// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
 *    Copyright (C) 1996 Paul Mackerras
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  Dave Engebretsen <engebret@us.ibm.com>
 *      Rework for PPC64 port.
 */

#undef DEBUG

#include <linux/string.h>
#include <linux/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/kup.h>
#include <asm/smp.h>

phys_addr_t memstart_addr __ro_after_init = (phys_addr_t)~0ull;
EXPORT_SYMBOL_GPL(memstart_addr);
phys_addr_t kernstart_addr __ro_after_init;
EXPORT_SYMBOL_GPL(kernstart_addr);
unsigned long kernstart_virt_addr __ro_after_init = KERNELBASE;
EXPORT_SYMBOL_GPL(kernstart_virt_addr);

bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);
#ifdef CONFIG_KFENCE
bool __ro_after_init kfence_disabled;
bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL;
#endif

static int __init parse_nosmep(char *p)
{
        if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64))
                return 0;

        disable_kuep = true;
        pr_warn("Disabling Kernel Userspace Execution Prevention\n");
        return 0;
}
early_param("nosmep", parse_nosmep);

static int __init parse_nosmap(char *p)
{
        disable_kuap = true;
        pr_warn("Disabling Kernel Userspace Access Protection\n");
        return 0;
}
early_param("nosmap", parse_nosmap);

void __weak setup_kuep(bool disabled)
{
        if (!IS_ENABLED(CONFIG_PPC_KUEP) || disabled)
                return;

        if (smp_processor_id() != boot_cpuid)
                return;

        pr_info("Activating Kernel Userspace Execution Prevention\n");
}

void setup_kup(void)
{
        setup_kuap(disable_kuap);
        setup_kuep(disable_kuep);
}

#define CTOR(shift) static void ctor_##shift(void *addr) \
{                                                       \
        memset(addr, 0, sizeof(pgd_t) << (shift));      \
}

CTOR(0); CTOR(1); CTOR(2); CTOR(3); CTOR(4); CTOR(5); CTOR(6); CTOR(7);
CTOR(8); CTOR(9); CTOR(10); CTOR(11); CTOR(12); CTOR(13); CTOR(14); CTOR(15);

static inline void (*ctor(int shift))(void *)
{
        BUILD_BUG_ON(MAX_PGTABLE_INDEX_SIZE != 15);

        switch (shift) {
        case 0: return ctor_0;
        case 1: return ctor_1;
        case 2: return ctor_2;
        case 3: return ctor_3;
        case 4: return ctor_4;
        case 5: return ctor_5;
        case 6: return ctor_6;
        case 7: return ctor_7;
        case 8: return ctor_8;
        case 9: return ctor_9;
        case 10: return ctor_10;
        case 11: return ctor_11;
        case 12: return ctor_12;
        case 13: return ctor_13;
        case 14: return ctor_14;
        case 15: return ctor_15;
        }
        return NULL;
}

struct kmem_cache *pgtable_cache[MAX_PGTABLE_INDEX_SIZE + 1];
EXPORT_SYMBOL_GPL(pgtable_cache);       /* used by kvm_hv module */

/*
 * Create a kmem_cache() for pagetables.  This is not used for PTE
 * pages - they're linked to struct page, come from the normal free
 * pages pool and have a different entry size (see real_pte_t) to
 * everything else.  Caches created by this function are used for all
 * the higher level pagetables, and for hugepage pagetables.
 */
void pgtable_cache_add(unsigned int shift)
{
        char *name;
        unsigned long table_size = sizeof(pgd_t) << shift;
        unsigned long align = table_size;

        /* When batching pgtable pointers for RCU freeing, we store
         * the index size in the low bits.  Table alignment must be
         * big enough to fit it.
         */
        unsigned long minalign = MAX_PGTABLE_INDEX_SIZE + 1;
        struct kmem_cache *new = NULL;

        /* It would be nice if this was a BUILD_BUG_ON(), but at the
         * moment, gcc doesn't seem to recognize is_power_of_2 as a
         * constant expression, so so much for that. */
        BUG_ON(!is_power_of_2(minalign));
        BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);

        if (PGT_CACHE(shift))
                return; /* Already have a cache of this size */

        align = max_t(unsigned long, align, minalign);
        name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
        if (name)
                new = kmem_cache_create(name, table_size, align, 0, ctor(shift));
        if (!new)
                panic("Could not allocate pgtable cache for order %d", shift);

        kfree(name);
        pgtable_cache[shift] = new;

        pr_debug("Allocated pgtable cache for order %d\n", shift);
}
EXPORT_SYMBOL_GPL(pgtable_cache_add);   /* used by kvm_hv module */

void pgtable_cache_init(void)
{
        pgtable_cache_add(PGD_INDEX_SIZE);

        if (PMD_CACHE_INDEX)
                pgtable_cache_add(PMD_CACHE_INDEX);
        /*
         * In all current configs, when the PUD index exists it's the
         * same size as either the pgd or pmd index except with THP enabled
         * on book3s 64
         */
        if (PUD_CACHE_INDEX)
                pgtable_cache_add(PUD_CACHE_INDEX);
}