); |
| 78 | |
| 79 | /* |
| 80 | * A failed jump only occurs in extreme conditions, so abort the IPL entirely. |
| 81 | * This also prevents attempts to boot from the chain area if it has been |
| 82 | * overwritten with component data. |
| 83 | */ |
| 84 | qipl.chain_len = 0; |
| 85 | return -1; |
| 86 | } |
| 87 | |
| 88 | void jump_to_low_kernel(void) |
| 89 | { |
| 90 | /* |
| 91 | * If it looks like a Linux binary, i.e. there is the "S390EP" magic from |
| 92 | * arch/s390/kernel/head.S here, then let's jump to the well-known Linux |
| 93 | * kernel start address (when jumping to the PSW-at-zero address instead, |
| 94 | * the kernel startup code fails when we booted from a network device). |
| 95 | */ |
| 96 | if (!memcmp((char *)S390EP, "S390EP", 6)) { |
| 97 | jump_to_IPL_code(KERN_IMAGE_START); |
| 98 | } |
| 99 | |
| 100 | /* Trying to get PSW at zero address (pointed to by reset_psw) */ |
| 101 | if (*reset_psw & RESET_PSW_MASK) { |
| 102 | /* |
| 103 | * Surely nobody will try running directly from lowcore, so |
| 104 | * let's use 0 as an indication that we want to load the reset |
| 105 | * psw at 0x0 and not jump to the entry. |
| 106 | */ |
| 107 | jump_to_IPL_code(0); |
| 108 | } |
| 109 | |
| 110 | /* No other option left, so use the Linux kernel start address */ |
| 111 | jump_to_IPL_code(KERN_IMAGE_START); |
| 112 | } |