s390/hypfs: factor out filesystem code

The s390_hypfs filesystem is deprecated and shouldn't be used due to its
rather odd semantics. It creates a whole directory structure with static
file contents so a user can read a consistent state while within that
directory.
Writing to its update attribute will remove and rebuild nearly the whole
filesystem, so that again a user can read a consistent state, even if
multiple files need to be read.

Given that this wastes a lot of CPU cycles, and involves a lot of code,
binary interfaces have been added quite a couple of years ago, which simply
pass the binary data to user space, and let user space decode the data.
This is the preferred and only way how the data should be retrieved.

The assumption is that there are no users of the s390_hypfs filesystem.
However instead of just removing the code, and having to revert in case
there are actually users, factor the filesystem code out and make it only
available via a new config option.

This config option is supposed to be disabled. If it turns out there are no
complaints the filesystem code can be removed probably in a couple of
years.

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 393 insertions, 0 deletions

diff --git a/arch/s390/hypfs/hypfs_diag_fs.c b/arch/s390/hypfs/hypfs_diag_fs.c
new file mode 100644
index 000000000000..00a6d370a280
--- /dev/null
+++ b/arch/s390/hypfs/hypfs_diag_fs.c
@@ -0,0 +1,393 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *    Hypervisor filesystem for Linux on s390. Diag 204 and 224
+ *    implementation.
+ *
+ *    Copyright IBM Corp. 2006, 2008
+ *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
+ */
+
+#define KMSG_COMPONENT "hypfs"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <asm/diag.h>
+#include <asm/ebcdic.h>
+#include "hypfs_diag.h"
+#include "hypfs.h"
+
+#define TMP_SIZE 64		/* size of temporary buffers */
+
+static char *diag224_cpu_names;			/* diag 224 name table */
+static int diag224_idx2name(int index, char *name);
+
+/*
+ * DIAG 204 member access functions.
+ *
+ * Since we have two different diag 204 data formats for old and new s390
+ * machines, we do not access the structs directly, but use getter functions for
+ * each struct member instead. This should make the code more readable.
+ */
+
+/* Time information block */
+
+static inline int info_blk_hdr__size(enum diag204_format type)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return sizeof(struct diag204_info_blk_hdr);
+	else /* DIAG204_INFO_EXT */
+		return sizeof(struct diag204_x_info_blk_hdr);
+}
+
+static inline __u8 info_blk_hdr__npar(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_info_blk_hdr *)hdr)->npar;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_info_blk_hdr *)hdr)->npar;
+}
+
+static inline __u8 info_blk_hdr__flags(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_info_blk_hdr *)hdr)->flags;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_info_blk_hdr *)hdr)->flags;
+}
+
+/* Partition header */
+
+static inline int part_hdr__size(enum diag204_format type)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return sizeof(struct diag204_part_hdr);
+	else /* DIAG204_INFO_EXT */
+		return sizeof(struct diag204_x_part_hdr);
+}
+
+static inline __u8 part_hdr__rcpus(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_part_hdr *)hdr)->cpus;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_part_hdr *)hdr)->rcpus;
+}
+
+static inline void part_hdr__part_name(enum diag204_format type, void *hdr,
+				       char *name)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		memcpy(name, ((struct diag204_part_hdr *)hdr)->part_name,
+		       DIAG204_LPAR_NAME_LEN);
+	else /* DIAG204_INFO_EXT */
+		memcpy(name, ((struct diag204_x_part_hdr *)hdr)->part_name,
+		       DIAG204_LPAR_NAME_LEN);
+	EBCASC(name, DIAG204_LPAR_NAME_LEN);
+	name[DIAG204_LPAR_NAME_LEN] = 0;
+	strim(name);
+}
+
+/* CPU info block */
+
+static inline int cpu_info__size(enum diag204_format type)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return sizeof(struct diag204_cpu_info);
+	else /* DIAG204_INFO_EXT */
+		return sizeof(struct diag204_x_cpu_info);
+}
+
+static inline __u8 cpu_info__ctidx(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_cpu_info *)hdr)->ctidx;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_cpu_info *)hdr)->ctidx;
+}
+
+static inline __u16 cpu_info__cpu_addr(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_cpu_info *)hdr)->cpu_addr;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_cpu_info *)hdr)->cpu_addr;
+}
+
+static inline __u64 cpu_info__acc_time(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_cpu_info *)hdr)->acc_time;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_cpu_info *)hdr)->acc_time;
+}
+
+static inline __u64 cpu_info__lp_time(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_cpu_info *)hdr)->lp_time;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_cpu_info *)hdr)->lp_time;
+}
+
+static inline __u64 cpu_info__online_time(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return 0;	/* online_time not available in simple info */
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_cpu_info *)hdr)->online_time;
+}
+
+/* Physical header */
+
+static inline int phys_hdr__size(enum diag204_format type)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return sizeof(struct diag204_phys_hdr);
+	else /* DIAG204_INFO_EXT */
+		return sizeof(struct diag204_x_phys_hdr);
+}
+
+static inline __u8 phys_hdr__cpus(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_phys_hdr *)hdr)->cpus;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_phys_hdr *)hdr)->cpus;
+}
+
+/* Physical CPU info block */
+
+static inline int phys_cpu__size(enum diag204_format type)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return sizeof(struct diag204_phys_cpu);
+	else /* DIAG204_INFO_EXT */
+		return sizeof(struct diag204_x_phys_cpu);
+}
+
+static inline __u16 phys_cpu__cpu_addr(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_phys_cpu *)hdr)->cpu_addr;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_phys_cpu *)hdr)->cpu_addr;
+}
+
+static inline __u64 phys_cpu__mgm_time(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_phys_cpu *)hdr)->mgm_time;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_phys_cpu *)hdr)->mgm_time;
+}
+
+static inline __u64 phys_cpu__ctidx(enum diag204_format type, void *hdr)
+{
+	if (type == DIAG204_INFO_SIMPLE)
+		return ((struct diag204_phys_cpu *)hdr)->ctidx;
+	else /* DIAG204_INFO_EXT */
+		return ((struct diag204_x_phys_cpu *)hdr)->ctidx;
+}
+
+/*
+ * Functions to create the directory structure
+ * *******************************************
+ */
+
+static int hypfs_create_cpu_files(struct dentry *cpus_dir, void *cpu_info)
+{
+	struct dentry *cpu_dir;
+	char buffer[TMP_SIZE];
+	void *rc;
+
+	snprintf(buffer, TMP_SIZE, "%d", cpu_info__cpu_addr(diag204_get_info_type(),
+							    cpu_info));
+	cpu_dir = hypfs_mkdir(cpus_dir, buffer);
+	rc = hypfs_create_u64(cpu_dir, "mgmtime",
+			      cpu_info__acc_time(diag204_get_info_type(), cpu_info) -
+			      cpu_info__lp_time(diag204_get_info_type(), cpu_info));
+	if (IS_ERR(rc))
+		return PTR_ERR(rc);
+	rc = hypfs_create_u64(cpu_dir, "cputime",
+			      cpu_info__lp_time(diag204_get_info_type(), cpu_info));
+	if (IS_ERR(rc))
+		return PTR_ERR(rc);
+	if (diag204_get_info_type() == DIAG204_INFO_EXT) {
+		rc = hypfs_create_u64(cpu_dir, "onlinetime",
+				      cpu_info__online_time(diag204_get_info_type(),
+							    cpu_info));
+		if (IS_ERR(rc))
+			return PTR_ERR(rc);
+	}
+	diag224_idx2name(cpu_info__ctidx(diag204_get_info_type(), cpu_info), buffer);
+	rc = hypfs_create_str(cpu_dir, "type", buffer);
+	return PTR_ERR_OR_ZERO(rc);
+}
+
+static void *hypfs_create_lpar_files(struct dentry *systems_dir, void *part_hdr)
+{
+	struct dentry *cpus_dir;
+	struct dentry *lpar_dir;
+	char lpar_name[DIAG204_LPAR_NAME_LEN + 1];
+	void *cpu_info;
+	int i;
+
+	part_hdr__part_name(diag204_get_info_type(), part_hdr, lpar_name);
+	lpar_name[DIAG204_LPAR_NAME_LEN] = 0;
+	lpar_dir = hypfs_mkdir(systems_dir, lpar_name);
+	if (IS_ERR(lpar_dir))
+		return lpar_dir;
+	cpus_dir = hypfs_mkdir(lpar_dir, "cpus");
+	if (IS_ERR(cpus_dir))
+		return cpus_dir;
+	cpu_info = part_hdr + part_hdr__size(diag204_get_info_type());
+	for (i = 0; i < part_hdr__rcpus(diag204_get_info_type(), part_hdr); i++) {
+		int rc;
+
+		rc = hypfs_create_cpu_files(cpus_dir, cpu_info);
+		if (rc)
+			return ERR_PTR(rc);
+		cpu_info += cpu_info__size(diag204_get_info_type());
+	}
+	return cpu_info;
+}
+
+static int hypfs_create_phys_cpu_files(struct dentry *cpus_dir, void *cpu_info)
+{
+	struct dentry *cpu_dir;
+	char buffer[TMP_SIZE];
+	void *rc;
+
+	snprintf(buffer, TMP_SIZE, "%i", phys_cpu__cpu_addr(diag204_get_info_type(),
+							    cpu_info));
+	cpu_dir = hypfs_mkdir(cpus_dir, buffer);
+	if (IS_ERR(cpu_dir))
+		return PTR_ERR(cpu_dir);
+	rc = hypfs_create_u64(cpu_dir, "mgmtime",
+			      phys_cpu__mgm_time(diag204_get_info_type(), cpu_info));
+	if (IS_ERR(rc))
+		return PTR_ERR(rc);
+	diag224_idx2name(phys_cpu__ctidx(diag204_get_info_type(), cpu_info), buffer);
+	rc = hypfs_create_str(cpu_dir, "type", buffer);
+	return PTR_ERR_OR_ZERO(rc);
+}
+
+static void *hypfs_create_phys_files(struct dentry *parent_dir, void *phys_hdr)
+{
+	int i;
+	void *cpu_info;
+	struct dentry *cpus_dir;
+
+	cpus_dir = hypfs_mkdir(parent_dir, "cpus");
+	if (IS_ERR(cpus_dir))
+		return cpus_dir;
+	cpu_info = phys_hdr + phys_hdr__size(diag204_get_info_type());
+	for (i = 0; i < phys_hdr__cpus(diag204_get_info_type(), phys_hdr); i++) {
+		int rc;
+
+		rc = hypfs_create_phys_cpu_files(cpus_dir, cpu_info);
+		if (rc)
+			return ERR_PTR(rc);
+		cpu_info += phys_cpu__size(diag204_get_info_type());
+	}
+	return cpu_info;
+}
+
+int hypfs_diag_create_files(struct dentry *root)
+{
+	struct dentry *systems_dir, *hyp_dir;
+	void *time_hdr, *part_hdr;
+	void *buffer, *ptr;
+	int i, rc, pages;
+
+	buffer = diag204_get_buffer(diag204_get_info_type(), &pages);
+	if (IS_ERR(buffer))
+		return PTR_ERR(buffer);
+	rc = diag204_store(buffer, pages);
+	if (rc)
+		return rc;
+
+	systems_dir = hypfs_mkdir(root, "systems");
+	if (IS_ERR(systems_dir)) {
+		rc = PTR_ERR(systems_dir);
+		goto err_out;
+	}
+	time_hdr = (struct x_info_blk_hdr *)buffer;
+	part_hdr = time_hdr + info_blk_hdr__size(diag204_get_info_type());
+	for (i = 0; i < info_blk_hdr__npar(diag204_get_info_type(), time_hdr); i++) {
+		part_hdr = hypfs_create_lpar_files(systems_dir, part_hdr);
+		if (IS_ERR(part_hdr)) {
+			rc = PTR_ERR(part_hdr);
+			goto err_out;
+		}
+	}
+	if (info_blk_hdr__flags(diag204_get_info_type(), time_hdr) &
+	    DIAG204_LPAR_PHYS_FLG) {
+		ptr = hypfs_create_phys_files(root, part_hdr);
+		if (IS_ERR(ptr)) {
+			rc = PTR_ERR(ptr);
+			goto err_out;
+		}
+	}
+	hyp_dir = hypfs_mkdir(root, "hyp");
+	if (IS_ERR(hyp_dir)) {
+		rc = PTR_ERR(hyp_dir);
+		goto err_out;
+	}
+	ptr = hypfs_create_str(hyp_dir, "type", "LPAR Hypervisor");
+	if (IS_ERR(ptr)) {
+		rc = PTR_ERR(ptr);
+		goto err_out;
+	}
+	rc = 0;
+
+err_out:
+	return rc;
+}
+
+/* Diagnose 224 functions */
+
+static int diag224_idx2name(int index, char *name)
+{
+	memcpy(name, diag224_cpu_names + ((index + 1) * DIAG204_CPU_NAME_LEN),
+	       DIAG204_CPU_NAME_LEN);
+	name[DIAG204_CPU_NAME_LEN] = 0;
+	strim(name);
+	return 0;
+}
+
+static int diag224_get_name_table(void)
+{
+	/* memory must be below 2GB */
+	diag224_cpu_names = (char *)__get_free_page(GFP_KERNEL | GFP_DMA);
+	if (!diag224_cpu_names)
+		return -ENOMEM;
+	if (diag224(diag224_cpu_names)) {
+		free_page((unsigned long)diag224_cpu_names);
+		return -EOPNOTSUPP;
+	}
+	EBCASC(diag224_cpu_names + 16, (*diag224_cpu_names + 1) * 16);
+	return 0;
+}
+
+static void diag224_delete_name_table(void)
+{
+	free_page((unsigned long)diag224_cpu_names);
+}
+
+int __init __hypfs_diag_fs_init(void)
+{
+	if (MACHINE_IS_LPAR)
+		return diag224_get_name_table();
+	return 0;
+}
+
+void __hypfs_diag_fs_exit(void)
+{
+	diag224_delete_name_table();
+}