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-rw-r--r--arch/s390/mm/dump_pagetables.c315
1 files changed, 315 insertions, 0 deletions
diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c
new file mode 100644
index 0000000000..b51666967a
--- /dev/null
+++ b/arch/s390/mm/dump_pagetables.c
@@ -0,0 +1,315 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/set_memory.h>
+#include <linux/ptdump.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include <linux/mm.h>
+#include <linux/kfence.h>
+#include <linux/kasan.h>
+#include <asm/ptdump.h>
+#include <asm/kasan.h>
+#include <asm/abs_lowcore.h>
+#include <asm/nospec-branch.h>
+#include <asm/sections.h>
+#include <asm/maccess.h>
+
+static unsigned long max_addr;
+
+struct addr_marker {
+ unsigned long start_address;
+ const char *name;
+};
+
+enum address_markers_idx {
+ IDENTITY_BEFORE_NR = 0,
+ IDENTITY_BEFORE_END_NR,
+ AMODE31_START_NR,
+ AMODE31_END_NR,
+ KERNEL_START_NR,
+ KERNEL_END_NR,
+#ifdef CONFIG_KFENCE
+ KFENCE_START_NR,
+ KFENCE_END_NR,
+#endif
+ IDENTITY_AFTER_NR,
+ IDENTITY_AFTER_END_NR,
+ VMEMMAP_NR,
+ VMEMMAP_END_NR,
+ VMALLOC_NR,
+ VMALLOC_END_NR,
+ MODULES_NR,
+ MODULES_END_NR,
+ ABS_LOWCORE_NR,
+ ABS_LOWCORE_END_NR,
+ MEMCPY_REAL_NR,
+ MEMCPY_REAL_END_NR,
+#ifdef CONFIG_KASAN
+ KASAN_SHADOW_START_NR,
+ KASAN_SHADOW_END_NR,
+#endif
+};
+
+static struct addr_marker address_markers[] = {
+ [IDENTITY_BEFORE_NR] = {0, "Identity Mapping Start"},
+ [IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"},
+ [AMODE31_START_NR] = {0, "Amode31 Area Start"},
+ [AMODE31_END_NR] = {0, "Amode31 Area End"},
+ [KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"},
+ [KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"},
+#ifdef CONFIG_KFENCE
+ [KFENCE_START_NR] = {0, "KFence Pool Start"},
+ [KFENCE_END_NR] = {0, "KFence Pool End"},
+#endif
+ [IDENTITY_AFTER_NR] = {(unsigned long)_end, "Identity Mapping Start"},
+ [IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"},
+ [VMEMMAP_NR] = {0, "vmemmap Area Start"},
+ [VMEMMAP_END_NR] = {0, "vmemmap Area End"},
+ [VMALLOC_NR] = {0, "vmalloc Area Start"},
+ [VMALLOC_END_NR] = {0, "vmalloc Area End"},
+ [MODULES_NR] = {0, "Modules Area Start"},
+ [MODULES_END_NR] = {0, "Modules Area End"},
+ [ABS_LOWCORE_NR] = {0, "Lowcore Area Start"},
+ [ABS_LOWCORE_END_NR] = {0, "Lowcore Area End"},
+ [MEMCPY_REAL_NR] = {0, "Real Memory Copy Area Start"},
+ [MEMCPY_REAL_END_NR] = {0, "Real Memory Copy Area End"},
+#ifdef CONFIG_KASAN
+ [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
+ [KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"},
+#endif
+ { -1, NULL }
+};
+
+struct pg_state {
+ struct ptdump_state ptdump;
+ struct seq_file *seq;
+ int level;
+ unsigned int current_prot;
+ bool check_wx;
+ unsigned long wx_pages;
+ unsigned long start_address;
+ const struct addr_marker *marker;
+};
+
+#define pt_dump_seq_printf(m, fmt, args...) \
+({ \
+ struct seq_file *__m = (m); \
+ \
+ if (__m) \
+ seq_printf(__m, fmt, ##args); \
+})
+
+#define pt_dump_seq_puts(m, fmt) \
+({ \
+ struct seq_file *__m = (m); \
+ \
+ if (__m) \
+ seq_printf(__m, fmt); \
+})
+
+static void print_prot(struct seq_file *m, unsigned int pr, int level)
+{
+ static const char * const level_name[] =
+ { "ASCE", "PGD", "PUD", "PMD", "PTE" };
+
+ pt_dump_seq_printf(m, "%s ", level_name[level]);
+ if (pr & _PAGE_INVALID) {
+ pt_dump_seq_printf(m, "I\n");
+ return;
+ }
+ pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
+ pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
+}
+
+static void note_prot_wx(struct pg_state *st, unsigned long addr)
+{
+#ifdef CONFIG_DEBUG_WX
+ if (!st->check_wx)
+ return;
+ if (st->current_prot & _PAGE_INVALID)
+ return;
+ if (st->current_prot & _PAGE_PROTECT)
+ return;
+ if (st->current_prot & _PAGE_NOEXEC)
+ return;
+ /*
+ * The first lowcore page is W+X if spectre mitigations are using
+ * trampolines or the BEAR enhancements facility is not installed,
+ * in which case we have two lpswe instructions in lowcore that need
+ * to be executable.
+ */
+ if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)))
+ return;
+ WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
+ (void *)st->start_address);
+ st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
+#endif /* CONFIG_DEBUG_WX */
+}
+
+static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
+{
+ int width = sizeof(unsigned long) * 2;
+ static const char units[] = "KMGTPE";
+ const char *unit = units;
+ unsigned long delta;
+ struct pg_state *st;
+ struct seq_file *m;
+ unsigned int prot;
+
+ st = container_of(pt_st, struct pg_state, ptdump);
+ m = st->seq;
+ prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
+ if (level == 4 && (val & _PAGE_INVALID))
+ prot = _PAGE_INVALID;
+ /* For pmd_none() & friends val gets passed as zero. */
+ if (level != 4 && !val)
+ prot = _PAGE_INVALID;
+ /* Final flush from generic code. */
+ if (level == -1)
+ addr = max_addr;
+ if (st->level == -1) {
+ pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
+ st->start_address = addr;
+ st->current_prot = prot;
+ st->level = level;
+ } else if (prot != st->current_prot || level != st->level ||
+ addr >= st->marker[1].start_address) {
+ note_prot_wx(st, addr);
+ pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
+ width, st->start_address,
+ width, addr);
+ delta = (addr - st->start_address) >> 10;
+ while (!(delta & 0x3ff) && unit[1]) {
+ delta >>= 10;
+ unit++;
+ }
+ pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
+ print_prot(m, st->current_prot, st->level);
+ while (addr >= st->marker[1].start_address) {
+ st->marker++;
+ pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
+ }
+ st->start_address = addr;
+ st->current_prot = prot;
+ st->level = level;
+ }
+}
+
+#ifdef CONFIG_DEBUG_WX
+void ptdump_check_wx(void)
+{
+ struct pg_state st = {
+ .ptdump = {
+ .note_page = note_page,
+ .range = (struct ptdump_range[]) {
+ {.start = 0, .end = max_addr},
+ {.start = 0, .end = 0},
+ }
+ },
+ .seq = NULL,
+ .level = -1,
+ .current_prot = 0,
+ .check_wx = true,
+ .wx_pages = 0,
+ .start_address = 0,
+ .marker = (struct addr_marker[]) {
+ { .start_address = 0, .name = NULL},
+ { .start_address = -1, .name = NULL},
+ },
+ };
+
+ if (!MACHINE_HAS_NX)
+ return;
+ ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
+ if (st.wx_pages)
+ pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
+ else
+ pr_info("Checked W+X mappings: passed, no %sW+X pages found\n",
+ (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ?
+ "unexpected " : "");
+}
+#endif /* CONFIG_DEBUG_WX */
+
+#ifdef CONFIG_PTDUMP_DEBUGFS
+static int ptdump_show(struct seq_file *m, void *v)
+{
+ struct pg_state st = {
+ .ptdump = {
+ .note_page = note_page,
+ .range = (struct ptdump_range[]) {
+ {.start = 0, .end = max_addr},
+ {.start = 0, .end = 0},
+ }
+ },
+ .seq = m,
+ .level = -1,
+ .current_prot = 0,
+ .check_wx = false,
+ .wx_pages = 0,
+ .start_address = 0,
+ .marker = address_markers,
+ };
+
+ get_online_mems();
+ mutex_lock(&cpa_mutex);
+ ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
+ mutex_unlock(&cpa_mutex);
+ put_online_mems();
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(ptdump);
+#endif /* CONFIG_PTDUMP_DEBUGFS */
+
+/*
+ * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
+ * insertion sort to preserve the original order of markers with the same
+ * start address.
+ */
+static void sort_address_markers(void)
+{
+ struct addr_marker tmp;
+ int i, j;
+
+ for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
+ tmp = address_markers[i];
+ for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
+ address_markers[j + 1] = address_markers[j];
+ address_markers[j + 1] = tmp;
+ }
+}
+
+static int pt_dump_init(void)
+{
+#ifdef CONFIG_KFENCE
+ unsigned long kfence_start = (unsigned long)__kfence_pool;
+#endif
+ /*
+ * Figure out the maximum virtual address being accessible with the
+ * kernel ASCE. We need this to keep the page table walker functions
+ * from accessing non-existent entries.
+ */
+ max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
+ max_addr = 1UL << (max_addr * 11 + 31);
+ address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size;
+ address_markers[AMODE31_START_NR].start_address = (unsigned long)__samode31;
+ address_markers[AMODE31_END_NR].start_address = (unsigned long)__eamode31;
+ address_markers[MODULES_NR].start_address = MODULES_VADDR;
+ address_markers[MODULES_END_NR].start_address = MODULES_END;
+ address_markers[ABS_LOWCORE_NR].start_address = __abs_lowcore;
+ address_markers[ABS_LOWCORE_END_NR].start_address = __abs_lowcore + ABS_LOWCORE_MAP_SIZE;
+ address_markers[MEMCPY_REAL_NR].start_address = __memcpy_real_area;
+ address_markers[MEMCPY_REAL_END_NR].start_address = __memcpy_real_area + MEMCPY_REAL_SIZE;
+ address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
+ address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size;
+ address_markers[VMALLOC_NR].start_address = VMALLOC_START;
+ address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
+#ifdef CONFIG_KFENCE
+ address_markers[KFENCE_START_NR].start_address = kfence_start;
+ address_markers[KFENCE_END_NR].start_address = kfence_start + KFENCE_POOL_SIZE;
+#endif
+ sort_address_markers();
+#ifdef CONFIG_PTDUMP_DEBUGFS
+ debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
+#endif /* CONFIG_PTDUMP_DEBUGFS */
+ return 0;
+}
+device_initcall(pt_dump_init);