summaryrefslogtreecommitdiffstats
path: root/arch/arm64/mm/pageattr.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm64/mm/pageattr.c')
-rw-r--r--arch/arm64/mm/pageattr.c250
1 files changed, 250 insertions, 0 deletions
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
new file mode 100644
index 000000000..826cb200b
--- /dev/null
+++ b/arch/arm64/mm/pageattr.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ */
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/vmalloc.h>
+
+#include <asm/cacheflush.h>
+#include <asm/set_memory.h>
+#include <asm/tlbflush.h>
+#include <asm/kfence.h>
+
+struct page_change_data {
+ pgprot_t set_mask;
+ pgprot_t clear_mask;
+};
+
+bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED);
+
+bool can_set_direct_map(void)
+{
+ /*
+ * rodata_full and DEBUG_PAGEALLOC require linear map to be
+ * mapped at page granularity, so that it is possible to
+ * protect/unprotect single pages.
+ *
+ * KFENCE pool requires page-granular mapping if initialized late.
+ */
+ return rodata_full || debug_pagealloc_enabled() ||
+ arm64_kfence_can_set_direct_map();
+}
+
+static int change_page_range(pte_t *ptep, unsigned long addr, void *data)
+{
+ struct page_change_data *cdata = data;
+ pte_t pte = READ_ONCE(*ptep);
+
+ pte = clear_pte_bit(pte, cdata->clear_mask);
+ pte = set_pte_bit(pte, cdata->set_mask);
+
+ set_pte(ptep, pte);
+ return 0;
+}
+
+/*
+ * This function assumes that the range is mapped with PAGE_SIZE pages.
+ */
+static int __change_memory_common(unsigned long start, unsigned long size,
+ pgprot_t set_mask, pgprot_t clear_mask)
+{
+ struct page_change_data data;
+ int ret;
+
+ data.set_mask = set_mask;
+ data.clear_mask = clear_mask;
+
+ ret = apply_to_page_range(&init_mm, start, size, change_page_range,
+ &data);
+
+ flush_tlb_kernel_range(start, start + size);
+ return ret;
+}
+
+static int change_memory_common(unsigned long addr, int numpages,
+ pgprot_t set_mask, pgprot_t clear_mask)
+{
+ unsigned long start = addr;
+ unsigned long size = PAGE_SIZE * numpages;
+ unsigned long end = start + size;
+ struct vm_struct *area;
+ int i;
+
+ if (!PAGE_ALIGNED(addr)) {
+ start &= PAGE_MASK;
+ end = start + size;
+ WARN_ON_ONCE(1);
+ }
+
+ /*
+ * Kernel VA mappings are always live, and splitting live section
+ * mappings into page mappings may cause TLB conflicts. This means
+ * we have to ensure that changing the permission bits of the range
+ * we are operating on does not result in such splitting.
+ *
+ * Let's restrict ourselves to mappings created by vmalloc (or vmap).
+ * Those are guaranteed to consist entirely of page mappings, and
+ * splitting is never needed.
+ *
+ * So check whether the [addr, addr + size) interval is entirely
+ * covered by precisely one VM area that has the VM_ALLOC flag set.
+ */
+ area = find_vm_area((void *)addr);
+ if (!area ||
+ end > (unsigned long)kasan_reset_tag(area->addr) + area->size ||
+ !(area->flags & VM_ALLOC))
+ return -EINVAL;
+
+ if (!numpages)
+ return 0;
+
+ /*
+ * If we are manipulating read-only permissions, apply the same
+ * change to the linear mapping of the pages that back this VM area.
+ */
+ if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
+ pgprot_val(clear_mask) == PTE_RDONLY)) {
+ for (i = 0; i < area->nr_pages; i++) {
+ __change_memory_common((u64)page_address(area->pages[i]),
+ PAGE_SIZE, set_mask, clear_mask);
+ }
+ }
+
+ /*
+ * Get rid of potentially aliasing lazily unmapped vm areas that may
+ * have permissions set that deviate from the ones we are setting here.
+ */
+ vm_unmap_aliases();
+
+ return __change_memory_common(start, size, set_mask, clear_mask);
+}
+
+int set_memory_ro(unsigned long addr, int numpages)
+{
+ return change_memory_common(addr, numpages,
+ __pgprot(PTE_RDONLY),
+ __pgprot(PTE_WRITE));
+}
+
+int set_memory_rw(unsigned long addr, int numpages)
+{
+ return change_memory_common(addr, numpages,
+ __pgprot(PTE_WRITE),
+ __pgprot(PTE_RDONLY));
+}
+
+int set_memory_nx(unsigned long addr, int numpages)
+{
+ return change_memory_common(addr, numpages,
+ __pgprot(PTE_PXN),
+ __pgprot(PTE_MAYBE_GP));
+}
+
+int set_memory_x(unsigned long addr, int numpages)
+{
+ return change_memory_common(addr, numpages,
+ __pgprot(PTE_MAYBE_GP),
+ __pgprot(PTE_PXN));
+}
+
+int set_memory_valid(unsigned long addr, int numpages, int enable)
+{
+ if (enable)
+ return __change_memory_common(addr, PAGE_SIZE * numpages,
+ __pgprot(PTE_VALID),
+ __pgprot(0));
+ else
+ return __change_memory_common(addr, PAGE_SIZE * numpages,
+ __pgprot(0),
+ __pgprot(PTE_VALID));
+}
+
+int set_direct_map_invalid_noflush(struct page *page)
+{
+ struct page_change_data data = {
+ .set_mask = __pgprot(0),
+ .clear_mask = __pgprot(PTE_VALID),
+ };
+
+ if (!can_set_direct_map())
+ return 0;
+
+ return apply_to_page_range(&init_mm,
+ (unsigned long)page_address(page),
+ PAGE_SIZE, change_page_range, &data);
+}
+
+int set_direct_map_default_noflush(struct page *page)
+{
+ struct page_change_data data = {
+ .set_mask = __pgprot(PTE_VALID | PTE_WRITE),
+ .clear_mask = __pgprot(PTE_RDONLY),
+ };
+
+ if (!can_set_direct_map())
+ return 0;
+
+ return apply_to_page_range(&init_mm,
+ (unsigned long)page_address(page),
+ PAGE_SIZE, change_page_range, &data);
+}
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+void __kernel_map_pages(struct page *page, int numpages, int enable)
+{
+ if (!can_set_direct_map())
+ return;
+
+ set_memory_valid((unsigned long)page_address(page), numpages, enable);
+}
+#endif /* CONFIG_DEBUG_PAGEALLOC */
+
+/*
+ * This function is used to determine if a linear map page has been marked as
+ * not-valid. Walk the page table and check the PTE_VALID bit. This is based
+ * on kern_addr_valid(), which almost does what we need.
+ *
+ * Because this is only called on the kernel linear map, p?d_sect() implies
+ * p?d_present(). When debug_pagealloc is enabled, sections mappings are
+ * disabled.
+ */
+bool kernel_page_present(struct page *page)
+{
+ pgd_t *pgdp;
+ p4d_t *p4dp;
+ pud_t *pudp, pud;
+ pmd_t *pmdp, pmd;
+ pte_t *ptep;
+ unsigned long addr = (unsigned long)page_address(page);
+
+ if (!can_set_direct_map())
+ return true;
+
+ pgdp = pgd_offset_k(addr);
+ if (pgd_none(READ_ONCE(*pgdp)))
+ return false;
+
+ p4dp = p4d_offset(pgdp, addr);
+ if (p4d_none(READ_ONCE(*p4dp)))
+ return false;
+
+ pudp = pud_offset(p4dp, addr);
+ pud = READ_ONCE(*pudp);
+ if (pud_none(pud))
+ return false;
+ if (pud_sect(pud))
+ return true;
+
+ pmdp = pmd_offset(pudp, addr);
+ pmd = READ_ONCE(*pmdp);
+ if (pmd_none(pmd))
+ return false;
+ if (pmd_sect(pmd))
+ return true;
+
+ ptep = pte_offset_kernel(pmdp, addr);
+ return pte_valid(READ_ONCE(*ptep));
+}