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374 lines
9.4 KiB
374 lines
9.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright 2016, Rashmica Gupta, IBM Corp. |
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* |
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* This traverses the kernel pagetables and dumps the |
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* information about the used sections of memory to |
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* /sys/kernel/debug/kernel_pagetables. |
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* |
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* Derived from the arm64 implementation: |
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* Copyright (c) 2014, The Linux Foundation, Laura Abbott. |
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* (C) Copyright 2008 Intel Corporation, Arjan van de Ven. |
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*/ |
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#include <linux/debugfs.h> |
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#include <linux/fs.h> |
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#include <linux/hugetlb.h> |
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#include <linux/io.h> |
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#include <linux/mm.h> |
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#include <linux/highmem.h> |
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#include <linux/ptdump.h> |
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#include <linux/sched.h> |
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#include <linux/seq_file.h> |
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#include <asm/fixmap.h> |
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#include <linux/const.h> |
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#include <asm/page.h> |
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#include <asm/hugetlb.h> |
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#include <mm/mmu_decl.h> |
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#include "ptdump.h" |
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/* |
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* To visualise what is happening, |
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* |
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* - PTRS_PER_P** = how many entries there are in the corresponding P** |
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* - P**_SHIFT = how many bits of the address we use to index into the |
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* corresponding P** |
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* - P**_SIZE is how much memory we can access through the table - not the |
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* size of the table itself. |
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* P**={PGD, PUD, PMD, PTE} |
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* |
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* |
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* Each entry of the PGD points to a PUD. Each entry of a PUD points to a |
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* PMD. Each entry of a PMD points to a PTE. And every PTE entry points to |
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* a page. |
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* |
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* In the case where there are only 3 levels, the PUD is folded into the |
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* PGD: every PUD has only one entry which points to the PMD. |
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* |
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* The page dumper groups page table entries of the same type into a single |
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* description. It uses pg_state to track the range information while |
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* iterating over the PTE entries. When the continuity is broken it then |
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* dumps out a description of the range - ie PTEs that are virtually contiguous |
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* with the same PTE flags are chunked together. This is to make it clear how |
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* different areas of the kernel virtual memory are used. |
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* |
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*/ |
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struct pg_state { |
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struct ptdump_state ptdump; |
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struct seq_file *seq; |
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const struct addr_marker *marker; |
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unsigned long start_address; |
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unsigned long start_pa; |
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int level; |
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u64 current_flags; |
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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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}; |
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static struct addr_marker address_markers[] = { |
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{ 0, "Start of kernel VM" }, |
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#ifdef MODULES_VADDR |
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{ 0, "modules start" }, |
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{ 0, "modules end" }, |
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#endif |
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{ 0, "vmalloc() Area" }, |
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{ 0, "vmalloc() End" }, |
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#ifdef CONFIG_PPC64 |
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{ 0, "isa I/O start" }, |
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{ 0, "isa I/O end" }, |
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{ 0, "phb I/O start" }, |
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{ 0, "phb I/O end" }, |
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{ 0, "I/O remap start" }, |
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{ 0, "I/O remap end" }, |
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{ 0, "vmemmap start" }, |
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#else |
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{ 0, "Early I/O remap start" }, |
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{ 0, "Early I/O remap end" }, |
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#ifdef CONFIG_HIGHMEM |
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{ 0, "Highmem PTEs start" }, |
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{ 0, "Highmem PTEs end" }, |
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#endif |
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{ 0, "Fixmap start" }, |
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{ 0, "Fixmap end" }, |
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#endif |
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#ifdef CONFIG_KASAN |
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{ 0, "kasan shadow mem start" }, |
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{ 0, "kasan shadow mem end" }, |
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#endif |
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{ -1, NULL }, |
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}; |
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static struct ptdump_range ptdump_range[] __ro_after_init = { |
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{TASK_SIZE_MAX, ~0UL}, |
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{0, 0} |
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}; |
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#define pt_dump_seq_printf(m, fmt, args...) \ |
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({ \ |
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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_seq_putc(m, c) \ |
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({ \ |
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if (m) \ |
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seq_putc(m, c); \ |
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}) |
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void pt_dump_size(struct seq_file *m, unsigned long size) |
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{ |
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static const char units[] = "KMGTPE"; |
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const char *unit = units; |
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/* Work out what appropriate unit to use */ |
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while (!(size & 1023) && unit[1]) { |
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size >>= 10; |
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unit++; |
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} |
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pt_dump_seq_printf(m, "%9lu%c ", size, *unit); |
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} |
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static void dump_flag_info(struct pg_state *st, const struct flag_info |
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*flag, u64 pte, int num) |
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{ |
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unsigned int i; |
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for (i = 0; i < num; i++, flag++) { |
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const char *s = NULL; |
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u64 val; |
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/* flag not defined so don't check it */ |
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if (flag->mask == 0) |
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continue; |
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/* Some 'flags' are actually values */ |
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if (flag->is_val) { |
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val = pte & flag->val; |
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if (flag->shift) |
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val = val >> flag->shift; |
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pt_dump_seq_printf(st->seq, " %s:%llx", flag->set, val); |
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} else { |
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if ((pte & flag->mask) == flag->val) |
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s = flag->set; |
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else |
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s = flag->clear; |
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if (s) |
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pt_dump_seq_printf(st->seq, " %s", s); |
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} |
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st->current_flags &= ~flag->mask; |
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} |
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if (st->current_flags != 0) |
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pt_dump_seq_printf(st->seq, " unknown flags:%llx", st->current_flags); |
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} |
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static void dump_addr(struct pg_state *st, unsigned long addr) |
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{ |
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#ifdef CONFIG_PPC64 |
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#define REG "0x%016lx" |
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#else |
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#define REG "0x%08lx" |
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#endif |
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pt_dump_seq_printf(st->seq, REG "-" REG " ", st->start_address, addr - 1); |
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pt_dump_seq_printf(st->seq, " " REG " ", st->start_pa); |
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pt_dump_size(st->seq, (addr - st->start_address) >> 10); |
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} |
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static void note_prot_wx(struct pg_state *st, unsigned long addr) |
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{ |
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pte_t pte = __pte(st->current_flags); |
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if (!IS_ENABLED(CONFIG_PPC_DEBUG_WX) || !st->check_wx) |
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return; |
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if (!pte_write(pte) || !pte_exec(pte)) |
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return; |
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WARN_ONCE(1, "powerpc/mm: Found insecure W+X mapping at address %p/%pS\n", |
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(void *)st->start_address, (void *)st->start_address); |
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st->wx_pages += (addr - st->start_address) / PAGE_SIZE; |
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} |
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static void note_page_update_state(struct pg_state *st, unsigned long addr, int level, u64 val) |
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{ |
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u64 flag = level >= 0 ? val & pg_level[level].mask : 0; |
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u64 pa = val & PTE_RPN_MASK; |
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st->level = level; |
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st->current_flags = flag; |
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st->start_address = addr; |
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st->start_pa = pa; |
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while (addr >= st->marker[1].start_address) { |
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st->marker++; |
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pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
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} |
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} |
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static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val) |
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{ |
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u64 flag = level >= 0 ? val & pg_level[level].mask : 0; |
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struct pg_state *st = container_of(pt_st, struct pg_state, ptdump); |
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/* At first no level is set */ |
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if (st->level == -1) { |
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pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
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note_page_update_state(st, addr, level, val); |
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/* |
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* Dump the section of virtual memory when: |
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* - the PTE flags from one entry to the next differs. |
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* - we change levels in the tree. |
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* - the address is in a different section of memory and is thus |
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* used for a different purpose, regardless of the flags. |
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*/ |
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} else if (flag != st->current_flags || level != st->level || |
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addr >= st->marker[1].start_address) { |
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/* Check the PTE flags */ |
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if (st->current_flags) { |
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note_prot_wx(st, addr); |
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dump_addr(st, addr); |
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/* Dump all the flags */ |
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if (pg_level[st->level].flag) |
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dump_flag_info(st, pg_level[st->level].flag, |
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st->current_flags, |
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pg_level[st->level].num); |
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pt_dump_seq_putc(st->seq, '\n'); |
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} |
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/* |
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* Address indicates we have passed the end of the |
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* current section of virtual memory |
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*/ |
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note_page_update_state(st, addr, level, val); |
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} |
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} |
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static void populate_markers(void) |
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{ |
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int i = 0; |
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#ifdef CONFIG_PPC64 |
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address_markers[i++].start_address = PAGE_OFFSET; |
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#else |
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address_markers[i++].start_address = TASK_SIZE; |
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#endif |
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#ifdef MODULES_VADDR |
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address_markers[i++].start_address = MODULES_VADDR; |
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address_markers[i++].start_address = MODULES_END; |
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#endif |
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address_markers[i++].start_address = VMALLOC_START; |
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address_markers[i++].start_address = VMALLOC_END; |
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#ifdef CONFIG_PPC64 |
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address_markers[i++].start_address = ISA_IO_BASE; |
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address_markers[i++].start_address = ISA_IO_END; |
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address_markers[i++].start_address = PHB_IO_BASE; |
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address_markers[i++].start_address = PHB_IO_END; |
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address_markers[i++].start_address = IOREMAP_BASE; |
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address_markers[i++].start_address = IOREMAP_END; |
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/* What is the ifdef about? */ |
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#ifdef CONFIG_PPC_BOOK3S_64 |
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address_markers[i++].start_address = H_VMEMMAP_START; |
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#else |
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address_markers[i++].start_address = VMEMMAP_BASE; |
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#endif |
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#else /* !CONFIG_PPC64 */ |
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address_markers[i++].start_address = ioremap_bot; |
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address_markers[i++].start_address = IOREMAP_TOP; |
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#ifdef CONFIG_HIGHMEM |
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address_markers[i++].start_address = PKMAP_BASE; |
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address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP); |
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#endif |
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address_markers[i++].start_address = FIXADDR_START; |
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address_markers[i++].start_address = FIXADDR_TOP; |
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#ifdef CONFIG_KASAN |
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address_markers[i++].start_address = KASAN_SHADOW_START; |
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address_markers[i++].start_address = KASAN_SHADOW_END; |
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#endif |
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#endif /* CONFIG_PPC64 */ |
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} |
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static int ptdump_show(struct seq_file *m, void *v) |
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{ |
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struct pg_state st = { |
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.seq = m, |
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.marker = address_markers, |
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.level = -1, |
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.ptdump = { |
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.note_page = note_page, |
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.range = ptdump_range, |
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} |
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}; |
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/* Traverse kernel page tables */ |
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ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); |
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return 0; |
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} |
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DEFINE_SHOW_ATTRIBUTE(ptdump); |
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static void build_pgtable_complete_mask(void) |
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{ |
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unsigned int i, j; |
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for (i = 0; i < ARRAY_SIZE(pg_level); i++) |
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if (pg_level[i].flag) |
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for (j = 0; j < pg_level[i].num; j++) |
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pg_level[i].mask |= pg_level[i].flag[j].mask; |
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} |
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#ifdef CONFIG_DEBUG_WX |
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void ptdump_check_wx(void) |
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{ |
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struct pg_state st = { |
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.seq = NULL, |
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.marker = (struct addr_marker[]) { |
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{ 0, NULL}, |
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{ -1, NULL}, |
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}, |
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.level = -1, |
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.check_wx = true, |
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.ptdump = { |
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.note_page = note_page, |
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.range = ptdump_range, |
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} |
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}; |
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ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); |
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if (st.wx_pages) |
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pr_warn("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("Checked W+X mappings: passed, no W+X pages found\n"); |
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} |
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#endif |
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static int __init ptdump_init(void) |
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{ |
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#ifdef CONFIG_PPC64 |
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if (!radix_enabled()) |
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ptdump_range[0].start = KERN_VIRT_START; |
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else |
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ptdump_range[0].start = PAGE_OFFSET; |
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ptdump_range[0].end = PAGE_OFFSET + (PGDIR_SIZE * PTRS_PER_PGD); |
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#endif |
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populate_markers(); |
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build_pgtable_complete_mask(); |
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if (IS_ENABLED(CONFIG_PTDUMP_DEBUGFS)) |
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debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops); |
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return 0; |
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} |
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device_initcall(ptdump_init);
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