arm64/mm/ptdump: Add address markers for BPF regions

Kernel virtual region [BPF_JIT_REGION_START..BPF_JIT_REGION_END] is missing
from address_markers[], hence relevant page table entries are not displayed
with /sys/kernel/debug/kernel_page_tables. This adds those missing markers.
While here, also rename arch/arm64/mm/dump.c which sounds bit ambiguous, as
arch/arm64/mm/ptdump.c instead.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/1599208259-11191-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 389 insertions, 0 deletions

diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
new file mode 100644
index 000000000000..265284dc942d
--- /dev/null
+++ b/arch/arm64/mm/ptdump.c
@@ -0,0 +1,389 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ * Debug helper to dump the current kernel pagetables of the system
+ * so that we can see what the various memory ranges are set to.
+ *
+ * Derived from x86 and arm implementation:
+ * (C) Copyright 2008 Intel Corporation
+ *
+ * Author: Arjan van de Ven <arjan@linux.intel.com>
+ */
+#include <linux/debugfs.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/ptdump.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+
+#include <asm/fixmap.h>
+#include <asm/kasan.h>
+#include <asm/memory.h>
+#include <asm/pgtable-hwdef.h>
+#include <asm/ptdump.h>
+
+
+enum address_markers_idx {
+	PAGE_OFFSET_NR = 0,
+	PAGE_END_NR,
+#ifdef CONFIG_KASAN
+	KASAN_START_NR,
+#endif
+};
+
+static struct addr_marker address_markers[] = {
+	{ PAGE_OFFSET,			"Linear Mapping start" },
+	{ 0 /* PAGE_END */,		"Linear Mapping end" },
+#ifdef CONFIG_KASAN
+	{ 0 /* KASAN_SHADOW_START */,	"Kasan shadow start" },
+	{ KASAN_SHADOW_END,		"Kasan shadow end" },
+#endif
+	{ BPF_JIT_REGION_START,		"BPF start" },
+	{ BPF_JIT_REGION_END,		"BPF end" },
+	{ MODULES_VADDR,		"Modules start" },
+	{ MODULES_END,			"Modules end" },
+	{ VMALLOC_START,		"vmalloc() area" },
+	{ VMALLOC_END,			"vmalloc() end" },
+	{ FIXADDR_START,		"Fixmap start" },
+	{ FIXADDR_TOP,			"Fixmap end" },
+	{ PCI_IO_START,			"PCI I/O start" },
+	{ PCI_IO_END,			"PCI I/O end" },
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+	{ VMEMMAP_START,		"vmemmap start" },
+	{ VMEMMAP_START + VMEMMAP_SIZE,	"vmemmap end" },
+#endif
+	{ -1,				NULL },
+};
+
+#define pt_dump_seq_printf(m, fmt, args...)	\
+({						\
+	if (m)					\
+		seq_printf(m, fmt, ##args);	\
+})
+
+#define pt_dump_seq_puts(m, fmt)	\
+({					\
+	if (m)				\
+		seq_printf(m, fmt);	\
+})
+
+/*
+ * The page dumper groups page table entries of the same type into a single
+ * description. It uses pg_state to track the range information while
+ * iterating over the pte entries. When the continuity is broken it then
+ * dumps out a description of the range.
+ */
+struct pg_state {
+	struct ptdump_state ptdump;
+	struct seq_file *seq;
+	const struct addr_marker *marker;
+	unsigned long start_address;
+	int level;
+	u64 current_prot;
+	bool check_wx;
+	unsigned long wx_pages;
+	unsigned long uxn_pages;
+};
+
+struct prot_bits {
+	u64		mask;
+	u64		val;
+	const char	*set;
+	const char	*clear;
+};
+
+static const struct prot_bits pte_bits[] = {
+	{
+		.mask	= PTE_VALID,
+		.val	= PTE_VALID,
+		.set	= " ",
+		.clear	= "F",
+	}, {
+		.mask	= PTE_USER,
+		.val	= PTE_USER,
+		.set	= "USR",
+		.clear	= "   ",
+	}, {
+		.mask	= PTE_RDONLY,
+		.val	= PTE_RDONLY,
+		.set	= "ro",
+		.clear	= "RW",
+	}, {
+		.mask	= PTE_PXN,
+		.val	= PTE_PXN,
+		.set	= "NX",
+		.clear	= "x ",
+	}, {
+		.mask	= PTE_SHARED,
+		.val	= PTE_SHARED,
+		.set	= "SHD",
+		.clear	= "   ",
+	}, {
+		.mask	= PTE_AF,
+		.val	= PTE_AF,
+		.set	= "AF",
+		.clear	= "  ",
+	}, {
+		.mask	= PTE_NG,
+		.val	= PTE_NG,
+		.set	= "NG",
+		.clear	= "  ",
+	}, {
+		.mask	= PTE_CONT,
+		.val	= PTE_CONT,
+		.set	= "CON",
+		.clear	= "   ",
+	}, {
+		.mask	= PTE_TABLE_BIT,
+		.val	= PTE_TABLE_BIT,
+		.set	= "   ",
+		.clear	= "BLK",
+	}, {
+		.mask	= PTE_UXN,
+		.val	= PTE_UXN,
+		.set	= "UXN",
+		.clear	= "   ",
+	}, {
+		.mask	= PTE_GP,
+		.val	= PTE_GP,
+		.set	= "GP",
+		.clear	= "  ",
+	}, {
+		.mask	= PTE_ATTRINDX_MASK,
+		.val	= PTE_ATTRINDX(MT_DEVICE_nGnRnE),
+		.set	= "DEVICE/nGnRnE",
+	}, {
+		.mask	= PTE_ATTRINDX_MASK,
+		.val	= PTE_ATTRINDX(MT_DEVICE_nGnRE),
+		.set	= "DEVICE/nGnRE",
+	}, {
+		.mask	= PTE_ATTRINDX_MASK,
+		.val	= PTE_ATTRINDX(MT_DEVICE_GRE),
+		.set	= "DEVICE/GRE",
+	}, {
+		.mask	= PTE_ATTRINDX_MASK,
+		.val	= PTE_ATTRINDX(MT_NORMAL_NC),
+		.set	= "MEM/NORMAL-NC",
+	}, {
+		.mask	= PTE_ATTRINDX_MASK,
+		.val	= PTE_ATTRINDX(MT_NORMAL),
+		.set	= "MEM/NORMAL",
+	}
+};
+
+struct pg_level {
+	const struct prot_bits *bits;
+	const char *name;
+	size_t num;
+	u64 mask;
+};
+
+static struct pg_level pg_level[] = {
+	{ /* pgd */
+		.name	= "PGD",
+		.bits	= pte_bits,
+		.num	= ARRAY_SIZE(pte_bits),
+	}, { /* p4d */
+		.name	= "P4D",
+		.bits	= pte_bits,
+		.num	= ARRAY_SIZE(pte_bits),
+	}, { /* pud */
+		.name	= (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
+		.bits	= pte_bits,
+		.num	= ARRAY_SIZE(pte_bits),
+	}, { /* pmd */
+		.name	= (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD",
+		.bits	= pte_bits,
+		.num	= ARRAY_SIZE(pte_bits),
+	}, { /* pte */
+		.name	= "PTE",
+		.bits	= pte_bits,
+		.num	= ARRAY_SIZE(pte_bits),
+	},
+};
+
+static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
+			size_t num)
+{
+	unsigned i;
+
+	for (i = 0; i < num; i++, bits++) {
+		const char *s;
+
+		if ((st->current_prot & bits->mask) == bits->val)
+			s = bits->set;
+		else
+			s = bits->clear;
+
+		if (s)
+			pt_dump_seq_printf(st->seq, " %s", s);
+	}
+}
+
+static void note_prot_uxn(struct pg_state *st, unsigned long addr)
+{
+	if (!st->check_wx)
+		return;
+
+	if ((st->current_prot & PTE_UXN) == PTE_UXN)
+		return;
+
+	WARN_ONCE(1, "arm64/mm: Found non-UXN mapping at address %p/%pS\n",
+		  (void *)st->start_address, (void *)st->start_address);
+
+	st->uxn_pages += (addr - st->start_address) / PAGE_SIZE;
+}
+
+static void note_prot_wx(struct pg_state *st, unsigned long addr)
+{
+	if (!st->check_wx)
+		return;
+	if ((st->current_prot & PTE_RDONLY) == PTE_RDONLY)
+		return;
+	if ((st->current_prot & PTE_PXN) == PTE_PXN)
+		return;
+
+	WARN_ONCE(1, "arm64/mm: Found insecure W+X mapping at address %p/%pS\n",
+		  (void *)st->start_address, (void *)st->start_address);
+
+	st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
+}
+
+static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
+		      u64 val)
+{
+	struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
+	static const char units[] = "KMGTPE";
+	u64 prot = 0;
+
+	if (level >= 0)
+		prot = val & pg_level[level].mask;
+
+	if (st->level == -1) {
+		st->level = level;
+		st->current_prot = prot;
+		st->start_address = addr;
+		pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+	} else if (prot != st->current_prot || level != st->level ||
+		   addr >= st->marker[1].start_address) {
+		const char *unit = units;
+		unsigned long delta;
+
+		if (st->current_prot) {
+			note_prot_uxn(st, addr);
+			note_prot_wx(st, addr);
+		}
+
+		pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx   ",
+				   st->start_address, addr);
+
+		delta = (addr - st->start_address) >> 10;
+		while (!(delta & 1023) && unit[1]) {
+			delta >>= 10;
+			unit++;
+		}
+		pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
+				   pg_level[st->level].name);
+		if (st->current_prot && pg_level[st->level].bits)
+			dump_prot(st, pg_level[st->level].bits,
+				  pg_level[st->level].num);
+		pt_dump_seq_puts(st->seq, "\n");
+
+		if (addr >= st->marker[1].start_address) {
+			st->marker++;
+			pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+		}
+
+		st->start_address = addr;
+		st->current_prot = prot;
+		st->level = level;
+	}
+
+	if (addr >= st->marker[1].start_address) {
+		st->marker++;
+		pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+	}
+
+}
+
+void ptdump_walk(struct seq_file *s, struct ptdump_info *info)
+{
+	unsigned long end = ~0UL;
+	struct pg_state st;
+
+	if (info->base_addr < TASK_SIZE_64)
+		end = TASK_SIZE_64;
+
+	st = (struct pg_state){
+		.seq = s,
+		.marker = info->markers,
+		.ptdump = {
+			.note_page = note_page,
+			.range = (struct ptdump_range[]){
+				{info->base_addr, end},
+				{0, 0}
+			}
+		}
+	};
+
+	ptdump_walk_pgd(&st.ptdump, info->mm, NULL);
+}
+
+static void ptdump_initialize(void)
+{
+	unsigned i, j;
+
+	for (i = 0; i < ARRAY_SIZE(pg_level); i++)
+		if (pg_level[i].bits)
+			for (j = 0; j < pg_level[i].num; j++)
+				pg_level[i].mask |= pg_level[i].bits[j].mask;
+}
+
+static struct ptdump_info kernel_ptdump_info = {
+	.mm		= &init_mm,
+	.markers	= address_markers,
+	.base_addr	= PAGE_OFFSET,
+};
+
+void ptdump_check_wx(void)
+{
+	struct pg_state st = {
+		.seq = NULL,
+		.marker = (struct addr_marker[]) {
+			{ 0, NULL},
+			{ -1, NULL},
+		},
+		.level = -1,
+		.check_wx = true,
+		.ptdump = {
+			.note_page = note_page,
+			.range = (struct ptdump_range[]) {
+				{PAGE_OFFSET, ~0UL},
+				{0, 0}
+			}
+		}
+	};
+
+	ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
+
+	if (st.wx_pages || st.uxn_pages)
+		pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found, %lu non-UXN pages found\n",
+			st.wx_pages, st.uxn_pages);
+	else
+		pr_info("Checked W+X mappings: passed, no W+X pages found\n");
+}
+
+static int ptdump_init(void)
+{
+	address_markers[PAGE_END_NR].start_address = PAGE_END;
+#ifdef CONFIG_KASAN
+	address_markers[KASAN_START_NR].start_address = KASAN_SHADOW_START;
+#endif
+	ptdump_initialize();
+	ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
+	return 0;
+}
+device_initcall(ptdump_init);