s390/sclp: Add SCLP character device driver

Add a character misc device "sclp_ctl" that allows to run SCCBs
from user space using the SCLP_CTL_SCCB ioctl.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Documentation/ioctl/ioctl-number.txt

@@ -72,6 +72,7 @@ Code  Seq#(hex)	Include File		Comments
 0x06	all	linux/lp.h
 0x09	all	linux/raid/md_u.h
 0x10	00-0F	drivers/char/s390/vmcp.h
+0x10	10-1F	arch/s390/include/uapi/sclp_ctl.h
 0x12	all	linux/fs.h
 		linux/blkpg.h
 0x1b	all	InfiniBand Subsystem	<http://infiniband.sourceforge.net/>

arch/s390/include/uapi/asm/Kbuild

@@ -35,6 +35,7 @@ header-y += siginfo.h
 header-y += signal.h
 header-y += socket.h
 header-y += sockios.h
+header-y += sclp_ctl.h
 header-y += stat.h
 header-y += statfs.h
 header-y += swab.h

arch/s390/include/uapi/asm/sclp_ctl.h

+/*
+ * IOCTL interface for SCLP
+ *
+ * Copyright IBM Corp. 2012
+ *
+ * Author: Michael Holzheu <holzheu@linux.vnet.ibm.com>
+ */
+
+#ifndef _ASM_SCLP_CTL_H
+#define _ASM_SCLP_CTL_H
+
+#include <linux/types.h>
+
+struct sclp_ctl_sccb {
+	__u32	cmdw;
+	__u64	sccb;
+} __attribute__((packed));
+
+#define SCLP_CTL_IOCTL_MAGIC 0x10
+
+#define SCLP_CTL_SCCB \
+	_IOWR(SCLP_CTL_IOCTL_MAGIC, 0x10, struct sclp_ctl_sccb)
+
+#endif

drivers/s390/char/Makefile

@@ -3,7 +3,7 @@
 #
 
 obj-y += ctrlchar.o keyboard.o defkeymap.o sclp.o sclp_rw.o sclp_quiesce.o \
-	 sclp_cmd.o sclp_config.o sclp_cpi_sys.o sclp_ocf.o
+	 sclp_cmd.o sclp_config.o sclp_cpi_sys.o sclp_ocf.o sclp_ctl.o
 
 obj-$(CONFIG_TN3270) += raw3270.o
 obj-$(CONFIG_TN3270_CONSOLE) += con3270.o

drivers/s390/char/sclp.c

@@ -148,14 +148,19 @@ static int sclp_init(void);
 int
 sclp_service_call(sclp_cmdw_t command, void *sccb)
 {
-	int cc;
+	int cc = 4; /* Initialize for program check handling */
 
 	asm volatile(
-		"	.insn	rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
-		"	ipm	%0\n"
-		"	srl	%0,28"
-		: "=&d" (cc) : "d" (command), "a" (__pa(sccb))
+		"0:	.insn	rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
+		"1:	ipm	%0\n"
+		"	srl	%0,28\n"
+		"2:\n"
+		EX_TABLE(0b, 2b)
+		EX_TABLE(1b, 2b)
+		: "+&d" (cc) : "d" (command), "a" (__pa(sccb))
 		: "cc", "memory");
+	if (cc == 4)
+		return -EINVAL;
 	if (cc == 3)
 		return -EIO;
 	if (cc == 2)

drivers/s390/char/sclp.h

@@ -171,6 +171,7 @@ int sclp_remove_processed(struct sccb_header *sccb);
 int sclp_deactivate(void);
 int sclp_reactivate(void);
 int sclp_service_call(sclp_cmdw_t command, void *sccb);
+int sclp_sync_request(sclp_cmdw_t command, void *sccb);
 
 int sclp_sdias_init(void);
 void sclp_sdias_exit(void);

drivers/s390/char/sclp_cmd.c

@@ -195,7 +195,7 @@ static void sclp_sync_callback(struct sclp_req *req, void *data)
 	complete(completion);
 }
 
-static int do_sync_request(sclp_cmdw_t cmd, void *sccb)
+int sclp_sync_request(sclp_cmdw_t cmd, void *sccb)
 {
 	struct completion completion;
 	struct sclp_req *request;
@@ -270,7 +270,7 @@ int sclp_get_cpu_info(struct sclp_cpu_info *info)
 	if (!sccb)
 		return -ENOMEM;
 	sccb->header.length = sizeof(*sccb);
-	rc = do_sync_request(SCLP_CMDW_READ_CPU_INFO, sccb);
+	rc = sclp_sync_request(SCLP_CMDW_READ_CPU_INFO, sccb);
 	if (rc)
 		goto out;
 	if (sccb->header.response_code != 0x0010) {
@@ -304,7 +304,7 @@ static int do_cpu_configure(sclp_cmdw_t cmd)
 	if (!sccb)
 		return -ENOMEM;
 	sccb->header.length = sizeof(*sccb);
-	rc = do_sync_request(cmd, sccb);
+	rc = sclp_sync_request(cmd, sccb);
 	if (rc)
 		goto out;
 	switch (sccb->header.response_code) {
@@ -374,7 +374,7 @@ static int do_assign_storage(sclp_cmdw_t cmd, u16 rn)
 		return -ENOMEM;
 	sccb->header.length = PAGE_SIZE;
 	sccb->rn = rn;
-	rc = do_sync_request(cmd, sccb);
+	rc = sclp_sync_request(cmd, sccb);
 	if (rc)
 		goto out;
 	switch (sccb->header.response_code) {
@@ -429,7 +429,7 @@ static int sclp_attach_storage(u8 id)
 	if (!sccb)
 		return -ENOMEM;
 	sccb->header.length = PAGE_SIZE;
-	rc = do_sync_request(0x00080001 | id << 8, sccb);
+	rc = sclp_sync_request(0x00080001 | id << 8, sccb);
 	if (rc)
 		goto out;
 	switch (sccb->header.response_code) {
@@ -627,7 +627,7 @@ static int __init sclp_detect_standby_memory(void)
 	for (id = 0; id <= sclp_max_storage_id; id++) {
 		memset(sccb, 0, PAGE_SIZE);
 		sccb->header.length = PAGE_SIZE;
-		rc = do_sync_request(0x00040001 | id << 8, sccb);
+		rc = sclp_sync_request(0x00040001 | id << 8, sccb);
 		if (rc)
 			goto out;
 		switch (sccb->header.response_code) {
@@ -714,7 +714,7 @@ static int do_pci_configure(sclp_cmdw_t cmd, u32 fid)
 	sccb->header.length = PAGE_SIZE;
 	sccb->atype = SCLP_RECONFIG_PCI_ATPYE;
 	sccb->aid = fid;
-	rc = do_sync_request(cmd, sccb);
+	rc = sclp_sync_request(cmd, sccb);
 	if (rc)
 		goto out;
 	switch (sccb->header.response_code) {
@@ -771,7 +771,7 @@ static int do_chp_configure(sclp_cmdw_t cmd)
 	if (!sccb)
 		return -ENOMEM;
 	sccb->header.length = sizeof(*sccb);
-	rc = do_sync_request(cmd, sccb);
+	rc = sclp_sync_request(cmd, sccb);
 	if (rc)
 		goto out;
 	switch (sccb->header.response_code) {
@@ -846,7 +846,7 @@ int sclp_chp_read_info(struct sclp_chp_info *info)
 	if (!sccb)
 		return -ENOMEM;
 	sccb->header.length = sizeof(*sccb);
-	rc = do_sync_request(SCLP_CMDW_READ_CHPATH_INFORMATION, sccb);
+	rc = sclp_sync_request(SCLP_CMDW_READ_CHPATH_INFORMATION, sccb);
 	if (rc)
 		goto out;
 	if (sccb->header.response_code != 0x0010) {

drivers/s390/char/sclp_ctl.c

+/*
+ * IOCTL interface for SCLP
+ *
+ * Copyright IBM Corp. 2012
+ *
+ * Author: Michael Holzheu <holzheu@linux.vnet.ibm.com>
+ */
+
+#include <linux/compat.h>
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+#include <linux/gfp.h>
+#include <linux/module.h>
+#include <linux/ioctl.h>
+#include <linux/fs.h>
+#include <linux/compat.h>
+#include <asm/compat.h>
+#include <asm/sclp_ctl.h>
+#include <asm/sclp.h>
+
+#include "sclp.h"
+
+/*
+ * Supported command words
+ */
+static unsigned int sclp_ctl_sccb_wlist[] = {
+	0x00400002,
+	0x00410002,
+};
+
+/*
+ * Check if command word is supported
+ */
+static int sclp_ctl_cmdw_supported(unsigned int cmdw)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(sclp_ctl_sccb_wlist); i++) {
+		if (cmdw == sclp_ctl_sccb_wlist[i])
+			return 1;
+	}
+	return 0;
+}
+
+static void __user *u64_to_uptr(u64 value)
+{
+	if (is_compat_task())
+		return compat_ptr(value);
+	else
+		return (void __user *)(unsigned long)value;
+}
+
+/*
+ * Start SCLP request
+ */
+static int sclp_ctl_ioctl_sccb(void __user *user_area)
+{
+	struct sclp_ctl_sccb ctl_sccb;
+	struct sccb_header *sccb;
+	int rc;
+
+	if (copy_from_user(&ctl_sccb, user_area, sizeof(ctl_sccb)))
+		return -EFAULT;
+	if (!sclp_ctl_cmdw_supported(ctl_sccb.cmdw))
+		return -EOPNOTSUPP;
+	sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!sccb)
+		return -ENOMEM;
+	if (copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), sizeof(*sccb))) {
+		rc = -EFAULT;
+		goto out_free;
+	}
+	if (sccb->length > PAGE_SIZE || sccb->length < 8)
+		return -EINVAL;
+	if (copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), sccb->length)) {
+		rc = -EFAULT;
+		goto out_free;
+	}
+	rc = sclp_sync_request(ctl_sccb.cmdw, sccb);
+	if (rc)
+		goto out_free;
+	if (copy_to_user(u64_to_uptr(ctl_sccb.sccb), sccb, sccb->length))
+		rc = -EFAULT;
+out_free:
+	free_page((unsigned long) sccb);
+	return rc;
+}
+
+/*
+ * SCLP SCCB ioctl function
+ */
+static long sclp_ctl_ioctl(struct file *filp, unsigned int cmd,
+			   unsigned long arg)
+{
+	void __user *argp;
+
+	if (is_compat_task())
+		argp = compat_ptr(arg);
+	else
+		argp = (void __user *) arg;
+	switch (cmd) {
+	case SCLP_CTL_SCCB:
+		return sclp_ctl_ioctl_sccb(argp);
+	default: /* unknown ioctl number */
+		return -ENOTTY;
+	}
+}
+
+/*
+ * File operations
+ */
+static const struct file_operations sclp_ctl_fops = {
+	.owner = THIS_MODULE,
+	.open = nonseekable_open,
+	.unlocked_ioctl = sclp_ctl_ioctl,
+	.compat_ioctl = sclp_ctl_ioctl,
+	.llseek = no_llseek,
+};
+
+/*
+ * Misc device definition
+ */
+static struct miscdevice sclp_ctl_device = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "sclp",
+	.fops = &sclp_ctl_fops,
+};
+
+/*
+ * Register sclp_ctl misc device
+ */
+static int __init sclp_ctl_init(void)
+{
+	return misc_register(&sclp_ctl_device);
+}
+module_init(sclp_ctl_init);
+
+/*
+ * Deregister sclp_ctl misc device
+ */
+static void __exit sclp_ctl_exit(void)
+{
+	misc_deregister(&sclp_ctl_device);
+}
+module_exit(sclp_ctl_exit);