// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 
 * Common boot and setup code.
 *
 * Copyright (C) 2001 PPC64 Team, IBM Corp
 */

#include <linux/export.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/initrd.h>
#include <linux/seq_file.h>
#include <linux/ioport.h>
#include <linux/console.h>
#include <linux/utsname.h>
#include <linux/tty.h>
#include <linux/root_dev.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/unistd.h>
#include <linux/serial.h>
#include <linux/serial_8250.h>
#include <linux/memblock.h>
#include <linux/pci.h>
#include <linux/lockdep.h>
#include <linux/memory.h>
#include <linux/nmi.h>
#include <linux/pgtable.h>
#include <linux/of.h>
#include <linux/of_fdt.h>

#include <asm/asm-prototypes.h>
#include <asm/kvm_guest.h>
#include <asm/io.h>
#include <asm/kdump.h>
#include <asm/processor.h>
#include <asm/smp.h>
#include <asm/elf.h>
#include <asm/machdep.h>
#include <asm/paca.h>
#include <asm/time.h>
#include <asm/cputable.h>
#include <asm/dt_cpu_ftrs.h>
#include <asm/sections.h>
#include <asm/btext.h>
#include <asm/nvram.h>
#include <asm/setup.h>
#include <asm/rtas.h>
#include <asm/iommu.h>
#include <asm/serial.h>
#include <asm/cache.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/firmware.h>
#include <asm/xmon.h>
#include <asm/udbg.h>
#include <asm/kexec.h>
#include <asm/text-patching.h>
#include <asm/ftrace.h>
#include <asm/opal.h>
#include <asm/cputhreads.h>
#include <asm/hw_irq.h>
#include <asm/feature-fixups.h>
#include <asm/kup.h>
#include <asm/early_ioremap.h>
#include <asm/pgalloc.h>

#include "setup.h"

int spinning_secondaries;
u64 ppc64_pft_size;

struct ppc64_caches ppc64_caches = {
        .l1d = {
                .block_size = 0x40,
                .log_block_size = 6,
        },
        .l1i = {
                .block_size = 0x40,
                .log_block_size = 6
        },
};
EXPORT_SYMBOL_GPL(ppc64_caches);

#if defined(CONFIG_PPC_BOOK3E_64) && defined(CONFIG_SMP)
void __init setup_tlb_core_data(void)
{
        int cpu;

        BUILD_BUG_ON(offsetof(struct tlb_core_data, lock) != 0);

        for_each_possible_cpu(cpu) {
                int first = cpu_first_thread_sibling(cpu);

                /*
                 * If we boot via kdump on a non-primary thread,
                 * make sure we point at the thread that actually
                 * set up this TLB.
                 */
                if (cpu_first_thread_sibling(boot_cpuid) == first)
                        first = boot_cpuid;

                paca_ptrs[cpu]->tcd_ptr = &paca_ptrs[first]->tcd;

                /*
                 * If we have threads, we need either tlbsrx.
                 * or e6500 tablewalk mode, or else TLB handlers
                 * will be racy and could produce duplicate entries.
                 * Should we panic instead?
                 */
                WARN_ONCE(smt_enabled_at_boot >= 2 &&
                          book3e_htw_mode != PPC_HTW_E6500,
                          "%s: unsupported MMU configuration\n", __func__);
        }
}
#endif

#ifdef CONFIG_SMP

static char *smt_enabled_cmdline;

/* Look for ibm,smt-enabled OF option */
void __init check_smt_enabled(void)
{
        struct device_node *dn;
        const char *smt_option;

        /* Default to enabling all threads */
        smt_enabled_at_boot = threads_per_core;

        /* Allow the command line to overrule the OF option */
        if (smt_enabled_cmdline) {
                if (!strcmp(smt_enabled_cmdline, "on"))
                        smt_enabled_at_boot = threads_per_core;
                else if (!strcmp(smt_enabled_cmdline, "off"))
                        smt_enabled_at_boot = 0;
                else {
                        int smt;
                        if (!kstrtoint(smt_enabled_cmdline, 10, &smt))
                                smt_enabled_at_boot =
                                        min(threads_per_core, smt);
                }
        } else {
                dn = of_find_node_by_path("/options");
                if (dn) {
                        smt_option = of_get_property(dn, "ibm,smt-enabled",
                                                     NULL);

                        if (smt_option) {
                                if (!strcmp(smt_option, "on"))
                                        smt_enabled_at_boot = threads_per_core;
                                else if (!strcmp(smt_option, "off"))
                                        smt_enabled_at_boot = 0;
                        }

                        of_node_put(dn);
                }
        }
}

/* Look for smt-enabled= cmdline option */
static int __init early_smt_enabled(char *p)
{
        smt_enabled_cmdline = p;
        return 0;
}
early_param("smt-enabled", early_smt_enabled);

#endif /* CONFIG_SMP */

/** Fix up paca fields required for the boot cpu */
static void __init fixup_boot_paca(struct paca_struct *boot_paca)
{
        /* The boot cpu is started */
        boot_paca->cpu_start = 1;
#ifdef CONFIG_PPC_BOOK3S_64
        /*
         * Give the early boot machine check stack somewhere to use, use
         * half of the init stack. This is a bit hacky but there should not be
         * deep stack usage in early init so shouldn't overflow it or overwrite
         * things.
         */
        boot_paca->mc_emergency_sp = (void *)&init_thread_union +
                (THREAD_SIZE/2);
#endif
        /* Allow percpu accesses to work until we setup percpu data */
        boot_paca->data_offset = 0;
        /* Mark interrupts soft and hard disabled in PACA */
        boot_paca->irq_soft_mask = IRQS_DISABLED;
        boot_paca->irq_happened = PACA_IRQ_HARD_DIS;
        WARN_ON(mfmsr() & MSR_EE);
}

static void __init configure_exceptions(void)
{
        /*
         * Setup the trampolines from the lowmem exception vectors
         * to the kdump kernel when not using a relocatable kernel.
         */
        setup_kdump_trampoline();

        /* Under a PAPR hypervisor, we need hypercalls */
        if (firmware_has_feature(FW_FEATURE_SET_MODE)) {
                /*
                 * - PR KVM does not support AIL mode interrupts in the host
                 *   while a PR guest is running.
                 *
                 * - SCV system call interrupt vectors are only implemented for
                 *   AIL mode interrupts.
                 *
                 * - On pseries, AIL mode can only be enabled and disabled
                 *   system-wide so when a PR VM is created on a pseries host,
                 *   all CPUs of the host are set to AIL=0 mode.
                 *
                 * - Therefore host CPUs must not execute scv while a PR VM
                 *   exists.
                 *
                 * - SCV support can not be disabled dynamically because the
                 *   feature is advertised to host userspace. Disabling the
                 *   facility and emulating it would be possible but is not
                 *   implemented.
                 *
                 * - So SCV support is blanket disabled if PR KVM could possibly
                 *   run. That is, PR support compiled in, booting on pseries
                 *   with hash MMU.
                 */
                if (IS_ENABLED(CONFIG_KVM_BOOK3S_PR_POSSIBLE) && !radix_enabled()) {
                        init_task.thread.fscr &= ~FSCR_SCV;
                        cur_cpu_spec->cpu_user_features2 &= ~PPC_FEATURE2_SCV;
                }

                /* Enable AIL if possible */
                if (!pseries_enable_reloc_on_exc()) {
                        init_task.thread.fscr &= ~FSCR_SCV;
                        cur_cpu_spec->cpu_user_features2 &= ~PPC_FEATURE2_SCV;
                }

                /*
                 * Tell the hypervisor that we want our exceptions to
                 * be taken in little endian mode.
                 *
                 * We don't call this for big endian as our calling convention
                 * makes us always enter in BE, and the call may fail under
                 * some circumstances with kdump.
                 */
#ifdef __LITTLE_ENDIAN__
                pseries_little_endian_exceptions();
#endif
        } else {
                /* Set endian mode using OPAL */
                if (firmware_has_feature(FW_FEATURE_OPAL))
                        opal_configure_cores();

                /* AIL on native is done in cpu_ready_for_interrupts() */
        }
}

static void cpu_ready_for_interrupts(void)
{
        /*
         * Enable AIL if supported, and we are in hypervisor mode. This
         * is called once for every processor.
         *
         * If we are not in hypervisor mode the job is done once for
         * the whole partition in configure_exceptions().
         */
        if (cpu_has_feature(CPU_FTR_HVMODE)) {
                unsigned long lpcr = mfspr(SPRN_LPCR);
                unsigned long new_lpcr = lpcr;

                if (cpu_has_feature(CPU_FTR_ARCH_31)) {
                        /* P10 DD1 does not have HAIL */
                        if (pvr_version_is(PVR_POWER10) &&
                                        (mfspr(SPRN_PVR) & 0xf00) == 0x100)
                                new_lpcr |= LPCR_AIL_3;
                        else
                                new_lpcr |= LPCR_HAIL;
                } else if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
                        new_lpcr |= LPCR_AIL_3;
                }

                if (new_lpcr != lpcr)
                        mtspr(SPRN_LPCR, new_lpcr);
        }

        /*
         * Set HFSCR:TM based on CPU features:
         * In the special case of TM no suspend (P9N DD2.1), Linux is
         * told TM is off via the dt-ftrs but told to (partially) use
         * it via OPAL_REINIT_CPUS_TM_SUSPEND_DISABLED. So HFSCR[TM]
         * will be off from dt-ftrs but we need to turn it on for the
         * no suspend case.
         */
        if (cpu_has_feature(CPU_FTR_HVMODE)) {
                if (cpu_has_feature(CPU_FTR_TM_COMP))
                        mtspr(SPRN_HFSCR, mfspr(SPRN_HFSCR) | HFSCR_TM);
                else
                        mtspr(SPRN_HFSCR, mfspr(SPRN_HFSCR) & ~HFSCR_TM);
        }

        /* Set IR and DR in PACA MSR */
        get_paca()->kernel_msr = MSR_KERNEL;
}

unsigned long spr_default_dscr = 0;

static void __init record_spr_defaults(void)
{
        if (early_cpu_has_feature(CPU_FTR_DSCR))
                spr_default_dscr = mfspr(SPRN_DSCR);
}

/*
 * Early initialization entry point. This is called by head.S
 * with MMU translation disabled. We rely on the "feature" of
 * the CPU that ignores the top 2 bits of the address in real
 * mode so we can access kernel globals normally provided we
 * only toy with things in the RMO region. From here, we do
 * some early parsing of the device-tree to setup out MEMBLOCK
 * data structures, and allocate & initialize the hash table
 * and segment tables so we can start running with translation
 * enabled.
 *
 * It is this function which will call the probe() callback of
 * the various platform types and copy the matching one to the
 * global ppc_md structure. Your platform can eventually do
 * some very early initializations from the probe() routine, but
 * this is not recommended, be very careful as, for example, the
 * device-tree is not accessible via normal means at this point.
 */

void __init early_setup(unsigned long dt_ptr)
{
        static __initdata struct paca_struct boot_paca;

        /* -------- printk is _NOT_ safe to use here ! ------- */

        /*
         * Assume we're on cpu 0 for now.
         *
         * We need to load a PACA very early for a few reasons.
         *
         * The stack protector canary is stored in the paca, so as soon as we
         * call any stack protected code we need r13 pointing somewhere valid.
         *
         * If we are using kcov it will call in_task() in its instrumentation,
         * which relies on the current task from the PACA.
         *
         * dt_cpu_ftrs_init() calls into generic OF/fdt code, as well as
         * printk(), which can trigger both stack protector and kcov.
         *
         * percpu variables and spin locks also use the paca.
         *
         * So set up a temporary paca. It will be replaced below once we know
         * what CPU we are on.
         */
        initialise_paca(&boot_paca, 0);
        fixup_boot_paca(&boot_paca);
        WARN_ON(local_paca);
        setup_paca(&boot_paca); /* install the paca into registers */

        /* -------- printk is now safe to use ------- */

        if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && (mfmsr() & MSR_HV))
                enable_machine_check();

        /* Try new device tree based feature discovery ... */
        if (!dt_cpu_ftrs_init(__va(dt_ptr)))
                /* Otherwise use the old style CPU table */
                identify_cpu(0, mfspr(SPRN_PVR));

        /* Enable early debugging if any specified (see udbg.h) */
        udbg_early_init();

        udbg_printf(" -> %s(), dt_ptr: 0x%lx\n", __func__, dt_ptr);

        /*
         * Do early initialization using the flattened device
         * tree, such as retrieving the physical memory map or
         * calculating/retrieving the hash table size, discover
         * boot_cpuid and boot_cpu_hwid.
         */
        early_init_devtree(__va(dt_ptr));

        allocate_paca_ptrs();
        allocate_paca(boot_cpuid);
        set_hard_smp_processor_id(boot_cpuid, boot_cpu_hwid);
        fixup_boot_paca(paca_ptrs[boot_cpuid]);
        setup_paca(paca_ptrs[boot_cpuid]); /* install the paca into registers */
        // smp_processor_id() now reports boot_cpuid

#ifdef CONFIG_SMP
        task_thread_info(current)->cpu = boot_cpuid; // fix task_cpu(current)
#endif

        /*
         * Configure exception handlers. This include setting up trampolines
         * if needed, setting exception endian mode, etc...
         */
        configure_exceptions();

        /*
         * Configure Kernel Userspace Protection. This needs to happen before
         * feature fixups for platforms that implement this using features.
         */
        setup_kup();

        /* Apply all the dynamic patching */
        apply_feature_fixups();
        setup_feature_keys();

        /* Initialize the hash table or TLB handling */
        early_init_mmu();

        early_ioremap_setup();

        /*
         * After firmware and early platform setup code has set things up,
         * we note the SPR values for configurable control/performance
         * registers, and use those as initial defaults.
         */
        record_spr_defaults();

        /*
         * At this point, we can let interrupts switch to virtual mode
         * (the MMU has been setup), so adjust the MSR in the PACA to
         * have IR and DR set and enable AIL if it exists
         */
        cpu_ready_for_interrupts();

        /*
         * We enable ftrace here, but since we only support DYNAMIC_FTRACE, it
         * will only actually get enabled on the boot cpu much later once
         * ftrace itself has been initialized.
         */
        this_cpu_enable_ftrace();

        udbg_printf(" <- %s()\n", __func__);

#ifdef CONFIG_PPC_EARLY_DEBUG_BOOTX
        /*
         * This needs to be done *last* (after the above udbg_printf() even)
         *
         * Right after we return from this function, we turn on the MMU
         * which means the real-mode access trick that btext does will
         * no longer work, it needs to switch to using a real MMU
         * mapping. This call will ensure that it does
         */
        btext_map();
#endif /* CONFIG_PPC_EARLY_DEBUG_BOOTX */
}

#ifdef CONFIG_SMP
void early_setup_secondary(void)
{
        /* Mark interrupts disabled in PACA */
        irq_soft_mask_set(IRQS_DISABLED);

        /* Initialize the hash table or TLB handling */
        early_init_mmu_secondary();

        /* Perform any KUP setup that is per-cpu */
        setup_kup();

        /*
         * At this point, we can let interrupts switch to virtual mode
         * (the MMU has been setup), so adjust the MSR in the PACA to
         * have IR and DR set.
         */
        cpu_ready_for_interrupts();
}

#endif /* CONFIG_SMP */

void __noreturn panic_smp_self_stop(void)
{
        hard_irq_disable();
        spin_begin();
        while (1)
                spin_cpu_relax();
}

#if defined(CONFIG_SMP) || defined(CONFIG_KEXEC_CORE)
static bool use_spinloop(void)
{
        if (IS_ENABLED(CONFIG_PPC_BOOK3S)) {
                /*
                 * See comments in head_64.S -- not all platforms insert
                 * secondaries at __secondary_hold and wait at the spin
                 * loop.
                 */
                if (firmware_has_feature(FW_FEATURE_OPAL))
                        return false;
                return true;
        }

        /*
         * When book3e boots from kexec, the ePAPR spin table does
         * not get used.
         */
        return of_property_read_bool(of_chosen, "linux,booted-from-kexec");
}

void smp_release_cpus(void)
{
        unsigned long *ptr;
        int i;

        if (!use_spinloop())
                return;

        /* All secondary cpus are spinning on a common spinloop, release them
         * all now so they can start to spin on their individual paca
         * spinloops. For non SMP kernels, the secondary cpus never get out
         * of the common spinloop.
         */

        ptr  = (unsigned long *)((unsigned long)&__secondary_hold_spinloop
                        - PHYSICAL_START);
        *ptr = ppc_function_entry(generic_secondary_smp_init);

        /* And wait a bit for them to catch up */
        for (i = 0; i < 100000; i++) {
                mb();
                HMT_low();
                if (spinning_secondaries == 0)
                        break;
                udelay(1);
        }
        pr_debug("spinning_secondaries = %d\n", spinning_secondaries);
}
#endif /* CONFIG_SMP || CONFIG_KEXEC_CORE */

/*
 * Initialize some remaining members of the ppc64_caches and systemcfg
 * structures
 * (at least until we get rid of them completely). This is mostly some
 * cache informations about the CPU that will be used by cache flush
 * routines and/or provided to userland
 */

static void __init init_cache_info(struct ppc_cache_info *info, u32 size, u32 lsize,
                            u32 bsize, u32 sets)
{
        info->size = size;
        info->sets = sets;
        info->line_size = lsize;
        info->block_size = bsize;
        info->log_block_size = __ilog2(bsize);
        if (bsize)
                info->blocks_per_page = PAGE_SIZE / bsize;
        else
                info->blocks_per_page = 0;

        if (sets == 0)
                info->assoc = 0xffff;
        else
                info->assoc = size / (sets * lsize);
}

static bool __init parse_cache_info(struct device_node *np,
                                    bool icache,
                                    struct ppc_cache_info *info)
{
        static const char *ipropnames[] __initdata = {
                "i-cache-size",
                "i-cache-sets",
                "i-cache-block-size",
                "i-cache-line-size",
        };
        static const char *dpropnames[] __initdata = {
                "d-cache-size",
                "d-cache-sets",
                "d-cache-block-size",
                "d-cache-line-size",
        };
        const char **propnames = icache ? ipropnames : dpropnames;
        const __be32 *sizep, *lsizep, *bsizep, *setsp;
        u32 size, lsize, bsize, sets;
        bool success = true;

        size = 0;
        sets = -1u;
        lsize = bsize = cur_cpu_spec->dcache_bsize;
        sizep = of_get_property(np, propnames[0], NULL);
        if (sizep != NULL)
                size = be32_to_cpu(*sizep);
        setsp = of_get_property(np, propnames[1], NULL);
        if (setsp != NULL)
                sets = be32_to_cpu(*setsp);
        bsizep = of_get_property(np, propnames[2], NULL);
        lsizep = of_get_property(np, propnames[3], NULL);
        if (bsizep == NULL)
                bsizep = lsizep;
        if (lsizep == NULL)
                lsizep = bsizep;
        if (lsizep != NULL)
                lsize = be32_to_cpu(*lsizep);
        if (bsizep != NULL)
                bsize = be32_to_cpu(*bsizep);
        if (sizep == NULL || bsizep == NULL || lsizep == NULL)
                success = false;

        /*
         * OF is weird .. it represents fully associative caches
         * as "1 way" which doesn't make much sense and doesn't
         * leave room for direct mapped. We'll assume that 0
         * in OF means direct mapped for that reason.
         */
        if (sets == 1)
                sets = 0;
        else if (sets == 0)
                sets = 1;

        init_cache_info(info, size, lsize, bsize, sets);

        return success;
}

void __init initialize_cache_info(void)
{
        struct device_node *cpu = NULL, *l2, *l3 = NULL;
        u32 pvr;

        /*
         * All shipping POWER8 machines have a firmware bug that
         * puts incorrect information in the device-tree. This will
         * be (hopefully) fixed for future chips but for now hard
         * code the values if we are running on one of these
         */
        pvr = PVR_VER(mfspr(SPRN_PVR));
        if (pvr == PVR_POWER8 || pvr == PVR_POWER8E ||
            pvr == PVR_POWER8NVL) {
                                                /* size    lsize   blk  sets */
                init_cache_info(&ppc64_caches.l1i, 0x8000,   128,  128, 32);
                init_cache_info(&ppc64_caches.l1d, 0x10000,  128,  128, 64);
                init_cache_info(&ppc64_caches.l2,  0x80000,  128,  0,   512);
                init_cache_info(&ppc64_caches.l3,  0x800000, 128,  0,   8192);
        } else
                cpu = of_find_node_by_type(NULL, "cpu");

        /*
         * We're assuming *all* of the CPUs have the same
         * d-cache and i-cache sizes... -Peter
         */
        if (cpu) {
                if (!parse_cache_info(cpu, false, &ppc64_caches.l1d))
                        pr_warn("Argh, can't find dcache properties !\n");

                if (!parse_cache_info(cpu, true, &ppc64_caches.l1i))
                        pr_warn("Argh, can't find icache properties !\n");

                /*
                 * Try to find the L2 and L3 if any. Assume they are
                 * unified and use the D-side properties.
                 */
                l2 = of_find_next_cache_node(cpu);
                of_node_put(cpu);
                if (l2) {
                        parse_cache_info(l2, false, &ppc64_caches.l2);
                        l3 = of_find_next_cache_node(l2);
                        of_node_put(l2);
                }
                if (l3) {
                        parse_cache_info(l3, false, &ppc64_caches.l3);
                        of_node_put(l3);
                }
        }

        /* For use by binfmt_elf */
        dcache_bsize = ppc64_caches.l1d.block_size;
        icache_bsize = ppc64_caches.l1i.block_size;

        cur_cpu_spec->dcache_bsize = dcache_bsize;
        cur_cpu_spec->icache_bsize = icache_bsize;
}

/*
 * This returns the limit below which memory accesses to the linear
 * mapping are guarnateed not to cause an architectural exception (e.g.,
 * TLB or SLB miss fault).
 *
 * This is used to allocate PACAs and various interrupt stacks that
 * that are accessed early in interrupt handlers that must not cause
 * re-entrant interrupts.
 */
__init u64 ppc64_bolted_size(void)
{
#ifdef CONFIG_PPC_BOOK3E_64
        /* Freescale BookE bolts the entire linear mapping */
        return linear_map_top;
#else
        /* BookS radix, does not take faults on linear mapping */
        if (early_radix_enabled())
                return ULONG_MAX;

        /* BookS hash, the first segment is bolted */
        if (early_mmu_has_feature(MMU_FTR_1T_SEGMENT))
                return 1UL << SID_SHIFT_1T;
        return 1UL << SID_SHIFT;
#endif
}

static void *__init alloc_stack(unsigned long limit, int cpu)
{
        void *ptr;

        BUILD_BUG_ON(STACK_INT_FRAME_SIZE % 16);

        ptr = memblock_alloc_try_nid(THREAD_SIZE, THREAD_ALIGN,
                                     MEMBLOCK_LOW_LIMIT, limit,
                                     early_cpu_to_node(cpu));
        if (!ptr)
                panic("cannot allocate stacks");

        return ptr;
}

void __init irqstack_early_init(void)
{
        u64 limit = ppc64_bolted_size();
        unsigned int i;

        /*
         * Interrupt stacks must be in the first segment since we
         * cannot afford to take SLB misses on them. They are not
         * accessed in realmode.
         */
        for_each_possible_cpu(i) {
                softirq_ctx[i] = alloc_stack(limit, i);
                hardirq_ctx[i] = alloc_stack(limit, i);
        }
}

#ifdef CONFIG_PPC_BOOK3E_64
void __init exc_lvl_early_init(void)
{
        unsigned int i;

        for_each_possible_cpu(i) {
                void *sp;

                sp = alloc_stack(ULONG_MAX, i);
                critirq_ctx[i] = sp;
                paca_ptrs[i]->crit_kstack = sp + THREAD_SIZE;

                sp = alloc_stack(ULONG_MAX, i);
                dbgirq_ctx[i] = sp;
                paca_ptrs[i]->dbg_kstack = sp + THREAD_SIZE;

                sp = alloc_stack(ULONG_MAX, i);
                mcheckirq_ctx[i] = sp;
                paca_ptrs[i]->mc_kstack = sp + THREAD_SIZE;
        }

        if (cpu_has_feature(CPU_FTR_DEBUG_LVL_EXC))
                patch_exception(0x040, exc_debug_debug_book3e);
}
#endif

/*
 * Stack space used when we detect a bad kernel stack pointer, and
 * early in SMP boots before relocation is enabled. Exclusive emergency
 * stack for machine checks.
 */
void __init emergency_stack_init(void)
{
        u64 limit, mce_limit;
        unsigned int i;

        /*
         * Emergency stacks must be under 256MB, we cannot afford to take
         * SLB misses on them. The ABI also requires them to be 128-byte
         * aligned.
         *
         * Since we use these as temporary stacks during secondary CPU
         * bringup, machine check, system reset, and HMI, we need to get
         * at them in real mode. This means they must also be within the RMO
         * region.
         *
         * The IRQ stacks allocated elsewhere in this file are zeroed and
         * initialized in kernel/irq.c. These are initialized here in order
         * to have emergency stacks available as early as possible.
         */
        limit = mce_limit = min(ppc64_bolted_size(), ppc64_rma_size);

        /*
         * Machine check on pseries calls rtas, but can't use the static
         * rtas_args due to a machine check hitting while the lock is held.
         * rtas args have to be under 4GB, so the machine check stack is
         * limited to 4GB so args can be put on stack.
         */
        if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit > SZ_4G)
                mce_limit = SZ_4G;

        for_each_possible_cpu(i) {
                paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;

#ifdef CONFIG_PPC_BOOK3S_64
                /* emergency stack for NMI exception handling. */
                paca_ptrs[i]->nmi_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;

                /* emergency stack for machine check exception handling. */
                paca_ptrs[i]->mc_emergency_sp = alloc_stack(mce_limit, i) + THREAD_SIZE;
#endif
        }
}

#ifdef CONFIG_SMP
static int pcpu_cpu_distance(unsigned int from, unsigned int to)
{
        if (early_cpu_to_node(from) == early_cpu_to_node(to))
                return LOCAL_DISTANCE;
        else
                return REMOTE_DISTANCE;
}

static __init int pcpu_cpu_to_node(int cpu)
{
        return early_cpu_to_node(cpu);
}

unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(__per_cpu_offset);
DEFINE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged);

void __init setup_per_cpu_areas(void)
{
        const size_t dyn_size = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;
        size_t atom_size;
        unsigned long delta;
        unsigned int cpu;
        int rc = -EINVAL;

        /*
         * BookE and BookS radix are historical values and should be revisited.
         */
        if (IS_ENABLED(CONFIG_PPC_BOOK3E_64)) {
                atom_size = SZ_1M;
        } else if (radix_enabled()) {
                atom_size = PAGE_SIZE;
        } else if (IS_ENABLED(CONFIG_PPC_64S_HASH_MMU)) {
                /*
                 * Linear mapping is one of 4K, 1M and 16M.  For 4K, no need
                 * to group units.  For larger mappings, use 1M atom which
                 * should be large enough to contain a number of units.
                 */
                if (mmu_linear_psize == MMU_PAGE_4K)
                        atom_size = PAGE_SIZE;
                else
                        atom_size = SZ_1M;
        }

        if (pcpu_chosen_fc != PCPU_FC_PAGE) {
                rc = pcpu_embed_first_chunk(0, dyn_size, atom_size, pcpu_cpu_distance,
                                            pcpu_cpu_to_node);
                if (rc)
                        pr_warn("PERCPU: %s allocator failed (%d), "
                                "falling back to page size\n",
                                pcpu_fc_names[pcpu_chosen_fc], rc);
        }

        if (rc < 0)
                rc = pcpu_page_first_chunk(0, pcpu_cpu_to_node);
        if (rc < 0)
                panic("cannot initialize percpu area (err=%d)", rc);

        static_key_enable(&__percpu_first_chunk_is_paged.key);
        delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
        for_each_possible_cpu(cpu) {
                __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
                paca_ptrs[cpu]->data_offset = __per_cpu_offset[cpu];
        }
}
#endif

#ifdef CONFIG_MEMORY_HOTPLUG
unsigned long memory_block_size_bytes(void)
{
        if (ppc_md.memory_block_size)
                return ppc_md.memory_block_size();

        return MIN_MEMORY_BLOCK_SIZE;
}
#endif

#ifdef CONFIG_PPC_INDIRECT_PIO
struct ppc_pci_io ppc_pci_io;
EXPORT_SYMBOL(ppc_pci_io);
#endif

#ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
u64 hw_nmi_get_sample_period(int watchdog_thresh)
{
        return ppc_proc_freq * watchdog_thresh;
}
#endif

/*
 * The perf based hardlockup detector breaks PMU event based branches, so
 * disable it by default. Book3S has a soft-nmi hardlockup detector based
 * on the decrementer interrupt, so it does not suffer from this problem.
 *
 * It is likely to get false positives in KVM guests, so disable it there
 * by default too. PowerVM will not stop or arbitrarily oversubscribe
 * CPUs, but give a minimum regular allotment even with SPLPAR, so enable
 * the detector for non-KVM guests, assume PowerVM.
 */
static int __init disable_hardlockup_detector(void)
{
#ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
        hardlockup_detector_disable();
#else
        if (firmware_has_feature(FW_FEATURE_LPAR)) {
                check_kvm_guest();
                if (is_kvm_guest())
                        hardlockup_detector_disable();
        }
#endif

        return 0;
}
early_initcall(disable_hardlockup_detector);