s390/mm: enable ARCH_HAS_SET_DIRECT_MAP

Implement the set_direct_map_*() API, which allows to invalidate and set
default permissions to pages within the direct mapping.

Note that kernel_page_present(), which is also supposed to be part of this
API, is intentionally not implemented. The reason for this is that
kernel_page_present() is only used (and currently only makes sense) for
suspend/resume, which isn't supported on s390.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/Kconfig

@@ -77,6 +77,7 @@ config S390
 	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SCALED_CPUTIME
+	select ARCH_HAS_SET_DIRECT_MAP
 	select ARCH_HAS_SET_MEMORY
 	select ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_HAS_STRICT_MODULE_RWX

arch/s390/include/asm/set_memory.h

@@ -12,6 +12,8 @@ enum {
 	_SET_MEMORY_NX_BIT,
 	_SET_MEMORY_X_BIT,
 	_SET_MEMORY_4K_BIT,
+	_SET_MEMORY_INV_BIT,
+	_SET_MEMORY_DEF_BIT,
 };
 
 #define SET_MEMORY_RO	BIT(_SET_MEMORY_RO_BIT)
@@ -19,6 +21,8 @@ enum {
 #define SET_MEMORY_NX	BIT(_SET_MEMORY_NX_BIT)
 #define SET_MEMORY_X	BIT(_SET_MEMORY_X_BIT)
 #define SET_MEMORY_4K	BIT(_SET_MEMORY_4K_BIT)
+#define SET_MEMORY_INV	BIT(_SET_MEMORY_INV_BIT)
+#define SET_MEMORY_DEF	BIT(_SET_MEMORY_DEF_BIT)
 
 int __set_memory(unsigned long addr, int numpages, unsigned long flags);
 
@@ -58,4 +62,7 @@ static inline int set_memory_4k(unsigned long addr, int numpages)
 	return __set_memory(addr, numpages, SET_MEMORY_4K);
 }
 
+int set_direct_map_invalid_noflush(struct page *page);
+int set_direct_map_default_noflush(struct page *page);
+
 #endif

arch/s390/mm/pageattr.c

@@ -4,6 +4,7 @@
  * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
  */
 #include <linux/hugetlb.h>
+#include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <asm/cacheflush.h>
 #include <asm/facility.h>
@@ -101,6 +102,14 @@ static int walk_pte_level(pmd_t *pmdp, unsigned long addr, unsigned long end,
 			new = set_pte_bit(new, __pgprot(_PAGE_NOEXEC));
 		else if (flags & SET_MEMORY_X)
 			new = clear_pte_bit(new, __pgprot(_PAGE_NOEXEC));
+		if (flags & SET_MEMORY_INV) {
+			new = set_pte_bit(new, __pgprot(_PAGE_INVALID));
+		} else if (flags & SET_MEMORY_DEF) {
+			new = __pte(pte_val(new) & PAGE_MASK);
+			new = set_pte_bit(new, PAGE_KERNEL);
+			if (!MACHINE_HAS_NX)
+				new = clear_pte_bit(new, __pgprot(_PAGE_NOEXEC));
+		}
 		pgt_set((unsigned long *)ptep, pte_val(new), addr, CRDTE_DTT_PAGE);
 		ptep++;
 		addr += PAGE_SIZE;
@@ -151,6 +160,14 @@ static void modify_pmd_page(pmd_t *pmdp, unsigned long addr,
 		new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
 	else if (flags & SET_MEMORY_X)
 		new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
+	if (flags & SET_MEMORY_INV) {
+		new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
+	} else if (flags & SET_MEMORY_DEF) {
+		new = __pmd(pmd_val(new) & PMD_MASK);
+		new = set_pmd_bit(new, SEGMENT_KERNEL);
+		if (!MACHINE_HAS_NX)
+			new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
+	}
 	pgt_set((unsigned long *)pmdp, pmd_val(new), addr, CRDTE_DTT_SEGMENT);
 }
 
@@ -232,6 +249,14 @@ static void modify_pud_page(pud_t *pudp, unsigned long addr,
 		new = set_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
 	else if (flags & SET_MEMORY_X)
 		new = clear_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
+	if (flags & SET_MEMORY_INV) {
+		new = set_pud_bit(new, __pgprot(_REGION_ENTRY_INVALID));
+	} else if (flags & SET_MEMORY_DEF) {
+		new = __pud(pud_val(new) & PUD_MASK);
+		new = set_pud_bit(new, REGION3_KERNEL);
+		if (!MACHINE_HAS_NX)
+			new = clear_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
+	}
 	pgt_set((unsigned long *)pudp, pud_val(new), addr, CRDTE_DTT_REGION3);
 }
 
@@ -325,6 +350,16 @@ int __set_memory(unsigned long addr, int numpages, unsigned long flags)
 	return change_page_attr(addr, addr + numpages * PAGE_SIZE, flags);
 }
 
+int set_direct_map_invalid_noflush(struct page *page)
+{
+	return __set_memory((unsigned long)page_to_virt(page), 1, SET_MEMORY_INV);
+}
+
+int set_direct_map_default_noflush(struct page *page)
+{
+	return __set_memory((unsigned long)page_to_virt(page), 1, SET_MEMORY_DEF);
+}
+
 #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
 
 static void ipte_range(pte_t *pte, unsigned long address, int nr)