296 lines
8.0 KiB
C
296 lines
8.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/set_memory.h>
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#include <linux/ptdump.h>
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#include <linux/seq_file.h>
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#include <linux/debugfs.h>
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#include <linux/mm.h>
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#include <linux/kfence.h>
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#include <linux/kasan.h>
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#include <asm/ptdump.h>
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#include <asm/kasan.h>
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#include <asm/nospec-branch.h>
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#include <asm/sections.h>
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static unsigned long max_addr;
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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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enum address_markers_idx {
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IDENTITY_BEFORE_NR = 0,
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IDENTITY_BEFORE_END_NR,
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KERNEL_START_NR,
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KERNEL_END_NR,
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#ifdef CONFIG_KFENCE
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KFENCE_START_NR,
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KFENCE_END_NR,
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#endif
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IDENTITY_AFTER_NR,
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IDENTITY_AFTER_END_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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VMEMMAP_NR,
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VMEMMAP_END_NR,
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VMALLOC_NR,
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VMALLOC_END_NR,
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MODULES_NR,
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MODULES_END_NR,
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};
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static struct addr_marker address_markers[] = {
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[IDENTITY_BEFORE_NR] = {0, "Identity Mapping Start"},
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[IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"},
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[KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"},
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[KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"},
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#ifdef CONFIG_KFENCE
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[KFENCE_START_NR] = {0, "KFence Pool Start"},
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[KFENCE_END_NR] = {0, "KFence Pool End"},
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#endif
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[IDENTITY_AFTER_NR] = {(unsigned long)_end, "Identity Mapping Start"},
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[IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"},
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#ifdef CONFIG_KASAN
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[KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
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[KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"},
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#endif
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[VMEMMAP_NR] = {0, "vmemmap Area Start"},
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[VMEMMAP_END_NR] = {0, "vmemmap Area End"},
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[VMALLOC_NR] = {0, "vmalloc Area Start"},
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[VMALLOC_END_NR] = {0, "vmalloc Area End"},
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[MODULES_NR] = {0, "Modules Area Start"},
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[MODULES_END_NR] = {0, "Modules Area End"},
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{ -1, NULL }
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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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int level;
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unsigned int current_prot;
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bool check_wx;
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unsigned long wx_pages;
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unsigned long start_address;
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const struct addr_marker *marker;
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};
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#define pt_dump_seq_printf(m, fmt, args...) \
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({ \
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struct seq_file *__m = (m); \
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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_puts(m, fmt) \
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({ \
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struct seq_file *__m = (m); \
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\
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if (__m) \
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seq_printf(__m, fmt); \
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})
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static void print_prot(struct seq_file *m, unsigned int pr, int level)
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{
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static const char * const level_name[] =
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{ "ASCE", "PGD", "PUD", "PMD", "PTE" };
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pt_dump_seq_printf(m, "%s ", level_name[level]);
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if (pr & _PAGE_INVALID) {
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pt_dump_seq_printf(m, "I\n");
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return;
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}
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pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
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pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
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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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#ifdef CONFIG_DEBUG_WX
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if (!st->check_wx)
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return;
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if (st->current_prot & _PAGE_INVALID)
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return;
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if (st->current_prot & _PAGE_PROTECT)
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return;
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if (st->current_prot & _PAGE_NOEXEC)
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return;
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/*
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* The first lowcore page is W+X if spectre mitigations are using
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* trampolines or the BEAR enhancements facility is not installed,
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* in which case we have two lpswe instructions in lowcore that need
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* to be executable.
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*/
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if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)))
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return;
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WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
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(void *)st->start_address);
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st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
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#endif /* CONFIG_DEBUG_WX */
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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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int width = sizeof(unsigned long) * 2;
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static const char units[] = "KMGTPE";
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const char *unit = units;
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unsigned long delta;
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struct pg_state *st;
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struct seq_file *m;
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unsigned int prot;
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st = container_of(pt_st, struct pg_state, ptdump);
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m = st->seq;
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prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
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if (level == 4 && (val & _PAGE_INVALID))
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prot = _PAGE_INVALID;
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/* For pmd_none() & friends val gets passed as zero. */
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if (level != 4 && !val)
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prot = _PAGE_INVALID;
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/* Final flush from generic code. */
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if (level == -1)
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addr = max_addr;
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if (st->level == -1) {
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pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
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st->start_address = addr;
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st->current_prot = prot;
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st->level = level;
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} else if (prot != st->current_prot || level != st->level ||
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addr >= st->marker[1].start_address) {
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note_prot_wx(st, addr);
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pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
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width, st->start_address,
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width, addr);
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delta = (addr - st->start_address) >> 10;
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while (!(delta & 0x3ff) && unit[1]) {
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delta >>= 10;
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unit++;
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}
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pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
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print_prot(m, st->current_prot, st->level);
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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(m, "---[ %s ]---\n", st->marker->name);
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}
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st->start_address = addr;
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st->current_prot = prot;
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st->level = level;
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}
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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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.ptdump = {
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.note_page = note_page,
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.range = (struct ptdump_range[]) {
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{.start = 0, .end = max_addr},
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{.start = 0, .end = 0},
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}
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},
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.seq = NULL,
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.level = -1,
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.current_prot = 0,
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.check_wx = true,
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.wx_pages = 0,
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.start_address = 0,
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.marker = (struct addr_marker[]) {
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{ .start_address = 0, .name = NULL},
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{ .start_address = -1, .name = NULL},
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},
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};
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if (!MACHINE_HAS_NX)
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return;
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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", st.wx_pages);
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else
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pr_info("Checked W+X mappings: passed, no %sW+X pages found\n",
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(nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ?
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"unexpected " : "");
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}
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#endif /* CONFIG_DEBUG_WX */
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#ifdef CONFIG_PTDUMP_DEBUGFS
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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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.ptdump = {
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.note_page = note_page,
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.range = (struct ptdump_range[]) {
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{.start = 0, .end = max_addr},
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{.start = 0, .end = 0},
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}
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},
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.seq = m,
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.level = -1,
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.current_prot = 0,
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.check_wx = false,
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.wx_pages = 0,
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.start_address = 0,
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.marker = address_markers,
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};
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get_online_mems();
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mutex_lock(&cpa_mutex);
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ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
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mutex_unlock(&cpa_mutex);
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put_online_mems();
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return 0;
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}
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DEFINE_SHOW_ATTRIBUTE(ptdump);
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#endif /* CONFIG_PTDUMP_DEBUGFS */
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/*
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* Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
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* insertion sort to preserve the original order of markers with the same
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* start address.
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*/
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static void sort_address_markers(void)
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{
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struct addr_marker tmp;
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int i, j;
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for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
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tmp = address_markers[i];
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for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
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address_markers[j + 1] = address_markers[j];
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address_markers[j + 1] = tmp;
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}
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}
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static int pt_dump_init(void)
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{
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#ifdef CONFIG_KFENCE
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unsigned long kfence_start = (unsigned long)__kfence_pool;
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#endif
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/*
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* Figure out the maximum virtual address being accessible with the
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* kernel ASCE. We need this to keep the page table walker functions
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* from accessing non-existent entries.
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*/
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max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
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max_addr = 1UL << (max_addr * 11 + 31);
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address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size;
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address_markers[MODULES_NR].start_address = MODULES_VADDR;
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address_markers[MODULES_END_NR].start_address = MODULES_END;
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address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
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address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size;
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address_markers[VMALLOC_NR].start_address = VMALLOC_START;
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address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
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#ifdef CONFIG_KFENCE
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address_markers[KFENCE_START_NR].start_address = kfence_start;
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address_markers[KFENCE_END_NR].start_address = kfence_start + KFENCE_POOL_SIZE;
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#endif
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sort_address_markers();
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#ifdef CONFIG_PTDUMP_DEBUGFS
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debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
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#endif /* CONFIG_PTDUMP_DEBUGFS */
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return 0;
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}
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device_initcall(pt_dump_init);
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