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-rw-r--r--arch/x86/mm/dump_pagetables.c471
1 files changed, 471 insertions, 0 deletions
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
new file mode 100644
index 000000000..e1b599ecb
--- /dev/null
+++ b/arch/x86/mm/dump_pagetables.c
@@ -0,0 +1,471 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Debug helper to dump the current kernel pagetables of the system
+ * so that we can see what the various memory ranges are set to.
+ *
+ * (C) Copyright 2008 Intel Corporation
+ *
+ * Author: Arjan van de Ven <arjan@linux.intel.com>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/kasan.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <linux/highmem.h>
+#include <linux/pci.h>
+#include <linux/ptdump.h>
+
+#include <asm/e820/types.h>
+
+/*
+ * The dumper groups pagetable entries of the same type into one, and for
+ * that it needs to keep some state when walking, and flush this state
+ * when a "break" in the continuity is found.
+ */
+struct pg_state {
+ struct ptdump_state ptdump;
+ int level;
+ pgprotval_t current_prot;
+ pgprotval_t effective_prot;
+ pgprotval_t prot_levels[5];
+ unsigned long start_address;
+ const struct addr_marker *marker;
+ unsigned long lines;
+ bool to_dmesg;
+ bool check_wx;
+ unsigned long wx_pages;
+ struct seq_file *seq;
+};
+
+struct addr_marker {
+ unsigned long start_address;
+ const char *name;
+ unsigned long max_lines;
+};
+
+/* Address space markers hints */
+
+#ifdef CONFIG_X86_64
+
+enum address_markers_idx {
+ USER_SPACE_NR = 0,
+ KERNEL_SPACE_NR,
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+ LDT_NR,
+#endif
+ LOW_KERNEL_NR,
+ VMALLOC_START_NR,
+ VMEMMAP_START_NR,
+#ifdef CONFIG_KASAN
+ KASAN_SHADOW_START_NR,
+ KASAN_SHADOW_END_NR,
+#endif
+ CPU_ENTRY_AREA_NR,
+#ifdef CONFIG_X86_ESPFIX64
+ ESPFIX_START_NR,
+#endif
+#ifdef CONFIG_EFI
+ EFI_END_NR,
+#endif
+ HIGH_KERNEL_NR,
+ MODULES_VADDR_NR,
+ MODULES_END_NR,
+ FIXADDR_START_NR,
+ END_OF_SPACE_NR,
+};
+
+static struct addr_marker address_markers[] = {
+ [USER_SPACE_NR] = { 0, "User Space" },
+ [KERNEL_SPACE_NR] = { (1UL << 63), "Kernel Space" },
+ [LOW_KERNEL_NR] = { 0UL, "Low Kernel Mapping" },
+ [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
+ [VMEMMAP_START_NR] = { 0UL, "Vmemmap" },
+#ifdef CONFIG_KASAN
+ /*
+ * These fields get initialized with the (dynamic)
+ * KASAN_SHADOW_{START,END} values in pt_dump_init().
+ */
+ [KASAN_SHADOW_START_NR] = { 0UL, "KASAN shadow" },
+ [KASAN_SHADOW_END_NR] = { 0UL, "KASAN shadow end" },
+#endif
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+ [LDT_NR] = { 0UL, "LDT remap" },
+#endif
+ [CPU_ENTRY_AREA_NR] = { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
+#ifdef CONFIG_X86_ESPFIX64
+ [ESPFIX_START_NR] = { ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
+#endif
+#ifdef CONFIG_EFI
+ [EFI_END_NR] = { EFI_VA_END, "EFI Runtime Services" },
+#endif
+ [HIGH_KERNEL_NR] = { __START_KERNEL_map, "High Kernel Mapping" },
+ [MODULES_VADDR_NR] = { MODULES_VADDR, "Modules" },
+ [MODULES_END_NR] = { MODULES_END, "End Modules" },
+ [FIXADDR_START_NR] = { FIXADDR_START, "Fixmap Area" },
+ [END_OF_SPACE_NR] = { -1, NULL }
+};
+
+#define INIT_PGD ((pgd_t *) &init_top_pgt)
+
+#else /* CONFIG_X86_64 */
+
+enum address_markers_idx {
+ USER_SPACE_NR = 0,
+ KERNEL_SPACE_NR,
+ VMALLOC_START_NR,
+ VMALLOC_END_NR,
+#ifdef CONFIG_HIGHMEM
+ PKMAP_BASE_NR,
+#endif
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+ LDT_NR,
+#endif
+ CPU_ENTRY_AREA_NR,
+ FIXADDR_START_NR,
+ END_OF_SPACE_NR,
+};
+
+static struct addr_marker address_markers[] = {
+ [USER_SPACE_NR] = { 0, "User Space" },
+ [KERNEL_SPACE_NR] = { PAGE_OFFSET, "Kernel Mapping" },
+ [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
+ [VMALLOC_END_NR] = { 0UL, "vmalloc() End" },
+#ifdef CONFIG_HIGHMEM
+ [PKMAP_BASE_NR] = { 0UL, "Persistent kmap() Area" },
+#endif
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+ [LDT_NR] = { 0UL, "LDT remap" },
+#endif
+ [CPU_ENTRY_AREA_NR] = { 0UL, "CPU entry area" },
+ [FIXADDR_START_NR] = { 0UL, "Fixmap area" },
+ [END_OF_SPACE_NR] = { -1, NULL }
+};
+
+#define INIT_PGD (swapper_pg_dir)
+
+#endif /* !CONFIG_X86_64 */
+
+/* Multipliers for offsets within the PTEs */
+#define PTE_LEVEL_MULT (PAGE_SIZE)
+#define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
+#define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
+#define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
+#define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
+
+#define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
+({ \
+ if (to_dmesg) \
+ printk(KERN_INFO fmt, ##args); \
+ else \
+ if (m) \
+ seq_printf(m, fmt, ##args); \
+})
+
+#define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
+({ \
+ if (to_dmesg) \
+ printk(KERN_CONT fmt, ##args); \
+ else \
+ if (m) \
+ seq_printf(m, fmt, ##args); \
+})
+
+/*
+ * Print a readable form of a pgprot_t to the seq_file
+ */
+static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg)
+{
+ static const char * const level_name[] =
+ { "pgd", "p4d", "pud", "pmd", "pte" };
+
+ if (!(pr & _PAGE_PRESENT)) {
+ /* Not present */
+ pt_dump_cont_printf(m, dmsg, " ");
+ } else {
+ if (pr & _PAGE_USER)
+ pt_dump_cont_printf(m, dmsg, "USR ");
+ else
+ pt_dump_cont_printf(m, dmsg, " ");
+ if (pr & _PAGE_RW)
+ pt_dump_cont_printf(m, dmsg, "RW ");
+ else
+ pt_dump_cont_printf(m, dmsg, "ro ");
+ if (pr & _PAGE_PWT)
+ pt_dump_cont_printf(m, dmsg, "PWT ");
+ else
+ pt_dump_cont_printf(m, dmsg, " ");
+ if (pr & _PAGE_PCD)
+ pt_dump_cont_printf(m, dmsg, "PCD ");
+ else
+ pt_dump_cont_printf(m, dmsg, " ");
+
+ /* Bit 7 has a different meaning on level 3 vs 4 */
+ if (level <= 3 && pr & _PAGE_PSE)
+ pt_dump_cont_printf(m, dmsg, "PSE ");
+ else
+ pt_dump_cont_printf(m, dmsg, " ");
+ if ((level == 4 && pr & _PAGE_PAT) ||
+ ((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
+ pt_dump_cont_printf(m, dmsg, "PAT ");
+ else
+ pt_dump_cont_printf(m, dmsg, " ");
+ if (pr & _PAGE_GLOBAL)
+ pt_dump_cont_printf(m, dmsg, "GLB ");
+ else
+ pt_dump_cont_printf(m, dmsg, " ");
+ if (pr & _PAGE_NX)
+ pt_dump_cont_printf(m, dmsg, "NX ");
+ else
+ pt_dump_cont_printf(m, dmsg, "x ");
+ }
+ pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
+}
+
+static void note_wx(struct pg_state *st, unsigned long addr)
+{
+ unsigned long npages;
+
+ npages = (addr - st->start_address) / PAGE_SIZE;
+
+#ifdef CONFIG_PCI_BIOS
+ /*
+ * If PCI BIOS is enabled, the PCI BIOS area is forced to WX.
+ * Inform about it, but avoid the warning.
+ */
+ if (pcibios_enabled && st->start_address >= PAGE_OFFSET + BIOS_BEGIN &&
+ addr <= PAGE_OFFSET + BIOS_END) {
+ pr_warn_once("x86/mm: PCI BIOS W+X mapping %lu pages\n", npages);
+ return;
+ }
+#endif
+ /* Account the WX pages */
+ st->wx_pages += npages;
+ WARN_ONCE(__supported_pte_mask & _PAGE_NX,
+ "x86/mm: Found insecure W+X mapping at address %pS\n",
+ (void *)st->start_address);
+}
+
+static void effective_prot(struct ptdump_state *pt_st, int level, u64 val)
+{
+ struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
+ pgprotval_t prot = val & PTE_FLAGS_MASK;
+ pgprotval_t effective;
+
+ if (level > 0) {
+ pgprotval_t higher_prot = st->prot_levels[level - 1];
+
+ effective = (higher_prot & prot & (_PAGE_USER | _PAGE_RW)) |
+ ((higher_prot | prot) & _PAGE_NX);
+ } else {
+ effective = prot;
+ }
+
+ st->prot_levels[level] = effective;
+}
+
+/*
+ * This function gets called on a break in a continuous series
+ * of PTE entries; the next one is different so we need to
+ * print what we collected so far.
+ */
+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);
+ pgprotval_t new_prot, new_eff;
+ pgprotval_t cur, eff;
+ static const char units[] = "BKMGTPE";
+ struct seq_file *m = st->seq;
+
+ new_prot = val & PTE_FLAGS_MASK;
+ if (!val)
+ new_eff = 0;
+ else
+ new_eff = st->prot_levels[level];
+
+ /*
+ * If we have a "break" in the series, we need to flush the state that
+ * we have now. "break" is either changing perms, levels or
+ * address space marker.
+ */
+ cur = st->current_prot;
+ eff = st->effective_prot;
+
+ if (st->level == -1) {
+ /* First entry */
+ st->current_prot = new_prot;
+ st->effective_prot = new_eff;
+ st->level = level;
+ st->marker = address_markers;
+ st->lines = 0;
+ pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
+ st->marker->name);
+ } else if (new_prot != cur || new_eff != eff || level != st->level ||
+ addr >= st->marker[1].start_address) {
+ const char *unit = units;
+ unsigned long delta;
+ int width = sizeof(unsigned long) * 2;
+
+ if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX))
+ note_wx(st, addr);
+
+ /*
+ * Now print the actual finished series
+ */
+ if (!st->marker->max_lines ||
+ st->lines < st->marker->max_lines) {
+ pt_dump_seq_printf(m, st->to_dmesg,
+ "0x%0*lx-0x%0*lx ",
+ width, st->start_address,
+ width, addr);
+
+ delta = addr - st->start_address;
+ while (!(delta & 1023) && unit[1]) {
+ delta >>= 10;
+ unit++;
+ }
+ pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
+ delta, *unit);
+ printk_prot(m, st->current_prot, st->level,
+ st->to_dmesg);
+ }
+ st->lines++;
+
+ /*
+ * We print markers for special areas of address space,
+ * such as the start of vmalloc space etc.
+ * This helps in the interpretation.
+ */
+ if (addr >= st->marker[1].start_address) {
+ if (st->marker->max_lines &&
+ st->lines > st->marker->max_lines) {
+ unsigned long nskip =
+ st->lines - st->marker->max_lines;
+ pt_dump_seq_printf(m, st->to_dmesg,
+ "... %lu entr%s skipped ... \n",
+ nskip,
+ nskip == 1 ? "y" : "ies");
+ }
+ st->marker++;
+ st->lines = 0;
+ pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
+ st->marker->name);
+ }
+
+ st->start_address = addr;
+ st->current_prot = new_prot;
+ st->effective_prot = new_eff;
+ st->level = level;
+ }
+}
+
+static void ptdump_walk_pgd_level_core(struct seq_file *m,
+ struct mm_struct *mm, pgd_t *pgd,
+ bool checkwx, bool dmesg)
+{
+ const struct ptdump_range ptdump_ranges[] = {
+#ifdef CONFIG_X86_64
+ {0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
+ {GUARD_HOLE_END_ADDR, ~0UL},
+#else
+ {0, ~0UL},
+#endif
+ {0, 0}
+};
+
+ struct pg_state st = {
+ .ptdump = {
+ .note_page = note_page,
+ .effective_prot = effective_prot,
+ .range = ptdump_ranges
+ },
+ .level = -1,
+ .to_dmesg = dmesg,
+ .check_wx = checkwx,
+ .seq = m
+ };
+
+ ptdump_walk_pgd(&st.ptdump, mm, pgd);
+
+ if (!checkwx)
+ return;
+ if (st.wx_pages)
+ pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
+ st.wx_pages);
+ else
+ pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
+}
+
+void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
+{
+ ptdump_walk_pgd_level_core(m, mm, mm->pgd, false, true);
+}
+
+void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
+ bool user)
+{
+ pgd_t *pgd = mm->pgd;
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+ if (user && boot_cpu_has(X86_FEATURE_PTI))
+ pgd = kernel_to_user_pgdp(pgd);
+#endif
+ ptdump_walk_pgd_level_core(m, mm, pgd, false, false);
+}
+EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
+
+void ptdump_walk_user_pgd_level_checkwx(void)
+{
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+ pgd_t *pgd = INIT_PGD;
+
+ if (!(__supported_pte_mask & _PAGE_NX) ||
+ !boot_cpu_has(X86_FEATURE_PTI))
+ return;
+
+ pr_info("x86/mm: Checking user space page tables\n");
+ pgd = kernel_to_user_pgdp(pgd);
+ ptdump_walk_pgd_level_core(NULL, &init_mm, pgd, true, false);
+#endif
+}
+
+void ptdump_walk_pgd_level_checkwx(void)
+{
+ ptdump_walk_pgd_level_core(NULL, &init_mm, INIT_PGD, true, false);
+}
+
+static int __init pt_dump_init(void)
+{
+ /*
+ * Various markers are not compile-time constants, so assign them
+ * here.
+ */
+#ifdef CONFIG_X86_64
+ address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
+ address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
+ address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+ address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
+#endif
+#ifdef CONFIG_KASAN
+ address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
+ address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
+#endif
+#endif
+#ifdef CONFIG_X86_32
+ address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
+ address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
+# ifdef CONFIG_HIGHMEM
+ address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
+# endif
+ address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
+ address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
+# ifdef CONFIG_MODIFY_LDT_SYSCALL
+ address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
+# endif
+#endif
+ return 0;
+}
+__initcall(pt_dump_init);
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