mirror of https://gitee.com/openkylin/linux.git
514 lines
13 KiB
C
514 lines
13 KiB
C
/*
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* Debug helper to dump the current kernel pagetables of the system
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* so that we can see what the various memory ranges are set to.
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*
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* (C) Copyright 2008 Intel Corporation
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*
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* Author: Arjan van de Ven <arjan@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*/
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#include <linux/debugfs.h>
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#include <linux/mm.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <asm/kasan.h>
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#include <asm/pgtable.h>
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/*
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* The dumper groups pagetable entries of the same type into one, and for
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* that it needs to keep some state when walking, and flush this state
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* when a "break" in the continuity is found.
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*/
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struct pg_state {
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int level;
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pgprot_t current_prot;
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unsigned long start_address;
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unsigned long current_address;
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const struct addr_marker *marker;
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unsigned long lines;
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bool to_dmesg;
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bool check_wx;
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unsigned long wx_pages;
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};
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struct addr_marker {
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unsigned long start_address;
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const char *name;
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unsigned long max_lines;
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};
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/* indices for address_markers; keep sync'd w/ address_markers below */
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enum address_markers_idx {
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USER_SPACE_NR = 0,
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#ifdef CONFIG_X86_64
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KERNEL_SPACE_NR,
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LOW_KERNEL_NR,
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VMALLOC_START_NR,
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VMEMMAP_START_NR,
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#ifdef CONFIG_KASAN
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KASAN_SHADOW_START_NR,
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KASAN_SHADOW_END_NR,
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#endif
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# ifdef CONFIG_X86_ESPFIX64
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ESPFIX_START_NR,
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# endif
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HIGH_KERNEL_NR,
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MODULES_VADDR_NR,
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MODULES_END_NR,
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#else
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KERNEL_SPACE_NR,
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VMALLOC_START_NR,
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VMALLOC_END_NR,
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# ifdef CONFIG_HIGHMEM
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PKMAP_BASE_NR,
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# endif
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FIXADDR_START_NR,
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#endif
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};
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/* Address space markers hints */
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static struct addr_marker address_markers[] = {
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{ 0, "User Space" },
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#ifdef CONFIG_X86_64
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{ 0x8000000000000000UL, "Kernel Space" },
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{ 0/* PAGE_OFFSET */, "Low Kernel Mapping" },
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{ 0/* VMALLOC_START */, "vmalloc() Area" },
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{ 0/* VMEMMAP_START */, "Vmemmap" },
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#ifdef CONFIG_KASAN
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{ KASAN_SHADOW_START, "KASAN shadow" },
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{ KASAN_SHADOW_END, "KASAN shadow end" },
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#endif
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# ifdef CONFIG_X86_ESPFIX64
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{ ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
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# endif
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# ifdef CONFIG_EFI
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{ EFI_VA_END, "EFI Runtime Services" },
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# endif
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{ __START_KERNEL_map, "High Kernel Mapping" },
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{ MODULES_VADDR, "Modules" },
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{ MODULES_END, "End Modules" },
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#else
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{ PAGE_OFFSET, "Kernel Mapping" },
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{ 0/* VMALLOC_START */, "vmalloc() Area" },
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{ 0/*VMALLOC_END*/, "vmalloc() End" },
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# ifdef CONFIG_HIGHMEM
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{ 0/*PKMAP_BASE*/, "Persistent kmap() Area" },
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# endif
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{ 0/*FIXADDR_START*/, "Fixmap Area" },
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#endif
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{ -1, NULL } /* End of list */
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};
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/* Multipliers for offsets within the PTEs */
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#define PTE_LEVEL_MULT (PAGE_SIZE)
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#define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
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#define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
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#define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
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#define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
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#define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
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({ \
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if (to_dmesg) \
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printk(KERN_INFO fmt, ##args); \
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else \
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if (m) \
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seq_printf(m, fmt, ##args); \
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})
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#define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
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({ \
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if (to_dmesg) \
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printk(KERN_CONT fmt, ##args); \
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else \
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if (m) \
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seq_printf(m, fmt, ##args); \
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})
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/*
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* Print a readable form of a pgprot_t to the seq_file
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*/
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static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
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{
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pgprotval_t pr = pgprot_val(prot);
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static const char * const level_name[] =
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{ "cr3", "pgd", "pud", "pmd", "pte" };
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if (!pgprot_val(prot)) {
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/* Not present */
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pt_dump_cont_printf(m, dmsg, " ");
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} else {
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if (pr & _PAGE_USER)
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pt_dump_cont_printf(m, dmsg, "USR ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if (pr & _PAGE_RW)
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pt_dump_cont_printf(m, dmsg, "RW ");
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else
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pt_dump_cont_printf(m, dmsg, "ro ");
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if (pr & _PAGE_PWT)
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pt_dump_cont_printf(m, dmsg, "PWT ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if (pr & _PAGE_PCD)
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pt_dump_cont_printf(m, dmsg, "PCD ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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/* Bit 7 has a different meaning on level 3 vs 4 */
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if (level <= 3 && pr & _PAGE_PSE)
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pt_dump_cont_printf(m, dmsg, "PSE ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if ((level == 4 && pr & _PAGE_PAT) ||
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((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
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pt_dump_cont_printf(m, dmsg, "PAT ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if (pr & _PAGE_GLOBAL)
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pt_dump_cont_printf(m, dmsg, "GLB ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if (pr & _PAGE_NX)
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pt_dump_cont_printf(m, dmsg, "NX ");
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else
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pt_dump_cont_printf(m, dmsg, "x ");
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}
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pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
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}
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/*
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* On 64 bits, sign-extend the 48 bit address to 64 bit
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*/
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static unsigned long normalize_addr(unsigned long u)
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{
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#ifdef CONFIG_X86_64
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return (signed long)(u << 16) >> 16;
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#else
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return u;
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#endif
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}
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/*
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* This function gets called on a break in a continuous series
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* of PTE entries; the next one is different so we need to
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* print what we collected so far.
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*/
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static void note_page(struct seq_file *m, struct pg_state *st,
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pgprot_t new_prot, int level)
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{
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pgprotval_t prot, cur;
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static const char units[] = "BKMGTPE";
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/*
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* If we have a "break" in the series, we need to flush the state that
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* we have now. "break" is either changing perms, levels or
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* address space marker.
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*/
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prot = pgprot_val(new_prot);
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cur = pgprot_val(st->current_prot);
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if (!st->level) {
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/* First entry */
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st->current_prot = new_prot;
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st->level = level;
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st->marker = address_markers;
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st->lines = 0;
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pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
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st->marker->name);
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} else if (prot != cur || level != st->level ||
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st->current_address >= st->marker[1].start_address) {
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const char *unit = units;
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unsigned long delta;
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int width = sizeof(unsigned long) * 2;
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pgprotval_t pr = pgprot_val(st->current_prot);
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if (st->check_wx && (pr & _PAGE_RW) && !(pr & _PAGE_NX)) {
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WARN_ONCE(1,
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"x86/mm: Found insecure W+X mapping at address %p/%pS\n",
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(void *)st->start_address,
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(void *)st->start_address);
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st->wx_pages += (st->current_address -
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st->start_address) / PAGE_SIZE;
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}
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/*
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* Now print the actual finished series
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*/
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if (!st->marker->max_lines ||
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st->lines < st->marker->max_lines) {
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pt_dump_seq_printf(m, st->to_dmesg,
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"0x%0*lx-0x%0*lx ",
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width, st->start_address,
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width, st->current_address);
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delta = st->current_address - st->start_address;
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while (!(delta & 1023) && unit[1]) {
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delta >>= 10;
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unit++;
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}
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pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
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delta, *unit);
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printk_prot(m, st->current_prot, st->level,
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st->to_dmesg);
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}
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st->lines++;
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/*
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* We print markers for special areas of address space,
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* such as the start of vmalloc space etc.
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* This helps in the interpretation.
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*/
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if (st->current_address >= st->marker[1].start_address) {
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if (st->marker->max_lines &&
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st->lines > st->marker->max_lines) {
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unsigned long nskip =
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st->lines - st->marker->max_lines;
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pt_dump_seq_printf(m, st->to_dmesg,
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"... %lu entr%s skipped ... \n",
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nskip,
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nskip == 1 ? "y" : "ies");
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}
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st->marker++;
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st->lines = 0;
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pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
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st->marker->name);
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}
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st->start_address = st->current_address;
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st->current_prot = new_prot;
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st->level = level;
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}
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}
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static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, unsigned long P)
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{
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int i;
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pte_t *start;
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pgprotval_t prot;
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start = (pte_t *)pmd_page_vaddr(addr);
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for (i = 0; i < PTRS_PER_PTE; i++) {
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prot = pte_flags(*start);
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st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
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note_page(m, st, __pgprot(prot), 4);
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start++;
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}
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}
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#if PTRS_PER_PMD > 1
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static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, unsigned long P)
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{
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int i;
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pmd_t *start;
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pgprotval_t prot;
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start = (pmd_t *)pud_page_vaddr(addr);
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for (i = 0; i < PTRS_PER_PMD; i++) {
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st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
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if (!pmd_none(*start)) {
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if (pmd_large(*start) || !pmd_present(*start)) {
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prot = pmd_flags(*start);
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note_page(m, st, __pgprot(prot), 3);
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} else {
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walk_pte_level(m, st, *start,
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P + i * PMD_LEVEL_MULT);
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}
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} else
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note_page(m, st, __pgprot(0), 3);
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start++;
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}
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}
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#else
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#define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
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#define pud_large(a) pmd_large(__pmd(pud_val(a)))
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#define pud_none(a) pmd_none(__pmd(pud_val(a)))
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#endif
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#if PTRS_PER_PUD > 1
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/*
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* This is an optimization for CONFIG_DEBUG_WX=y + CONFIG_KASAN=y
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* KASAN fills page tables with the same values. Since there is no
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* point in checking page table more than once we just skip repeated
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* entries. This saves us dozens of seconds during boot.
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*/
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static bool pud_already_checked(pud_t *prev_pud, pud_t *pud, bool checkwx)
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{
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return checkwx && prev_pud && (pud_val(*prev_pud) == pud_val(*pud));
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}
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static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr, unsigned long P)
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{
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int i;
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pud_t *start;
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pgprotval_t prot;
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pud_t *prev_pud = NULL;
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start = (pud_t *)p4d_page_vaddr(addr);
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for (i = 0; i < PTRS_PER_PUD; i++) {
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st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
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if (!pud_none(*start) &&
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!pud_already_checked(prev_pud, start, st->check_wx)) {
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if (pud_large(*start) || !pud_present(*start)) {
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prot = pud_flags(*start);
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note_page(m, st, __pgprot(prot), 2);
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} else {
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walk_pmd_level(m, st, *start,
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P + i * PUD_LEVEL_MULT);
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}
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} else
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note_page(m, st, __pgprot(0), 2);
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prev_pud = start;
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start++;
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}
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}
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#else
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#define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(p4d_val(a)),p)
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#define p4d_large(a) pud_large(__pud(p4d_val(a)))
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#define p4d_none(a) pud_none(__pud(p4d_val(a)))
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#endif
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#if PTRS_PER_P4D > 1
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static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr, unsigned long P)
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{
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int i;
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p4d_t *start;
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pgprotval_t prot;
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start = (p4d_t *)pgd_page_vaddr(addr);
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for (i = 0; i < PTRS_PER_P4D; i++) {
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st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT);
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if (!p4d_none(*start)) {
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if (p4d_large(*start) || !p4d_present(*start)) {
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prot = p4d_flags(*start);
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note_page(m, st, __pgprot(prot), 2);
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} else {
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walk_pud_level(m, st, *start,
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P + i * P4D_LEVEL_MULT);
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}
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} else
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note_page(m, st, __pgprot(0), 2);
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start++;
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}
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}
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#else
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#define walk_p4d_level(m,s,a,p) walk_pud_level(m,s,__p4d(pgd_val(a)),p)
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#define pgd_large(a) p4d_large(__p4d(pgd_val(a)))
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#define pgd_none(a) p4d_none(__p4d(pgd_val(a)))
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#endif
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static inline bool is_hypervisor_range(int idx)
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{
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#ifdef CONFIG_X86_64
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/*
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* ffff800000000000 - ffff87ffffffffff is reserved for
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* the hypervisor.
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*/
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return (idx >= pgd_index(__PAGE_OFFSET) - 16) &&
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(idx < pgd_index(__PAGE_OFFSET));
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#else
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return false;
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#endif
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}
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static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
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bool checkwx)
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{
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#ifdef CONFIG_X86_64
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pgd_t *start = (pgd_t *) &init_level4_pgt;
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#else
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pgd_t *start = swapper_pg_dir;
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#endif
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pgprotval_t prot;
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int i;
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struct pg_state st = {};
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if (pgd) {
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start = pgd;
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st.to_dmesg = true;
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}
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st.check_wx = checkwx;
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if (checkwx)
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st.wx_pages = 0;
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for (i = 0; i < PTRS_PER_PGD; i++) {
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st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
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if (!pgd_none(*start) && !is_hypervisor_range(i)) {
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if (pgd_large(*start) || !pgd_present(*start)) {
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prot = pgd_flags(*start);
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note_page(m, &st, __pgprot(prot), 1);
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} else {
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walk_p4d_level(m, &st, *start,
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i * PGD_LEVEL_MULT);
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}
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} else
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note_page(m, &st, __pgprot(0), 1);
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cond_resched();
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start++;
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}
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/* Flush out the last page */
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st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
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note_page(m, &st, __pgprot(0), 0);
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if (!checkwx)
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return;
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if (st.wx_pages)
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pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
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st.wx_pages);
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else
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pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
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}
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void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
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{
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ptdump_walk_pgd_level_core(m, pgd, false);
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}
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EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level);
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void ptdump_walk_pgd_level_checkwx(void)
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{
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ptdump_walk_pgd_level_core(NULL, NULL, true);
|
|
}
|
|
|
|
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;
|
|
#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;
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
__initcall(pt_dump_init);
|