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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"
#include "s390-arch.h"
#define KERN_IMAGE_START 0x010000UL
#define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_64)
#define RESET_PSW ((uint64_t)&jump_to_IPL_addr | RESET_PSW_MASK)
static uint64_t *reset_psw = 0, save_psw, ipl_continue;
void write_reset_psw(uint64_t psw)
{
*reset_psw = psw;
}
static void jump_to_IPL_addr(void)
{
__attribute__((noreturn)) void (*ipl)(void) = (void *)ipl_continue;
/* Restore reset PSW */
write_reset_psw(save_psw);
ipl();
/* should not return */
}
void jump_to_IPL_code(uint64_t address)
{
/* store the subsystem information _after_ the bootmap was loaded */
write_subsystem_identification();
write_iplb_location();
/* 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.
*/
if (address) {
save_psw = *reset_psw;
write_reset_psw(RESET_PSW);
ipl_continue = address;
}
debug_print_int("set IPL addr to", address ?: *reset_psw & PSW_MASK_SHORT_ADDR);
/* 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 %%r1,1\n\t"
"diag %%r1,%%r1,0x308\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 *)S390EP, "S390EP", 6)) {
jump_to_IPL_code(KERN_IMAGE_START);
}
/* Trying to get PSW at zero address (pointed to by reset_psw) */
if (*reset_psw & RESET_PSW_MASK) {
/*
* Surely nobody will try running directly from lowcore, so
* let's use 0 as an indication that we want to load the reset
* psw at 0x0 and not jump to the entry.
*/
jump_to_IPL_code(0);
}
/* No other option left, so use the Linux kernel start address */
jump_to_IPL_code(KERN_IMAGE_START);
}
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