// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2005, Paul Mackerras, IBM Corporation.
 * Copyright 2009, Benjamin Herrenschmidt, IBM Corporation.
 * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation.
 */

#include <linux/sched.h>
#include <linux/memblock.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/dma.h>
#include <asm/text-patching.h>

#include <mm/mmu_decl.h>

#ifdef CONFIG_SPARSEMEM_VMEMMAP
/*
 * On Book3E CPUs, the vmemmap is currently mapped in the top half of
 * the vmalloc space using normal page tables, though the size of
 * pages encoded in the PTEs can be different
 */
int __meminit vmemmap_create_mapping(unsigned long start,
                                     unsigned long page_size,
                                     unsigned long phys)
{
        /* Create a PTE encoding without page size */
        unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
                _PAGE_KERNEL_RW;

        /* PTEs only contain page size encodings up to 32M */
        BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].shift - 10 > 0xf);

        /* Encode the size in the PTE */
        flags |= (mmu_psize_defs[mmu_vmemmap_psize].shift - 10) << 8;

        /* For each PTE for that area, map things. Note that we don't
         * increment phys because all PTEs are of the large size and
         * thus must have the low bits clear
         */
        for (i = 0; i < page_size; i += PAGE_SIZE)
                BUG_ON(map_kernel_page(start + i, phys, __pgprot(flags)));

        return 0;
}

#ifdef CONFIG_MEMORY_HOTPLUG
void vmemmap_remove_mapping(unsigned long start,
                            unsigned long page_size)
{
}
#endif
#endif /* CONFIG_SPARSEMEM_VMEMMAP */

static void __init *early_alloc_pgtable(unsigned long size)
{
        void *ptr;

        ptr = memblock_alloc_try_nid(size, size, MEMBLOCK_LOW_LIMIT,
                                     __pa(MAX_DMA_ADDRESS), NUMA_NO_NODE);

        if (!ptr)
                panic("%s: Failed to allocate %lu bytes align=0x%lx max_addr=%lx\n",
                      __func__, size, size, __pa(MAX_DMA_ADDRESS));

        return ptr;
}

/*
 * map_kernel_page currently only called by __ioremap
 * map_kernel_page adds an entry to the ioremap page table
 * and adds an entry to the HPT, possibly bolting it
 */
int __ref map_kernel_page(unsigned long ea, phys_addr_t pa, pgprot_t prot)
{
        pgd_t *pgdp;
        p4d_t *p4dp;
        pud_t *pudp;
        pmd_t *pmdp;
        pte_t *ptep;

        BUILD_BUG_ON(TASK_SIZE_USER64 > PGTABLE_RANGE);
        if (slab_is_available()) {
                pgdp = pgd_offset_k(ea);
                p4dp = p4d_offset(pgdp, ea);
                pudp = pud_alloc(&init_mm, p4dp, ea);
                if (!pudp)
                        return -ENOMEM;
                pmdp = pmd_alloc(&init_mm, pudp, ea);
                if (!pmdp)
                        return -ENOMEM;
                ptep = pte_alloc_kernel(pmdp, ea);
                if (!ptep)
                        return -ENOMEM;
        } else {
                pgdp = pgd_offset_k(ea);
                p4dp = p4d_offset(pgdp, ea);
                if (p4d_none(*p4dp)) {
                        pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
                        p4d_populate(&init_mm, p4dp, pudp);
                }
                pudp = pud_offset(p4dp, ea);
                if (pud_none(*pudp)) {
                        pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
                        pud_populate(&init_mm, pudp, pmdp);
                }
                pmdp = pmd_offset(pudp, ea);
                if (!pmd_present(*pmdp)) {
                        ptep = early_alloc_pgtable(PTE_TABLE_SIZE);
                        pmd_populate_kernel(&init_mm, pmdp, ptep);
                }
                ptep = pte_offset_kernel(pmdp, ea);
        }
        set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot));

        smp_wmb();
        return 0;
}

void __patch_exception(int exc, unsigned long addr)
{
        unsigned int *ibase = &interrupt_base_book3e;

        /*
         * Our exceptions vectors start with a NOP and -then- a branch
         * to deal with single stepping from userspace which stops on
         * the second instruction. Thus we need to patch the second
         * instruction of the exception, not the first one.
         */

        patch_branch(ibase + (exc / 4) + 1, addr, 0);
}