1 files changed, 417 insertions, 0 deletions
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
new file mode 100644
index 000000000000..f0e784b963e6
--- /dev/null
+++ b/arch/arm64/mm/pageattr.c
@@ -0,0 +1,417 @@
+// 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/mem_encrypt.h>
+#include <linux/sched.h>
+#include <linux/vmalloc.h>
+#include <linux/pagewalk.h>
+
+#include <asm/cacheflush.h>
+#include <asm/pgtable-prot.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;
+};
+
+static ptdesc_t set_pageattr_masks(ptdesc_t val, struct mm_walk *walk)
+{
+	struct page_change_data *masks = walk->private;
+
+	val &= ~(pgprot_val(masks->clear_mask));
+	val |= (pgprot_val(masks->set_mask));
+
+	return val;
+}
+
+static int pageattr_pud_entry(pud_t *pud, unsigned long addr,
+			      unsigned long next, struct mm_walk *walk)
+{
+	pud_t val = pudp_get(pud);
+
+	if (pud_sect(val)) {
+		if (WARN_ON_ONCE((next - addr) != PUD_SIZE))
+			return -EINVAL;
+		val = __pud(set_pageattr_masks(pud_val(val), walk));
+		set_pud(pud, val);
+		walk->action = ACTION_CONTINUE;
+	}
+
+	return 0;
+}
+
+static int pageattr_pmd_entry(pmd_t *pmd, unsigned long addr,
+			      unsigned long next, struct mm_walk *walk)
+{
+	pmd_t val = pmdp_get(pmd);
+
+	if (pmd_sect(val)) {
+		if (WARN_ON_ONCE((next - addr) != PMD_SIZE))
+			return -EINVAL;
+		val = __pmd(set_pageattr_masks(pmd_val(val), walk));
+		set_pmd(pmd, val);
+		walk->action = ACTION_CONTINUE;
+	}
+
+	return 0;
+}
+
+static int pageattr_pte_entry(pte_t *pte, unsigned long addr,
+			      unsigned long next, struct mm_walk *walk)
+{
+	pte_t val = __ptep_get(pte);
+
+	val = __pte(set_pageattr_masks(pte_val(val), walk));
+	__set_pte(pte, val);
+
+	return 0;
+}
+
+static const struct mm_walk_ops pageattr_ops = {
+	.pud_entry	= pageattr_pud_entry,
+	.pmd_entry	= pageattr_pmd_entry,
+	.pte_entry	= pageattr_pte_entry,
+};
+
+bool rodata_full __ro_after_init = true;
+
+bool can_set_direct_map(void)
+{
+	/*
+	 * rodata_full, DEBUG_PAGEALLOC and a Realm guest all 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.
+	 *
+	 * Realms need to make pages shared/protected at page granularity.
+	 */
+	return rodata_full || debug_pagealloc_enabled() ||
+		arm64_kfence_can_set_direct_map() || is_realm_world();
+}
+
+static int update_range_prot(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 = split_kernel_leaf_mapping(start, start + size);
+	if (WARN_ON_ONCE(ret))
+		return ret;
+
+	arch_enter_lazy_mmu_mode();
+
+	/*
+	 * The caller must ensure that the range we are operating on does not
+	 * partially overlap a block mapping, or a cont mapping. Any such case
+	 * must be eliminated by splitting the mapping.
+	 */
+	ret = walk_kernel_page_table_range_lockless(start, start + size,
+						    &pageattr_ops, NULL, &data);
+	arch_leave_lazy_mmu_mode();
+
+	return ret;
+}
+
+static int __change_memory_common(unsigned long start, unsigned long size,
+				  pgprot_t set_mask, pgprot_t clear_mask)
+{
+	int ret;
+
+	ret = update_range_prot(start, size, set_mask, clear_mask);
+
+	/*
+	 * If the memory is being made valid without changing any other bits
+	 * then a TLBI isn't required as a non-valid entry cannot be cached in
+	 * the TLB.
+	 */
+	if (pgprot_val(set_mask) != PTE_VALID || pgprot_val(clear_mask))
+		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 ret;
+
+	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).
+	 * Disallow VM_ALLOW_HUGE_VMAP mappings to guarantee that only page
+	 * mappings are updated 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 | VM_ALLOW_HUGE_VMAP)) != 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)) {
+		unsigned long idx = (start - (unsigned long)kasan_reset_tag(area->addr))
+				    >> PAGE_SHIFT;
+		for (; numpages; idx++, numpages--) {
+			ret = __change_memory_common((u64)page_address(area->pages[idx]),
+						     PAGE_SIZE, set_mask, clear_mask);
+			if (ret)
+				return ret;
+		}
+	}
+
+	/*
+	 * 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)
+{
+	pgprot_t clear_mask = __pgprot(PTE_VALID);
+	pgprot_t set_mask = __pgprot(0);
+
+	if (!can_set_direct_map())
+		return 0;
+
+	return update_range_prot((unsigned long)page_address(page),
+				 PAGE_SIZE, set_mask, clear_mask);
+}
+
+int set_direct_map_default_noflush(struct page *page)
+{
+	pgprot_t set_mask = __pgprot(PTE_VALID | PTE_WRITE);
+	pgprot_t clear_mask = __pgprot(PTE_RDONLY);
+
+	if (!can_set_direct_map())
+		return 0;
+
+	return update_range_prot((unsigned long)page_address(page),
+				 PAGE_SIZE, set_mask, clear_mask);
+}
+
+static int __set_memory_enc_dec(unsigned long addr,
+				int numpages,
+				bool encrypt)
+{
+	unsigned long set_prot = 0, clear_prot = 0;
+	phys_addr_t start, end;
+	int ret;
+
+	if (!is_realm_world())
+		return 0;
+
+	if (!__is_lm_address(addr))
+		return -EINVAL;
+
+	start = __virt_to_phys(addr);
+	end = start + numpages * PAGE_SIZE;
+
+	if (encrypt)
+		clear_prot = PROT_NS_SHARED;
+	else
+		set_prot = PROT_NS_SHARED;
+
+	/*
+	 * Break the mapping before we make any changes to avoid stale TLB
+	 * entries or Synchronous External Aborts caused by RIPAS_EMPTY
+	 */
+	ret = __change_memory_common(addr, PAGE_SIZE * numpages,
+				     __pgprot(set_prot),
+				     __pgprot(clear_prot | PTE_VALID));
+
+	if (ret)
+		return ret;
+
+	if (encrypt)
+		ret = rsi_set_memory_range_protected(start, end);
+	else
+		ret = rsi_set_memory_range_shared(start, end);
+
+	if (ret)
+		return ret;
+
+	return __change_memory_common(addr, PAGE_SIZE * numpages,
+				      __pgprot(PTE_VALID),
+				      __pgprot(0));
+}
+
+static int realm_set_memory_encrypted(unsigned long addr, int numpages)
+{
+	int ret = __set_memory_enc_dec(addr, numpages, true);
+
+	/*
+	 * If the request to change state fails, then the only sensible cause
+	 * of action for the caller is to leak the memory
+	 */
+	WARN(ret, "Failed to encrypt memory, %d pages will be leaked",
+	     numpages);
+
+	return ret;
+}
+
+static int realm_set_memory_decrypted(unsigned long addr, int numpages)
+{
+	int ret = __set_memory_enc_dec(addr, numpages, false);
+
+	WARN(ret, "Failed to decrypt memory, %d pages will be leaked",
+	     numpages);
+
+	return ret;
+}
+
+static const struct arm64_mem_crypt_ops realm_crypt_ops = {
+	.encrypt = realm_set_memory_encrypted,
+	.decrypt = realm_set_memory_decrypted,
+};
+
+int realm_register_memory_enc_ops(void)
+{
+	return arm64_mem_crypt_ops_register(&realm_crypt_ops);
+}
+
+int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
+{
+	unsigned long addr = (unsigned long)page_address(page);
+
+	if (!can_set_direct_map())
+		return 0;
+
+	return set_memory_valid(addr, nr, valid);
+}
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+/*
+ * This is - apart from the return value - doing the same
+ * thing as the new set_direct_map_valid_noflush() function.
+ *
+ * Unify? Explain the conceptual differences?
+ */
+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.
+ *
+ * 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);
+
+	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(__ptep_get(ptep));
+}