1 files changed, 134 insertions, 0 deletions
diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c
new file mode 100644
index 000000000000..0876216ceee6
--- /dev/null
+++ b/arch/powerpc/mm/pageattr.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * MMU-generic set_memory implementation for powerpc
+ *
+ * Copyright 2019-2021, IBM Corporation.
+ */
+
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/set_memory.h>
+
+#include <asm/mmu.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+
+
+/*
+ * Updates the attributes of a page in three steps:
+ *
+ * 1. invalidate the page table entry
+ * 2. flush the TLB
+ * 3. install the new entry with the updated attributes
+ *
+ * Invalidating the pte means there are situations where this will not work
+ * when in theory it should.
+ * For example:
+ * - removing write from page whilst it is being executed
+ * - setting a page read-only whilst it is being read by another CPU
+ *
+ */
+static int change_page_attr(pte_t *ptep, unsigned long addr, void *data)
+{
+	long action = (long)data;
+	pte_t pte;
+
+	spin_lock(&init_mm.page_table_lock);
+
+	/* invalidate the PTE so it's safe to modify */
+	pte = ptep_get_and_clear(&init_mm, addr, ptep);
+	flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+
+	/* modify the PTE bits as desired, then apply */
+	switch (action) {
+	case SET_MEMORY_RO:
+		pte = pte_wrprotect(pte);
+		break;
+	case SET_MEMORY_RW:
+		pte = pte_mkwrite(pte_mkdirty(pte));
+		break;
+	case SET_MEMORY_NX:
+		pte = pte_exprotect(pte);
+		break;
+	case SET_MEMORY_X:
+		pte = pte_mkexec(pte);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+
+	set_pte_at(&init_mm, addr, ptep, pte);
+
+	/* See ptesync comment in radix__set_pte_at() */
+	if (radix_enabled())
+		asm volatile("ptesync": : :"memory");
+	spin_unlock(&init_mm.page_table_lock);
+
+	return 0;
+}
+
+int change_memory_attr(unsigned long addr, int numpages, long action)
+{
+	unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
+	unsigned long size = numpages * PAGE_SIZE;
+
+	if (!numpages)
+		return 0;
+
+	if (WARN_ON_ONCE(is_vmalloc_or_module_addr((void *)addr) &&
+			 is_vm_area_hugepages((void *)addr)))
+		return -EINVAL;
+
+#ifdef CONFIG_PPC_BOOK3S_64
+	/*
+	 * On hash, the linear mapping is not in the Linux page table so
+	 * apply_to_existing_page_range() will have no effect. If in the future
+	 * the set_memory_* functions are used on the linear map this will need
+	 * to be updated.
+	 */
+	if (!radix_enabled()) {
+		int region = get_region_id(addr);
+
+		if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID))
+			return -EINVAL;
+	}
+#endif
+
+	return apply_to_existing_page_range(&init_mm, start, size,
+					    change_page_attr, (void *)action);
+}
+
+/*
+ * Set the attributes of a page:
+ *
+ * This function is used by PPC32 at the end of init to set final kernel memory
+ * protection. It includes changing the maping of the page it is executing from
+ * and data pages it is using.
+ */
+static int set_page_attr(pte_t *ptep, unsigned long addr, void *data)
+{
+	pgprot_t prot = __pgprot((unsigned long)data);
+
+	spin_lock(&init_mm.page_table_lock);
+
+	set_pte_at(&init_mm, addr, ptep, pte_modify(*ptep, prot));
+	flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+
+	spin_unlock(&init_mm.page_table_lock);
+
+	return 0;
+}
+
+int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot)
+{
+	unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
+	unsigned long sz = numpages * PAGE_SIZE;
+
+	if (numpages <= 0)
+		return 0;
+
+	return apply_to_existing_page_range(&init_mm, start, sz, set_page_attr,
+					    (void *)pgprot_val(prot));
+}