powerpc/mm: Dump hash table

obj-$(CONFIG_HIGHMEM)		+= highmem.o

obj-$(CONFIG_PPC_COPRO_BASE)	+= copro_fault.o

obj-$(CONFIG_SPAPR_TCE_IOMMU)	+= mmu_context_iommu.o

obj-$(CONFIG_PPC_PTDUMP)	+= dump_linuxpagetables.o

obj-$(CONFIG_PPC_PTDUMP)	+= dump_linuxpagetables.o \

				   dump_hashpagetable.o

/*

 * 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/fixmap.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_puts(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) & ~0x7UL;

	/* 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_phys_mem_size(); 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_STD_MMU_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);