hypfs_diag.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *    Hypervisor filesystem for Linux on s390. Diag 204 and 224
  4 *    implementation.
  5 *
  6 *    Copyright IBM Corp. 2006, 2008
  7 *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
  8 */
  9
 10#define pr_fmt(fmt) "hypfs: " fmt
 11
 12#include <linux/types.h>
 13#include <linux/errno.h>
 14#include <linux/slab.h>
 15#include <linux/string.h>
 16#include <linux/vmalloc.h>
 17#include <linux/mm.h>
 18#include <asm/diag.h>
 19#include <asm/ebcdic.h>
 20#include "hypfs_diag.h"
 21#include "hypfs.h"
 22
 23#define DBFS_D204_HDR_VERSION	0
 24
 25static enum diag204_sc diag204_store_sc;	/* used subcode for store */
 26static enum diag204_format diag204_info_type;	/* used diag 204 data format */
 27
 28static void *diag204_buf;		/* 4K aligned buffer for diag204 data */
 29static int diag204_buf_pages;		/* number of pages for diag204 data */
 30
 31enum diag204_format diag204_get_info_type(void)
 32{
 33	return diag204_info_type;
 34}
 35
 36static void diag204_set_info_type(enum diag204_format type)
 37{
 38	diag204_info_type = type;
 39}
 40
 41/* Diagnose 204 functions */
 42/*
 43 * For the old diag subcode 4 with simple data format we have to use real
 44 * memory. If we use subcode 6 or 7 with extended data format, we can (and
 45 * should) use vmalloc, since we need a lot of memory in that case. Currently
 46 * up to 93 pages!
 47 */
 48
 49static void diag204_free_buffer(void)
 50{
 51	vfree(diag204_buf);
 52	diag204_buf = NULL;
 53}
 54
 55void *diag204_get_buffer(enum diag204_format fmt, int *pages)
 56{
 57	if (diag204_buf) {
 58		*pages = diag204_buf_pages;
 59		return diag204_buf;
 60	}
 61	if (fmt == DIAG204_INFO_SIMPLE) {
 62		*pages = 1;
 63	} else {/* DIAG204_INFO_EXT */
 64		*pages = diag204((unsigned long)DIAG204_SUBC_RSI |
 65				 (unsigned long)DIAG204_INFO_EXT, 0, NULL);
 66		if (*pages <= 0)
 67			return ERR_PTR(-EOPNOTSUPP);
 68	}
 69	diag204_buf = __vmalloc_node(array_size(*pages, PAGE_SIZE),
 70				     PAGE_SIZE, GFP_KERNEL, NUMA_NO_NODE,
 71				     __builtin_return_address(0));
 72	if (!diag204_buf)
 73		return ERR_PTR(-ENOMEM);
 74	diag204_buf_pages = *pages;
 75	return diag204_buf;
 76}
 77
 78/*
 79 * diag204_probe() has to find out, which type of diagnose 204 implementation
 80 * we have on our machine. Currently there are three possible scanarios:
 81 *   - subcode 4   + simple data format (only one page)
 82 *   - subcode 4-6 + extended data format
 83 *   - subcode 4-7 + extended data format
 84 *
 85 * Subcode 5 is used to retrieve the size of the data, provided by subcodes
 86 * 6 and 7. Subcode 7 basically has the same function as subcode 6. In addition
 87 * to subcode 6 it provides also information about secondary cpus.
 88 * In order to get as much information as possible, we first try
 89 * subcode 7, then 6 and if both fail, we use subcode 4.
 90 */
 91
 92static int diag204_probe(void)
 93{
 94	void *buf;
 95	int pages, rc;
 96
 97	buf = diag204_get_buffer(DIAG204_INFO_EXT, &pages);
 98	if (!IS_ERR(buf)) {
 99		if (diag204((unsigned long)DIAG204_SUBC_STIB7 |
100			    (unsigned long)DIAG204_INFO_EXT, pages, buf) >= 0) {
101			diag204_store_sc = DIAG204_SUBC_STIB7;
102			diag204_set_info_type(DIAG204_INFO_EXT);
103			goto out;
104		}
105		if (diag204((unsigned long)DIAG204_SUBC_STIB6 |
106			    (unsigned long)DIAG204_INFO_EXT, pages, buf) >= 0) {
107			diag204_store_sc = DIAG204_SUBC_STIB6;
108			diag204_set_info_type(DIAG204_INFO_EXT);
109			goto out;
110		}
111		diag204_free_buffer();
112	}
113
114	/* subcodes 6 and 7 failed, now try subcode 4 */
115
116	buf = diag204_get_buffer(DIAG204_INFO_SIMPLE, &pages);
117	if (IS_ERR(buf)) {
118		rc = PTR_ERR(buf);
119		goto fail_alloc;
120	}
121	if (diag204((unsigned long)DIAG204_SUBC_STIB4 |
122		    (unsigned long)DIAG204_INFO_SIMPLE, pages, buf) >= 0) {
123		diag204_store_sc = DIAG204_SUBC_STIB4;
124		diag204_set_info_type(DIAG204_INFO_SIMPLE);
125		goto out;
126	} else {
127		rc = -EOPNOTSUPP;
128		goto fail_store;
129	}
130out:
131	rc = 0;
132fail_store:
133	diag204_free_buffer();
134fail_alloc:
135	return rc;
136}
137
138int diag204_store(void *buf, int pages)
139{
140	unsigned long subcode;
141	int rc;
142
143	subcode = diag204_get_info_type();
144	subcode |= diag204_store_sc;
145	if (diag204_has_bif())
146		subcode |= DIAG204_BIF_BIT;
147	while (1) {
148		rc = diag204(subcode, pages, buf);
149		if (rc != -EBUSY)
150			break;
151		if (signal_pending(current))
152			return -ERESTARTSYS;
153		schedule_timeout_interruptible(DIAG204_BUSY_WAIT);
154	}
155	return rc < 0 ? rc : 0;
156}
157
158struct dbfs_d204_hdr {
159	u64	len;		/* Length of d204 buffer without header */
160	u16	version;	/* Version of header */
161	u8	sc;		/* Used subcode */
162	char	reserved[53];
163} __attribute__ ((packed));
164
165struct dbfs_d204 {
166	struct dbfs_d204_hdr	hdr;	/* 64 byte header */
167	char			buf[];	/* d204 buffer */
168} __attribute__ ((packed));
169
170static int dbfs_d204_create(void **data, void **data_free_ptr, size_t *size)
171{
172	struct dbfs_d204 *d204;
173	int rc, buf_size;
174	void *base;
175
176	buf_size = PAGE_SIZE * (diag204_buf_pages + 1) + sizeof(d204->hdr);
177	base = vzalloc(buf_size);
178	if (!base)
179		return -ENOMEM;
180	d204 = PTR_ALIGN(base + sizeof(d204->hdr), PAGE_SIZE) - sizeof(d204->hdr);
181	rc = diag204_store(d204->buf, diag204_buf_pages);
182	if (rc) {
183		vfree(base);
184		return rc;
185	}
186	d204->hdr.version = DBFS_D204_HDR_VERSION;
187	d204->hdr.len = PAGE_SIZE * diag204_buf_pages;
188	d204->hdr.sc = diag204_store_sc;
189	*data = d204;
190	*data_free_ptr = base;
191	*size = d204->hdr.len + sizeof(struct dbfs_d204_hdr);
192	return 0;
193}
194
195static struct hypfs_dbfs_file dbfs_file_d204 = {
196	.name		= "diag_204",
197	.data_create	= dbfs_d204_create,
198	.data_free	= vfree,
199};
200
201__init int hypfs_diag_init(void)
202{
203	int rc;
204
205	if (diag204_probe()) {
206		pr_info("The hardware system does not support hypfs\n");
207		return -ENODATA;
208	}
209
210	if (diag204_get_info_type() == DIAG204_INFO_EXT)
211		hypfs_dbfs_create_file(&dbfs_file_d204);
212
213	rc = hypfs_diag_fs_init();
214	if (rc)
215		pr_err("The hardware system does not provide all functions required by hypfs\n");
216	return rc;
217}
218
219void hypfs_diag_exit(void)
220{
221	hypfs_diag_fs_exit();
222	diag204_free_buffer();
223	hypfs_dbfs_remove_file(&dbfs_file_d204);
224}