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 <rashm...@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)
+{
+ 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)
+{
+ 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);
--
2.5.0
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