/*
 * Copyright 2016, Rashmica Gupta, IBM Corp.
 *
 * This traverses the kernel virtual memory and dumps the pages that are in
 * the hash pagetable, along with their flags to
 * /sys/kernel/debug/kernel_hash_pagetable.
 *
 * If radix is enabled then there is no hash page table and so no debugfs file
 * is generated.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 */
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <asm/pgtable.h>
#include <linux/const.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/plpar_wrappers.h>
#include <linux/memblock.h>
#include <asm/firmware.h>

struct pg_state {
        struct seq_file *seq;
        const struct addr_marker *marker;
        unsigned long start_address;
        unsigned int level;
        u64 current_flags;
};

struct addr_marker {
        unsigned long start_address;
        const char *name;
};

static struct addr_marker address_markers[] = {
        { 0,    "Start of kernel VM" },
        { 0,    "vmalloc() Area" },
        { 0,    "vmalloc() End" },
        { 0,    "isa I/O start" },
        { 0,    "isa I/O end" },
        { 0,    "phb I/O start" },
        { 0,    "phb I/O end" },
        { 0,    "I/O remap start" },
        { 0,    "I/O remap end" },
        { 0,    "vmemmap start" },
        { -1,   NULL },
};

struct flag_info {
        u64             mask;
        u64             val;
        const char      *set;
        const char      *clear;
        bool            is_val;
        int             shift;
};

static const struct flag_info v_flag_array[] = {
        {
                .mask   = SLB_VSID_B,
                .val    = SLB_VSID_B_256M,
                .set    = "ssize: 256M",
                .clear  = "ssize: 1T  ",
        }, {
                .mask   = HPTE_V_SECONDARY,
                .val    = HPTE_V_SECONDARY,
                .set    = "secondary",
                .clear  = "primary  ",
        }, {
                .mask   = HPTE_V_VALID,
                .val    = HPTE_V_VALID,
                .set    = "valid  ",
                .clear  = "invalid",
        }, {
                .mask   = HPTE_V_BOLTED,
                .val    = HPTE_V_BOLTED,
                .set    = "bolted",
                .clear  = "",
        }
};

static const struct flag_info r_flag_array[] = {
        {
                .mask   = HPTE_R_PP0 | HPTE_R_PP,
                .val    = PP_RWXX,
                .set    = "prot:RW--",
        }, {
                .mask   = HPTE_R_PP0 | HPTE_R_PP,
                .val    = PP_RWRX,
                .set    = "prot:RWR-",
        }, {
                .mask   = HPTE_R_PP0 | HPTE_R_PP,
                .val    = PP_RWRW,
                .set    = "prot:RWRW",
        }, {
                .mask   = HPTE_R_PP0 | HPTE_R_PP,
                .val    = PP_RXRX,
                .set    = "prot:R-R-",
        }, {
                .mask   = HPTE_R_PP0 | HPTE_R_PP,
                .val    = PP_RXXX,
                .set    = "prot:R---",
        }, {
                .mask   = HPTE_R_KEY_HI | HPTE_R_KEY_LO,
                .val    = HPTE_R_KEY_HI | HPTE_R_KEY_LO,
                .set    = "key",
                .clear  = "",
                .is_val = true,
        }, {
                .mask   = HPTE_R_R,
                .val    = HPTE_R_R,
                .set    = "ref",
                .clear  = "   ",
        }, {
                .mask   = HPTE_R_C,
                .val    = HPTE_R_C,
                .set    = "changed",
                .clear  = "       ",
        }, {
                .mask   = HPTE_R_N,
                .val    = HPTE_R_N,
                .set    = "no execute",
        }, {
                .mask   = HPTE_R_WIMG,
                .val    = HPTE_R_W,
                .set    = "writethru",
        }, {
                .mask   = HPTE_R_WIMG,
                .val    = HPTE_R_I,
                .set    = "no cache",
        }, {
                .mask   = HPTE_R_WIMG,
                .val    = HPTE_R_G,
                .set    = "guarded",
        }
};

static int calculate_pagesize(struct pg_state *st, int ps, char s[])
{
        static const char units[] = "BKMGTPE";
        const char *unit = units;

        while (ps > 9 && unit[1]) {
                ps -= 10;
                unit++;
        }
        seq_printf(st->seq, "  %s_ps: %i%c\t", s, 1<<ps, *unit);
        return ps;
}

static void dump_flag_info(struct pg_state *st, const struct flag_info
                *flag, u64 pte, int num)
{
        unsigned int i;

        for (i = 0; i < num; i++, flag++) {
                const char *s = NULL;
                u64 val;

                /* flag not defined so don't check it */
                if (flag->mask == 0)
                        continue;
                /* Some 'flags' are actually values */
                if (flag->is_val) {
                        val = pte & flag->val;
                        if (flag->shift)
                                val = val >> flag->shift;
                        seq_printf(st->seq, "  %s:%llx", flag->set, val);
                } else {
                        if ((pte & flag->mask) == flag->val)
                                s = flag->set;
                        else
                                s = flag->clear;
                        if (s)
                                seq_printf(st->seq, "  %s", s);
                }
        }
}

static void dump_hpte_info(struct pg_state *st, unsigned long ea, u64 v, u64 r,
                unsigned long rpn, int bps, int aps, unsigned long lp)
{
        int aps_index;

        while (ea >= st->marker[1].start_address) {
                st->marker++;
                seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
        }
        seq_printf(st->seq, "0x%lx:\t", ea);
        seq_printf(st->seq, "AVPN:%llx\t", HPTE_V_AVPN_VAL(v));
        dump_flag_info(st, v_flag_array, v, ARRAY_SIZE(v_flag_array));
        seq_printf(st->seq, "  rpn: %lx\t", rpn);
        dump_flag_info(st, r_flag_array, r, ARRAY_SIZE(r_flag_array));

        calculate_pagesize(st, bps, "base");
        aps_index = calculate_pagesize(st, aps, "actual");
        if (aps_index != 2)
                seq_printf(st->seq, "LP enc: %lx", lp);
        seq_putc(st->seq, '\n');
}


static int native_find(unsigned long ea, int psize, bool primary, u64 *v, u64
                *r)
{
        struct hash_pte *hptep;
        unsigned long hash, vsid, vpn, hpte_group, want_v, hpte_v;
        int i, ssize = mmu_kernel_ssize;
        unsigned long shift = mmu_psize_defs[psize].shift;

        /* calculate hash */
        vsid = get_kernel_vsid(ea, ssize);
        vpn  = hpt_vpn(ea, vsid, ssize);
        hash = hpt_hash(vpn, shift, ssize);
        want_v = hpte_encode_avpn(vpn, psize, ssize);

        /* to check in the secondary hash table, we invert the hash */
        if (!primary)
                hash = ~hash;
        hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
        for (i = 0; i < HPTES_PER_GROUP; i++) {
                hptep = htab_address + hpte_group;
                hpte_v = be64_to_cpu(hptep->v);

                if (HPTE_V_COMPARE(hpte_v, want_v) && (hpte_v & HPTE_V_VALID)) {
                        /* HPTE matches */
                        *v = be64_to_cpu(hptep->v);
                        *r = be64_to_cpu(hptep->r);
                        return 0;
                }
                ++hpte_group;
        }
        return -1;
}

#ifdef CONFIG_PPC_PSERIES
static int pseries_find(unsigned long ea, int psize, bool primary, u64 *v, u64 *r)
{
        struct hash_pte ptes[4];
        unsigned long vsid, vpn, hash, hpte_group, want_v;
        int i, j, ssize = mmu_kernel_ssize;
        long lpar_rc = 0;
        unsigned long shift = mmu_psize_defs[psize].shift;

        /* calculate hash */
        vsid = get_kernel_vsid(ea, ssize);
        vpn  = hpt_vpn(ea, vsid, ssize);
        hash = hpt_hash(vpn, shift, ssize);
        want_v = hpte_encode_avpn(vpn, psize, ssize);

        /* to check in the secondary hash table, we invert the hash */
        if (!primary)
                hash = ~hash;
        hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
        /* see if we can find an entry in the hpte with this hash */
        for (i = 0; i < HPTES_PER_GROUP; i += 4, hpte_group += 4) {
                lpar_rc = plpar_pte_read_4(0, hpte_group, (void *)ptes);

                if (lpar_rc != H_SUCCESS)
                        continue;
                for (j = 0; j < 4; j++) {
                        if (HPTE_V_COMPARE(ptes[j].v, want_v) &&
                                        (ptes[j].v & HPTE_V_VALID)) {
                                /* HPTE matches */
                                *v = ptes[j].v;
                                *r = ptes[j].r;
                                return 0;
                        }
                }
        }
        return -1;
}
#endif

static void decode_r(int bps, unsigned long r, unsigned long *rpn, int *aps,
                unsigned long *lp_bits)
{
        struct mmu_psize_def entry;
        unsigned long arpn, mask, lp;
        int penc = -2, idx = 0, shift;

        /*.
         * The LP field has 8 bits. Depending on the actual page size, some of
         * these bits are concatenated with the APRN to get the RPN. The rest
         * of the bits in the LP field is the LP value and is an encoding for
         * the base page size and the actual page size.
         *
         *  -   find the mmu entry for our base page size
         *  -   go through all page encodings and use the associated mask to
         *      find an encoding that matches our encoding in the LP field.
         */
        arpn = (r & HPTE_R_RPN) >> HPTE_R_RPN_SHIFT;
        lp = arpn & 0xff;

        entry = mmu_psize_defs[bps];
        while (idx < MMU_PAGE_COUNT) {
                penc = entry.penc[idx];
                if ((penc != -1) && (mmu_psize_defs[idx].shift)) {
                        shift = mmu_psize_defs[idx].shift -  HPTE_R_RPN_SHIFT;
                        mask = (0x1 << (shift)) - 1;
                        if ((lp & mask) == penc) {
                                *aps = mmu_psize_to_shift(idx);
                                *lp_bits = lp & mask;
                                *rpn = arpn >> shift;
                                return;
                        }
                }
                idx++;
        }
}

static int base_hpte_find(unsigned long ea, int psize, bool primary, u64 *v,
                          u64 *r)
{
#ifdef CONFIG_PPC_PSERIES
        if (firmware_has_feature(FW_FEATURE_LPAR))
                return pseries_find(ea, psize, primary, v, r);
#endif
        return native_find(ea, psize, primary, v, r);
}

static unsigned long hpte_find(struct pg_state *st, unsigned long ea, int psize)
{
        unsigned long slot;
        u64 v  = 0, r = 0;
        unsigned long rpn, lp_bits;
        int base_psize = 0, actual_psize = 0;

        if (ea < PAGE_OFFSET)
                return -1;

        /* Look in primary table */
        slot = base_hpte_find(ea, psize, true, &v, &r);

        /* Look in secondary table */
        if (slot == -1)
                slot = base_hpte_find(ea, psize, true, &v, &r);

        /* No entry found */
        if (slot == -1)
                return -1;

        /*
         * We found an entry in the hash page table:
         *  - check that this has the same base page
         *  - find the actual page size
         *  - find the RPN
         */
        base_psize = mmu_psize_to_shift(psize);

        if ((v & HPTE_V_LARGE) == HPTE_V_LARGE) {
                decode_r(psize, r, &rpn, &actual_psize, &lp_bits);
        } else {
                /* 4K actual page size */
                actual_psize = 12;
                rpn = (r & HPTE_R_RPN) >> HPTE_R_RPN_SHIFT;
                /* In this case there are no LP bits */
                lp_bits = -1;
        }
        /*
         * We didn't find a matching encoding, so the PTE we found isn't for
         * this address.
         */
        if (actual_psize == -1)
                return -1;

        dump_hpte_info(st, ea, v, r, rpn, base_psize, actual_psize, lp_bits);
        return 0;
}

static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
{
        pte_t *pte = pte_offset_kernel(pmd, 0);
        unsigned long addr, pteval, psize;
        int i, status;

        for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
                addr = start + i * PAGE_SIZE;
                pteval = pte_val(*pte);

                if (addr < VMALLOC_END)
                        psize = mmu_vmalloc_psize;
                else
                        psize = mmu_io_psize;
#ifdef CONFIG_PPC_64K_PAGES
                /* check for secret 4K mappings */
                if (((pteval & H_PAGE_COMBO) == H_PAGE_COMBO) ||
                        ((pteval & H_PAGE_4K_PFN) == H_PAGE_4K_PFN))
                        psize = mmu_io_psize;
#endif
                /* check for hashpte */
                status = hpte_find(st, addr, psize);

                if (((pteval & H_PAGE_HASHPTE) != H_PAGE_HASHPTE)
                                && (status != -1)) {
                /* found a hpte that is not in the linux page tables */
                        seq_printf(st->seq, "page probably bolted before linux"
                                " pagetables were set: addr:%lx, pteval:%lx\n",
                                addr, pteval);
                }
        }
}

static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
{
        pmd_t *pmd = pmd_offset(pud, 0);
        unsigned long addr;
        unsigned int i;

        for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
                addr = start + i * PMD_SIZE;
                if (!pmd_none(*pmd))
                        /* pmd exists */
                        walk_pte(st, pmd, addr);
        }
}

static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
{
        pud_t *pud = pud_offset(pgd, 0);
        unsigned long addr;
        unsigned int i;

        for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
                addr = start + i * PUD_SIZE;
                if (!pud_none(*pud))
                        /* pud exists */
                        walk_pmd(st, pud, addr);
        }
}

static void walk_pagetables(struct pg_state *st)
{
        pgd_t *pgd = pgd_offset_k(0UL);
        unsigned int i;
        unsigned long addr;

        /*
         * Traverse the linux pagetable structure and dump pages that are in
         * the hash pagetable.
         */
        for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
                addr = KERN_VIRT_START + i * PGDIR_SIZE;
                if (!pgd_none(*pgd))
                        /* pgd exists */
                        walk_pud(st, pgd, addr);
        }
}


static void walk_linearmapping(struct pg_state *st)
{
        unsigned long addr;

        /*
         * Traverse the linear mapping section of virtual memory and dump pages
         * that are in the hash pagetable.
         */
        unsigned long psize = 1 << mmu_psize_defs[mmu_linear_psize].shift;

        for (addr = PAGE_OFFSET; addr < PAGE_OFFSET +
                        memblock_end_of_DRAM(); addr += psize)
                hpte_find(st, addr, mmu_linear_psize);
}

static void walk_vmemmap(struct pg_state *st)
{
#ifdef CONFIG_SPARSEMEM_VMEMMAP
        struct vmemmap_backing *ptr = vmemmap_list;

        /*
         * Traverse the vmemmaped memory and dump pages that are in the hash
         * pagetable.
         */
        while (ptr->list) {
                hpte_find(st, ptr->virt_addr, mmu_vmemmap_psize);
                ptr = ptr->list;
        }
        seq_puts(st->seq, "---[ vmemmap end ]---\n");
#endif
}

static void populate_markers(void)
{
        address_markers[0].start_address = PAGE_OFFSET;
        address_markers[1].start_address = VMALLOC_START;
        address_markers[2].start_address = VMALLOC_END;
        address_markers[3].start_address = ISA_IO_BASE;
        address_markers[4].start_address = ISA_IO_END;
        address_markers[5].start_address = PHB_IO_BASE;
        address_markers[6].start_address = PHB_IO_END;
        address_markers[7].start_address = IOREMAP_BASE;
        address_markers[8].start_address = IOREMAP_END;
#ifdef CONFIG_PPC_BOOK3S_64
        address_markers[9].start_address =  H_VMEMMAP_BASE;
#else
        address_markers[9].start_address =  VMEMMAP_BASE;
#endif
}

static int ptdump_show(struct seq_file *m, void *v)
{
        struct pg_state st = {
                .seq = m,
                .start_address = PAGE_OFFSET,
                .marker = address_markers,
        };
        /*
         * Traverse the 0xc, 0xd and 0xf areas of the kernel virtual memory and
         * dump pages that are in the hash pagetable.
         */
        walk_linearmapping(&st);
        walk_pagetables(&st);
        walk_vmemmap(&st);
        return 0;
}

static int ptdump_open(struct inode *inode, struct file *file)
{
        return single_open(file, ptdump_show, NULL);
}

static const struct file_operations ptdump_fops = {
        .open           = ptdump_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int ptdump_init(void)
{
        struct dentry *debugfs_file;

        if (!radix_enabled()) {
                populate_markers();
                debugfs_file = debugfs_create_file("kernel_hash_pagetable",
                                0400, NULL, NULL, &ptdump_fops);
                return debugfs_file ? 0 : -ENOMEM;
        }
        return 0;
}
device_initcall(ptdump_init);