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/*
* QEMU s390-ccw firmware - jump to IPL code
*
* This work is licensed under the terms of the GNU GPL, version 2 or (at
* your option) any later version. See the COPYING file in the top-level
* directory.
*/
#include "libc.h"
#include "s390-ccw.h"
#define KERN_IMAGE_START 0x010000UL
#define PSW_MASK_64 0x0000000100000000ULL
#define PSW_MASK_32 0x0000000080000000ULL
#define PSW_MASK_SHORTPSW 0x0008000000000000ULL
#define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_32 | PSW_MASK_64)
typedef struct ResetInfo {
uint64_t ipl_psw;
uint32_t ipl_continue;
} ResetInfo;
static ResetInfo save;
static void jump_to_IPL_2(void)
{
ResetInfo *current = 0;
void (*ipl)(void) = (void *) (uint64_t) current->ipl_continue;
*current = save;
ipl(); /* should not return */
}
void jump_to_IPL_code(uint64_t address)
{
/* store the subsystem information _after_ the bootmap was loaded */
write_subsystem_identification();
/* prevent unknown IPL types in the guest */
if (iplb.pbt == S390_IPL_TYPE_QEMU_SCSI) {
iplb.pbt = S390_IPL_TYPE_CCW;
set_iplb(&iplb);
}
/*
* The IPL PSW is at address 0. We also must not overwrite the
* content of non-BIOS memory after we loaded the guest, so we
* save the original content and restore it in jump_to_IPL_2.
*/
ResetInfo *current = 0;
save = *current;
current->ipl_psw = (uint64_t) &jump_to_IPL_2;
current->ipl_psw |= RESET_PSW_MASK;
current->ipl_continue = address & 0x7fffffff;
debug_print_int("set IPL addr to", current->ipl_continue);
/* Ensure the guest output starts fresh */
sclp_print("\n");
/*
* HACK ALERT.
* We use the load normal reset to keep r15 unchanged. jump_to_IPL_2
* can then use r15 as its stack pointer.
*/
asm volatile("lghi 1,1\n\t"
"diag 1,1,0x308\n\t"
: : : "1", "memory");
panic("\n! IPL returns !\n");
}
void jump_to_low_kernel(void)
{
/*
* If it looks like a Linux binary, i.e. there is the "S390EP" magic from
* arch/s390/kernel/head.S here, then let's jump to the well-known Linux
* kernel start address (when jumping to the PSW-at-zero address instead,
* the kernel startup code fails when we booted from a network device).
*/
if (!memcmp((char *)0x10008, "S390EP", 6)) {
jump_to_IPL_code(KERN_IMAGE_START);
}
/* Trying to get PSW at zero address */
if (*((uint64_t *)0) & RESET_PSW_MASK) {
jump_to_IPL_code((*((uint64_t *)0)) & 0x7fffffff);
}
/* No other option left, so use the Linux kernel start address */
jump_to_IPL_code(KERN_IMAGE_START);
}
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