[PATCH 2/2] powerpc/pagetable: Add option to dump kernel hashpagetable
Balbir Singh
bsingharora at gmail.com
Wed Mar 30 14:32:17 AEDT 2016
On 22/03/16 09:04, Rashmica Gupta wrote:
> Useful to be able to dump the kernel hash page table to check
> which pages are hashed along with their sizes and other details.
>
> Add a debugfs file to check the page tables. To use this the PPC_PTDUMP
> config option must be selected.
>
> Signed-off-by: Rashmica Gupta <rashmicy at gmail.com>
> ---
> arch/powerpc/mm/Makefile | 3 +-
> arch/powerpc/mm/dump_hashpagetable.c | 488 +++++++++++++++++++++++++++++++++++
> 2 files changed, 490 insertions(+), 1 deletion(-)
> create mode 100644 arch/powerpc/mm/dump_hashpagetable.c
>
> diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
> index 6935c6204fbc..0bd48b345ff3 100644
> --- a/arch/powerpc/mm/Makefile
> +++ b/arch/powerpc/mm/Makefile
> @@ -41,4 +41,5 @@ obj-$(CONFIG_NOT_COHERENT_CACHE) += dma-noncoherent.o
> obj-$(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
> diff --git a/arch/powerpc/mm/dump_hashpagetable.c b/arch/powerpc/mm/dump_hashpagetable.c
> new file mode 100644
> index 000000000000..044fd13e4d07
> --- /dev/null
> +++ b/arch/powerpc/mm/dump_hashpagetable.c
> @@ -0,0 +1,488 @@
> +/*
> + * 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.
> + *
> + * 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 addr_marker {
> + unsigned long start_address;
> + const char *name;
> +};
> +
> +static struct addr_marker address_markers[] = {
> + { PAGE_OFFSET, "Start of kernel VM"},
> + { VMALLOC_START, "vmalloc() Area" },
> + { VMALLOC_END, "vmalloc() End" },
> + { ISA_IO_BASE, "isa I/O start" },
> + { ISA_IO_END, "isa I/O end" },
> + { PHB_IO_BASE, "phb I/O start" },
> + { PHB_IO_END, "phb I/O end" },
> + { IOREMAP_BASE, "I/O remap start" },
> + { IOREMAP_END, "I/O remap end" },
> + { VMEMMAP_BASE, "vmemmap start" },
> + { -1, NULL },
> +};
> +
> +struct pg_state {
> + struct seq_file *seq;
> + const struct addr_marker *marker;
> + unsigned long start_address;
> + unsigned level;
> + u64 current_flags;
> +};
> +
> +struct flag_info {
> + u64 mask;
> + u64 val;
> + const char *set;
> + const char *clear;
> + bool is_val;
> +};
> +
> +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 = HPTE_R_PP0 | HPTE_R_PP,
> + .set = "prot",
> + .clear = "",
> + .is_val = true,
> + }, {
> + .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",
> + .clear = "",
> + }, {
> + .mask = HPTE_R_WIMG,
> + .val = HPTE_R_W,
> + .set = "writethru",
> + .clear = "",
> + }, {
> + .mask = HPTE_R_WIMG,
> + .val = HPTE_R_I,
> + .set = "no cache",
> + .clear = "",
> + }, {
> + .mask = HPTE_R_WIMG,
> + .val = HPTE_R_G,
> + .set = "guarded",
> + .clear = "",
> + }
> +};
> +
> +static void dump_flag_info(struct pg_state *st, const struct flag_info
> + *flag, unsigned long pte, int num)
> +{
> + unsigned i;
> +
> + for (i = 0; i < num; i++, flag++) {
> + const char *s = NULL;
> +
> + if (flag->is_val) {
> + seq_printf(st->seq, " %s:%llx", flag->set, pte &
> + flag->val);
> + } else {
> + if ((pte & flag->mask) == flag->val)
> + s = flag->set;
> + else
> + s = flag->clear;
> + seq_printf(st->seq, " %s", s);
> + }
> + }
> +}
> +
> +static void dump_hpte_info(struct pg_state *st, unsigned long ea, unsigned long
> + v, unsigned long r, unsigned long rpn, int bps, int aps,
> + unsigned long lp)
> +{
> + static const char units[] = "BKMGTPE";
> + const char *unit = units;
> +
> + 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:%lx\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));
> +
> + while (bps > 9 && unit[1]) {
> + bps -= 10;
> + unit++;
> + }
> + seq_printf(st->seq, "base_ps: %i%c\t", 1<<bps, *unit);
> + while (aps > 9 && unit[1]) {
> + aps -= 10;
> + unit++;
> + }
> + seq_printf(st->seq, "actual_ps: %i%c", 1<<aps, *unit);
> + if (lp != -1)
> + seq_printf(st->seq, "\tLP enc: %lx", lp);
> + seq_puts(st->seq, "\n");
> +}
> +
> +static int native_find(unsigned long ea, int psize, bool primary, unsigned long
> + *v, unsigned long *r)
You probably need a #ifdef around this
> +{
> + 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;
> +}
> +
> +static int pseries_find(unsigned long ea, int psize, bool primary, unsigned
> + long *v, unsigned long *r)
> +{
Same here, should compile only if PLATFORM pseries is set, you need an #ifdef around this
> + 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;
> +}
> +
> +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 unsigned long hpte_find(struct pg_state *st, unsigned long ea, int psize)
> +{
> + unsigned long slot;
> + unsigned long v = 0, r = 0, rpn, lp_bits;
> + int base_psize = 0, actual_psize = 0;
> +
> + if (ea <= PAGE_OFFSET)
> + return -1;
> +
> + /* Look in primary table */
> + if (firmware_has_feature(FW_FEATURE_LPAR))
> + slot = pseries_find(ea, psize, true, &v, &r);
> + else
> + slot = native_find(ea, psize, true, &v, &r);
> +
> + /* Look in secondary table */
> + if (slot == -1) {
> + if (firmware_has_feature(FW_FEATURE_LPAR))
> + slot = pseries_find(ea, psize, false, &v, &r);
> + else
> + slot = native_find(ea, psize, false, &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;
> +
> + /* check for secret 4K mappings */
> + if (((pteval & _PAGE_COMBO) == _PAGE_COMBO) ||
> + ((pteval & _PAGE_4K_PFN) == _PAGE_4K_PFN))
> + psize = mmu_io_psize;
> +
> + /* check for hashpte */
> + status = hpte_find(st, addr, psize);
> +
> + if (((pteval & _PAGE_HASHPTE) != _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 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 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_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.
> + */
> + for (addr = PAGE_OFFSET; addr < PAGE_OFFSET +
> + memblock_phys_mem_size(); addr += PAGE_SIZE)
> + hpte_find(st, addr, mmu_linear_psize);
> +}
> +
> +static void walk_pagetables(struct pg_state *st)
> +{
> + pgd_t *pgd = pgd_offset_k(0UL);
> + unsigned 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 = VMALLOC_START + i * PGDIR_SIZE;
> + if (!pgd_none(*pgd))
> + /* pgd exists */
> + walk_pud(st, pgd, addr);
> + }
> +}
> +
> +static void walk_vmemmap(struct pg_state *st)
> +{
> + 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");
> +}
> +
> +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;
> +
> + debugfs_file = debugfs_create_file("kernel_hash_pagetable", 0400,
> + NULL, NULL, &ptdump_fops);
> + return debugfs_file ? 0 : -ENOMEM;
> +}
> +device_initcall(ptdump_init);
Otherwise (also check the _PAGE_COMBO build failure reports)
Acked-by: Balbir Singh <bsingharora at gmail.com>
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