Merge tag 'linux-user-for-7.1-pull-request' of https://gitlab.com/laurent_vivier...
[qemu.git] / 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 #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 %%r1,1\n\t"
68 "diag %%r1,%%r1,0x308\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 *)S390EP, "S390EP", 6)) {
82 jump_to_IPL_code(KERN_IMAGE_START);
83 }
84
85 /* Trying to get PSW at zero address (pointed to by reset_psw) */
86 if (*reset_psw & 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 }