// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * This file contains the routines for flushing entries from the
 * TLB and MMU hash table.
 *
 *  Derived from arch/ppc64/mm/init.c:
 *    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.
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/tlb.h>
#include <asm/bug.h>
#include <asm/pte-walk.h>


#include <trace/events/thp.h>

DEFINE_PER_CPU(struct ppc64_tlb_batch, ppc64_tlb_batch);

/*
 * A linux PTE was changed and the corresponding hash table entry
 * neesd to be flushed. This function will either perform the flush
 * immediately or will batch it up if the current CPU has an active
 * batch on it.
 */
void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
                     pte_t *ptep, unsigned long pte, int huge)
{
        unsigned long vpn;
        struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
        unsigned long vsid;
        unsigned int psize;
        int ssize;
        real_pte_t rpte;
        int i, offset;

        i = batch->index;

        /*
         * Get page size (maybe move back to caller).
         *
         * NOTE: when using special 64K mappings in 4K environment like
         * for SPEs, we obtain the page size from the slice, which thus
         * must still exist (and thus the VMA not reused) at the time
         * of this call
         */
        if (huge) {
#ifdef CONFIG_HUGETLB_PAGE
                psize = get_slice_psize(mm, addr);
                /* Mask the address for the correct page size */
                addr &= ~((1UL << mmu_psize_defs[psize].shift) - 1);
                if (unlikely(psize == MMU_PAGE_16G))
                        offset = PTRS_PER_PUD;
                else
                        offset = PTRS_PER_PMD;
#else
                BUG();
                psize = pte_pagesize_index(mm, addr, pte); /* shutup gcc */
#endif
        } else {
                psize = pte_pagesize_index(mm, addr, pte);
                /*
                 * Mask the address for the standard page size.  If we
                 * have a 64k page kernel, but the hardware does not
                 * support 64k pages, this might be different from the
                 * hardware page size encoded in the slice table.
                 */
                addr &= PAGE_MASK;
                offset = PTRS_PER_PTE;
        }


        /* Build full vaddr */
        if (!is_kernel_addr(addr)) {
                ssize = user_segment_size(addr);
                vsid = get_user_vsid(&mm->context, addr, ssize);
        } else {
                vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
                ssize = mmu_kernel_ssize;
        }
        WARN_ON(vsid == 0);
        vpn = hpt_vpn(addr, vsid, ssize);
        rpte = __real_pte(__pte(pte), ptep, offset);

        /*
         * Check if we have an active batch on this CPU. If not, just
         * flush now and return.
         */
        if (!batch->active) {
                flush_hash_page(vpn, rpte, psize, ssize, mm_is_thread_local(mm));
                put_cpu_var(ppc64_tlb_batch);
                return;
        }

        /*
         * This can happen when we are in the middle of a TLB batch and
         * we encounter memory pressure (eg copy_page_range when it tries
         * to allocate a new pte). If we have to reclaim memory and end
         * up scanning and resetting referenced bits then our batch context
         * will change mid stream.
         *
         * We also need to ensure only one page size is present in a given
         * batch
         */
        if (i != 0 && (mm != batch->mm || batch->psize != psize ||
                       batch->ssize != ssize)) {
                __flush_tlb_pending(batch);
                i = 0;
        }
        if (i == 0) {
                batch->mm = mm;
                batch->psize = psize;
                batch->ssize = ssize;
        }
        batch->pte[i] = rpte;
        batch->vpn[i] = vpn;
        batch->index = ++i;
        if (i >= PPC64_TLB_BATCH_NR)
                __flush_tlb_pending(batch);
        put_cpu_var(ppc64_tlb_batch);
}

/*
 * This function is called when terminating an mmu batch or when a batch
 * is full. It will perform the flush of all the entries currently stored
 * in a batch.
 *
 * Must be called from within some kind of spinlock/non-preempt region...
 */
void __flush_tlb_pending(struct ppc64_tlb_batch *batch)
{
        int i, local;

        i = batch->index;
        local = mm_is_thread_local(batch->mm);
        if (i == 1)
                flush_hash_page(batch->vpn[0], batch->pte[0],
                                batch->psize, batch->ssize, local);
        else
                flush_hash_range(i, local);
        batch->index = 0;
}

void hash__tlb_flush(struct mmu_gather *tlb)
{
        struct ppc64_tlb_batch *tlbbatch = &get_cpu_var(ppc64_tlb_batch);

        /*
         * If there's a TLB batch pending, then we must flush it because the
         * pages are going to be freed and we really don't want to have a CPU
         * access a freed page because it has a stale TLB
         */
        if (tlbbatch->index)
                __flush_tlb_pending(tlbbatch);

        put_cpu_var(ppc64_tlb_batch);
}

/**
 * __flush_hash_table_range - Flush all HPTEs for a given address range
 *                            from the hash table (and the TLB). But keeps
 *                            the linux PTEs intact.
 *
 * @start       : starting address
 * @end         : ending address (not included in the flush)
 *
 * This function is mostly to be used by some IO hotplug code in order
 * to remove all hash entries from a given address range used to map IO
 * space on a removed PCI-PCI bidge without tearing down the full mapping
 * since 64K pages may overlap with other bridges when using 64K pages
 * with 4K HW pages on IO space.
 *
 * Because of that usage pattern, it is implemented for small size rather
 * than speed.
 */
void __flush_hash_table_range(unsigned long start, unsigned long end)
{
        int hugepage_shift;
        unsigned long flags;

        start = ALIGN_DOWN(start, PAGE_SIZE);
        end = ALIGN(end, PAGE_SIZE);


        /*
         * Note: Normally, we should only ever use a batch within a
         * PTE locked section. This violates the rule, but will work
         * since we don't actually modify the PTEs, we just flush the
         * hash while leaving the PTEs intact (including their reference
         * to being hashed). This is not the most performance oriented
         * way to do things but is fine for our needs here.
         */
        local_irq_save(flags);
        arch_enter_lazy_mmu_mode();
        for (; start < end; start += PAGE_SIZE) {
                pte_t *ptep = find_init_mm_pte(start, &hugepage_shift);
                unsigned long pte;

                if (ptep == NULL)
                        continue;
                pte = pte_val(*ptep);
                if (!(pte & H_PAGE_HASHPTE))
                        continue;
                hpte_need_flush(&init_mm, start, ptep, pte, hugepage_shift);
        }
        arch_leave_lazy_mmu_mode();
        local_irq_restore(flags);
}

void flush_tlb_pmd_range(struct mm_struct *mm, pmd_t *pmd, unsigned long addr)
{
        pte_t *pte;
        pte_t *start_pte;
        unsigned long flags;

        addr = ALIGN_DOWN(addr, PMD_SIZE);
        /*
         * Note: Normally, we should only ever use a batch within a
         * PTE locked section. This violates the rule, but will work
         * since we don't actually modify the PTEs, we just flush the
         * hash while leaving the PTEs intact (including their reference
         * to being hashed). This is not the most performance oriented
         * way to do things but is fine for our needs here.
         */
        local_irq_save(flags);
        arch_enter_lazy_mmu_mode();
        start_pte = pte_offset_map(pmd, addr);
        for (pte = start_pte; pte < start_pte + PTRS_PER_PTE; pte++) {
                unsigned long pteval = pte_val(*pte);
                if (pteval & H_PAGE_HASHPTE)
                        hpte_need_flush(mm, addr, pte, pteval, 0);
                addr += PAGE_SIZE;
        }
        arch_leave_lazy_mmu_mode();
        local_irq_restore(flags);
}