// SPDX-License-Identifier: GPL-2.0
/*
 * Initialize MMU support.
 *
 * Copyright (C) 1998-2003 Hewlett-Packard Co
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 */
#include <linux/kernel.h>
#include <linux/init.h>

#include <linux/dma-map-ops.h>
#include <linux/dmar.h>
#include <linux/efi.h>
#include <linux/elf.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/sched/signal.h>
#include <linux/mmzone.h>
#include <linux/module.h>
#include <linux/personality.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/proc_fs.h>
#include <linux/bitops.h>
#include <linux/kexec.h>
#include <linux/swiotlb.h>

#include <asm/dma.h>
#include <asm/efi.h>
#include <asm/io.h>
#include <asm/numa.h>
#include <asm/patch.h>
#include <asm/pgalloc.h>
#include <asm/sal.h>
#include <asm/sections.h>
#include <asm/tlb.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
#include <asm/mca.h>

extern void ia64_tlb_init (void);

unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;

struct page *zero_page_memmap_ptr;      /* map entry for zero page */
EXPORT_SYMBOL(zero_page_memmap_ptr);

void
__ia64_sync_icache_dcache (pte_t pte)
{
        unsigned long addr;
        struct page *page;

        page = pte_page(pte);
        addr = (unsigned long) page_address(page);

        if (test_bit(PG_arch_1, &page->flags))
                return;                         /* i-cache is already coherent with d-cache */

        flush_icache_range(addr, addr + page_size(page));
        set_bit(PG_arch_1, &page->flags);       /* mark page as clean */
}

/*
 * Since DMA is i-cache coherent, any (complete) pages that were written via
 * DMA can be marked as "clean" so that lazy_mmu_prot_update() doesn't have to
 * flush them when they get mapped into an executable vm-area.
 */
void arch_dma_mark_clean(phys_addr_t paddr, size_t size)
{
        unsigned long pfn = PHYS_PFN(paddr);

        do {
                set_bit(PG_arch_1, &pfn_to_page(pfn)->flags);
        } while (++pfn <= PHYS_PFN(paddr + size - 1));
}

inline void
ia64_set_rbs_bot (void)
{
        unsigned long stack_size = rlimit_max(RLIMIT_STACK) & -16;

        if (stack_size > MAX_USER_STACK_SIZE)
                stack_size = MAX_USER_STACK_SIZE;
        current->thread.rbs_bot = PAGE_ALIGN(current->mm->start_stack - stack_size);
}

/*
 * This performs some platform-dependent address space initialization.
 * On IA-64, we want to setup the VM area for the register backing
 * store (which grows upwards) and install the gateway page which is
 * used for signal trampolines, etc.
 */
void
ia64_init_addr_space (void)
{
        struct vm_area_struct *vma;

        ia64_set_rbs_bot();

        /*
         * If we're out of memory and kmem_cache_alloc() returns NULL, we simply ignore
         * the problem.  When the process attempts to write to the register backing store
         * for the first time, it will get a SEGFAULT in this case.
         */
        vma = vm_area_alloc(current->mm);
        if (vma) {
                vma_set_anonymous(vma);
                vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
                vma->vm_end = vma->vm_start + PAGE_SIZE;
                vma->vm_flags = VM_DATA_DEFAULT_FLAGS|VM_GROWSUP|VM_ACCOUNT;
                vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
                mmap_write_lock(current->mm);
                if (insert_vm_struct(current->mm, vma)) {
                        mmap_write_unlock(current->mm);
                        vm_area_free(vma);
                        return;
                }
                mmap_write_unlock(current->mm);
        }

        /* map NaT-page at address zero to speed up speculative dereferencing of NULL: */
        if (!(current->personality & MMAP_PAGE_ZERO)) {
                vma = vm_area_alloc(current->mm);
                if (vma) {
                        vma_set_anonymous(vma);
                        vma->vm_end = PAGE_SIZE;
                        vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) | _PAGE_MA_NAT);
                        vma->vm_flags = VM_READ | VM_MAYREAD | VM_IO |
                                        VM_DONTEXPAND | VM_DONTDUMP;
                        mmap_write_lock(current->mm);
                        if (insert_vm_struct(current->mm, vma)) {
                                mmap_write_unlock(current->mm);
                                vm_area_free(vma);
                                return;
                        }
                        mmap_write_unlock(current->mm);
                }
        }
}

void
free_initmem (void)
{
        free_reserved_area(ia64_imva(__init_begin), ia64_imva(__init_end),
                           -1, "unused kernel");
}

void __init
free_initrd_mem (unsigned long start, unsigned long end)
{
        /*
         * EFI uses 4KB pages while the kernel can use 4KB or bigger.
         * Thus EFI and the kernel may have different page sizes. It is
         * therefore possible to have the initrd share the same page as
         * the end of the kernel (given current setup).
         *
         * To avoid freeing/using the wrong page (kernel sized) we:
         *      - align up the beginning of initrd
         *      - align down the end of initrd
         *
         *  |             |
         *  |=============| a000
         *  |             |
         *  |             |
         *  |             | 9000
         *  |/////////////|
         *  |/////////////|
         *  |=============| 8000
         *  |///INITRD////|
         *  |/////////////|
         *  |/////////////| 7000
         *  |             |
         *  |KKKKKKKKKKKKK|
         *  |=============| 6000
         *  |KKKKKKKKKKKKK|
         *  |KKKKKKKKKKKKK|
         *  K=kernel using 8KB pages
         *
         * In this example, we must free page 8000 ONLY. So we must align up
         * initrd_start and keep initrd_end as is.
         */
        start = PAGE_ALIGN(start);
        end = end & PAGE_MASK;

        if (start < end)
                printk(KERN_INFO "Freeing initrd memory: %ldkB freed\n", (end - start) >> 10);

        for (; start < end; start += PAGE_SIZE) {
                if (!virt_addr_valid(start))
                        continue;
                free_reserved_page(virt_to_page(start));
        }
}

/*
 * This installs a clean page in the kernel's page table.
 */
static struct page * __init
put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
{
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        pgd = pgd_offset_k(address);            /* note: this is NOT pgd_offset()! */

        {
                p4d = p4d_alloc(&init_mm, pgd, address);
                if (!p4d)
                        goto out;
                pud = pud_alloc(&init_mm, p4d, address);
                if (!pud)
                        goto out;
                pmd = pmd_alloc(&init_mm, pud, address);
                if (!pmd)
                        goto out;
                pte = pte_alloc_kernel(pmd, address);
                if (!pte)
                        goto out;
                if (!pte_none(*pte))
                        goto out;
                set_pte(pte, mk_pte(page, pgprot));
        }
  out:
        /* no need for flush_tlb */
        return page;
}

static void __init
setup_gate (void)
{
        struct page *page;

        /*
         * Map the gate page twice: once read-only to export the ELF
         * headers etc. and once execute-only page to enable
         * privilege-promotion via "epc":
         */
        page = virt_to_page(ia64_imva(__start_gate_section));
        put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
#ifdef HAVE_BUGGY_SEGREL
        page = virt_to_page(ia64_imva(__start_gate_section + PAGE_SIZE));
        put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
#else
        put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
        /* Fill in the holes (if any) with read-only zero pages: */
        {
                unsigned long addr;

                for (addr = GATE_ADDR + PAGE_SIZE;
                     addr < GATE_ADDR + PERCPU_PAGE_SIZE;
                     addr += PAGE_SIZE)
                {
                        put_kernel_page(ZERO_PAGE(0), addr,
                                        PAGE_READONLY);
                        put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
                                        PAGE_READONLY);
                }
        }
#endif
        ia64_patch_gate();
}

static struct vm_area_struct gate_vma;

static int __init gate_vma_init(void)
{
        vma_init(&gate_vma, NULL);
        gate_vma.vm_start = FIXADDR_USER_START;
        gate_vma.vm_end = FIXADDR_USER_END;
        gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
        gate_vma.vm_page_prot = __P101;

        return 0;
}
__initcall(gate_vma_init);

struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
        return &gate_vma;
}

int in_gate_area_no_mm(unsigned long addr)
{
        if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
                return 1;
        return 0;
}

int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
        return in_gate_area_no_mm(addr);
}

void ia64_mmu_init(void *my_cpu_data)
{
        unsigned long pta, impl_va_bits;
        extern void tlb_init(void);

#ifdef CONFIG_DISABLE_VHPT
#       define VHPT_ENABLE_BIT  0
#else
#       define VHPT_ENABLE_BIT  1
#endif

        /*
         * Check if the virtually mapped linear page table (VMLPT) overlaps with a mapped
         * address space.  The IA-64 architecture guarantees that at least 50 bits of
         * virtual address space are implemented but if we pick a large enough page size
         * (e.g., 64KB), the mapped address space is big enough that it will overlap with
         * VMLPT.  I assume that once we run on machines big enough to warrant 64KB pages,
         * IMPL_VA_MSB will be significantly bigger, so this is unlikely to become a
         * problem in practice.  Alternatively, we could truncate the top of the mapped
         * address space to not permit mappings that would overlap with the VMLPT.
         * --davidm 00/12/06
         */
#       define pte_bits                 3
#       define mapped_space_bits        (3*(PAGE_SHIFT - pte_bits) + PAGE_SHIFT)
        /*
         * The virtual page table has to cover the entire implemented address space within
         * a region even though not all of this space may be mappable.  The reason for
         * this is that the Access bit and Dirty bit fault handlers perform
         * non-speculative accesses to the virtual page table, so the address range of the
         * virtual page table itself needs to be covered by virtual page table.
         */
#       define vmlpt_bits               (impl_va_bits - PAGE_SHIFT + pte_bits)
#       define POW2(n)                  (1ULL << (n))

        impl_va_bits = ffz(~(local_cpu_data->unimpl_va_mask | (7UL << 61)));

        if (impl_va_bits < 51 || impl_va_bits > 61)
                panic("CPU has bogus IMPL_VA_MSB value of %lu!\n", impl_va_bits - 1);
        /*
         * mapped_space_bits - PAGE_SHIFT is the total number of ptes we need,
         * which must fit into "vmlpt_bits - pte_bits" slots. Second half of
         * the test makes sure that our mapped space doesn't overlap the
         * unimplemented hole in the middle of the region.
         */
        if ((mapped_space_bits - PAGE_SHIFT > vmlpt_bits - pte_bits) ||
            (mapped_space_bits > impl_va_bits - 1))
                panic("Cannot build a big enough virtual-linear page table"
                      " to cover mapped address space.\n"
                      " Try using a smaller page size.\n");


        /* place the VMLPT at the end of each page-table mapped region: */
        pta = POW2(61) - POW2(vmlpt_bits);

        /*
         * Set the (virtually mapped linear) page table address.  Bit
         * 8 selects between the short and long format, bits 2-7 the
         * size of the table, and bit 0 whether the VHPT walker is
         * enabled.
         */
        ia64_set_pta(pta | (0 << 8) | (vmlpt_bits << 2) | VHPT_ENABLE_BIT);

        ia64_tlb_init();

#ifdef  CONFIG_HUGETLB_PAGE
        ia64_set_rr(HPAGE_REGION_BASE, HPAGE_SHIFT << 2);
        ia64_srlz_d();
#endif
}

int __init register_active_ranges(u64 start, u64 len, int nid)
{
        u64 end = start + len;

#ifdef CONFIG_KEXEC
        if (start > crashk_res.start && start < crashk_res.end)
                start = crashk_res.end;
        if (end > crashk_res.start && end < crashk_res.end)
                end = crashk_res.start;
#endif

        if (start < end)
                memblock_add_node(__pa(start), end - start, nid);
        return 0;
}

int
find_max_min_low_pfn (u64 start, u64 end, void *arg)
{
        unsigned long pfn_start, pfn_end;
#ifdef CONFIG_FLATMEM
        pfn_start = (PAGE_ALIGN(__pa(start))) >> PAGE_SHIFT;
        pfn_end = (PAGE_ALIGN(__pa(end - 1))) >> PAGE_SHIFT;
#else
        pfn_start = GRANULEROUNDDOWN(__pa(start)) >> PAGE_SHIFT;
        pfn_end = GRANULEROUNDUP(__pa(end - 1)) >> PAGE_SHIFT;
#endif
        min_low_pfn = min(min_low_pfn, pfn_start);
        max_low_pfn = max(max_low_pfn, pfn_end);
        return 0;
}

/*
 * Boot command-line option "nolwsys" can be used to disable the use of any light-weight
 * system call handler.  When this option is in effect, all fsyscalls will end up bubbling
 * down into the kernel and calling the normal (heavy-weight) syscall handler.  This is
 * useful for performance testing, but conceivably could also come in handy for debugging
 * purposes.
 */

static int nolwsys __initdata;

static int __init
nolwsys_setup (char *s)
{
        nolwsys = 1;
        return 1;
}

__setup("nolwsys", nolwsys_setup);

void __init
mem_init (void)
{
        int i;

        BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
        BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
        BUG_ON(PTRS_PER_PTE * sizeof(pte_t) != PAGE_SIZE);

        /*
         * This needs to be called _after_ the command line has been parsed but
         * _before_ any drivers that may need the PCI DMA interface are
         * initialized or bootmem has been freed.
         */
        do {
#ifdef CONFIG_INTEL_IOMMU
                detect_intel_iommu();
                if (iommu_detected)
                        break;
#endif
#ifdef CONFIG_SWIOTLB
                swiotlb_init(1);
#endif
        } while (0);

#ifdef CONFIG_FLATMEM
        BUG_ON(!mem_map);
#endif

        set_max_mapnr(max_low_pfn);
        high_memory = __va(max_low_pfn * PAGE_SIZE);
        memblock_free_all();

        /*
         * For fsyscall entrpoints with no light-weight handler, use the ordinary
         * (heavy-weight) handler, but mark it by setting bit 0, so the fsyscall entry
         * code can tell them apart.
         */
        for (i = 0; i < NR_syscalls; ++i) {
                extern unsigned long fsyscall_table[NR_syscalls];
                extern unsigned long sys_call_table[NR_syscalls];

                if (!fsyscall_table[i] || nolwsys)
                        fsyscall_table[i] = sys_call_table[i] | 1;
        }
        setup_gate();
}

#ifdef CONFIG_MEMORY_HOTPLUG
int arch_add_memory(int nid, u64 start, u64 size,
                    struct mhp_params *params)
{
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
        int ret;

        if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
                return -EINVAL;

        ret = __add_pages(nid, start_pfn, nr_pages, params);
        if (ret)
                printk("%s: Problem encountered in __add_pages() as ret=%d\n",
                       __func__,  ret);

        return ret;
}

void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
{
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;

        __remove_pages(start_pfn, nr_pages, altmap);
}
#endif