early.c

// SPDX-License-Identifier: GPL-2.0
/*
 *    Copyright IBM Corp. 2007, 2009
 *    Author(s): Hongjie Yang <hongjie@us.ibm.com>,
 *		 Heiko Carstens <heiko.carstens@de.ibm.com>
 */

#define KMSG_COMPONENT "setup"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/compiler.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/lockdep.h>
#include <linux/extable.h>
#include <linux/pfn.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <asm/diag.h>
#include <asm/ebcdic.h>
#include <asm/ipl.h>
#include <asm/lowcore.h>
#include <asm/processor.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/sysinfo.h>
#include <asm/cpcmd.h>
#include <asm/sclp.h>
#include <asm/facility.h>
#include <asm/boot_data.h>
#include <asm/switch_to.h>
#include "entry.h"

static void __init reset_tod_clock(void)
{
	union tod_clock clk;

	if (store_tod_clock_ext_cc(&clk) == 0)
		return;
	/* TOD clock not running. Set the clock to Unix Epoch. */
	if (set_tod_clock(TOD_UNIX_EPOCH) || store_tod_clock_ext_cc(&clk))
		disabled_wait();

	memset(&tod_clock_base, 0, sizeof(tod_clock_base));
	tod_clock_base.tod = TOD_UNIX_EPOCH;
	S390_lowcore.last_update_clock = TOD_UNIX_EPOCH;
}

/*
 * Initialize storage key for kernel pages
 */
static noinline __init void init_kernel_storage_key(void)
{
#if PAGE_DEFAULT_KEY
	unsigned long end_pfn, init_pfn;

	end_pfn = PFN_UP(__pa(_end));

	for (init_pfn = 0 ; init_pfn < end_pfn; init_pfn++)
		page_set_storage_key(init_pfn << PAGE_SHIFT,
				     PAGE_DEFAULT_KEY, 0);
#endif
}

static __initdata char sysinfo_page[PAGE_SIZE] __aligned(PAGE_SIZE);

static noinline __init void detect_machine_type(void)
{
	struct sysinfo_3_2_2 *vmms = (struct sysinfo_3_2_2 *)&sysinfo_page;

	/* Check current-configuration-level */
	if (stsi(NULL, 0, 0, 0) <= 2) {
		S390_lowcore.machine_flags |= MACHINE_FLAG_LPAR;
		return;
	}
	/* Get virtual-machine cpu information. */
	if (stsi(vmms, 3, 2, 2) || !vmms->count)
		return;

	/* Detect known hypervisors */
	if (!memcmp(vmms->vm[0].cpi, "\xd2\xe5\xd4", 3))
		S390_lowcore.machine_flags |= MACHINE_FLAG_KVM;
	else if (!memcmp(vmms->vm[0].cpi, "\xa9\x61\xe5\xd4", 4))
		S390_lowcore.machine_flags |= MACHINE_FLAG_VM;
}

/* Remove leading, trailing and double whitespace. */
static inline void strim_all(char *str)
{
	char *s;

	s = strim(str);
	if (s != str)
		memmove(str, s, strlen(s));
	while (*str) {
		if (!isspace(*str++))
			continue;
		if (isspace(*str)) {
			s = skip_spaces(str);
			memmove(str, s, strlen(s) + 1);
		}
	}
}

static noinline __init void setup_arch_string(void)
{
	struct sysinfo_1_1_1 *mach = (struct sysinfo_1_1_1 *)&sysinfo_page;
	struct sysinfo_3_2_2 *vm = (struct sysinfo_3_2_2 *)&sysinfo_page;
	char mstr[80], hvstr[17];

	if (stsi(mach, 1, 1, 1))
		return;
	EBCASC(mach->manufacturer, sizeof(mach->manufacturer));
	EBCASC(mach->type, sizeof(mach->type));
	EBCASC(mach->model, sizeof(mach->model));
	EBCASC(mach->model_capacity, sizeof(mach->model_capacity));
	sprintf(mstr, "%-16.16s %-4.4s %-16.16s %-16.16s",
		mach->manufacturer, mach->type,
		mach->model, mach->model_capacity);
	strim_all(mstr);
	if (stsi(vm, 3, 2, 2) == 0 && vm->count) {
		EBCASC(vm->vm[0].cpi, sizeof(vm->vm[0].cpi));
		sprintf(hvstr, "%-16.16s", vm->vm[0].cpi);
		strim_all(hvstr);
	} else {
		sprintf(hvstr, "%s",
			MACHINE_IS_LPAR ? "LPAR" :
			MACHINE_IS_VM ? "z/VM" :
			MACHINE_IS_KVM ? "KVM" : "unknown");
	}
	dump_stack_set_arch_desc("%s (%s)", mstr, hvstr);
}

static __init void setup_topology(void)
{
	int max_mnest;

	if (!test_facility(11))
		return;
	S390_lowcore.machine_flags |= MACHINE_FLAG_TOPOLOGY;
	for (max_mnest = 6; max_mnest > 1; max_mnest--) {
		if (stsi(&sysinfo_page, 15, 1, max_mnest) == 0)
			break;
	}
	topology_max_mnest = max_mnest;
}

static void early_pgm_check_handler(void)
{
	const struct exception_table_entry *fixup;
	unsigned long cr0, cr0_new;
	unsigned long addr;

	addr = S390_lowcore.program_old_psw.addr;
	fixup = s390_search_extables(addr);
	if (!fixup)
		disabled_wait();
	/* Disable low address protection before storing into lowcore. */
	__ctl_store(cr0, 0, 0);
	cr0_new = cr0 & ~(1UL << 28);
	__ctl_load(cr0_new, 0, 0);
	S390_lowcore.program_old_psw.addr = extable_fixup(fixup);
	__ctl_load(cr0, 0, 0);
}

static noinline __init void setup_lowcore_early(void)
{
	psw_t psw;

	psw.addr = (unsigned long)s390_base_pgm_handler;
	psw.mask = PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA;
	if (IS_ENABLED(CONFIG_KASAN))
		psw.mask |= PSW_MASK_DAT;
	S390_lowcore.program_new_psw = psw;
	s390_base_pgm_handler_fn = early_pgm_check_handler;
	S390_lowcore.preempt_count = INIT_PREEMPT_COUNT;
}

static noinline __init void setup_facility_list(void)
{
	memcpy(S390_lowcore.alt_stfle_fac_list,
	       S390_lowcore.stfle_fac_list,
	       sizeof(S390_lowcore.alt_stfle_fac_list));
	if (!IS_ENABLED(CONFIG_KERNEL_NOBP))
		__clear_facility(82, S390_lowcore.alt_stfle_fac_list);
}

static __init void detect_diag9c(void)
{
	unsigned int cpu_address;
	int rc;

	cpu_address = stap();
	diag_stat_inc(DIAG_STAT_X09C);
	asm volatile(
		"	diag	%2,0,0x9c\n"
		"0:	la	%0,0\n"
		"1:\n"
		EX_TABLE(0b,1b)
		: "=d" (rc) : "0" (-EOPNOTSUPP), "d" (cpu_address) : "cc");
	if (!rc)
		S390_lowcore.machine_flags |= MACHINE_FLAG_DIAG9C;
}

static __init void detect_machine_facilities(void)
{
	if (test_facility(8)) {
		S390_lowcore.machine_flags |= MACHINE_FLAG_EDAT1;
		__ctl_set_bit(0, 23);
	}
	if (test_facility(78))
		S390_lowcore.machine_flags |= MACHINE_FLAG_EDAT2;
	if (test_facility(3))
		S390_lowcore.machine_flags |= MACHINE_FLAG_IDTE;
	if (test_facility(50) && test_facility(73)) {
		S390_lowcore.machine_flags |= MACHINE_FLAG_TE;
		__ctl_set_bit(0, 55);
	}
	if (test_facility(51))
		S390_lowcore.machine_flags |= MACHINE_FLAG_TLB_LC;
	if (test_facility(129)) {
		S390_lowcore.machine_flags |= MACHINE_FLAG_VX;
		__ctl_set_bit(0, 17);
	}
	if (test_facility(130) && !noexec_disabled) {
		S390_lowcore.machine_flags |= MACHINE_FLAG_NX;
		__ctl_set_bit(0, 20);
	}
	if (test_facility(133))
		S390_lowcore.machine_flags |= MACHINE_FLAG_GS;
	if (test_facility(139) && (tod_clock_base.tod >> 63)) {
		/* Enabled signed clock comparator comparisons */
		S390_lowcore.machine_flags |= MACHINE_FLAG_SCC;
		clock_comparator_max = -1ULL >> 1;
		__ctl_set_bit(0, 53);
	}
	if (IS_ENABLED(CONFIG_PCI) && test_facility(153)) {
		S390_lowcore.machine_flags |= MACHINE_FLAG_PCI_MIO;
		/* the control bit is set during PCI initialization */
	}
}

static inline void save_vector_registers(void)
{
#ifdef CONFIG_CRASH_DUMP
	if (test_facility(129))
		save_vx_regs(boot_cpu_vector_save_area);
#endif
}

static inline void setup_control_registers(void)
{
	unsigned long reg;

	__ctl_store(reg, 0, 0);
	reg |= CR0_LOW_ADDRESS_PROTECTION;
	reg |= CR0_EMERGENCY_SIGNAL_SUBMASK;
	reg |= CR0_EXTERNAL_CALL_SUBMASK;
	__ctl_load(reg, 0, 0);
}

static inline void setup_access_registers(void)
{
	unsigned int acrs[NUM_ACRS] = { 0 };

	restore_access_regs(acrs);
}

static int __init disable_vector_extension(char *str)
{
	S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX;
	__ctl_clear_bit(0, 17);
	return 0;
}
early_param("novx", disable_vector_extension);

char __bootdata(early_command_line)[COMMAND_LINE_SIZE];
static void __init setup_boot_command_line(void)
{
	/* copy arch command line */
	strlcpy(boot_command_line, early_command_line, ARCH_COMMAND_LINE_SIZE);
}

static void __init check_image_bootable(void)
{
	if (!memcmp(EP_STRING, (void *)EP_OFFSET, strlen(EP_STRING)))
		return;

	sclp_early_printk("Linux kernel boot failure: An attempt to boot a vmlinux ELF image failed.\n");
	sclp_early_printk("This image does not contain all parts necessary for starting up. Use\n");
	sclp_early_printk("bzImage or arch/s390/boot/compressed/vmlinux instead.\n");
	disabled_wait();
}

void __init startup_init(void)
{
	reset_tod_clock();
	check_image_bootable();
	time_early_init();
	init_kernel_storage_key();
	lockdep_off();
	setup_lowcore_early();
	setup_facility_list();
	detect_machine_type();
	setup_arch_string();
	setup_boot_command_line();
	detect_diag9c();
	detect_machine_facilities();
	save_vector_registers();
	setup_topology();
	sclp_early_detect();
	setup_control_registers();
	setup_access_registers();
	lockdep_on();
}