From: Peter Oberparleiter <oberpar@linux.ibm.com>
Subject: s390/mm: provide base_asce_alloc() / base_asce_free() helper functions
Patch-mainline: v4.17-rc1
Git-commit: 1caf170df9bac49bb198c424aee45f5ecced076a
References: FATE#326357, LTC#169111, bsc#1113500

Summary:     kernel: Add support for reading I/O configuration data
Description: LPARs that are running in IBM Dynamic Partition Manager (DPM) mode
             can access a firmware-generated I/O configuration data file that
             contains s390-specific information about available I/O devices
             such as qeth device numbers and parameters, and FCP device IDs.

             This data file is intended to remove the need for users to
             manually enter the corresponding device data during installation.

             This patch set makes the data file available at the following
             location:

               /sys/firmware/sclp_sd/config/data


Upstream-Description:

             s390/mm: provide base_asce_alloc() / base_asce_free() helper functions

             Provide base_asce_alloc() and base_asce_free() helper functions which
             can be used to allocate an ASCE and all required region, segment and
             page tables required to access memory regions of the virtual kernel
             address space.

             Both, the ASCE and all tables, do not use any features that correspond
             to e.g. enhanced DAT features. This is required for some I/O functions
             that pass an ASCE, like e.g. some service call requests, but which may
             not use any enhanced features.

             Acked-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
             Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com>
             Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
             Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 arch/s390/include/asm/pgalloc.h |    3 
 arch/s390/mm/pgalloc.c          |  293 +++++++++++++++++++++++++++++++-
 2 files changed, 295 insertions(+), 1 deletion(-)

--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -143,4 +143,7 @@ static inline void pmd_populate(struct m
 
 extern void rcu_table_freelist_finish(void);
 
+unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages);
+void base_asce_free(unsigned long asce);
+
 #endif /* _S390_PGALLOC_H */
--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -5,8 +5,9 @@
  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
  */
 
-#include <linux/mm.h>
 #include <linux/sysctl.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
 #include <asm/mmu_context.h>
 #include <asm/pgalloc.h>
 #include <asm/gmap.h>
@@ -352,3 +353,293 @@ void tlb_remove_table(struct mmu_gather
 	if ((*batch)->nr == MAX_TABLE_BATCH)
 		tlb_flush_mmu(tlb);
 }
+
+/*
+ * Base infrastructure required to generate basic asces, region, segment,
+ * and page tables that do not make use of enhanced features like EDAT1.
+ */
+
+static struct kmem_cache *base_pgt_cache;
+
+static unsigned long base_pgt_alloc(void)
+{
+	u64 *table;
+
+	table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL);
+	if (table)
+		memset(table, _PAGE_INVALID, PTRS_PER_PTE);
+	return (unsigned long) table;
+}
+
+static void base_pgt_free(unsigned long table)
+{
+	kmem_cache_free(base_pgt_cache, (void *) table);
+}
+
+static unsigned long base_crst_alloc(unsigned long val)
+{
+	unsigned long table;
+
+	table =	 __get_free_pages(GFP_KERNEL, CRST_ALLOC_ORDER);
+	if (table)
+		crst_table_init((unsigned long *)table, val);
+	return table;
+}
+
+static void base_crst_free(unsigned long table)
+{
+	free_pages(table, CRST_ALLOC_ORDER);
+}
+
+#define BASE_ADDR_END_FUNC(NAME, SIZE)					\
+static inline unsigned long base_##NAME##_addr_end(unsigned long addr,	\
+						   unsigned long end)	\
+{									\
+	unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1);		\
+									\
+	return (next - 1) < (end - 1) ? next : end;			\
+}
+
+BASE_ADDR_END_FUNC(page,    _PAGE_SIZE)
+BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE)
+BASE_ADDR_END_FUNC(region3, _REGION3_SIZE)
+BASE_ADDR_END_FUNC(region2, _REGION2_SIZE)
+BASE_ADDR_END_FUNC(region1, _REGION1_SIZE)
+
+static inline unsigned long base_lra(unsigned long address)
+{
+	unsigned long real;
+
+	asm volatile(
+		"	lra	%0,0(%1)\n"
+		: "=d" (real) : "a" (address) : "cc");
+	return real;
+}
+
+static int base_page_walk(unsigned long origin, unsigned long addr,
+			  unsigned long end, int alloc)
+{
+	unsigned long *pte, next;
+
+	if (!alloc)
+		return 0;
+	pte = (unsigned long *) origin;
+	pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT;
+	do {
+		next = base_page_addr_end(addr, end);
+		*pte = base_lra(addr);
+	} while (pte++, addr = next, addr < end);
+	return 0;
+}
+
+static int base_segment_walk(unsigned long origin, unsigned long addr,
+			     unsigned long end, int alloc)
+{
+	unsigned long *ste, next, table;
+	int rc;
+
+	ste = (unsigned long *) origin;
+	ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
+	do {
+		next = base_segment_addr_end(addr, end);
+		if (*ste & _SEGMENT_ENTRY_INVALID) {
+			if (!alloc)
+				continue;
+			table = base_pgt_alloc();
+			if (!table)
+				return -ENOMEM;
+			*ste = table | _SEGMENT_ENTRY;
+		}
+		table = *ste & _SEGMENT_ENTRY_ORIGIN;
+		rc = base_page_walk(table, addr, next, alloc);
+		if (rc)
+			return rc;
+		if (!alloc)
+			base_pgt_free(table);
+		cond_resched();
+	} while (ste++, addr = next, addr < end);
+	return 0;
+}
+
+static int base_region3_walk(unsigned long origin, unsigned long addr,
+			     unsigned long end, int alloc)
+{
+	unsigned long *rtte, next, table;
+	int rc;
+
+	rtte = (unsigned long *) origin;
+	rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT;
+	do {
+		next = base_region3_addr_end(addr, end);
+		if (*rtte & _REGION_ENTRY_INVALID) {
+			if (!alloc)
+				continue;
+			table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
+			if (!table)
+				return -ENOMEM;
+			*rtte = table | _REGION3_ENTRY;
+		}
+		table = *rtte & _REGION_ENTRY_ORIGIN;
+		rc = base_segment_walk(table, addr, next, alloc);
+		if (rc)
+			return rc;
+		if (!alloc)
+			base_crst_free(table);
+	} while (rtte++, addr = next, addr < end);
+	return 0;
+}
+
+static int base_region2_walk(unsigned long origin, unsigned long addr,
+			     unsigned long end, int alloc)
+{
+	unsigned long *rste, next, table;
+	int rc;
+
+	rste = (unsigned long *) origin;
+	rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT;
+	do {
+		next = base_region2_addr_end(addr, end);
+		if (*rste & _REGION_ENTRY_INVALID) {
+			if (!alloc)
+				continue;
+			table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
+			if (!table)
+				return -ENOMEM;
+			*rste = table | _REGION2_ENTRY;
+		}
+		table = *rste & _REGION_ENTRY_ORIGIN;
+		rc = base_region3_walk(table, addr, next, alloc);
+		if (rc)
+			return rc;
+		if (!alloc)
+			base_crst_free(table);
+	} while (rste++, addr = next, addr < end);
+	return 0;
+}
+
+static int base_region1_walk(unsigned long origin, unsigned long addr,
+			     unsigned long end, int alloc)
+{
+	unsigned long *rfte, next, table;
+	int rc;
+
+	rfte = (unsigned long *) origin;
+	rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT;
+	do {
+		next = base_region1_addr_end(addr, end);
+		if (*rfte & _REGION_ENTRY_INVALID) {
+			if (!alloc)
+				continue;
+			table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
+			if (!table)
+				return -ENOMEM;
+			*rfte = table | _REGION1_ENTRY;
+		}
+		table = *rfte & _REGION_ENTRY_ORIGIN;
+		rc = base_region2_walk(table, addr, next, alloc);
+		if (rc)
+			return rc;
+		if (!alloc)
+			base_crst_free(table);
+	} while (rfte++, addr = next, addr < end);
+	return 0;
+}
+
+/**
+ * base_asce_free - free asce and tables returned from base_asce_alloc()
+ * @asce: asce to be freed
+ *
+ * Frees all region, segment, and page tables that were allocated with a
+ * corresponding base_asce_alloc() call.
+ */
+void base_asce_free(unsigned long asce)
+{
+	unsigned long table = asce & _ASCE_ORIGIN;
+
+	if (!asce)
+		return;
+	switch (asce & _ASCE_TYPE_MASK) {
+	case _ASCE_TYPE_SEGMENT:
+		base_segment_walk(table, 0, _REGION3_SIZE, 0);
+		break;
+	case _ASCE_TYPE_REGION3:
+		base_region3_walk(table, 0, _REGION2_SIZE, 0);
+		break;
+	case _ASCE_TYPE_REGION2:
+		base_region2_walk(table, 0, _REGION1_SIZE, 0);
+		break;
+	case _ASCE_TYPE_REGION1:
+		base_region1_walk(table, 0, -_PAGE_SIZE, 0);
+		break;
+	}
+	base_crst_free(table);
+}
+
+static int base_pgt_cache_init(void)
+{
+	static DEFINE_MUTEX(base_pgt_cache_mutex);
+	unsigned long sz = _PAGE_TABLE_SIZE;
+
+	if (base_pgt_cache)
+		return 0;
+	mutex_lock(&base_pgt_cache_mutex);
+	if (!base_pgt_cache)
+		base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL);
+	mutex_unlock(&base_pgt_cache_mutex);
+	return base_pgt_cache ? 0 : -ENOMEM;
+}
+
+/**
+ * base_asce_alloc - create kernel mapping without enhanced DAT features
+ * @addr: virtual start address of kernel mapping
+ * @num_pages: number of consecutive pages
+ *
+ * Generate an asce, including all required region, segment and page tables,
+ * that can be used to access the virtual kernel mapping. The difference is
+ * that the returned asce does not make use of any enhanced DAT features like
+ * e.g. large pages. This is required for some I/O functions that pass an
+ * asce, like e.g. some service call requests.
+ *
+ * Note: the returned asce may NEVER be attached to any cpu. It may only be
+ *	 used for I/O requests. tlb entries that might result because the
+ *	 asce was attached to a cpu won't be cleared.
+ */
+unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages)
+{
+	unsigned long asce, table, end;
+	int rc;
+
+	if (base_pgt_cache_init())
+		return 0;
+	end = addr + num_pages * PAGE_SIZE;
+	if (end <= _REGION3_SIZE) {
+		table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
+		if (!table)
+			return 0;
+		rc = base_segment_walk(table, addr, end, 1);
+		asce = table | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH;
+	} else if (end <= _REGION2_SIZE) {
+		table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
+		if (!table)
+			return 0;
+		rc = base_region3_walk(table, addr, end, 1);
+		asce = table | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;
+	} else if (end <= _REGION1_SIZE) {
+		table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
+		if (!table)
+			return 0;
+		rc = base_region2_walk(table, addr, end, 1);
+		asce = table | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH;
+	} else {
+		table = base_crst_alloc(_REGION1_ENTRY_EMPTY);
+		if (!table)
+			return 0;
+		rc = base_region1_walk(table, addr, end, 1);
+		asce = table | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH;
+	}
+	if (rc) {
+		base_asce_free(asce);
+		asce = 0;
+	}
+	return asce;
+}