WIP FPC-III support

[linux/fpc-iii.git] / arch / powerpc / mm / book3s64 / hash_utils.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * PowerPC64 port by Mike Corrigan and Dave Engebretsen
 *   {mikejc|engebret}@us.ibm.com
 *
 *    Copyright (c) 2000 Mike Corrigan <mikejc@us.ibm.com>
 *
 * SMP scalability work:
 *    Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
 *
 *    Module name: htab.c
 *
 *    Description:
 *      PowerPC Hashed Page Table functions
 */

#undef DEBUG
#undef DEBUG_LOW

#define pr_fmt(fmt) "hash-mmu: " fmt
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/sched/mm.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/sysctl.h>
#include <linux/export.h>
#include <linux/ctype.h>
#include <linux/cache.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/memblock.h>
#include <linux/context_tracking.h>
#include <linux/libfdt.h>
#include <linux/pkeys.h>
#include <linux/hugetlb.h>
#include <linux/cpu.h>
#include <linux/pgtable.h>

#include <asm/debugfs.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/page.h>
#include <asm/types.h>
#include <linux/uaccess.h>
#include <asm/machdep.h>
#include <asm/prom.h>
#include <asm/io.h>
#include <asm/eeh.h>
#include <asm/tlb.h>
#include <asm/cacheflush.h>
#include <asm/cputable.h>
#include <asm/sections.h>
#include <asm/copro.h>
#include <asm/udbg.h>
#include <asm/code-patching.h>
#include <asm/fadump.h>
#include <asm/firmware.h>
#include <asm/tm.h>
#include <asm/trace.h>
#include <asm/ps3.h>
#include <asm/pte-walk.h>
#include <asm/asm-prototypes.h>
#include <asm/ultravisor.h>

#include <mm/mmu_decl.h>

#include "internal.h"


#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif

#ifdef DEBUG_LOW
#define DBG_LOW(fmt...) udbg_printf(fmt)
#else
#define DBG_LOW(fmt...)
#endif

#define KB (1024)
#define MB (1024*KB)
#define GB (1024L*MB)

/*
 * Note:  pte   --> Linux PTE
 *        HPTE  --> PowerPC Hashed Page Table Entry
 *
 * Execution context:
 *   htab_initialize is called with the MMU off (of course), but
 *   the kernel has been copied down to zero so it can directly
 *   reference global data.  At this point it is very difficult
 *   to print debug info.
 *
 */

static unsigned long _SDR1;
struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT];
EXPORT_SYMBOL_GPL(mmu_psize_defs);

u8 hpte_page_sizes[1 << LP_BITS];
EXPORT_SYMBOL_GPL(hpte_page_sizes);

struct hash_pte *htab_address;
unsigned long htab_size_bytes;
unsigned long htab_hash_mask;
EXPORT_SYMBOL_GPL(htab_hash_mask);
int mmu_linear_psize = MMU_PAGE_4K;
EXPORT_SYMBOL_GPL(mmu_linear_psize);
int mmu_virtual_psize = MMU_PAGE_4K;
int mmu_vmalloc_psize = MMU_PAGE_4K;
EXPORT_SYMBOL_GPL(mmu_vmalloc_psize);
#ifdef CONFIG_SPARSEMEM_VMEMMAP
int mmu_vmemmap_psize = MMU_PAGE_4K;
#endif
int mmu_io_psize = MMU_PAGE_4K;
int mmu_kernel_ssize = MMU_SEGSIZE_256M;
EXPORT_SYMBOL_GPL(mmu_kernel_ssize);
int mmu_highuser_ssize = MMU_SEGSIZE_256M;
u16 mmu_slb_size = 64;
EXPORT_SYMBOL_GPL(mmu_slb_size);
#ifdef CONFIG_PPC_64K_PAGES
int mmu_ci_restrictions;
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
static u8 *linear_map_hash_slots;
static unsigned long linear_map_hash_count;
static DEFINE_SPINLOCK(linear_map_hash_lock);
#endif /* CONFIG_DEBUG_PAGEALLOC */
struct mmu_hash_ops mmu_hash_ops;
EXPORT_SYMBOL(mmu_hash_ops);

/*
 * These are definitions of page sizes arrays to be used when none
 * is provided by the firmware.
 */

/*
 * Fallback (4k pages only)
 */
static struct mmu_psize_def mmu_psize_defaults[] = {
        [MMU_PAGE_4K] = {
                .shift  = 12,
                .sllp   = 0,
                .penc   = {[MMU_PAGE_4K] = 0, [1 ... MMU_PAGE_COUNT - 1] = -1},
                .avpnm  = 0,
                .tlbiel = 0,
        },
};

/*
 * POWER4, GPUL, POWER5
 *
 * Support for 16Mb large pages
 */
static struct mmu_psize_def mmu_psize_defaults_gp[] = {
        [MMU_PAGE_4K] = {
                .shift  = 12,
                .sllp   = 0,
                .penc   = {[MMU_PAGE_4K] = 0, [1 ... MMU_PAGE_COUNT - 1] = -1},
                .avpnm  = 0,
                .tlbiel = 1,
        },
        [MMU_PAGE_16M] = {
                .shift  = 24,
                .sllp   = SLB_VSID_L,
                .penc   = {[0 ... MMU_PAGE_16M - 1] = -1, [MMU_PAGE_16M] = 0,
                            [MMU_PAGE_16M + 1 ... MMU_PAGE_COUNT - 1] = -1 },
                .avpnm  = 0x1UL,
                .tlbiel = 0,
        },
};

/*
 * 'R' and 'C' update notes:
 *  - Under pHyp or KVM, the updatepp path will not set C, thus it *will*
 *     create writeable HPTEs without C set, because the hcall H_PROTECT
 *     that we use in that case will not update C
 *  - The above is however not a problem, because we also don't do that
 *     fancy "no flush" variant of eviction and we use H_REMOVE which will
 *     do the right thing and thus we don't have the race I described earlier
 *
 *    - Under bare metal,  we do have the race, so we need R and C set
 *    - We make sure R is always set and never lost
 *    - C is _PAGE_DIRTY, and *should* always be set for a writeable mapping
 */
unsigned long htab_convert_pte_flags(unsigned long pteflags, unsigned long flags)
{
        unsigned long rflags = 0;

        /* _PAGE_EXEC -> NOEXEC */
        if ((pteflags & _PAGE_EXEC) == 0)
                rflags |= HPTE_R_N;
        /*
         * PPP bits:
         * Linux uses slb key 0 for kernel and 1 for user.
         * kernel RW areas are mapped with PPP=0b000
         * User area is mapped with PPP=0b010 for read/write
         * or PPP=0b011 for read-only (including writeable but clean pages).
         */
        if (pteflags & _PAGE_PRIVILEGED) {
                /*
                 * Kernel read only mapped with ppp bits 0b110
                 */
                if (!(pteflags & _PAGE_WRITE)) {
                        if (mmu_has_feature(MMU_FTR_KERNEL_RO))
                                rflags |= (HPTE_R_PP0 | 0x2);
                        else
                                rflags |= 0x3;
                }
        } else {
                if (pteflags & _PAGE_RWX)
                        rflags |= 0x2;
                if (!((pteflags & _PAGE_WRITE) && (pteflags & _PAGE_DIRTY)))
                        rflags |= 0x1;
        }
        /*
         * We can't allow hardware to update hpte bits. Hence always
         * set 'R' bit and set 'C' if it is a write fault
         */
        rflags |=  HPTE_R_R;

        if (pteflags & _PAGE_DIRTY)
                rflags |= HPTE_R_C;
        /*
         * Add in WIG bits
         */

        if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_TOLERANT)
                rflags |= HPTE_R_I;
        else if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_NON_IDEMPOTENT)
                rflags |= (HPTE_R_I | HPTE_R_G);
        else if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_SAO)
                rflags |= (HPTE_R_W | HPTE_R_I | HPTE_R_M);
        else
                /*
                 * Add memory coherence if cache inhibited is not set
                 */
                rflags |= HPTE_R_M;

        rflags |= pte_to_hpte_pkey_bits(pteflags, flags);
        return rflags;
}

int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
                      unsigned long pstart, unsigned long prot,
                      int psize, int ssize)
{
        unsigned long vaddr, paddr;
        unsigned int step, shift;
        int ret = 0;

        shift = mmu_psize_defs[psize].shift;
        step = 1 << shift;

        prot = htab_convert_pte_flags(prot, HPTE_USE_KERNEL_KEY);

        DBG("htab_bolt_mapping(%lx..%lx -> %lx (%lx,%d,%d)\n",
            vstart, vend, pstart, prot, psize, ssize);

        /* Carefully map only the possible range */
        vaddr = ALIGN(vstart, step);
        paddr = ALIGN(pstart, step);
        vend  = ALIGN_DOWN(vend, step);

        for (; vaddr < vend; vaddr += step, paddr += step) {
                unsigned long hash, hpteg;
                unsigned long vsid = get_kernel_vsid(vaddr, ssize);
                unsigned long vpn  = hpt_vpn(vaddr, vsid, ssize);
                unsigned long tprot = prot;
                bool secondary_hash = false;

                /*
                 * If we hit a bad address return error.
                 */
                if (!vsid)
                        return -1;
                /* Make kernel text executable */
                if (overlaps_kernel_text(vaddr, vaddr + step))
                        tprot &= ~HPTE_R_N;

                /*
                 * If relocatable, check if it overlaps interrupt vectors that
                 * are copied down to real 0. For relocatable kernel
                 * (e.g. kdump case) we copy interrupt vectors down to real
                 * address 0. Mark that region as executable. This is
                 * because on p8 system with relocation on exception feature
                 * enabled, exceptions are raised with MMU (IR=DR=1) ON. Hence
                 * in order to execute the interrupt handlers in virtual
                 * mode the vector region need to be marked as executable.
                 */
                if ((PHYSICAL_START > MEMORY_START) &&
                        overlaps_interrupt_vector_text(vaddr, vaddr + step))
                                tprot &= ~HPTE_R_N;

                hash = hpt_hash(vpn, shift, ssize);
                hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);

                BUG_ON(!mmu_hash_ops.hpte_insert);
repeat:
                ret = mmu_hash_ops.hpte_insert(hpteg, vpn, paddr, tprot,
                                               HPTE_V_BOLTED, psize, psize,
                                               ssize);
                if (ret == -1) {
                        /*
                         * Try to to keep bolted entries in primary.
                         * Remove non bolted entries and try insert again
                         */
                        ret = mmu_hash_ops.hpte_remove(hpteg);
                        if (ret != -1)
                                ret = mmu_hash_ops.hpte_insert(hpteg, vpn, paddr, tprot,
                                                               HPTE_V_BOLTED, psize, psize,
                                                               ssize);
                        if (ret == -1 && !secondary_hash) {
                                secondary_hash = true;
                                hpteg = ((~hash & htab_hash_mask) * HPTES_PER_GROUP);
                                goto repeat;
                        }
                }

                if (ret < 0)
                        break;

                cond_resched();
#ifdef CONFIG_DEBUG_PAGEALLOC
                if (debug_pagealloc_enabled() &&
                        (paddr >> PAGE_SHIFT) < linear_map_hash_count)
                        linear_map_hash_slots[paddr >> PAGE_SHIFT] = ret | 0x80;
#endif /* CONFIG_DEBUG_PAGEALLOC */
        }
        return ret < 0 ? ret : 0;
}

int htab_remove_mapping(unsigned long vstart, unsigned long vend,
                      int psize, int ssize)
{
        unsigned long vaddr;
        unsigned int step, shift;
        int rc;
        int ret = 0;

        shift = mmu_psize_defs[psize].shift;
        step = 1 << shift;

        if (!mmu_hash_ops.hpte_removebolted)
                return -ENODEV;

        /* Unmap the full range specificied */
        vaddr = ALIGN_DOWN(vstart, step);
        for (;vaddr < vend; vaddr += step) {
                rc = mmu_hash_ops.hpte_removebolted(vaddr, psize, ssize);
                if (rc == -ENOENT) {
                        ret = -ENOENT;
                        continue;
                }
                if (rc < 0)
                        return rc;
        }

        return ret;
}

static bool disable_1tb_segments = false;

static int __init parse_disable_1tb_segments(char *p)
{
        disable_1tb_segments = true;
        return 0;
}
early_param("disable_1tb_segments", parse_disable_1tb_segments);

static int __init htab_dt_scan_seg_sizes(unsigned long node,
                                         const char *uname, int depth,
                                         void *data)
{
        const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
        const __be32 *prop;
        int size = 0;

        /* We are scanning "cpu" nodes only */
        if (type == NULL || strcmp(type, "cpu") != 0)
                return 0;

        prop = of_get_flat_dt_prop(node, "ibm,processor-segment-sizes", &size);
        if (prop == NULL)
                return 0;
        for (; size >= 4; size -= 4, ++prop) {
                if (be32_to_cpu(prop[0]) == 40) {
                        DBG("1T segment support detected\n");

                        if (disable_1tb_segments) {
                                DBG("1T segments disabled by command line\n");
                                break;
                        }

                        cur_cpu_spec->mmu_features |= MMU_FTR_1T_SEGMENT;
                        return 1;
                }
        }
        cur_cpu_spec->mmu_features &= ~MMU_FTR_NO_SLBIE_B;
        return 0;
}

static int __init get_idx_from_shift(unsigned int shift)
{
        int idx = -1;

        switch (shift) {
        case 0xc:
                idx = MMU_PAGE_4K;
                break;
        case 0x10:
                idx = MMU_PAGE_64K;
                break;
        case 0x14:
                idx = MMU_PAGE_1M;
                break;
        case 0x18:
                idx = MMU_PAGE_16M;
                break;
        case 0x22:
                idx = MMU_PAGE_16G;
                break;
        }
        return idx;
}

static int __init htab_dt_scan_page_sizes(unsigned long node,
                                          const char *uname, int depth,
                                          void *data)
{
        const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
        const __be32 *prop;
        int size = 0;

        /* We are scanning "cpu" nodes only */
        if (type == NULL || strcmp(type, "cpu") != 0)
                return 0;

        prop = of_get_flat_dt_prop(node, "ibm,segment-page-sizes", &size);
        if (!prop)
                return 0;

        pr_info("Page sizes from device-tree:\n");
        size /= 4;
        cur_cpu_spec->mmu_features &= ~(MMU_FTR_16M_PAGE);
        while(size > 0) {
                unsigned int base_shift = be32_to_cpu(prop[0]);
                unsigned int slbenc = be32_to_cpu(prop[1]);
                unsigned int lpnum = be32_to_cpu(prop[2]);
                struct mmu_psize_def *def;
                int idx, base_idx;

                size -= 3; prop += 3;
                base_idx = get_idx_from_shift(base_shift);
                if (base_idx < 0) {
                        /* skip the pte encoding also */
                        prop += lpnum * 2; size -= lpnum * 2;
                        continue;
                }
                def = &mmu_psize_defs[base_idx];
                if (base_idx == MMU_PAGE_16M)
                        cur_cpu_spec->mmu_features |= MMU_FTR_16M_PAGE;

                def->shift = base_shift;
                if (base_shift <= 23)
                        def->avpnm = 0;
                else
                        def->avpnm = (1 << (base_shift - 23)) - 1;
                def->sllp = slbenc;
                /*
                 * We don't know for sure what's up with tlbiel, so
                 * for now we only set it for 4K and 64K pages
                 */
                if (base_idx == MMU_PAGE_4K || base_idx == MMU_PAGE_64K)
                        def->tlbiel = 1;
                else
                        def->tlbiel = 0;

                while (size > 0 && lpnum) {
                        unsigned int shift = be32_to_cpu(prop[0]);
                        int penc  = be32_to_cpu(prop[1]);

                        prop += 2; size -= 2;
                        lpnum--;

                        idx = get_idx_from_shift(shift);
                        if (idx < 0)
                                continue;

                        if (penc == -1)
                                pr_err("Invalid penc for base_shift=%d "
                                       "shift=%d\n", base_shift, shift);

                        def->penc[idx] = penc;
                        pr_info("base_shift=%d: shift=%d, sllp=0x%04lx,"
                                " avpnm=0x%08lx, tlbiel=%d, penc=%d\n",
                                base_shift, shift, def->sllp,
                                def->avpnm, def->tlbiel, def->penc[idx]);
                }
        }

        return 1;
}

#ifdef CONFIG_HUGETLB_PAGE
/*
 * Scan for 16G memory blocks that have been set aside for huge pages
 * and reserve those blocks for 16G huge pages.
 */
static int __init htab_dt_scan_hugepage_blocks(unsigned long node,
                                        const char *uname, int depth,
                                        void *data) {
        const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
        const __be64 *addr_prop;
        const __be32 *page_count_prop;
        unsigned int expected_pages;
        long unsigned int phys_addr;
        long unsigned int block_size;

        /* We are scanning "memory" nodes only */
        if (type == NULL || strcmp(type, "memory") != 0)
                return 0;

        /*
         * This property is the log base 2 of the number of virtual pages that
         * will represent this memory block.
         */
        page_count_prop = of_get_flat_dt_prop(node, "ibm,expected#pages", NULL);
        if (page_count_prop == NULL)
                return 0;
        expected_pages = (1 << be32_to_cpu(page_count_prop[0]));
        addr_prop = of_get_flat_dt_prop(node, "reg", NULL);
        if (addr_prop == NULL)
                return 0;
        phys_addr = be64_to_cpu(addr_prop[0]);
        block_size = be64_to_cpu(addr_prop[1]);
        if (block_size != (16 * GB))
                return 0;
        printk(KERN_INFO "Huge page(16GB) memory: "
                        "addr = 0x%lX size = 0x%lX pages = %d\n",
                        phys_addr, block_size, expected_pages);
        if (phys_addr + block_size * expected_pages <= memblock_end_of_DRAM()) {
                memblock_reserve(phys_addr, block_size * expected_pages);
                pseries_add_gpage(phys_addr, block_size, expected_pages);
        }
        return 0;
}
#endif /* CONFIG_HUGETLB_PAGE */

static void mmu_psize_set_default_penc(void)
{
        int bpsize, apsize;
        for (bpsize = 0; bpsize < MMU_PAGE_COUNT; bpsize++)
                for (apsize = 0; apsize < MMU_PAGE_COUNT; apsize++)
                        mmu_psize_defs[bpsize].penc[apsize] = -1;
}

#ifdef CONFIG_PPC_64K_PAGES

static bool might_have_hea(void)
{
        /*
         * The HEA ethernet adapter requires awareness of the
         * GX bus. Without that awareness we can easily assume
         * we will never see an HEA ethernet device.
         */
#ifdef CONFIG_IBMEBUS
        return !cpu_has_feature(CPU_FTR_ARCH_207S) &&
                firmware_has_feature(FW_FEATURE_SPLPAR);
#else
        return false;
#endif
}

#endif /* #ifdef CONFIG_PPC_64K_PAGES */

static void __init htab_scan_page_sizes(void)
{
        int rc;

        /* se the invalid penc to -1 */
        mmu_psize_set_default_penc();

        /* Default to 4K pages only */
        memcpy(mmu_psize_defs, mmu_psize_defaults,
               sizeof(mmu_psize_defaults));

        /*
         * Try to find the available page sizes in the device-tree
         */
        rc = of_scan_flat_dt(htab_dt_scan_page_sizes, NULL);
        if (rc == 0 && early_mmu_has_feature(MMU_FTR_16M_PAGE)) {
                /*
                 * Nothing in the device-tree, but the CPU supports 16M pages,
                 * so let's fallback on a known size list for 16M capable CPUs.
                 */
                memcpy(mmu_psize_defs, mmu_psize_defaults_gp,
                       sizeof(mmu_psize_defaults_gp));
        }

#ifdef CONFIG_HUGETLB_PAGE
        if (!hugetlb_disabled && !early_radix_enabled() ) {
                /* Reserve 16G huge page memory sections for huge pages */
                of_scan_flat_dt(htab_dt_scan_hugepage_blocks, NULL);
        }
#endif /* CONFIG_HUGETLB_PAGE */
}

/*
 * Fill in the hpte_page_sizes[] array.
 * We go through the mmu_psize_defs[] array looking for all the
 * supported base/actual page size combinations.  Each combination
 * has a unique pagesize encoding (penc) value in the low bits of
 * the LP field of the HPTE.  For actual page sizes less than 1MB,
 * some of the upper LP bits are used for RPN bits, meaning that
 * we need to fill in several entries in hpte_page_sizes[].
 *
 * In diagrammatic form, with r = RPN bits and z = page size bits:
 *        PTE LP     actual page size
 *    rrrr rrrz         >=8KB
 *    rrrr rrzz         >=16KB
 *    rrrr rzzz         >=32KB
 *    rrrr zzzz         >=64KB
 *    ...
 *
 * The zzzz bits are implementation-specific but are chosen so that
 * no encoding for a larger page size uses the same value in its
 * low-order N bits as the encoding for the 2^(12+N) byte page size
 * (if it exists).
 */
static void init_hpte_page_sizes(void)
{
        long int ap, bp;
        long int shift, penc;

        for (bp = 0; bp < MMU_PAGE_COUNT; ++bp) {
                if (!mmu_psize_defs[bp].shift)
                        continue;       /* not a supported page size */
                for (ap = bp; ap < MMU_PAGE_COUNT; ++ap) {
                        penc = mmu_psize_defs[bp].penc[ap];
                        if (penc == -1 || !mmu_psize_defs[ap].shift)
                                continue;
                        shift = mmu_psize_defs[ap].shift - LP_SHIFT;
                        if (shift <= 0)
                                continue;       /* should never happen */
                        /*
                         * For page sizes less than 1MB, this loop
                         * replicates the entry for all possible values
                         * of the rrrr bits.
                         */
                        while (penc < (1 << LP_BITS)) {
                                hpte_page_sizes[penc] = (ap << 4) | bp;
                                penc += 1 << shift;
                        }
                }
        }
}

static void __init htab_init_page_sizes(void)
{
        bool aligned = true;
        init_hpte_page_sizes();

        if (!debug_pagealloc_enabled()) {
                /*
                 * Pick a size for the linear mapping. Currently, we only
                 * support 16M, 1M and 4K which is the default
                 */
                if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) &&
                    (unsigned long)_stext % 0x1000000) {
                        if (mmu_psize_defs[MMU_PAGE_16M].shift)
                                pr_warn("Kernel not 16M aligned, disabling 16M linear map alignment\n");
                        aligned = false;
                }

                if (mmu_psize_defs[MMU_PAGE_16M].shift && aligned)
                        mmu_linear_psize = MMU_PAGE_16M;
                else if (mmu_psize_defs[MMU_PAGE_1M].shift)
                        mmu_linear_psize = MMU_PAGE_1M;
        }

#ifdef CONFIG_PPC_64K_PAGES
        /*
         * Pick a size for the ordinary pages. Default is 4K, we support
         * 64K for user mappings and vmalloc if supported by the processor.
         * We only use 64k for ioremap if the processor
         * (and firmware) support cache-inhibited large pages.
         * If not, we use 4k and set mmu_ci_restrictions so that
         * hash_page knows to switch processes that use cache-inhibited
         * mappings to 4k pages.
         */
        if (mmu_psize_defs[MMU_PAGE_64K].shift) {
                mmu_virtual_psize = MMU_PAGE_64K;
                mmu_vmalloc_psize = MMU_PAGE_64K;
                if (mmu_linear_psize == MMU_PAGE_4K)
                        mmu_linear_psize = MMU_PAGE_64K;
                if (mmu_has_feature(MMU_FTR_CI_LARGE_PAGE)) {
                        /*
                         * When running on pSeries using 64k pages for ioremap
                         * would stop us accessing the HEA ethernet. So if we
                         * have the chance of ever seeing one, stay at 4k.
                         */
                        if (!might_have_hea())
                                mmu_io_psize = MMU_PAGE_64K;
                } else
                        mmu_ci_restrictions = 1;
        }
#endif /* CONFIG_PPC_64K_PAGES */

#ifdef CONFIG_SPARSEMEM_VMEMMAP
        /*
         * We try to use 16M pages for vmemmap if that is supported
         * and we have at least 1G of RAM at boot
         */
        if (mmu_psize_defs[MMU_PAGE_16M].shift &&
            memblock_phys_mem_size() >= 0x40000000)
                mmu_vmemmap_psize = MMU_PAGE_16M;
        else
                mmu_vmemmap_psize = mmu_virtual_psize;
#endif /* CONFIG_SPARSEMEM_VMEMMAP */

        printk(KERN_DEBUG "Page orders: linear mapping = %d, "
               "virtual = %d, io = %d"
#ifdef CONFIG_SPARSEMEM_VMEMMAP
               ", vmemmap = %d"
#endif
               "\n",
               mmu_psize_defs[mmu_linear_psize].shift,
               mmu_psize_defs[mmu_virtual_psize].shift,
               mmu_psize_defs[mmu_io_psize].shift
#ifdef CONFIG_SPARSEMEM_VMEMMAP
               ,mmu_psize_defs[mmu_vmemmap_psize].shift
#endif
               );
}

static int __init htab_dt_scan_pftsize(unsigned long node,
                                       const char *uname, int depth,
                                       void *data)
{
        const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
        const __be32 *prop;

        /* We are scanning "cpu" nodes only */
        if (type == NULL || strcmp(type, "cpu") != 0)
                return 0;

        prop = of_get_flat_dt_prop(node, "ibm,pft-size", NULL);
        if (prop != NULL) {
                /* pft_size[0] is the NUMA CEC cookie */
                ppc64_pft_size = be32_to_cpu(prop[1]);
                return 1;
        }
        return 0;
}

unsigned htab_shift_for_mem_size(unsigned long mem_size)
{
        unsigned memshift = __ilog2(mem_size);
        unsigned pshift = mmu_psize_defs[mmu_virtual_psize].shift;
        unsigned pteg_shift;

        /* round mem_size up to next power of 2 */
        if ((1UL << memshift) < mem_size)
                memshift += 1;

        /* aim for 2 pages / pteg */
        pteg_shift = memshift - (pshift + 1);

        /*
         * 2^11 PTEGS of 128 bytes each, ie. 2^18 bytes is the minimum htab
         * size permitted by the architecture.
         */
        return max(pteg_shift + 7, 18U);
}

static unsigned long __init htab_get_table_size(void)
{
        /*
         * If hash size isn't already provided by the platform, we try to
         * retrieve it from the device-tree. If it's not there neither, we
         * calculate it now based on the total RAM size
         */
        if (ppc64_pft_size == 0)
                of_scan_flat_dt(htab_dt_scan_pftsize, NULL);
        if (ppc64_pft_size)
                return 1UL << ppc64_pft_size;

        return 1UL << htab_shift_for_mem_size(memblock_phys_mem_size());
}

#ifdef CONFIG_MEMORY_HOTPLUG
static int resize_hpt_for_hotplug(unsigned long new_mem_size)
{
        unsigned target_hpt_shift;

        if (!mmu_hash_ops.resize_hpt)
                return 0;

        target_hpt_shift = htab_shift_for_mem_size(new_mem_size);

        /*
         * To avoid lots of HPT resizes if memory size is fluctuating
         * across a boundary, we deliberately have some hysterisis
         * here: we immediately increase the HPT size if the target
         * shift exceeds the current shift, but we won't attempt to
         * reduce unless the target shift is at least 2 below the
         * current shift
         */
        if (target_hpt_shift > ppc64_pft_size ||
            target_hpt_shift < ppc64_pft_size - 1)
                return mmu_hash_ops.resize_hpt(target_hpt_shift);

        return 0;
}

int hash__create_section_mapping(unsigned long start, unsigned long end,
                                 int nid, pgprot_t prot)
{
        int rc;

        if (end >= H_VMALLOC_START) {
                pr_warn("Outside the supported range\n");
                return -1;
        }

        resize_hpt_for_hotplug(memblock_phys_mem_size());

        rc = htab_bolt_mapping(start, end, __pa(start),
                               pgprot_val(prot), mmu_linear_psize,
                               mmu_kernel_ssize);

        if (rc < 0) {
                int rc2 = htab_remove_mapping(start, end, mmu_linear_psize,
                                              mmu_kernel_ssize);
                BUG_ON(rc2 && (rc2 != -ENOENT));
        }
        return rc;
}

int hash__remove_section_mapping(unsigned long start, unsigned long end)
{
        int rc = htab_remove_mapping(start, end, mmu_linear_psize,
                                     mmu_kernel_ssize);

        if (resize_hpt_for_hotplug(memblock_phys_mem_size()) == -ENOSPC)
                pr_warn("Hash collision while resizing HPT\n");

        return rc;
}
#endif /* CONFIG_MEMORY_HOTPLUG */

static void __init hash_init_partition_table(phys_addr_t hash_table,
                                             unsigned long htab_size)
{
        mmu_partition_table_init();

        /*
         * PS field (VRMA page size) is not used for LPID 0, hence set to 0.
         * For now, UPRT is 0 and we have no segment table.
         */
        htab_size =  __ilog2(htab_size) - 18;
        mmu_partition_table_set_entry(0, hash_table | htab_size, 0, false);
        pr_info("Partition table %p\n", partition_tb);
}

static void __init htab_initialize(void)
{
        unsigned long table;
        unsigned long pteg_count;
        unsigned long prot;
        phys_addr_t base = 0, size = 0, end;
        u64 i;

        DBG(" -> htab_initialize()\n");

        if (mmu_has_feature(MMU_FTR_1T_SEGMENT)) {
                mmu_kernel_ssize = MMU_SEGSIZE_1T;
                mmu_highuser_ssize = MMU_SEGSIZE_1T;
                printk(KERN_INFO "Using 1TB segments\n");
        }

        if (stress_slb_enabled)
                static_branch_enable(&stress_slb_key);

        /*
         * Calculate the required size of the htab.  We want the number of
         * PTEGs to equal one half the number of real pages.
         */
        htab_size_bytes = htab_get_table_size();
        pteg_count = htab_size_bytes >> 7;

        htab_hash_mask = pteg_count - 1;

        if (firmware_has_feature(FW_FEATURE_LPAR) ||
            firmware_has_feature(FW_FEATURE_PS3_LV1)) {
                /* Using a hypervisor which owns the htab */
                htab_address = NULL;
                _SDR1 = 0;
#ifdef CONFIG_FA_DUMP
                /*
                 * If firmware assisted dump is active firmware preserves
                 * the contents of htab along with entire partition memory.
                 * Clear the htab if firmware assisted dump is active so
                 * that we dont end up using old mappings.
                 */
                if (is_fadump_active() && mmu_hash_ops.hpte_clear_all)
                        mmu_hash_ops.hpte_clear_all();
#endif
        } else {
                unsigned long limit = MEMBLOCK_ALLOC_ANYWHERE;

#ifdef CONFIG_PPC_CELL
                /*
                 * Cell may require the hash table down low when using the
                 * Axon IOMMU in order to fit the dynamic region over it, see
                 * comments in cell/iommu.c
                 */
                if (fdt_subnode_offset(initial_boot_params, 0, "axon") > 0) {
                        limit = 0x80000000;
                        pr_info("Hash table forced below 2G for Axon IOMMU\n");
                }
#endif /* CONFIG_PPC_CELL */

                table = memblock_phys_alloc_range(htab_size_bytes,
                                                  htab_size_bytes,
                                                  0, limit);
                if (!table)
                        panic("ERROR: Failed to allocate %pa bytes below %pa\n",
                              &htab_size_bytes, &limit);

                DBG("Hash table allocated at %lx, size: %lx\n", table,
                    htab_size_bytes);

                htab_address = __va(table);

                /* htab absolute addr + encoded htabsize */
                _SDR1 = table + __ilog2(htab_size_bytes) - 18;

                /* Initialize the HPT with no entries */
                memset((void *)table, 0, htab_size_bytes);

                if (!cpu_has_feature(CPU_FTR_ARCH_300))
                        /* Set SDR1 */
                        mtspr(SPRN_SDR1, _SDR1);
                else
                        hash_init_partition_table(table, htab_size_bytes);
        }

        prot = pgprot_val(PAGE_KERNEL);

#ifdef CONFIG_DEBUG_PAGEALLOC
        if (debug_pagealloc_enabled()) {
                linear_map_hash_count = memblock_end_of_DRAM() >> PAGE_SHIFT;
                linear_map_hash_slots = memblock_alloc_try_nid(
                                linear_map_hash_count, 1, MEMBLOCK_LOW_LIMIT,
                                ppc64_rma_size, NUMA_NO_NODE);
                if (!linear_map_hash_slots)
                        panic("%s: Failed to allocate %lu bytes max_addr=%pa\n",
                              __func__, linear_map_hash_count, &ppc64_rma_size);
        }
#endif /* CONFIG_DEBUG_PAGEALLOC */

        /* create bolted the linear mapping in the hash table */
        for_each_mem_range(i, &base, &end) {
                size = end - base;
                base = (unsigned long)__va(base);

                DBG("creating mapping for region: %lx..%lx (prot: %lx)\n",
                    base, size, prot);

                if ((base + size) >= H_VMALLOC_START) {
                        pr_warn("Outside the supported range\n");
                        continue;
                }

                BUG_ON(htab_bolt_mapping(base, base + size, __pa(base),
                                prot, mmu_linear_psize, mmu_kernel_ssize));
        }
        memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);

        /*
         * If we have a memory_limit and we've allocated TCEs then we need to
         * explicitly map the TCE area at the top of RAM. We also cope with the
         * case that the TCEs start below memory_limit.
         * tce_alloc_start/end are 16MB aligned so the mapping should work
         * for either 4K or 16MB pages.
         */
        if (tce_alloc_start) {
                tce_alloc_start = (unsigned long)__va(tce_alloc_start);
                tce_alloc_end = (unsigned long)__va(tce_alloc_end);

                if (base + size >= tce_alloc_start)
                        tce_alloc_start = base + size + 1;

                BUG_ON(htab_bolt_mapping(tce_alloc_start, tce_alloc_end,
                                         __pa(tce_alloc_start), prot,
                                         mmu_linear_psize, mmu_kernel_ssize));
        }


        DBG(" <- htab_initialize()\n");
}
#undef KB
#undef MB

void __init hash__early_init_devtree(void)
{
        /* Initialize segment sizes */
        of_scan_flat_dt(htab_dt_scan_seg_sizes, NULL);

        /* Initialize page sizes */
        htab_scan_page_sizes();
}

static struct hash_mm_context init_hash_mm_context;
void __init hash__early_init_mmu(void)
{
#ifndef CONFIG_PPC_64K_PAGES
        /*
         * We have code in __hash_page_4K() and elsewhere, which assumes it can
         * do the following:
         *   new_pte |= (slot << H_PAGE_F_GIX_SHIFT) & (H_PAGE_F_SECOND | H_PAGE_F_GIX);
         *
         * Where the slot number is between 0-15, and values of 8-15 indicate
         * the secondary bucket. For that code to work H_PAGE_F_SECOND and
         * H_PAGE_F_GIX must occupy four contiguous bits in the PTE, and
         * H_PAGE_F_SECOND must be placed above H_PAGE_F_GIX. Assert that here
         * with a BUILD_BUG_ON().
         */
        BUILD_BUG_ON(H_PAGE_F_SECOND != (1ul  << (H_PAGE_F_GIX_SHIFT + 3)));
#endif /* CONFIG_PPC_64K_PAGES */

        htab_init_page_sizes();

        /*
         * initialize page table size
         */
        __pte_frag_nr = H_PTE_FRAG_NR;
        __pte_frag_size_shift = H_PTE_FRAG_SIZE_SHIFT;
        __pmd_frag_nr = H_PMD_FRAG_NR;
        __pmd_frag_size_shift = H_PMD_FRAG_SIZE_SHIFT;

        __pte_index_size = H_PTE_INDEX_SIZE;
        __pmd_index_size = H_PMD_INDEX_SIZE;
        __pud_index_size = H_PUD_INDEX_SIZE;
        __pgd_index_size = H_PGD_INDEX_SIZE;
        __pud_cache_index = H_PUD_CACHE_INDEX;
        __pte_table_size = H_PTE_TABLE_SIZE;
        __pmd_table_size = H_PMD_TABLE_SIZE;
        __pud_table_size = H_PUD_TABLE_SIZE;
        __pgd_table_size = H_PGD_TABLE_SIZE;
        /*
         * 4k use hugepd format, so for hash set then to
         * zero
         */
        __pmd_val_bits = HASH_PMD_VAL_BITS;
        __pud_val_bits = HASH_PUD_VAL_BITS;
        __pgd_val_bits = HASH_PGD_VAL_BITS;

        __kernel_virt_start = H_KERN_VIRT_START;
        __vmalloc_start = H_VMALLOC_START;
        __vmalloc_end = H_VMALLOC_END;
        __kernel_io_start = H_KERN_IO_START;
        __kernel_io_end = H_KERN_IO_END;
        vmemmap = (struct page *)H_VMEMMAP_START;
        ioremap_bot = IOREMAP_BASE;

#ifdef CONFIG_PCI
        pci_io_base = ISA_IO_BASE;
#endif

        /* Select appropriate backend */
        if (firmware_has_feature(FW_FEATURE_PS3_LV1))
                ps3_early_mm_init();
        else if (firmware_has_feature(FW_FEATURE_LPAR))
                hpte_init_pseries();
        else if (IS_ENABLED(CONFIG_PPC_NATIVE))
                hpte_init_native();

        if (!mmu_hash_ops.hpte_insert)
                panic("hash__early_init_mmu: No MMU hash ops defined!\n");

        /*
         * Initialize the MMU Hash table and create the linear mapping
         * of memory. Has to be done before SLB initialization as this is
         * currently where the page size encoding is obtained.
         */
        htab_initialize();

        init_mm.context.hash_context = &init_hash_mm_context;
        mm_ctx_set_slb_addr_limit(&init_mm.context, SLB_ADDR_LIMIT_DEFAULT);

        pr_info("Initializing hash mmu with SLB\n");
        /* Initialize SLB management */
        slb_initialize();

        if (cpu_has_feature(CPU_FTR_ARCH_206)
                        && cpu_has_feature(CPU_FTR_HVMODE))
                tlbiel_all();
}

#ifdef CONFIG_SMP
void hash__early_init_mmu_secondary(void)
{
        /* Initialize hash table for that CPU */
        if (!firmware_has_feature(FW_FEATURE_LPAR)) {

                if (!cpu_has_feature(CPU_FTR_ARCH_300))
                        mtspr(SPRN_SDR1, _SDR1);
                else
                        set_ptcr_when_no_uv(__pa(partition_tb) |
                                            (PATB_SIZE_SHIFT - 12));
        }
        /* Initialize SLB */
        slb_initialize();

        if (cpu_has_feature(CPU_FTR_ARCH_206)
                        && cpu_has_feature(CPU_FTR_HVMODE))
                tlbiel_all();

#ifdef CONFIG_PPC_MEM_KEYS
        if (mmu_has_feature(MMU_FTR_PKEY))
                mtspr(SPRN_UAMOR, default_uamor);
#endif
}
#endif /* CONFIG_SMP */

/*
 * Called by asm hashtable.S for doing lazy icache flush
 */
unsigned int hash_page_do_lazy_icache(unsigned int pp, pte_t pte, int trap)
{
        struct page *page;

        if (!pfn_valid(pte_pfn(pte)))
                return pp;

        page = pte_page(pte);

        /* page is dirty */
        if (!test_bit(PG_arch_1, &page->flags) && !PageReserved(page)) {
                if (trap == 0x400) {
                        flush_dcache_icache_page(page);
                        set_bit(PG_arch_1, &page->flags);
                } else
                        pp |= HPTE_R_N;
        }
        return pp;
}

#ifdef CONFIG_PPC_MM_SLICES
static unsigned int get_paca_psize(unsigned long addr)
{
        unsigned char *psizes;
        unsigned long index, mask_index;

        if (addr < SLICE_LOW_TOP) {
                psizes = get_paca()->mm_ctx_low_slices_psize;
                index = GET_LOW_SLICE_INDEX(addr);
        } else {
                psizes = get_paca()->mm_ctx_high_slices_psize;
                index = GET_HIGH_SLICE_INDEX(addr);
        }
        mask_index = index & 0x1;
        return (psizes[index >> 1] >> (mask_index * 4)) & 0xF;
}

#else
unsigned int get_paca_psize(unsigned long addr)
{
        return get_paca()->mm_ctx_user_psize;
}
#endif

/*
 * Demote a segment to using 4k pages.
 * For now this makes the whole process use 4k pages.
 */
#ifdef CONFIG_PPC_64K_PAGES
void demote_segment_4k(struct mm_struct *mm, unsigned long addr)
{
        if (get_slice_psize(mm, addr) == MMU_PAGE_4K)
                return;
        slice_set_range_psize(mm, addr, 1, MMU_PAGE_4K);
        copro_flush_all_slbs(mm);
        if ((get_paca_psize(addr) != MMU_PAGE_4K) && (current->mm == mm)) {

                copy_mm_to_paca(mm);
                slb_flush_and_restore_bolted();
        }
}
#endif /* CONFIG_PPC_64K_PAGES */

#ifdef CONFIG_PPC_SUBPAGE_PROT
/*
 * This looks up a 2-bit protection code for a 4k subpage of a 64k page.
 * Userspace sets the subpage permissions using the subpage_prot system call.
 *
 * Result is 0: full permissions, _PAGE_RW: read-only,
 * _PAGE_RWX: no access.
 */
static int subpage_protection(struct mm_struct *mm, unsigned long ea)
{
        struct subpage_prot_table *spt = mm_ctx_subpage_prot(&mm->context);
        u32 spp = 0;
        u32 **sbpm, *sbpp;

        if (!spt)
                return 0;

        if (ea >= spt->maxaddr)
                return 0;
        if (ea < 0x100000000UL) {
                /* addresses below 4GB use spt->low_prot */
                sbpm = spt->low_prot;
        } else {
                sbpm = spt->protptrs[ea >> SBP_L3_SHIFT];
                if (!sbpm)
                        return 0;
        }
        sbpp = sbpm[(ea >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)];
        if (!sbpp)
                return 0;
        spp = sbpp[(ea >> PAGE_SHIFT) & (SBP_L1_COUNT - 1)];

        /* extract 2-bit bitfield for this 4k subpage */
        spp >>= 30 - 2 * ((ea >> 12) & 0xf);

        /*
         * 0 -> full premission
         * 1 -> Read only
         * 2 -> no access.
         * We return the flag that need to be cleared.
         */
        spp = ((spp & 2) ? _PAGE_RWX : 0) | ((spp & 1) ? _PAGE_WRITE : 0);
        return spp;
}

#else /* CONFIG_PPC_SUBPAGE_PROT */
static inline int subpage_protection(struct mm_struct *mm, unsigned long ea)
{
        return 0;
}
#endif

void hash_failure_debug(unsigned long ea, unsigned long access,
                        unsigned long vsid, unsigned long trap,
                        int ssize, int psize, int lpsize, unsigned long pte)
{
        if (!printk_ratelimit())
                return;
        pr_info("mm: Hashing failure ! EA=0x%lx access=0x%lx current=%s\n",
                ea, access, current->comm);
        pr_info("    trap=0x%lx vsid=0x%lx ssize=%d base psize=%d psize %d pte=0x%lx\n",
                trap, vsid, ssize, psize, lpsize, pte);
}

static void check_paca_psize(unsigned long ea, struct mm_struct *mm,
                             int psize, bool user_region)
{
        if (user_region) {
                if (psize != get_paca_psize(ea)) {
                        copy_mm_to_paca(mm);
                        slb_flush_and_restore_bolted();
                }
        } else if (get_paca()->vmalloc_sllp !=
                   mmu_psize_defs[mmu_vmalloc_psize].sllp) {
                get_paca()->vmalloc_sllp =
                        mmu_psize_defs[mmu_vmalloc_psize].sllp;
                slb_vmalloc_update();
        }
}

/*
 * Result code is:
 *  0 - handled
 *  1 - normal page fault
 * -1 - critical hash insertion error
 * -2 - access not permitted by subpage protection mechanism
 */
int hash_page_mm(struct mm_struct *mm, unsigned long ea,
                 unsigned long access, unsigned long trap,
                 unsigned long flags)
{
        bool is_thp;
        enum ctx_state prev_state = exception_enter();
        pgd_t *pgdir;
        unsigned long vsid;
        pte_t *ptep;
        unsigned hugeshift;
        int rc, user_region = 0;
        int psize, ssize;

        DBG_LOW("hash_page(ea=%016lx, access=%lx, trap=%lx\n",
                ea, access, trap);
        trace_hash_fault(ea, access, trap);

        /* Get region & vsid */
        switch (get_region_id(ea)) {
        case USER_REGION_ID:
                user_region = 1;
                if (! mm) {
                        DBG_LOW(" user region with no mm !\n");
                        rc = 1;
                        goto bail;
                }
                psize = get_slice_psize(mm, ea);
                ssize = user_segment_size(ea);
                vsid = get_user_vsid(&mm->context, ea, ssize);
                break;
        case VMALLOC_REGION_ID:
                vsid = get_kernel_vsid(ea, mmu_kernel_ssize);
                psize = mmu_vmalloc_psize;
                ssize = mmu_kernel_ssize;
                flags |= HPTE_USE_KERNEL_KEY;
                break;

        case IO_REGION_ID:
                vsid = get_kernel_vsid(ea, mmu_kernel_ssize);
                psize = mmu_io_psize;
                ssize = mmu_kernel_ssize;
                flags |= HPTE_USE_KERNEL_KEY;
                break;
        default:
                /*
                 * Not a valid range
                 * Send the problem up to do_page_fault()
                 */
                rc = 1;
                goto bail;
        }
        DBG_LOW(" mm=%p, mm->pgdir=%p, vsid=%016lx\n", mm, mm->pgd, vsid);

        /* Bad address. */
        if (!vsid) {
                DBG_LOW("Bad address!\n");
                rc = 1;
                goto bail;
        }
        /* Get pgdir */
        pgdir = mm->pgd;
        if (pgdir == NULL) {
                rc = 1;
                goto bail;
        }

        /* Check CPU locality */
        if (user_region && mm_is_thread_local(mm))
                flags |= HPTE_LOCAL_UPDATE;

#ifndef CONFIG_PPC_64K_PAGES
        /*
         * If we use 4K pages and our psize is not 4K, then we might
         * be hitting a special driver mapping, and need to align the
         * address before we fetch the PTE.
         *
         * It could also be a hugepage mapping, in which case this is
         * not necessary, but it's not harmful, either.
         */
        if (psize != MMU_PAGE_4K)
                ea &= ~((1ul << mmu_psize_defs[psize].shift) - 1);
#endif /* CONFIG_PPC_64K_PAGES */

        /* Get PTE and page size from page tables */
        ptep = find_linux_pte(pgdir, ea, &is_thp, &hugeshift);
        if (ptep == NULL || !pte_present(*ptep)) {
                DBG_LOW(" no PTE !\n");
                rc = 1;
                goto bail;
        }

        /*
         * Add _PAGE_PRESENT to the required access perm. If there are parallel
         * updates to the pte that can possibly clear _PAGE_PTE, catch that too.
         *
         * We can safely use the return pte address in rest of the function
         * because we do set H_PAGE_BUSY which prevents further updates to pte
         * from generic code.
         */
        access |= _PAGE_PRESENT | _PAGE_PTE;

        /*
         * Pre-check access permissions (will be re-checked atomically
         * in __hash_page_XX but this pre-check is a fast path
         */
        if (!check_pte_access(access, pte_val(*ptep))) {
                DBG_LOW(" no access !\n");
                rc = 1;
                goto bail;
        }

        if (hugeshift) {
                if (is_thp)
                        rc = __hash_page_thp(ea, access, vsid, (pmd_t *)ptep,
                                             trap, flags, ssize, psize);
#ifdef CONFIG_HUGETLB_PAGE
                else
                        rc = __hash_page_huge(ea, access, vsid, ptep, trap,
                                              flags, ssize, hugeshift, psize);
#else
                else {
                        /*
                         * if we have hugeshift, and is not transhuge with
                         * hugetlb disabled, something is really wrong.
                         */
                        rc = 1;
                        WARN_ON(1);
                }
#endif
                if (current->mm == mm)
                        check_paca_psize(ea, mm, psize, user_region);

                goto bail;
        }

#ifndef CONFIG_PPC_64K_PAGES
        DBG_LOW(" i-pte: %016lx\n", pte_val(*ptep));
#else
        DBG_LOW(" i-pte: %016lx %016lx\n", pte_val(*ptep),
                pte_val(*(ptep + PTRS_PER_PTE)));
#endif
        /* Do actual hashing */
#ifdef CONFIG_PPC_64K_PAGES
        /* If H_PAGE_4K_PFN is set, make sure this is a 4k segment */
        if ((pte_val(*ptep) & H_PAGE_4K_PFN) && psize == MMU_PAGE_64K) {
                demote_segment_4k(mm, ea);
                psize = MMU_PAGE_4K;
        }

        /*
         * If this PTE is non-cacheable and we have restrictions on
         * using non cacheable large pages, then we switch to 4k
         */
        if (mmu_ci_restrictions && psize == MMU_PAGE_64K && pte_ci(*ptep)) {
                if (user_region) {
                        demote_segment_4k(mm, ea);
                        psize = MMU_PAGE_4K;
                } else if (ea < VMALLOC_END) {
                        /*
                         * some driver did a non-cacheable mapping
                         * in vmalloc space, so switch vmalloc
                         * to 4k pages
                         */
                        printk(KERN_ALERT "Reducing vmalloc segment "
                               "to 4kB pages because of "
                               "non-cacheable mapping\n");
                        psize = mmu_vmalloc_psize = MMU_PAGE_4K;
                        copro_flush_all_slbs(mm);
                }
        }

#endif /* CONFIG_PPC_64K_PAGES */

        if (current->mm == mm)
                check_paca_psize(ea, mm, psize, user_region);

#ifdef CONFIG_PPC_64K_PAGES
        if (psize == MMU_PAGE_64K)
                rc = __hash_page_64K(ea, access, vsid, ptep, trap,
                                     flags, ssize);
        else
#endif /* CONFIG_PPC_64K_PAGES */
        {
                int spp = subpage_protection(mm, ea);
                if (access & spp)
                        rc = -2;
                else
                        rc = __hash_page_4K(ea, access, vsid, ptep, trap,
                                            flags, ssize, spp);
        }

        /*
         * Dump some info in case of hash insertion failure, they should
         * never happen so it is really useful to know if/when they do
         */
        if (rc == -1)
                hash_failure_debug(ea, access, vsid, trap, ssize, psize,
                                   psize, pte_val(*ptep));
#ifndef CONFIG_PPC_64K_PAGES
        DBG_LOW(" o-pte: %016lx\n", pte_val(*ptep));
#else
        DBG_LOW(" o-pte: %016lx %016lx\n", pte_val(*ptep),
                pte_val(*(ptep + PTRS_PER_PTE)));
#endif
        DBG_LOW(" -> rc=%d\n", rc);

bail:
        exception_exit(prev_state);
        return rc;
}
EXPORT_SYMBOL_GPL(hash_page_mm);

int hash_page(unsigned long ea, unsigned long access, unsigned long trap,
              unsigned long dsisr)
{
        unsigned long flags = 0;
        struct mm_struct *mm = current->mm;

        if ((get_region_id(ea) == VMALLOC_REGION_ID) ||
            (get_region_id(ea) == IO_REGION_ID))
                mm = &init_mm;

        if (dsisr & DSISR_NOHPTE)
                flags |= HPTE_NOHPTE_UPDATE;

        return hash_page_mm(mm, ea, access, trap, flags);
}
EXPORT_SYMBOL_GPL(hash_page);

int __hash_page(unsigned long trap, unsigned long ea, unsigned long dsisr,
                unsigned long msr)
{
        unsigned long access = _PAGE_PRESENT | _PAGE_READ;
        unsigned long flags = 0;
        struct mm_struct *mm = current->mm;
        unsigned int region_id = get_region_id(ea);

        if ((region_id == VMALLOC_REGION_ID) || (region_id == IO_REGION_ID))
                mm = &init_mm;

        if (dsisr & DSISR_NOHPTE)
                flags |= HPTE_NOHPTE_UPDATE;

        if (dsisr & DSISR_ISSTORE)
                access |= _PAGE_WRITE;
        /*
         * We set _PAGE_PRIVILEGED only when
         * kernel mode access kernel space.
         *
         * _PAGE_PRIVILEGED is NOT set
         * 1) when kernel mode access user space
         * 2) user space access kernel space.
         */
        access |= _PAGE_PRIVILEGED;
        if ((msr & MSR_PR) || (region_id == USER_REGION_ID))
                access &= ~_PAGE_PRIVILEGED;

        if (trap == 0x400)
                access |= _PAGE_EXEC;

        return hash_page_mm(mm, ea, access, trap, flags);
}

#ifdef CONFIG_PPC_MM_SLICES
static bool should_hash_preload(struct mm_struct *mm, unsigned long ea)
{
        int psize = get_slice_psize(mm, ea);

        /* We only prefault standard pages for now */
        if (unlikely(psize != mm_ctx_user_psize(&mm->context)))
                return false;

        /*
         * Don't prefault if subpage protection is enabled for the EA.
         */
        if (unlikely((psize == MMU_PAGE_4K) && subpage_protection(mm, ea)))
                return false;

        return true;
}
#else
static bool should_hash_preload(struct mm_struct *mm, unsigned long ea)
{
        return true;
}
#endif

static void hash_preload(struct mm_struct *mm, pte_t *ptep, unsigned long ea,
                         bool is_exec, unsigned long trap)
{
        unsigned long vsid;
        pgd_t *pgdir;
        int rc, ssize, update_flags = 0;
        unsigned long access = _PAGE_PRESENT | _PAGE_READ | (is_exec ? _PAGE_EXEC : 0);
        unsigned long flags;

        BUG_ON(get_region_id(ea) != USER_REGION_ID);

        if (!should_hash_preload(mm, ea))
                return;

        DBG_LOW("hash_preload(mm=%p, mm->pgdir=%p, ea=%016lx, access=%lx,"
                " trap=%lx\n", mm, mm->pgd, ea, access, trap);

        /* Get Linux PTE if available */
        pgdir = mm->pgd;
        if (pgdir == NULL)
                return;

        /* Get VSID */
        ssize = user_segment_size(ea);
        vsid = get_user_vsid(&mm->context, ea, ssize);
        if (!vsid)
                return;

#ifdef CONFIG_PPC_64K_PAGES
        /* If either H_PAGE_4K_PFN or cache inhibited is set (and we are on
         * a 64K kernel), then we don't preload, hash_page() will take
         * care of it once we actually try to access the page.
         * That way we don't have to duplicate all of the logic for segment
         * page size demotion here
         * Called with  PTL held, hence can be sure the value won't change in
         * between.
         */
        if ((pte_val(*ptep) & H_PAGE_4K_PFN) || pte_ci(*ptep))
                return;
#endif /* CONFIG_PPC_64K_PAGES */

        /*
         * __hash_page_* must run with interrupts off, as it sets the
         * H_PAGE_BUSY bit. It's possible for perf interrupts to hit at any
         * time and may take a hash fault reading the user stack, see
         * read_user_stack_slow() in the powerpc/perf code.
         *
         * If that takes a hash fault on the same page as we lock here, it
         * will bail out when seeing H_PAGE_BUSY set, and retry the access
         * leading to an infinite loop.
         *
         * Disabling interrupts here does not prevent perf interrupts, but it
         * will prevent them taking hash faults (see the NMI test in
         * do_hash_page), then read_user_stack's copy_from_user_nofault will
         * fail and perf will fall back to read_user_stack_slow(), which
         * walks the Linux page tables.
         *
         * Interrupts must also be off for the duration of the
         * mm_is_thread_local test and update, to prevent preempt running the
         * mm on another CPU (XXX: this may be racy vs kthread_use_mm).
         */
        local_irq_save(flags);

        /* Is that local to this CPU ? */
        if (mm_is_thread_local(mm))
                update_flags |= HPTE_LOCAL_UPDATE;

        /* Hash it in */
#ifdef CONFIG_PPC_64K_PAGES
        if (mm_ctx_user_psize(&mm->context) == MMU_PAGE_64K)
                rc = __hash_page_64K(ea, access, vsid, ptep, trap,
                                     update_flags, ssize);
        else
#endif /* CONFIG_PPC_64K_PAGES */
                rc = __hash_page_4K(ea, access, vsid, ptep, trap, update_flags,
                                    ssize, subpage_protection(mm, ea));

        /* Dump some info in case of hash insertion failure, they should
         * never happen so it is really useful to know if/when they do
         */
        if (rc == -1)
                hash_failure_debug(ea, access, vsid, trap, ssize,
                                   mm_ctx_user_psize(&mm->context),
                                   mm_ctx_user_psize(&mm->context),
                                   pte_val(*ptep));

        local_irq_restore(flags);
}

/*
 * This is called at the end of handling a user page fault, when the
 * fault has been handled by updating a PTE in the linux page tables.
 * We use it to preload an HPTE into the hash table corresponding to
 * the updated linux PTE.
 *
 * This must always be called with the pte lock held.
 */
void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
                      pte_t *ptep)
{
        /*
         * We don't need to worry about _PAGE_PRESENT here because we are
         * called with either mm->page_table_lock held or ptl lock held
         */
        unsigned long trap;
        bool is_exec;

        if (radix_enabled())
                return;

        /* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
        if (!pte_young(*ptep) || address >= TASK_SIZE)
                return;

        /*
         * We try to figure out if we are coming from an instruction
         * access fault and pass that down to __hash_page so we avoid
         * double-faulting on execution of fresh text. We have to test
         * for regs NULL since init will get here first thing at boot.
         *
         * We also avoid filling the hash if not coming from a fault.
         */

        trap = current->thread.regs ? TRAP(current->thread.regs) : 0UL;
        switch (trap) {
        case 0x300:
                is_exec = false;
                break;
        case 0x400:
                is_exec = true;
                break;
        default:
                return;
        }

        hash_preload(vma->vm_mm, ptep, address, is_exec, trap);
}

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
static inline void tm_flush_hash_page(int local)
{
        /*
         * Transactions are not aborted by tlbiel, only tlbie. Without, syncing a
         * page back to a block device w/PIO could pick up transactional data
         * (bad!) so we force an abort here. Before the sync the page will be
         * made read-only, which will flush_hash_page. BIG ISSUE here: if the
         * kernel uses a page from userspace without unmapping it first, it may
         * see the speculated version.
         */
        if (local && cpu_has_feature(CPU_FTR_TM) && current->thread.regs &&
            MSR_TM_ACTIVE(current->thread.regs->msr)) {
                tm_enable();
                tm_abort(TM_CAUSE_TLBI);
        }
}
#else
static inline void tm_flush_hash_page(int local)
{
}
#endif

/*
 * Return the global hash slot, corresponding to the given PTE, which contains
 * the HPTE.
 */
unsigned long pte_get_hash_gslot(unsigned long vpn, unsigned long shift,
                int ssize, real_pte_t rpte, unsigned int subpg_index)
{
        unsigned long hash, gslot, hidx;

        hash = hpt_hash(vpn, shift, ssize);
        hidx = __rpte_to_hidx(rpte, subpg_index);
        if (hidx & _PTEIDX_SECONDARY)
                hash = ~hash;
        gslot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
        gslot += hidx & _PTEIDX_GROUP_IX;
        return gslot;
}

void flush_hash_page(unsigned long vpn, real_pte_t pte, int psize, int ssize,
                     unsigned long flags)
{
        unsigned long index, shift, gslot;
        int local = flags & HPTE_LOCAL_UPDATE;

        DBG_LOW("flush_hash_page(vpn=%016lx)\n", vpn);
        pte_iterate_hashed_subpages(pte, psize, vpn, index, shift) {
                gslot = pte_get_hash_gslot(vpn, shift, ssize, pte, index);
                DBG_LOW(" sub %ld: gslot=%lx\n", index, gslot);
                /*
                 * We use same base page size and actual psize, because we don't
                 * use these functions for hugepage
                 */
                mmu_hash_ops.hpte_invalidate(gslot, vpn, psize, psize,
                                             ssize, local);
        } pte_iterate_hashed_end();

        tm_flush_hash_page(local);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void flush_hash_hugepage(unsigned long vsid, unsigned long addr,
                         pmd_t *pmdp, unsigned int psize, int ssize,
                         unsigned long flags)
{
        int i, max_hpte_count, valid;
        unsigned long s_addr;
        unsigned char *hpte_slot_array;
        unsigned long hidx, shift, vpn, hash, slot;
        int local = flags & HPTE_LOCAL_UPDATE;

        s_addr = addr & HPAGE_PMD_MASK;
        hpte_slot_array = get_hpte_slot_array(pmdp);
        /*
         * IF we try to do a HUGE PTE update after a withdraw is done.
         * we will find the below NULL. This happens when we do
         * split_huge_pmd
         */
        if (!hpte_slot_array)
                return;

        if (mmu_hash_ops.hugepage_invalidate) {
                mmu_hash_ops.hugepage_invalidate(vsid, s_addr, hpte_slot_array,
                                                 psize, ssize, local);
                goto tm_abort;
        }
        /*
         * No bluk hpte removal support, invalidate each entry
         */
        shift = mmu_psize_defs[psize].shift;
        max_hpte_count = HPAGE_PMD_SIZE >> shift;
        for (i = 0; i < max_hpte_count; i++) {
                /*
                 * 8 bits per each hpte entries
                 * 000| [ secondary group (one bit) | hidx (3 bits) | valid bit]
                 */
                valid = hpte_valid(hpte_slot_array, i);
                if (!valid)
                        continue;
                hidx =  hpte_hash_index(hpte_slot_array, i);

                /* get the vpn */
                addr = s_addr + (i * (1ul << shift));
                vpn = hpt_vpn(addr, vsid, ssize);
                hash = hpt_hash(vpn, shift, ssize);
                if (hidx & _PTEIDX_SECONDARY)
                        hash = ~hash;

                slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
                slot += hidx & _PTEIDX_GROUP_IX;
                mmu_hash_ops.hpte_invalidate(slot, vpn, psize,
                                             MMU_PAGE_16M, ssize, local);
        }
tm_abort:
        tm_flush_hash_page(local);
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

void flush_hash_range(unsigned long number, int local)
{
        if (mmu_hash_ops.flush_hash_range)
                mmu_hash_ops.flush_hash_range(number, local);
        else {
                int i;
                struct ppc64_tlb_batch *batch =
                        this_cpu_ptr(&ppc64_tlb_batch);

                for (i = 0; i < number; i++)
                        flush_hash_page(batch->vpn[i], batch->pte[i],
                                        batch->psize, batch->ssize, local);
        }
}

/*
 * low_hash_fault is called when we the low level hash code failed
 * to instert a PTE due to an hypervisor error
 */
void low_hash_fault(struct pt_regs *regs, unsigned long address, int rc)
{
        enum ctx_state prev_state = exception_enter();

        if (user_mode(regs)) {
#ifdef CONFIG_PPC_SUBPAGE_PROT
                if (rc == -2)
                        _exception(SIGSEGV, regs, SEGV_ACCERR, address);
                else
#endif
                        _exception(SIGBUS, regs, BUS_ADRERR, address);
        } else
                bad_page_fault(regs, address, SIGBUS);

        exception_exit(prev_state);
}

long hpte_insert_repeating(unsigned long hash, unsigned long vpn,
                           unsigned long pa, unsigned long rflags,
                           unsigned long vflags, int psize, int ssize)
{
        unsigned long hpte_group;
        long slot;

repeat:
        hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;

        /* Insert into the hash table, primary slot */
        slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, vflags,
                                        psize, psize, ssize);

        /* Primary is full, try the secondary */
        if (unlikely(slot == -1)) {
                hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
                slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags,
                                                vflags | HPTE_V_SECONDARY,
                                                psize, psize, ssize);
                if (slot == -1) {
                        if (mftb() & 0x1)
                                hpte_group = (hash & htab_hash_mask) *
                                                HPTES_PER_GROUP;

                        mmu_hash_ops.hpte_remove(hpte_group);
                        goto repeat;
                }
        }

        return slot;
}

#ifdef CONFIG_DEBUG_PAGEALLOC
static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
{
        unsigned long hash;
        unsigned long vsid = get_kernel_vsid(vaddr, mmu_kernel_ssize);
        unsigned long vpn = hpt_vpn(vaddr, vsid, mmu_kernel_ssize);
        unsigned long mode = htab_convert_pte_flags(pgprot_val(PAGE_KERNEL), HPTE_USE_KERNEL_KEY);
        long ret;

        hash = hpt_hash(vpn, PAGE_SHIFT, mmu_kernel_ssize);

        /* Don't create HPTE entries for bad address */
        if (!vsid)
                return;

        ret = hpte_insert_repeating(hash, vpn, __pa(vaddr), mode,
                                    HPTE_V_BOLTED,
                                    mmu_linear_psize, mmu_kernel_ssize);

        BUG_ON (ret < 0);
        spin_lock(&linear_map_hash_lock);
        BUG_ON(linear_map_hash_slots[lmi] & 0x80);
        linear_map_hash_slots[lmi] = ret | 0x80;
        spin_unlock(&linear_map_hash_lock);
}

static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi)
{
        unsigned long hash, hidx, slot;
        unsigned long vsid = get_kernel_vsid(vaddr, mmu_kernel_ssize);
        unsigned long vpn = hpt_vpn(vaddr, vsid, mmu_kernel_ssize);

        hash = hpt_hash(vpn, PAGE_SHIFT, mmu_kernel_ssize);
        spin_lock(&linear_map_hash_lock);
        BUG_ON(!(linear_map_hash_slots[lmi] & 0x80));
        hidx = linear_map_hash_slots[lmi] & 0x7f;
        linear_map_hash_slots[lmi] = 0;
        spin_unlock(&linear_map_hash_lock);
        if (hidx & _PTEIDX_SECONDARY)
                hash = ~hash;
        slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
        slot += hidx & _PTEIDX_GROUP_IX;
        mmu_hash_ops.hpte_invalidate(slot, vpn, mmu_linear_psize,
                                     mmu_linear_psize,
                                     mmu_kernel_ssize, 0);
}

void __kernel_map_pages(struct page *page, int numpages, int enable)
{
        unsigned long flags, vaddr, lmi;
        int i;

        local_irq_save(flags);
        for (i = 0; i < numpages; i++, page++) {
                vaddr = (unsigned long)page_address(page);
                lmi = __pa(vaddr) >> PAGE_SHIFT;
                if (lmi >= linear_map_hash_count)
                        continue;
                if (enable)
                        kernel_map_linear_page(vaddr, lmi);
                else
                        kernel_unmap_linear_page(vaddr, lmi);
        }
        local_irq_restore(flags);
}
#endif /* CONFIG_DEBUG_PAGEALLOC */

void hash__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);

        /*
         * On virtualized systems the first entry is our RMA region aka VRMA,
         * non-virtualized 64-bit hash MMU systems don't have a limitation
         * on real mode access.
         *
         * For guests on platforms before POWER9, we clamp the it limit to 1G
         * to avoid some funky things such as RTAS bugs etc...
         *
         * On POWER9 we limit to 1TB in case the host erroneously told us that
         * the RMA was >1TB. Effective address bits 0:23 are treated as zero
         * (meaning the access is aliased to zero i.e. addr = addr % 1TB)
         * for virtual real mode addressing and so it doesn't make sense to
         * have an area larger than 1TB as it can't be addressed.
         */
        if (!early_cpu_has_feature(CPU_FTR_HVMODE)) {
                ppc64_rma_size = first_memblock_size;
                if (!early_cpu_has_feature(CPU_FTR_ARCH_300))
                        ppc64_rma_size = min_t(u64, ppc64_rma_size, 0x40000000);
                else
                        ppc64_rma_size = min_t(u64, ppc64_rma_size,
                                               1UL << SID_SHIFT_1T);

                /* Finally limit subsequent allocations */
                memblock_set_current_limit(ppc64_rma_size);
        } else {
                ppc64_rma_size = ULONG_MAX;
        }
}

#ifdef CONFIG_DEBUG_FS

static int hpt_order_get(void *data, u64 *val)
{
        *val = ppc64_pft_size;
        return 0;
}

static int hpt_order_set(void *data, u64 val)
{
        int ret;

        if (!mmu_hash_ops.resize_hpt)
                return -ENODEV;

        cpus_read_lock();
        ret = mmu_hash_ops.resize_hpt(val);
        cpus_read_unlock();

        return ret;
}

DEFINE_DEBUGFS_ATTRIBUTE(fops_hpt_order, hpt_order_get, hpt_order_set, "%llu\n");

static int __init hash64_debugfs(void)
{
        debugfs_create_file("hpt_order", 0600, powerpc_debugfs_root, NULL,
                            &fops_hpt_order);
        return 0;
}
machine_device_initcall(pseries, hash64_debugfs);
#endif /* CONFIG_DEBUG_FS */

void __init print_system_hash_info(void)
{
        pr_info("ppc64_pft_size    = 0x%llx\n", ppc64_pft_size);

        if (htab_hash_mask)
                pr_info("htab_hash_mask    = 0x%lx\n", htab_hash_mask);
}