text: /*
   * salinfo.c
   *
   * Creates entries in /proc/sal for various system features.
   *
   * Copyright (c) 2003, 2006 Silicon Graphics, Inc.  All rights reserved.
   * Copyright (c) 2003 Hewlett-Packard Co
   *	Bjorn Helgaas <bjorn.helgaas@hp.com>
   *
   * 10/30/2001	jbarnes@sgi.com		copied much of Stephane's palinfo
   *					code to create this file
   * Oct 23 2003	kaos@sgi.com
   *   Replace IPI with set_cpus_allowed() to read a record from the required cpu.
   *   Redesign salinfo log processing to separate interrupt and user space
   *   contexts.
   *   Cache the record across multi-block reads from user space.
   *   Support > 64 cpus.
   *   Delete module_exit and MOD_INC/DEC_COUNT, salinfo cannot be a module.
   *
   * Jan 28 2004	kaos@sgi.com
   *   Periodically check for outstanding MCA or INIT records.
   *
   * Dec  5 2004	kaos@sgi.com
   *   Standardize which records are cleared automatically.
   *
   * Aug 18 2005	kaos@sgi.com
   *   mca.c may not pass a buffer, a NULL buffer just indicates that a new
   *   record is available in SAL.
   *   Replace some NR_CPUS by cpus_online, for hotplug cpu.
   *
   * Jan  5 2006        kaos@sgi.com
   *   Handle hotplug cpus coming online.
   *   Handle hotplug cpus going offline while they still have outstanding records.
   *   Use the cpu_* macros consistently.
   *   Replace the counting semaphore with a mutex and a test if the cpumask is non-empty.
   *   Modify the locking to make the test for "work to do" an atomic operation.
   */
  
  #include <linux/capability.h>
  #include <linux/cpu.h>
  #include <linux/types.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/module.h>
  #include <linux/smp.h>
  #include <linux/timer.h>
  #include <linux/vmalloc.h>
  #include <linux/semaphore.h>
  
  #include <asm/sal.h>
  #include <linux/uaccess.h>
  
  MODULE_AUTHOR("Jesse Barnes <jbarnes@sgi.com>");
  MODULE_DESCRIPTION("/proc interface to IA-64 SAL features");
  MODULE_LICENSE("GPL");
  
  static const struct file_operations proc_salinfo_fops;
  
  typedef struct {
  	const char		*name;		/* name of the proc entry */
  	unsigned long           feature;        /* feature bit */
  	struct proc_dir_entry	*entry;		/* registered entry (removal) */
  } salinfo_entry_t;
  
  /*
   * List {name,feature} pairs for every entry in /proc/sal/<feature>
   * that this module exports
   */
  static const salinfo_entry_t salinfo_entries[]={
  	{ "bus_lock",           IA64_SAL_PLATFORM_FEATURE_BUS_LOCK, },
  	{ "irq_redirection",	IA64_SAL_PLATFORM_FEATURE_IRQ_REDIR_HINT, },
  	{ "ipi_redirection",	IA64_SAL_PLATFORM_FEATURE_IPI_REDIR_HINT, },
  	{ "itc_drift",		IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT, },
  };
  
  #define NR_SALINFO_ENTRIES ARRAY_SIZE(salinfo_entries)
  
  static char *salinfo_log_name[] = {
  	"mca",
  	"init",
  	"cmc",
  	"cpe",
  };
  
  static struct proc_dir_entry *salinfo_proc_entries[
  	ARRAY_SIZE(salinfo_entries) +			/* /proc/sal/bus_lock */
  	ARRAY_SIZE(salinfo_log_name) +			/* /proc/sal/{mca,...} */
  	(2 * ARRAY_SIZE(salinfo_log_name)) +		/* /proc/sal/mca/{event,data} */
  	1];						/* /proc/sal */
  
  /* Some records we get ourselves, some are accessed as saved data in buffers
   * that are owned by mca.c.
   */
  struct salinfo_data_saved {
  	u8*			buffer;
  	u64			size;
  	u64			id;
  	int			cpu;
  };
  
  /* State transitions.  Actions are :-
   *   Write "read <cpunum>" to the data file.
   *   Write "clear <cpunum>" to the data file.
   *   Write "oemdata <cpunum> <offset> to the data file.
   *   Read from the data file.
   *   Close the data file.
   *
   * Start state is NO_DATA.
   *
   * NO_DATA
   *    write "read <cpunum>" -> NO_DATA or LOG_RECORD.
   *    write "clear <cpunum>" -> NO_DATA or LOG_RECORD.
   *    write "oemdata <cpunum> <offset> -> return -EINVAL.
   *    read data -> return EOF.
   *    close -> unchanged.  Free record areas.
   *
   * LOG_RECORD
   *    write "read <cpunum>" -> NO_DATA or LOG_RECORD.
   *    write "clear <cpunum>" -> NO_DATA or LOG_RECORD.
   *    write "oemdata <cpunum> <offset> -> format the oem data, goto OEMDATA.
   *    read data -> return the INIT/MCA/CMC/CPE record.
   *    close -> unchanged.  Keep record areas.
   *
   * OEMDATA
   *    write "read <cpunum>" -> NO_DATA or LOG_RECORD.
   *    write "clear <cpunum>" -> NO_DATA or LOG_RECORD.
   *    write "oemdata <cpunum> <offset> -> format the oem data, goto OEMDATA.
   *    read data -> return the formatted oemdata.
   *    close -> unchanged.  Keep record areas.
   *
   * Closing the data file does not change the state.  This allows shell scripts
   * to manipulate salinfo data, each shell redirection opens the file, does one
   * action then closes it again.  The record areas are only freed at close when
   * the state is NO_DATA.
   */
  enum salinfo_state {
  	STATE_NO_DATA,
  	STATE_LOG_RECORD,
  	STATE_OEMDATA,
  };
  
  struct salinfo_data {
  	cpumask_t		cpu_event;	/* which cpus have outstanding events */
  	wait_queue_head_t	read_wait;
  	u8			*log_buffer;
  	u64			log_size;
  	u8			*oemdata;	/* decoded oem data */
  	u64			oemdata_size;
  	int			open;		/* single-open to prevent races */
  	u8			type;
  	u8			saved_num;	/* using a saved record? */
  	enum salinfo_state	state :8;	/* processing state */
  	u8			padding;
  	int			cpu_check;	/* next CPU to check */
  	struct salinfo_data_saved data_saved[5];/* save last 5 records from mca.c, must be < 255 */
  };
  
  static struct salinfo_data salinfo_data[ARRAY_SIZE(salinfo_log_name)];
  
  static DEFINE_SPINLOCK(data_lock);
  static DEFINE_SPINLOCK(data_saved_lock);
  
  /** salinfo_platform_oemdata - optional callback to decode oemdata from an error
   * record.
   * @sect_header: pointer to the start of the section to decode.
   * @oemdata: returns vmalloc area containing the decoded output.
   * @oemdata_size: returns length of decoded output (strlen).
   *
   * Description: If user space asks for oem data to be decoded by the kernel
   * and/or prom and the platform has set salinfo_platform_oemdata to the address
   * of a platform specific routine then call that routine.  salinfo_platform_oemdata
   * vmalloc's and formats its output area, returning the address of the text
   * and its strlen.  Returns 0 for success, -ve for error.  The callback is
   * invoked on the cpu that generated the error record.
   */
  int (*salinfo_platform_oemdata)(const u8 *sect_header, u8 **oemdata, u64 *oemdata_size);
  
  struct salinfo_platform_oemdata_parms {
  	const u8 *efi_guid;
  	u8 **oemdata;
  	u64 *oemdata_size;
  	int ret;
  };
  
  static void
  salinfo_platform_oemdata_cpu(void *context)
  {
  	struct salinfo_platform_oemdata_parms *parms = context;
  	parms->ret = salinfo_platform_oemdata(parms->efi_guid, parms->oemdata, parms->oemdata_size);
  }
  
  static void
  shift1_data_saved (struct salinfo_data *data, int shift)
  {
  	memcpy(data->data_saved+shift, data->data_saved+shift+1,
  	       (ARRAY_SIZE(data->data_saved) - (shift+1)) * sizeof(data->data_saved[0]));
  	memset(data->data_saved + ARRAY_SIZE(data->data_saved) - 1, 0,
  	       sizeof(data->data_saved[0]));
  }
  
  /* This routine is invoked in interrupt context.  Note: mca.c enables
   * interrupts before calling this code for CMC/CPE.  MCA and INIT events are
   * not irq safe, do not call any routines that use spinlocks, they may deadlock.
   * MCA and INIT records are recorded, a timer event will look for any
   * outstanding events and wake up the user space code.
   *
   * The buffer passed from mca.c points to the output from ia64_log_get. This is
   * a persistent buffer but its contents can change between the interrupt and
   * when user space processes the record.  Save the record id to identify
   * changes.  If the buffer is NULL then just update the bitmap.
   */
  void
  salinfo_log_wakeup(int type, u8 *buffer, u64 size, int irqsafe)
  {
  	struct salinfo_data *data = salinfo_data + type;
  	struct salinfo_data_saved *data_saved;
  	unsigned long flags = 0;
  	int i;
  	int saved_size = ARRAY_SIZE(data->data_saved);
  
  	BUG_ON(type >= ARRAY_SIZE(salinfo_log_name));
  
  	if (irqsafe)
  		spin_lock_irqsave(&data_saved_lock, flags);
  	if (buffer) {
  		for (i = 0, data_saved = data->data_saved; i < saved_size; ++i, ++data_saved) {
  			if (!data_saved->buffer)
  				break;
  		}
  		if (i == saved_size) {
  			if (!data->saved_num) {
  				shift1_data_saved(data, 0);
  				data_saved = data->data_saved + saved_size - 1;
  			} else
  				data_saved = NULL;
  		}
  		if (data_saved) {
  			data_saved->cpu = smp_processor_id();
  			data_saved->id = ((sal_log_record_header_t *)buffer)->id;
  			data_saved->size = size;
  			data_saved->buffer = buffer;
  		}
  	}
  	cpumask_set_cpu(smp_processor_id(), &data->cpu_event);
  	if (irqsafe) {
  		wake_up_interruptible(&data->read_wait);
  		spin_unlock_irqrestore(&data_saved_lock, flags);
  	}
  }
  
  /* Check for outstanding MCA/INIT records every minute (arbitrary) */
  #define SALINFO_TIMER_DELAY (60*HZ)
  static struct timer_list salinfo_timer;
  extern void ia64_mlogbuf_dump(void);
  
  static void
  salinfo_timeout_check(struct salinfo_data *data)
  {
  	if (!data->open)
  		return;
  	if (!cpumask_empty(&data->cpu_event))
  		wake_up_interruptible(&data->read_wait);
  }
  
  static void
  salinfo_timeout (unsigned long arg)
  {
  	ia64_mlogbuf_dump();
  	salinfo_timeout_check(salinfo_data + SAL_INFO_TYPE_MCA);
  	salinfo_timeout_check(salinfo_data + SAL_INFO_TYPE_INIT);
  	salinfo_timer.expires = jiffies + SALINFO_TIMER_DELAY;
  	add_timer(&salinfo_timer);
  }
  
  static int
  salinfo_event_open(struct inode *inode, struct file *file)
  {
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  	return 0;
  }
  
  static ssize_t
  salinfo_event_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
  {
  	struct salinfo_data *data = PDE_DATA(file_inode(file));
  	char cmd[32];
  	size_t size;
  	int i, n, cpu = -1;
  
  retry:
  	if (cpumask_empty(&data->cpu_event)) {
  		if (file->f_flags & O_NONBLOCK)
  			return -EAGAIN;
  		if (wait_event_interruptible(data->read_wait,
  					     !cpumask_empty(&data->cpu_event)))
  			return -EINTR;
  	}
  
  	n = data->cpu_check;
  	for (i = 0; i < nr_cpu_ids; i++) {
  		if (cpumask_test_cpu(n, &data->cpu_event)) {
  			if (!cpu_online(n)) {
  				cpumask_clear_cpu(n, &data->cpu_event);
  				continue;
  			}
  			cpu = n;
  			break;
  		}
  		if (++n == nr_cpu_ids)
  			n = 0;
  	}
  
  	if (cpu == -1)
  		goto retry;
  
  	ia64_mlogbuf_dump();
  
  	/* for next read, start checking at next CPU */
  	data->cpu_check = cpu;
  	if (++data->cpu_check == nr_cpu_ids)
  		data->cpu_check = 0;
  
  	snprintf(cmd, sizeof(cmd), "read %d\n", cpu);
  
  	size = strlen(cmd);
  	if (size > count)
  		size = count;
  	if (copy_to_user(buffer, cmd, size))
  		return -EFAULT;
  
  	return size;
  }
  
  static const struct file_operations salinfo_event_fops = {
  	.open  = salinfo_event_open,
  	.read  = salinfo_event_read,
  	.llseek = noop_llseek,
  };
  
  static int
  salinfo_log_open(struct inode *inode, struct file *file)
  {
  	struct salinfo_data *data = PDE_DATA(inode);
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	spin_lock(&data_lock);
  	if (data->open) {
  		spin_unlock(&data_lock);
  		return -EBUSY;
  	}
  	data->open = 1;
  	spin_unlock(&data_lock);
  
  	if (data->state == STATE_NO_DATA &&
  	    !(data->log_buffer = vmalloc(ia64_sal_get_state_info_size(data->type)))) {
  		data->open = 0;
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  static int
  salinfo_log_release(struct inode *inode, struct file *file)
  {
  	struct salinfo_data *data = PDE_DATA(inode);
  
  	if (data->state == STATE_NO_DATA) {
  		vfree(data->log_buffer);
  		vfree(data->oemdata);
  		data->log_buffer = NULL;
  		data->oemdata = NULL;
  	}
  	spin_lock(&data_lock);
  	data->open = 0;
  	spin_unlock(&data_lock);
  	return 0;
  }
  
  static void
  call_on_cpu(int cpu, void (*fn)(void *), void *arg)
  {
  	cpumask_t save_cpus_allowed = current->cpus_allowed;
  	set_cpus_allowed_ptr(current, cpumask_of(cpu));
  	(*fn)(arg);
  	set_cpus_allowed_ptr(current, &save_cpus_allowed);
  }
  
  static void
  salinfo_log_read_cpu(void *context)
  {
  	struct salinfo_data *data = context;
  	sal_log_record_header_t *rh;
  	data->log_size = ia64_sal_get_state_info(data->type, (u64 *) data->log_buffer);
  	rh = (sal_log_record_header_t *)(data->log_buffer);
  	/* Clear corrected errors as they are read from SAL */
  	if (rh->severity == sal_log_severity_corrected)
  		ia64_sal_clear_state_info(data->type);
  }
  
  static void
  salinfo_log_new_read(int cpu, struct salinfo_data *data)
  {
  	struct salinfo_data_saved *data_saved;
  	unsigned long flags;
  	int i;
  	int saved_size = ARRAY_SIZE(data->data_saved);
  
  	data->saved_num = 0;
  	spin_lock_irqsave(&data_saved_lock, flags);
  retry:
  	for (i = 0, data_saved = data->data_saved; i < saved_size; ++i, ++data_saved) {
  		if (data_saved->buffer && data_saved->cpu == cpu) {
  			sal_log_record_header_t *rh = (sal_log_record_header_t *)(data_saved->buffer);
  			data->log_size = data_saved->size;
  			memcpy(data->log_buffer, rh, data->log_size);
  			barrier();	/* id check must not be moved */
  			if (rh->id == data_saved->id) {
  				data->saved_num = i+1;
  				break;
  			}
  			/* saved record changed by mca.c since interrupt, discard it */
  			shift1_data_saved(data, i);
  			goto retry;
  		}
  	}
  	spin_unlock_irqrestore(&data_saved_lock, flags);
  
  	if (!data->saved_num)
  		call_on_cpu(cpu, salinfo_log_read_cpu, data);
  	if (!data->log_size) {
  		data->state = STATE_NO_DATA;
  		cpumask_clear_cpu(cpu, &data->cpu_event);
  	} else {
  		data->state = STATE_LOG_RECORD;
  	}
  }
  
  static ssize_t
  salinfo_log_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
  {
  	struct salinfo_data *data = PDE_DATA(file_inode(file));
  	u8 *buf;
  	u64 bufsize;
  
  	if (data->state == STATE_LOG_RECORD) {
  		buf = data->log_buffer;
  		bufsize = data->log_size;
  	} else if (data->state == STATE_OEMDATA) {
  		buf = data->oemdata;
  		bufsize = data->oemdata_size;
  	} else {
  		buf = NULL;
  		bufsize = 0;
  	}
  	return simple_read_from_buffer(buffer, count, ppos, buf, bufsize);
  }
  
  static void
  salinfo_log_clear_cpu(void *context)
  {
  	struct salinfo_data *data = context;
  	ia64_sal_clear_state_info(data->type);
  }
  
  static int
  salinfo_log_clear(struct salinfo_data *data, int cpu)
  {
  	sal_log_record_header_t *rh;
  	unsigned long flags;
  	spin_lock_irqsave(&data_saved_lock, flags);
  	data->state = STATE_NO_DATA;
  	if (!cpumask_test_cpu(cpu, &data->cpu_event)) {
  		spin_unlock_irqrestore(&data_saved_lock, flags);
  		return 0;
  	}
  	cpumask_clear_cpu(cpu, &data->cpu_event);
  	if (data->saved_num) {
  		shift1_data_saved(data, data->saved_num - 1);
  		data->saved_num = 0;
  	}
  	spin_unlock_irqrestore(&data_saved_lock, flags);
  	rh = (sal_log_record_header_t *)(data->log_buffer);
  	/* Corrected errors have already been cleared from SAL */
  	if (rh->severity != sal_log_severity_corrected)
  		call_on_cpu(cpu, salinfo_log_clear_cpu, data);
  	/* clearing a record may make a new record visible */
  	salinfo_log_new_read(cpu, data);
  	if (data->state == STATE_LOG_RECORD) {
  		spin_lock_irqsave(&data_saved_lock, flags);
  		cpumask_set_cpu(cpu, &data->cpu_event);
  		wake_up_interruptible(&data->read_wait);
  		spin_unlock_irqrestore(&data_saved_lock, flags);
  	}
  	return 0;
  }
  
  static ssize_t
  salinfo_log_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
  {
  	struct salinfo_data *data = PDE_DATA(file_inode(file));
  	char cmd[32];
  	size_t size;
  	u32 offset;
  	int cpu;
  
  	size = sizeof(cmd);
  	if (count < size)
  		size = count;
  	if (copy_from_user(cmd, buffer, size))
  		return -EFAULT;
  
  	if (sscanf(cmd, "read %d", &cpu) == 1) {
  		salinfo_log_new_read(cpu, data);
  	} else if (sscanf(cmd, "clear %d", &cpu) == 1) {
  		int ret;
  		if ((ret = salinfo_log_clear(data, cpu)))
  			count = ret;
  	} else if (sscanf(cmd, "oemdata %d %d", &cpu, &offset) == 2) {
  		if (data->state != STATE_LOG_RECORD && data->state != STATE_OEMDATA)
  			return -EINVAL;
  		if (offset > data->log_size - sizeof(efi_guid_t))
  			return -EINVAL;
  		data->state = STATE_OEMDATA;
  		if (salinfo_platform_oemdata) {
  			struct salinfo_platform_oemdata_parms parms = {
  				.efi_guid = data->log_buffer + offset,
  				.oemdata = &data->oemdata,
  				.oemdata_size = &data->oemdata_size
  			};
  			call_on_cpu(cpu, salinfo_platform_oemdata_cpu, &parms);
  			if (parms.ret)
  				count = parms.ret;
  		} else
  			data->oemdata_size = 0;
  	} else
  		return -EINVAL;
  
  	return count;
  }
  
  static const struct file_operations salinfo_data_fops = {
  	.open    = salinfo_log_open,
  	.release = salinfo_log_release,
  	.read    = salinfo_log_read,
  	.write   = salinfo_log_write,
  	.llseek  = default_llseek,
  };
  
  static int salinfo_cpu_online(unsigned int cpu)
  {
  	unsigned int i, end = ARRAY_SIZE(salinfo_data);
  	struct salinfo_data *data;
  
  	spin_lock_irq(&data_saved_lock);
  	for (i = 0, data = salinfo_data; i < end; ++i, ++data) {
  		cpumask_set_cpu(cpu, &data->cpu_event);
  		wake_up_interruptible(&data->read_wait);
  	}
  	spin_unlock_irq(&data_saved_lock);
  	return 0;
  }
  
  static int salinfo_cpu_pre_down(unsigned int cpu)
  {
  	unsigned int i, end = ARRAY_SIZE(salinfo_data);
  	struct salinfo_data *data;
  
  	spin_lock_irq(&data_saved_lock);
  	for (i = 0, data = salinfo_data; i < end; ++i, ++data) {
  		struct salinfo_data_saved *data_saved;
  		int j = ARRAY_SIZE(data->data_saved) - 1;
  
  		for (data_saved = data->data_saved + j; j >= 0;
  		     --j, --data_saved) {
  			if (data_saved->buffer && data_saved->cpu == cpu)
  				shift1_data_saved(data, j);
  		}
  		cpumask_clear_cpu(cpu, &data->cpu_event);
  	}
  	spin_unlock_irq(&data_saved_lock);
  	return 0;
  }
  
  static int __init
  salinfo_init(void)
  {
  	struct proc_dir_entry *salinfo_dir; /* /proc/sal dir entry */
  	struct proc_dir_entry **sdir = salinfo_proc_entries; /* keeps track of every entry */
  	struct proc_dir_entry *dir, *entry;
  	struct salinfo_data *data;
  	int i;
  
  	salinfo_dir = proc_mkdir("sal", NULL);
  	if (!salinfo_dir)
  		return 0;
  
  	for (i=0; i < NR_SALINFO_ENTRIES; i++) {
  		/* pass the feature bit in question as misc data */
  		*sdir++ = proc_create_data(salinfo_entries[i].name, 0, salinfo_dir,
  					   &proc_salinfo_fops,
  					   (void *)salinfo_entries[i].feature);
  	}
  
  	for (i = 0; i < ARRAY_SIZE(salinfo_log_name); i++) {
  		data = salinfo_data + i;
  		data->type = i;
  		init_waitqueue_head(&data->read_wait);
  		dir = proc_mkdir(salinfo_log_name[i], salinfo_dir);
  		if (!dir)
  			continue;
  
  		entry = proc_create_data("event", S_IRUSR, dir,
  					 &salinfo_event_fops, data);
  		if (!entry)
  			continue;
  		*sdir++ = entry;
  
  		entry = proc_create_data("data", S_IRUSR | S_IWUSR, dir,
  					 &salinfo_data_fops, data);
  		if (!entry)
  			continue;
  		*sdir++ = entry;
  
  		*sdir++ = dir;
  	}
  
  	*sdir++ = salinfo_dir;
  
  	init_timer(&salinfo_timer);
  	salinfo_timer.expires = jiffies + SALINFO_TIMER_DELAY;
  	salinfo_timer.function = &salinfo_timeout;
  	add_timer(&salinfo_timer);
  
  	i = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "ia64/salinfo:online",
  			      salinfo_cpu_online, salinfo_cpu_pre_down);
  	WARN_ON(i < 0);
  	return 0;
  }
  
  /*
   * 'data' contains an integer that corresponds to the feature we're
   * testing
   */
  static int proc_salinfo_show(struct seq_file *m, void *v)
  {
  	unsigned long data = (unsigned long)v;
  	seq_puts(m, (sal_platform_features & data) ? "1\n" : "0\n");
  	return 0;
  }
  
  static int proc_salinfo_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, proc_salinfo_show, PDE_DATA(inode));
  }
  
  static const struct file_operations proc_salinfo_fops = {
  	.open		= proc_salinfo_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  module_init(salinfo_init);
  