x86/speculation/mds: Fix documentation typo

[linux/fpc-iii.git] / arch / s390 / kernel / setup.c

/*
 *  S390 version
 *    Copyright IBM Corp. 1999, 2012
 *    Author(s): Hartmut Penner (hp@de.ibm.com),
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 *  Derived from "arch/i386/kernel/setup.c"
 *    Copyright (C) 1995, Linus Torvalds
 */

/*
 * This file handles the architecture-dependent parts of initialization
 */

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

#include <linux/errno.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/cpu.h>
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/random.h>
#include <linux/user.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/bootmem.h>
#include <linux/root_dev.h>
#include <linux/console.h>
#include <linux/kernel_stat.h>
#include <linux/dma-contiguous.h>
#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/pfn.h>
#include <linux/ctype.h>
#include <linux/reboot.h>
#include <linux/topology.h>
#include <linux/kexec.h>
#include <linux/crash_dump.h>
#include <linux/memory.h>
#include <linux/compat.h>

#include <asm/ipl.h>
#include <asm/facility.h>
#include <asm/smp.h>
#include <asm/mmu_context.h>
#include <asm/cpcmd.h>
#include <asm/lowcore.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/ptrace.h>
#include <asm/sections.h>
#include <asm/ebcdic.h>
#include <asm/kvm_virtio.h>
#include <asm/diag.h>
#include <asm/os_info.h>
#include <asm/sclp.h>
#include <asm/sysinfo.h>
#include <asm/numa.h>
#include <asm/alternative.h>
#include <asm/nospec-branch.h>
#include "entry.h"

/*
 * Machine setup..
 */
unsigned int console_mode = 0;
EXPORT_SYMBOL(console_mode);

unsigned int console_devno = -1;
EXPORT_SYMBOL(console_devno);

unsigned int console_irq = -1;
EXPORT_SYMBOL(console_irq);

unsigned long elf_hwcap __read_mostly = 0;
char elf_platform[ELF_PLATFORM_SIZE];

unsigned long int_hwcap = 0;

int __initdata memory_end_set;
unsigned long __initdata memory_end;
unsigned long __initdata max_physmem_end;

unsigned long VMALLOC_START;
EXPORT_SYMBOL(VMALLOC_START);

unsigned long VMALLOC_END;
EXPORT_SYMBOL(VMALLOC_END);

struct page *vmemmap;
EXPORT_SYMBOL(vmemmap);

unsigned long MODULES_VADDR;
unsigned long MODULES_END;

/* An array with a pointer to the lowcore of every CPU. */
struct lowcore *lowcore_ptr[NR_CPUS];
EXPORT_SYMBOL(lowcore_ptr);

/*
 * This is set up by the setup-routine at boot-time
 * for S390 need to find out, what we have to setup
 * using address 0x10400 ...
 */

#include <asm/setup.h>

/*
 * condev= and conmode= setup parameter.
 */

static int __init condev_setup(char *str)
{
        int vdev;

        vdev = simple_strtoul(str, &str, 0);
        if (vdev >= 0 && vdev < 65536) {
                console_devno = vdev;
                console_irq = -1;
        }
        return 1;
}

__setup("condev=", condev_setup);

static void __init set_preferred_console(void)
{
        if (CONSOLE_IS_3215 || CONSOLE_IS_SCLP)
                add_preferred_console("ttyS", 0, NULL);
        else if (CONSOLE_IS_3270)
                add_preferred_console("tty3270", 0, NULL);
        else if (CONSOLE_IS_VT220)
                add_preferred_console("ttyS", 1, NULL);
        else if (CONSOLE_IS_HVC)
                add_preferred_console("hvc", 0, NULL);
}

static int __init conmode_setup(char *str)
{
#if defined(CONFIG_SCLP_CONSOLE) || defined(CONFIG_SCLP_VT220_CONSOLE)
        if (strncmp(str, "hwc", 4) == 0 || strncmp(str, "sclp", 5) == 0)
                SET_CONSOLE_SCLP;
#endif
#if defined(CONFIG_TN3215_CONSOLE)
        if (strncmp(str, "3215", 5) == 0)
                SET_CONSOLE_3215;
#endif
#if defined(CONFIG_TN3270_CONSOLE)
        if (strncmp(str, "3270", 5) == 0)
                SET_CONSOLE_3270;
#endif
        set_preferred_console();
        return 1;
}

__setup("conmode=", conmode_setup);

static void __init conmode_default(void)
{
        char query_buffer[1024];
        char *ptr;

        if (MACHINE_IS_VM) {
                cpcmd("QUERY CONSOLE", query_buffer, 1024, NULL);
                console_devno = simple_strtoul(query_buffer + 5, NULL, 16);
                ptr = strstr(query_buffer, "SUBCHANNEL =");
                console_irq = simple_strtoul(ptr + 13, NULL, 16);
                cpcmd("QUERY TERM", query_buffer, 1024, NULL);
                ptr = strstr(query_buffer, "CONMODE");
                /*
                 * Set the conmode to 3215 so that the device recognition 
                 * will set the cu_type of the console to 3215. If the
                 * conmode is 3270 and we don't set it back then both
                 * 3215 and the 3270 driver will try to access the console
                 * device (3215 as console and 3270 as normal tty).
                 */
                cpcmd("TERM CONMODE 3215", NULL, 0, NULL);
                if (ptr == NULL) {
#if defined(CONFIG_SCLP_CONSOLE) || defined(CONFIG_SCLP_VT220_CONSOLE)
                        SET_CONSOLE_SCLP;
#endif
                        return;
                }
                if (strncmp(ptr + 8, "3270", 4) == 0) {
#if defined(CONFIG_TN3270_CONSOLE)
                        SET_CONSOLE_3270;
#elif defined(CONFIG_TN3215_CONSOLE)
                        SET_CONSOLE_3215;
#elif defined(CONFIG_SCLP_CONSOLE) || defined(CONFIG_SCLP_VT220_CONSOLE)
                        SET_CONSOLE_SCLP;
#endif
                } else if (strncmp(ptr + 8, "3215", 4) == 0) {
#if defined(CONFIG_TN3215_CONSOLE)
                        SET_CONSOLE_3215;
#elif defined(CONFIG_TN3270_CONSOLE)
                        SET_CONSOLE_3270;
#elif defined(CONFIG_SCLP_CONSOLE) || defined(CONFIG_SCLP_VT220_CONSOLE)
                        SET_CONSOLE_SCLP;
#endif
                }
        } else if (MACHINE_IS_KVM) {
                if (sclp.has_vt220 && IS_ENABLED(CONFIG_SCLP_VT220_CONSOLE))
                        SET_CONSOLE_VT220;
                else if (sclp.has_linemode && IS_ENABLED(CONFIG_SCLP_CONSOLE))
                        SET_CONSOLE_SCLP;
                else
                        SET_CONSOLE_HVC;
        } else {
#if defined(CONFIG_SCLP_CONSOLE) || defined(CONFIG_SCLP_VT220_CONSOLE)
                SET_CONSOLE_SCLP;
#endif
        }
}

#ifdef CONFIG_CRASH_DUMP
static void __init setup_zfcpdump(void)
{
        if (ipl_info.type != IPL_TYPE_FCP_DUMP)
                return;
        if (OLDMEM_BASE)
                return;
        strcat(boot_command_line, " cio_ignore=all,!ipldev,!condev");
        console_loglevel = 2;
}
#else
static inline void setup_zfcpdump(void) {}
#endif /* CONFIG_CRASH_DUMP */

 /*
 * Reboot, halt and power_off stubs. They just call _machine_restart,
 * _machine_halt or _machine_power_off. 
 */

void machine_restart(char *command)
{
        if ((!in_interrupt() && !in_atomic()) || oops_in_progress)
                /*
                 * Only unblank the console if we are called in enabled
                 * context or a bust_spinlocks cleared the way for us.
                 */
                console_unblank();
        _machine_restart(command);
}

void machine_halt(void)
{
        if (!in_interrupt() || oops_in_progress)
                /*
                 * Only unblank the console if we are called in enabled
                 * context or a bust_spinlocks cleared the way for us.
                 */
                console_unblank();
        _machine_halt();
}

void machine_power_off(void)
{
        if (!in_interrupt() || oops_in_progress)
                /*
                 * Only unblank the console if we are called in enabled
                 * context or a bust_spinlocks cleared the way for us.
                 */
                console_unblank();
        _machine_power_off();
}

/*
 * Dummy power off function.
 */
void (*pm_power_off)(void) = machine_power_off;
EXPORT_SYMBOL_GPL(pm_power_off);

static int __init early_parse_mem(char *p)
{
        memory_end = memparse(p, &p);
        memory_end &= PAGE_MASK;
        memory_end_set = 1;
        return 0;
}
early_param("mem", early_parse_mem);

static int __init parse_vmalloc(char *arg)
{
        if (!arg)
                return -EINVAL;
        VMALLOC_END = (memparse(arg, &arg) + PAGE_SIZE - 1) & PAGE_MASK;
        return 0;
}
early_param("vmalloc", parse_vmalloc);

void *restart_stack __section(.data);

static void __init setup_lowcore_dat_off(void)
{
        struct lowcore *lc;

        /*
         * Setup lowcore for boot cpu
         */
        BUILD_BUG_ON(sizeof(struct lowcore) != LC_PAGES * PAGE_SIZE);
        lc = memblock_virt_alloc_low(sizeof(*lc), sizeof(*lc));
        lc->restart_psw.mask = PSW_KERNEL_BITS;
        lc->restart_psw.addr = (unsigned long) restart_int_handler;
        lc->external_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
        lc->external_new_psw.addr = (unsigned long) ext_int_handler;
        lc->svc_new_psw.mask = PSW_KERNEL_BITS |
                PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
        lc->svc_new_psw.addr = (unsigned long) system_call;
        lc->program_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
        lc->program_new_psw.addr = (unsigned long) pgm_check_handler;
        lc->mcck_new_psw.mask = PSW_KERNEL_BITS;
        lc->mcck_new_psw.addr = (unsigned long) mcck_int_handler;
        lc->io_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
        lc->io_new_psw.addr = (unsigned long) io_int_handler;
        lc->clock_comparator = clock_comparator_max;
        lc->kernel_stack = ((unsigned long) &init_thread_union)
                + THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
        lc->async_stack = (unsigned long)
                memblock_virt_alloc(ASYNC_SIZE, ASYNC_SIZE)
                + ASYNC_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
        lc->panic_stack = (unsigned long)
                memblock_virt_alloc(PAGE_SIZE, PAGE_SIZE)
                + PAGE_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
        lc->current_task = (unsigned long)&init_task;
        lc->lpp = LPP_MAGIC;
        lc->machine_flags = S390_lowcore.machine_flags;
        lc->preempt_count = S390_lowcore.preempt_count;
        lc->stfl_fac_list = S390_lowcore.stfl_fac_list;
        memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
               sizeof(lc->stfle_fac_list));
        memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
               sizeof(lc->alt_stfle_fac_list));
        if (MACHINE_HAS_VX || MACHINE_HAS_GS) {
                unsigned long bits, size;

                bits = MACHINE_HAS_GS ? 11 : 10;
                size = 1UL << bits;
                lc->mcesad = (__u64) memblock_virt_alloc(size, size);
                if (MACHINE_HAS_GS)
                        lc->mcesad |= bits;
        }
        lc->vdso_per_cpu_data = (unsigned long) &lc->paste[0];
        lc->sync_enter_timer = S390_lowcore.sync_enter_timer;
        lc->async_enter_timer = S390_lowcore.async_enter_timer;
        lc->exit_timer = S390_lowcore.exit_timer;
        lc->user_timer = S390_lowcore.user_timer;
        lc->system_timer = S390_lowcore.system_timer;
        lc->steal_timer = S390_lowcore.steal_timer;
        lc->last_update_timer = S390_lowcore.last_update_timer;
        lc->last_update_clock = S390_lowcore.last_update_clock;

        restart_stack = memblock_virt_alloc(ASYNC_SIZE, ASYNC_SIZE);
        restart_stack += ASYNC_SIZE;

        /*
         * Set up PSW restart to call ipl.c:do_restart(). Copy the relevant
         * restart data to the absolute zero lowcore. This is necessary if
         * PSW restart is done on an offline CPU that has lowcore zero.
         */
        lc->restart_stack = (unsigned long) restart_stack;
        lc->restart_fn = (unsigned long) do_restart;
        lc->restart_data = 0;
        lc->restart_source = -1UL;

        /* Setup absolute zero lowcore */
        mem_assign_absolute(S390_lowcore.restart_stack, lc->restart_stack);
        mem_assign_absolute(S390_lowcore.restart_fn, lc->restart_fn);
        mem_assign_absolute(S390_lowcore.restart_data, lc->restart_data);
        mem_assign_absolute(S390_lowcore.restart_source, lc->restart_source);
        mem_assign_absolute(S390_lowcore.restart_psw, lc->restart_psw);

#ifdef CONFIG_SMP
        lc->spinlock_lockval = arch_spin_lockval(0);
#endif
        lc->br_r1_trampoline = 0x07f1;  /* br %r1 */

        set_prefix((u32)(unsigned long) lc);
        lowcore_ptr[0] = lc;
}

static void __init setup_lowcore_dat_on(void)
{
        __ctl_clear_bit(0, 28);
        S390_lowcore.external_new_psw.mask |= PSW_MASK_DAT;
        S390_lowcore.svc_new_psw.mask |= PSW_MASK_DAT;
        S390_lowcore.program_new_psw.mask |= PSW_MASK_DAT;
        S390_lowcore.io_new_psw.mask |= PSW_MASK_DAT;
        __ctl_set_bit(0, 28);
}

static struct resource code_resource = {
        .name  = "Kernel code",
        .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
};

static struct resource data_resource = {
        .name = "Kernel data",
        .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
};

static struct resource bss_resource = {
        .name = "Kernel bss",
        .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
};

static struct resource __initdata *standard_resources[] = {
        &code_resource,
        &data_resource,
        &bss_resource,
};

static void __init setup_resources(void)
{
        struct resource *res, *std_res, *sub_res;
        struct memblock_region *reg;
        int j;

        code_resource.start = (unsigned long) &_text;
        code_resource.end = (unsigned long) &_etext - 1;
        data_resource.start = (unsigned long) &_etext;
        data_resource.end = (unsigned long) &_edata - 1;
        bss_resource.start = (unsigned long) &__bss_start;
        bss_resource.end = (unsigned long) &__bss_stop - 1;

        for_each_memblock(memory, reg) {
                res = memblock_virt_alloc(sizeof(*res), 8);
                res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;

                res->name = "System RAM";
                res->start = reg->base;
                res->end = reg->base + reg->size - 1;
                request_resource(&iomem_resource, res);

                for (j = 0; j < ARRAY_SIZE(standard_resources); j++) {
                        std_res = standard_resources[j];
                        if (std_res->start < res->start ||
                            std_res->start > res->end)
                                continue;
                        if (std_res->end > res->end) {
                                sub_res = memblock_virt_alloc(sizeof(*sub_res), 8);
                                *sub_res = *std_res;
                                sub_res->end = res->end;
                                std_res->start = res->end + 1;
                                request_resource(res, sub_res);
                        } else {
                                request_resource(res, std_res);
                        }
                }
        }
#ifdef CONFIG_CRASH_DUMP
        /*
         * Re-add removed crash kernel memory as reserved memory. This makes
         * sure it will be mapped with the identity mapping and struct pages
         * will be created, so it can be resized later on.
         * However add it later since the crash kernel resource should not be
         * part of the System RAM resource.
         */
        if (crashk_res.end) {
                memblock_add_node(crashk_res.start, resource_size(&crashk_res), 0);
                memblock_reserve(crashk_res.start, resource_size(&crashk_res));
                insert_resource(&iomem_resource, &crashk_res);
        }
#endif
}

static void __init setup_memory_end(void)
{
        unsigned long vmax, vmalloc_size, tmp;

        /* Choose kernel address space layout: 2, 3, or 4 levels. */
        vmalloc_size = VMALLOC_END ?: (128UL << 30) - MODULES_LEN;
        tmp = (memory_end ?: max_physmem_end) / PAGE_SIZE;
        tmp = tmp * (sizeof(struct page) + PAGE_SIZE);
        if (tmp + vmalloc_size + MODULES_LEN <= _REGION2_SIZE)
                vmax = _REGION2_SIZE; /* 3-level kernel page table */
        else
                vmax = _REGION1_SIZE; /* 4-level kernel page table */
        /* module area is at the end of the kernel address space. */
        MODULES_END = vmax;
        MODULES_VADDR = MODULES_END - MODULES_LEN;
        VMALLOC_END = MODULES_VADDR;
        VMALLOC_START = vmax - vmalloc_size;

        /* Split remaining virtual space between 1:1 mapping & vmemmap array */
        tmp = VMALLOC_START / (PAGE_SIZE + sizeof(struct page));
        /* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */
        tmp = SECTION_ALIGN_UP(tmp);
        tmp = VMALLOC_START - tmp * sizeof(struct page);
        tmp &= ~((vmax >> 11) - 1);     /* align to page table level */
        tmp = min(tmp, 1UL << MAX_PHYSMEM_BITS);
        vmemmap = (struct page *) tmp;

        /* Take care that memory_end is set and <= vmemmap */
        memory_end = min(memory_end ?: max_physmem_end, tmp);
        max_pfn = max_low_pfn = PFN_DOWN(memory_end);
        memblock_remove(memory_end, ULONG_MAX);

        pr_notice("The maximum memory size is %luMB\n", memory_end >> 20);
}

#ifdef CONFIG_CRASH_DUMP

/*
 * When kdump is enabled, we have to ensure that no memory from
 * the area [0 - crashkernel memory size] and
 * [crashk_res.start - crashk_res.end] is set offline.
 */
static int kdump_mem_notifier(struct notifier_block *nb,
                              unsigned long action, void *data)
{
        struct memory_notify *arg = data;

        if (action != MEM_GOING_OFFLINE)
                return NOTIFY_OK;
        if (arg->start_pfn < PFN_DOWN(resource_size(&crashk_res)))
                return NOTIFY_BAD;
        if (arg->start_pfn > PFN_DOWN(crashk_res.end))
                return NOTIFY_OK;
        if (arg->start_pfn + arg->nr_pages - 1 < PFN_DOWN(crashk_res.start))
                return NOTIFY_OK;
        return NOTIFY_BAD;
}

static struct notifier_block kdump_mem_nb = {
        .notifier_call = kdump_mem_notifier,
};

#endif

/*
 * Make sure that the area behind memory_end is protected
 */
static void reserve_memory_end(void)
{
#ifdef CONFIG_CRASH_DUMP
        if (ipl_info.type == IPL_TYPE_FCP_DUMP &&
            !OLDMEM_BASE && sclp.hsa_size) {
                memory_end = sclp.hsa_size;
                memory_end &= PAGE_MASK;
                memory_end_set = 1;
        }
#endif
        if (!memory_end_set)
                return;
        memblock_reserve(memory_end, ULONG_MAX);
}

/*
 * Make sure that oldmem, where the dump is stored, is protected
 */
static void reserve_oldmem(void)
{
#ifdef CONFIG_CRASH_DUMP
        if (OLDMEM_BASE)
                /* Forget all memory above the running kdump system */
                memblock_reserve(OLDMEM_SIZE, (phys_addr_t)ULONG_MAX);
#endif
}

/*
 * Make sure that oldmem, where the dump is stored, is protected
 */
static void remove_oldmem(void)
{
#ifdef CONFIG_CRASH_DUMP
        if (OLDMEM_BASE)
                /* Forget all memory above the running kdump system */
                memblock_remove(OLDMEM_SIZE, (phys_addr_t)ULONG_MAX);
#endif
}

/*
 * Reserve memory for kdump kernel to be loaded with kexec
 */
static void __init reserve_crashkernel(void)
{
#ifdef CONFIG_CRASH_DUMP
        unsigned long long crash_base, crash_size;
        phys_addr_t low, high;
        int rc;

        rc = parse_crashkernel(boot_command_line, memory_end, &crash_size,
                               &crash_base);

        crash_base = ALIGN(crash_base, KEXEC_CRASH_MEM_ALIGN);
        crash_size = ALIGN(crash_size, KEXEC_CRASH_MEM_ALIGN);
        if (rc || crash_size == 0)
                return;

        if (memblock.memory.regions[0].size < crash_size) {
                pr_info("crashkernel reservation failed: %s\n",
                        "first memory chunk must be at least crashkernel size");
                return;
        }

        low = crash_base ?: OLDMEM_BASE;
        high = low + crash_size;
        if (low >= OLDMEM_BASE && high <= OLDMEM_BASE + OLDMEM_SIZE) {
                /* The crashkernel fits into OLDMEM, reuse OLDMEM */
                crash_base = low;
        } else {
                /* Find suitable area in free memory */
                low = max_t(unsigned long, crash_size, sclp.hsa_size);
                high = crash_base ? crash_base + crash_size : ULONG_MAX;

                if (crash_base && crash_base < low) {
                        pr_info("crashkernel reservation failed: %s\n",
                                "crash_base too low");
                        return;
                }
                low = crash_base ?: low;
                crash_base = memblock_find_in_range(low, high, crash_size,
                                                    KEXEC_CRASH_MEM_ALIGN);
        }

        if (!crash_base) {
                pr_info("crashkernel reservation failed: %s\n",
                        "no suitable area found");
                return;
        }

        if (register_memory_notifier(&kdump_mem_nb))
                return;

        if (!OLDMEM_BASE && MACHINE_IS_VM)
                diag10_range(PFN_DOWN(crash_base), PFN_DOWN(crash_size));
        crashk_res.start = crash_base;
        crashk_res.end = crash_base + crash_size - 1;
        memblock_remove(crash_base, crash_size);
        pr_info("Reserving %lluMB of memory at %lluMB "
                "for crashkernel (System RAM: %luMB)\n",
                crash_size >> 20, crash_base >> 20,
                (unsigned long)memblock.memory.total_size >> 20);
        os_info_crashkernel_add(crash_base, crash_size);
#endif
}

/*
 * Reserve the initrd from being used by memblock
 */
static void __init reserve_initrd(void)
{
#ifdef CONFIG_BLK_DEV_INITRD
        if (!INITRD_START || !INITRD_SIZE)
                return;
        initrd_start = INITRD_START;
        initrd_end = initrd_start + INITRD_SIZE;
        memblock_reserve(INITRD_START, INITRD_SIZE);
#endif
}

/*
 * Check for initrd being in usable memory
 */
static void __init check_initrd(void)
{
#ifdef CONFIG_BLK_DEV_INITRD
        if (INITRD_START && INITRD_SIZE &&
            !memblock_is_region_memory(INITRD_START, INITRD_SIZE)) {
                pr_err("The initial RAM disk does not fit into the memory\n");
                memblock_free(INITRD_START, INITRD_SIZE);
                initrd_start = initrd_end = 0;
        }
#endif
}

/*
 * Reserve memory used for lowcore/command line/kernel image.
 */
static void __init reserve_kernel(void)
{
        unsigned long start_pfn = PFN_UP(__pa(&_end));

#ifdef CONFIG_DMA_API_DEBUG
        /*
         * DMA_API_DEBUG code stumbles over addresses from the
         * range [_ehead, _stext]. Mark the memory as reserved
         * so it is not used for CONFIG_DMA_API_DEBUG=y.
         */
        memblock_reserve(0, PFN_PHYS(start_pfn));
#else
        memblock_reserve(0, (unsigned long)_ehead);
        memblock_reserve((unsigned long)_stext, PFN_PHYS(start_pfn)
                         - (unsigned long)_stext);
#endif
}

static void __init setup_memory(void)
{
        struct memblock_region *reg;

        /*
         * Init storage key for present memory
         */
        for_each_memblock(memory, reg) {
                storage_key_init_range(reg->base, reg->base + reg->size);
        }
        psw_set_key(PAGE_DEFAULT_KEY);

        /* Only cosmetics */
        memblock_enforce_memory_limit(memblock_end_of_DRAM());
}

/*
 * Setup hardware capabilities.
 */
static int __init setup_hwcaps(void)
{
        static const int stfl_bits[6] = { 0, 2, 7, 17, 19, 21 };
        struct cpuid cpu_id;
        int i;

        /*
         * The store facility list bits numbers as found in the principles
         * of operation are numbered with bit 1UL<<31 as number 0 to
         * bit 1UL<<0 as number 31.
         *   Bit 0: instructions named N3, "backported" to esa-mode
         *   Bit 2: z/Architecture mode is active
         *   Bit 7: the store-facility-list-extended facility is installed
         *   Bit 17: the message-security assist is installed
         *   Bit 19: the long-displacement facility is installed
         *   Bit 21: the extended-immediate facility is installed
         *   Bit 22: extended-translation facility 3 is installed
         *   Bit 30: extended-translation facility 3 enhancement facility
         * These get translated to:
         *   HWCAP_S390_ESAN3 bit 0, HWCAP_S390_ZARCH bit 1,
         *   HWCAP_S390_STFLE bit 2, HWCAP_S390_MSA bit 3,
         *   HWCAP_S390_LDISP bit 4, HWCAP_S390_EIMM bit 5 and
         *   HWCAP_S390_ETF3EH bit 8 (22 && 30).
         */
        for (i = 0; i < 6; i++)
                if (test_facility(stfl_bits[i]))
                        elf_hwcap |= 1UL << i;

        if (test_facility(22) && test_facility(30))
                elf_hwcap |= HWCAP_S390_ETF3EH;

        /*
         * Check for additional facilities with store-facility-list-extended.
         * stfle stores doublewords (8 byte) with bit 1ULL<<63 as bit 0
         * and 1ULL<<0 as bit 63. Bits 0-31 contain the same information
         * as stored by stfl, bits 32-xxx contain additional facilities.
         * How many facility words are stored depends on the number of
         * doublewords passed to the instruction. The additional facilities
         * are:
         *   Bit 42: decimal floating point facility is installed
         *   Bit 44: perform floating point operation facility is installed
         * translated to:
         *   HWCAP_S390_DFP bit 6 (42 && 44).
         */
        if ((elf_hwcap & (1UL << 2)) && test_facility(42) && test_facility(44))
                elf_hwcap |= HWCAP_S390_DFP;

        /*
         * Huge page support HWCAP_S390_HPAGE is bit 7.
         */
        if (MACHINE_HAS_EDAT1)
                elf_hwcap |= HWCAP_S390_HPAGE;

        /*
         * 64-bit register support for 31-bit processes
         * HWCAP_S390_HIGH_GPRS is bit 9.
         */
        elf_hwcap |= HWCAP_S390_HIGH_GPRS;

        /*
         * Transactional execution support HWCAP_S390_TE is bit 10.
         */
        if (test_facility(50) && test_facility(73))
                elf_hwcap |= HWCAP_S390_TE;

        /*
         * Vector extension HWCAP_S390_VXRS is bit 11. The Vector extension
         * can be disabled with the "novx" parameter. Use MACHINE_HAS_VX
         * instead of facility bit 129.
         */
        if (MACHINE_HAS_VX) {
                elf_hwcap |= HWCAP_S390_VXRS;
                if (test_facility(134))
                        elf_hwcap |= HWCAP_S390_VXRS_EXT;
                if (test_facility(135))
                        elf_hwcap |= HWCAP_S390_VXRS_BCD;
        }

        /*
         * Guarded storage support HWCAP_S390_GS is bit 12.
         */
        if (MACHINE_HAS_GS)
                elf_hwcap |= HWCAP_S390_GS;

        get_cpu_id(&cpu_id);
        add_device_randomness(&cpu_id, sizeof(cpu_id));
        switch (cpu_id.machine) {
        case 0x2064:
        case 0x2066:
        default:        /* Use "z900" as default for 64 bit kernels. */
                strcpy(elf_platform, "z900");
                break;
        case 0x2084:
        case 0x2086:
                strcpy(elf_platform, "z990");
                break;
        case 0x2094:
        case 0x2096:
                strcpy(elf_platform, "z9-109");
                break;
        case 0x2097:
        case 0x2098:
                strcpy(elf_platform, "z10");
                break;
        case 0x2817:
        case 0x2818:
                strcpy(elf_platform, "z196");
                break;
        case 0x2827:
        case 0x2828:
                strcpy(elf_platform, "zEC12");
                break;
        case 0x2964:
        case 0x2965:
                strcpy(elf_platform, "z13");
                break;
        case 0x3906:
                strcpy(elf_platform, "z14");
                break;
        }

        /*
         * Virtualization support HWCAP_INT_SIE is bit 0.
         */
        if (sclp.has_sief2)
                int_hwcap |= HWCAP_INT_SIE;

        return 0;
}
arch_initcall(setup_hwcaps);

/*
 * Add system information as device randomness
 */
static void __init setup_randomness(void)
{
        struct sysinfo_3_2_2 *vmms;

        vmms = (struct sysinfo_3_2_2 *) memblock_alloc(PAGE_SIZE, PAGE_SIZE);
        if (stsi(vmms, 3, 2, 2) == 0 && vmms->count)
                add_device_randomness(&vmms->vm, sizeof(vmms->vm[0]) * vmms->count);
        memblock_free((unsigned long) vmms, PAGE_SIZE);
}

/*
 * Find the correct size for the task_struct. This depends on
 * the size of the struct fpu at the end of the thread_struct
 * which is embedded in the task_struct.
 */
static void __init setup_task_size(void)
{
        int task_size = sizeof(struct task_struct);

        if (!MACHINE_HAS_VX) {
                task_size -= sizeof(__vector128) * __NUM_VXRS;
                task_size += sizeof(freg_t) * __NUM_FPRS;
        }
        arch_task_struct_size = task_size;
}

/*
 * Setup function called from init/main.c just after the banner
 * was printed.
 */

void __init setup_arch(char **cmdline_p)
{
        /*
         * print what head.S has found out about the machine
         */
        if (MACHINE_IS_VM)
                pr_info("Linux is running as a z/VM "
                        "guest operating system in 64-bit mode\n");
        else if (MACHINE_IS_KVM)
                pr_info("Linux is running under KVM in 64-bit mode\n");
        else if (MACHINE_IS_LPAR)
                pr_info("Linux is running natively in 64-bit mode\n");
        else
                pr_info("Linux is running as a guest in 64-bit mode\n");

        /* Have one command line that is parsed and saved in /proc/cmdline */
        /* boot_command_line has been already set up in early.c */
        *cmdline_p = boot_command_line;

        ROOT_DEV = Root_RAM0;

        /* Is init_mm really needed? */
        init_mm.start_code = PAGE_OFFSET;
        init_mm.end_code = (unsigned long) &_etext;
        init_mm.end_data = (unsigned long) &_edata;
        init_mm.brk = (unsigned long) &_end;

        if (IS_ENABLED(CONFIG_EXPOLINE_AUTO))
                nospec_auto_detect();

        parse_early_param();
#ifdef CONFIG_CRASH_DUMP
        /* Deactivate elfcorehdr= kernel parameter */
        elfcorehdr_addr = ELFCORE_ADDR_MAX;
#endif

        os_info_init();
        setup_ipl();
        setup_task_size();

        /* Do some memory reservations *before* memory is added to memblock */
        reserve_memory_end();
        reserve_oldmem();
        reserve_kernel();
        reserve_initrd();
        memblock_allow_resize();

        /* Get information about *all* installed memory */
        detect_memory_memblock();

        remove_oldmem();

        /*
         * Make sure all chunks are MAX_ORDER aligned so we don't need the
         * extra checks that HOLES_IN_ZONE would require.
         *
         * Is this still required?
         */
        memblock_trim_memory(1UL << (MAX_ORDER - 1 + PAGE_SHIFT));

        setup_memory_end();
        setup_memory();
        dma_contiguous_reserve(memory_end);
        vmcp_cma_reserve();

        check_initrd();
        reserve_crashkernel();
#ifdef CONFIG_CRASH_DUMP
        /*
         * Be aware that smp_save_dump_cpus() triggers a system reset.
         * Therefore CPU and device initialization should be done afterwards.
         */
        smp_save_dump_cpus();
#endif

        setup_resources();
        setup_lowcore_dat_off();
        smp_fill_possible_mask();
        cpu_detect_mhz_feature();
        cpu_init();
        numa_setup();
        smp_detect_cpus();
        topology_init_early();

        /*
         * Create kernel page tables and switch to virtual addressing.
         */
        paging_init();

        /*
         * After paging_init created the kernel page table, the new PSWs
         * in lowcore can now run with DAT enabled.
         */
        setup_lowcore_dat_on();

        /* Setup default console */
        conmode_default();
        set_preferred_console();

        apply_alternative_instructions();
        if (IS_ENABLED(CONFIG_EXPOLINE))
                nospec_init_branches();

        /* Setup zfcpdump support */
        setup_zfcpdump();

        /* Add system specific data to the random pool */
        setup_randomness();
}