// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * This file contains the routines for initializing the MMU
 * on the 8xx series of chips.
 *  -- christophe
 *
 *  Derived from arch/powerpc/mm/40x_mmu.c:
 */

#include <linux/memblock.h>
#include <linux/mmu_context.h>
#include <linux/hugetlb.h>
#include <asm/fixmap.h>
#include <asm/code-patching.h>
#include <asm/inst.h>
#include <asm/pgalloc.h>

#include <mm/mmu_decl.h>

#define IMMR_SIZE (FIX_IMMR_SIZE << PAGE_SHIFT)

extern int __map_without_ltlbs;

static unsigned long block_mapped_ram;

/*
 * Return PA for this VA if it is in an area mapped with LTLBs or fixmap.
 * Otherwise, returns 0
 */
phys_addr_t v_block_mapped(unsigned long va)
{
        unsigned long p = PHYS_IMMR_BASE;

        if (va >= VIRT_IMMR_BASE && va < VIRT_IMMR_BASE + IMMR_SIZE)
                return p + va - VIRT_IMMR_BASE;
        if (__map_without_ltlbs)
                return 0;
        if (va >= PAGE_OFFSET && va < PAGE_OFFSET + block_mapped_ram)
                return __pa(va);
        return 0;
}

/*
 * Return VA for a given PA mapped with LTLBs or fixmap
 * Return 0 if not mapped
 */
unsigned long p_block_mapped(phys_addr_t pa)
{
        unsigned long p = PHYS_IMMR_BASE;

        if (pa >= p && pa < p + IMMR_SIZE)
                return VIRT_IMMR_BASE + pa - p;
        if (__map_without_ltlbs)
                return 0;
        if (pa < block_mapped_ram)
                return (unsigned long)__va(pa);
        return 0;
}

static pte_t __init *early_hugepd_alloc_kernel(hugepd_t *pmdp, unsigned long va)
{
        if (hpd_val(*pmdp) == 0) {
                pte_t *ptep = memblock_alloc(sizeof(pte_basic_t), SZ_4K);

                if (!ptep)
                        return NULL;

                hugepd_populate_kernel((hugepd_t *)pmdp, ptep, PAGE_SHIFT_8M);
                hugepd_populate_kernel((hugepd_t *)pmdp + 1, ptep, PAGE_SHIFT_8M);
        }
        return hugepte_offset(*(hugepd_t *)pmdp, va, PGDIR_SHIFT);
}

static int __ref __early_map_kernel_hugepage(unsigned long va, phys_addr_t pa,
                                             pgprot_t prot, int psize, bool new)
{
        pmd_t *pmdp = pmd_off_k(va);
        pte_t *ptep;

        if (WARN_ON(psize != MMU_PAGE_512K && psize != MMU_PAGE_8M))
                return -EINVAL;

        if (new) {
                if (WARN_ON(slab_is_available()))
                        return -EINVAL;

                if (psize == MMU_PAGE_512K)
                        ptep = early_pte_alloc_kernel(pmdp, va);
                else
                        ptep = early_hugepd_alloc_kernel((hugepd_t *)pmdp, va);
        } else {
                if (psize == MMU_PAGE_512K)
                        ptep = pte_offset_kernel(pmdp, va);
                else
                        ptep = hugepte_offset(*(hugepd_t *)pmdp, va, PGDIR_SHIFT);
        }

        if (WARN_ON(!ptep))
                return -ENOMEM;

        /* The PTE should never be already present */
        if (new && WARN_ON(pte_present(*ptep) && pgprot_val(prot)))
                return -EINVAL;

        set_huge_pte_at(&init_mm, va, ptep, pte_mkhuge(pfn_pte(pa >> PAGE_SHIFT, prot)));

        return 0;
}

/*
 * MMU_init_hw does the chip-specific initialization of the MMU hardware.
 */
void __init MMU_init_hw(void)
{
}

static bool immr_is_mapped __initdata;

void __init mmu_mapin_immr(void)
{
        if (immr_is_mapped)
                return;

        immr_is_mapped = true;

        __early_map_kernel_hugepage(VIRT_IMMR_BASE, PHYS_IMMR_BASE,
                                    PAGE_KERNEL_NCG, MMU_PAGE_512K, true);
}

static void mmu_mapin_ram_chunk(unsigned long offset, unsigned long top,
                                pgprot_t prot, bool new)
{
        unsigned long v = PAGE_OFFSET + offset;
        unsigned long p = offset;

        WARN_ON(!IS_ALIGNED(offset, SZ_512K) || !IS_ALIGNED(top, SZ_512K));

        for (; p < ALIGN(p, SZ_8M) && p < top; p += SZ_512K, v += SZ_512K)
                __early_map_kernel_hugepage(v, p, prot, MMU_PAGE_512K, new);
        for (; p < ALIGN_DOWN(top, SZ_8M) && p < top; p += SZ_8M, v += SZ_8M)
                __early_map_kernel_hugepage(v, p, prot, MMU_PAGE_8M, new);
        for (; p < ALIGN_DOWN(top, SZ_512K) && p < top; p += SZ_512K, v += SZ_512K)
                __early_map_kernel_hugepage(v, p, prot, MMU_PAGE_512K, new);

        if (!new)
                flush_tlb_kernel_range(PAGE_OFFSET + v, PAGE_OFFSET + top);
}

unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
{
        unsigned long etext8 = ALIGN(__pa(_etext), SZ_8M);
        unsigned long sinittext = __pa(_sinittext);
        bool strict_boundary = strict_kernel_rwx_enabled() || debug_pagealloc_enabled();
        unsigned long boundary = strict_boundary ? sinittext : etext8;
        unsigned long einittext8 = ALIGN(__pa(_einittext), SZ_8M);

        WARN_ON(top < einittext8);

        mmu_mapin_immr();

        if (__map_without_ltlbs)
                return 0;

        mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, true);
        if (debug_pagealloc_enabled()) {
                top = boundary;
        } else {
                mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL_TEXT, true);
                mmu_mapin_ram_chunk(einittext8, top, PAGE_KERNEL, true);
        }

        if (top > SZ_32M)
                memblock_set_current_limit(top);

        block_mapped_ram = top;

        return top;
}

void mmu_mark_initmem_nx(void)
{
        unsigned long etext8 = ALIGN(__pa(_etext), SZ_8M);
        unsigned long sinittext = __pa(_sinittext);
        unsigned long boundary = strict_kernel_rwx_enabled() ? sinittext : etext8;
        unsigned long einittext8 = ALIGN(__pa(_einittext), SZ_8M);

        mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
        mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);

        if (IS_ENABLED(CONFIG_PIN_TLB_TEXT))
                mmu_pin_tlb(block_mapped_ram, false);
}

#ifdef CONFIG_STRICT_KERNEL_RWX
void mmu_mark_rodata_ro(void)
{
        unsigned long sinittext = __pa(_sinittext);

        mmu_mapin_ram_chunk(0, sinittext, PAGE_KERNEL_ROX, false);
        if (IS_ENABLED(CONFIG_PIN_TLB_DATA))
                mmu_pin_tlb(block_mapped_ram, true);
}
#endif

void __init setup_initial_memory_limit(phys_addr_t first_memblock_base,
                                       phys_addr_t first_memblock_size)
{
        /* We don't currently support the first MEMBLOCK not mapping 0
         * physical on those processors
         */
        BUG_ON(first_memblock_base != 0);

        /* 8xx can only access 32MB at the moment */
        memblock_set_current_limit(min_t(u64, first_memblock_size, SZ_32M));
}

/*
 * Set up to use a given MMU context.
 * id is context number, pgd is PGD pointer.
 *
 * We place the physical address of the new task page directory loaded
 * into the MMU base register, and set the ASID compare register with
 * the new "context."
 */
void set_context(unsigned long id, pgd_t *pgd)
{
        s16 offset = (s16)(__pa(swapper_pg_dir));

        /* Context switch the PTE pointer for the Abatron BDI2000.
         * The PGDIR is passed as second argument.
         */
        if (IS_ENABLED(CONFIG_BDI_SWITCH))
                abatron_pteptrs[1] = pgd;

        /* Register M_TWB will contain base address of level 1 table minus the
         * lower part of the kernel PGDIR base address, so that all accesses to
         * level 1 table are done relative to lower part of kernel PGDIR base
         * address.
         */
        mtspr(SPRN_M_TWB, __pa(pgd) - offset);

        /* Update context */
        mtspr(SPRN_M_CASID, id - 1);
        /* sync */
        mb();
}

void flush_instruction_cache(void)
{
        isync();
        mtspr(SPRN_IC_CST, IDC_INVALL);
        isync();
}

#ifdef CONFIG_PPC_KUEP
void __init setup_kuep(bool disabled)
{
        if (disabled)
                return;

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

        mtspr(SPRN_MI_AP, MI_APG_KUEP);
}
#endif

#ifdef CONFIG_PPC_KUAP
void __init setup_kuap(bool disabled)
{
        pr_info("Activating Kernel Userspace Access Protection\n");

        if (disabled)
                pr_warn("KUAP cannot be disabled yet on 8xx when compiled in\n");

        mtspr(SPRN_MD_AP, MD_APG_KUAP);
}
#endif