Release 4.14 arch/powerpc/kernel/nvram_64.c

/*
 *  c 2001 PPC 64 Team, IBM Corp
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 * /dev/nvram driver for PPC64
 *
 * This perhaps should live in drivers/char
 *
 * TODO: Split the /dev/nvram part (that one can use
 *       drivers/char/generic_nvram.c) from the arch & partition
 *       parsing code.
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/nvram.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/kmsg_dump.h>
#include <linux/pagemap.h>
#include <linux/pstore.h>
#include <linux/zlib.h>
#include <linux/uaccess.h>
#include <asm/nvram.h>
#include <asm/rtas.h>
#include <asm/prom.h>
#include <asm/machdep.h>


#undef DEBUG_NVRAM


#define NVRAM_HEADER_LEN	sizeof(struct nvram_header)

#define NVRAM_BLOCK_LEN		NVRAM_HEADER_LEN

/* If change this size, then change the size of NVNAME_LEN */

struct nvram_header {
	
unsigned char signature;
	
unsigned char checksum;
	
unsigned short length;
	/* Terminating null required only for names < 12 chars. */
	
char name[12];
};


struct nvram_partition {
	
struct list_head partition;
	
struct nvram_header header;
	
unsigned int index;
};

static LIST_HEAD(nvram_partitions);

#ifdef CONFIG_PPC_PSERIES

struct nvram_os_partition rtas_log_partition = {
	.name = "ibm,rtas-log",
	.req_size = 2079,
	.min_size = 1055,
	.index = -1,
	.os_partition = true
};
#endif


struct nvram_os_partition oops_log_partition = {
	.name = "lnx,oops-log",
	.req_size = 4000,
	.min_size = 2000,
	.index = -1,
	.os_partition = true
};


static const char *nvram_os_partitions[] = {
#ifdef CONFIG_PPC_PSERIES
	"ibm,rtas-log",
#endif
	"lnx,oops-log",
	NULL
};

static void oops_to_nvram(struct kmsg_dumper *dumper,
			  enum kmsg_dump_reason reason);


static struct kmsg_dumper nvram_kmsg_dumper = {
	.dump = oops_to_nvram
};

/*
 * For capturing and compressing an oops or panic report...

 * big_oops_buf[] holds the uncompressed text we're capturing.
 *
 * oops_buf[] holds the compressed text, preceded by a oops header.
 * oops header has u16 holding the version of oops header (to differentiate
 * between old and new format header) followed by u16 holding the length of
 * the compressed* text (*Or uncompressed, if compression fails.) and u64
 * holding the timestamp. oops_buf[] gets written to NVRAM.
 *
 * oops_log_info points to the header. oops_data points to the compressed text.
 *
 * +- oops_buf
 * |                                   +- oops_data
 * v                                   v
 * +-----------+-----------+-----------+------------------------+
 * | version   | length    | timestamp | text                   |
 * | (2 bytes) | (2 bytes) | (8 bytes) | (oops_data_sz bytes)   |
 * +-----------+-----------+-----------+------------------------+
 * ^
 * +- oops_log_info
 *
 * We preallocate these buffers during init to avoid kmalloc during oops/panic.
 */

static size_t big_oops_buf_sz;


static char *big_oops_buf, *oops_buf;

static char *oops_data;

static size_t oops_data_sz;

/* Compression parameters */

#define COMPR_LEVEL 6

#define WINDOW_BITS 12

#define MEM_LEVEL 4

static struct z_stream_s stream;

#ifdef CONFIG_PSTORE
#ifdef CONFIG_PPC_POWERNV

static struct nvram_os_partition skiboot_partition = {
	.name = "ibm,skiboot",
	.index = -1,
	.os_partition = false
};
#endif

#ifdef CONFIG_PPC_PSERIES

static struct nvram_os_partition of_config_partition = {
	.name = "of-config",
	.index = -1,
	.os_partition = false
};
#endif


static struct nvram_os_partition common_partition = {
	.name = "common",
	.index = -1,
	.os_partition = false
};


static enum pstore_type_id nvram_type_ids[] = {
	PSTORE_TYPE_DMESG,
	PSTORE_TYPE_PPC_COMMON,
	-1,
	-1,
	-1
};

static int read_type;
#endif

/* nvram_write_os_partition
 *
 * We need to buffer the error logs into nvram to ensure that we have
 * the failure information to decode.  If we have a severe error there
 * is no way to guarantee that the OS or the machine is in a state to
 * get back to user land and write the error to disk.  For example if
 * the SCSI device driver causes a Machine Check by writing to a bad
 * IO address, there is no way of guaranteeing that the device driver
 * is in any state that is would also be able to write the error data
 * captured to disk, thus we buffer it in NVRAM for analysis on the
 * next boot.
 *
 * In NVRAM the partition containing the error log buffer will looks like:
 * Header (in bytes):
 * +-----------+----------+--------+------------+------------------+
 * | signature | checksum | length | name       | data             |
 * |0          |1         |2      3|4         15|16        length-1|
 * +-----------+----------+--------+------------+------------------+
 *
 * The 'data' section would look like (in bytes):
 * +--------------+------------+-----------------------------------+
 * | event_logged | sequence # | error log                         |
 * |0            3|4          7|8                  error_log_size-1|
 * +--------------+------------+-----------------------------------+
 *
 * event_logged: 0 if event has not been logged to syslog, 1 if it has
 * sequence #: The unique sequence # for each event. (until it wraps)
 * error log: The error log from event_scan
 */


int nvram_write_os_partition(struct nvram_os_partition *part,
			     char *buff, int length,
			     unsigned int err_type,
			     unsigned int error_log_cnt)
{
	int rc;
	loff_t tmp_index;
	struct err_log_info info;

	if (part->index == -1)
		return -ESPIPE;

	if (length > part->size)
		length = part->size;

	info.error_type = cpu_to_be32(err_type);
	info.seq_num = cpu_to_be32(error_log_cnt);

	tmp_index = part->index;

	rc = ppc_md.nvram_write((char *)&info, sizeof(struct err_log_info),
				&tmp_index);
	if (rc <= 0) {
		pr_err("%s: Failed nvram_write (%d)\n", __func__, rc);
		return rc;
	}

	rc = ppc_md.nvram_write(buff, length, &tmp_index);
	if (rc <= 0) {
		pr_err("%s: Failed nvram_write (%d)\n", __func__, rc);
		return rc;
	}

	return 0;
}

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/* nvram_read_partition
 *
 * Reads nvram partition for at most 'length'
 */


int nvram_read_partition(struct nvram_os_partition *part, char *buff,
			 int length, unsigned int *err_type,
			 unsigned int *error_log_cnt)
{
	int rc;
	loff_t tmp_index;
	struct err_log_info info;

	if (part->index == -1)
		return -1;

	if (length > part->size)
		length = part->size;

	tmp_index = part->index;

	if (part->os_partition) {
		rc = ppc_md.nvram_read((char *)&info,
					sizeof(struct err_log_info),
					&tmp_index);
		if (rc <= 0) {
			pr_err("%s: Failed nvram_read (%d)\n", __func__, rc);
			return rc;
		}
	}

	rc = ppc_md.nvram_read(buff, length, &tmp_index);
	if (rc <= 0) {
		pr_err("%s: Failed nvram_read (%d)\n", __func__, rc);
		return rc;
	}

	if (part->os_partition) {
		*error_log_cnt = be32_to_cpu(info.seq_num);
		*err_type = be32_to_cpu(info.error_type);
	}

	return 0;
}

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/* nvram_init_os_partition
 *
 * This sets up a partition with an "OS" signature.
 *
 * The general strategy is the following:
 * 1.) If a partition with the indicated name already exists...
 *      - If it's large enough, use it.
 *      - Otherwise, recycle it and keep going.
 * 2.) Search for a free partition that is large enough.
 * 3.) If there's not a free partition large enough, recycle any obsolete
 * OS partitions and try again.
 * 4.) Will first try getting a chunk that will satisfy the requested size.
 * 5.) If a chunk of the requested size cannot be allocated, then try finding
 * a chunk that will satisfy the minum needed.
 *
 * Returns 0 on success, else -1.
 */


int __init nvram_init_os_partition(struct nvram_os_partition *part)
{
	loff_t p;
	int size;

	/* Look for ours */
	p = nvram_find_partition(part->name, NVRAM_SIG_OS, &size);

	/* Found one but too small, remove it */
	if (p && size < part->min_size) {
		pr_info("nvram: Found too small %s partition,"
					" removing it...\n", part->name);
		nvram_remove_partition(part->name, NVRAM_SIG_OS, NULL);
		p = 0;
	}

	/* Create one if we didn't find */
	if (!p) {
		p = nvram_create_partition(part->name, NVRAM_SIG_OS,
					part->req_size, part->min_size);
		if (p == -ENOSPC) {
			pr_info("nvram: No room to create %s partition, "
				"deleting any obsolete OS partitions...\n",
				part->name);
			nvram_remove_partition(NULL, NVRAM_SIG_OS,
					nvram_os_partitions);
			p = nvram_create_partition(part->name, NVRAM_SIG_OS,
					part->req_size, part->min_size);
		}
	}

	if (p <= 0) {
		pr_err("nvram: Failed to find or create %s"
		       " partition, err %d\n", part->name, (int)p);
		return -1;
	}

	part->index = p;
	part->size = nvram_get_partition_size(p) - sizeof(struct err_log_info);

	return 0;
}

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/* Derived from logfs_compress() */


static int nvram_compress(const void *in, void *out, size_t inlen,
							size_t outlen)
{
	int err, ret;

	ret = -EIO;
	err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
						MEM_LEVEL, Z_DEFAULT_STRATEGY);
	if (err != Z_OK)
		goto error;

	stream.next_in = in;
	stream.avail_in = inlen;
	stream.total_in = 0;
	stream.next_out = out;
	stream.avail_out = outlen;
	stream.total_out = 0;

	err = zlib_deflate(&stream, Z_FINISH);
	if (err != Z_STREAM_END)
		goto error;

	err = zlib_deflateEnd(&stream);
	if (err != Z_OK)
		goto error;

	if (stream.total_out >= stream.total_in)
		goto error;

	ret = stream.total_out;
error:
	return ret;
}

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/* Compress the text from big_oops_buf into oops_buf. */


static int zip_oops(size_t text_len)
{
	struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
	int zipped_len = nvram_compress(big_oops_buf, oops_data, text_len,
								oops_data_sz);
	if (zipped_len < 0) {
		pr_err("nvram: compression failed; returned %d\n", zipped_len);
		pr_err("nvram: logging uncompressed oops/panic report\n");
		return -1;
	}
	oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION);
	oops_hdr->report_length = cpu_to_be16(zipped_len);
	oops_hdr->timestamp = cpu_to_be64(ktime_get_real_seconds());
	return 0;
}

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#ifdef CONFIG_PSTORE


static int nvram_pstore_open(struct pstore_info *psi)
{
	/* Reset the iterator to start reading partitions again */
	read_type = -1;
	return 0;
}

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/**
 * nvram_pstore_write - pstore write callback for nvram
 * @record:             pstore record to write, with @id to be set
 *
 * Called by pstore_dump() when an oops or panic report is logged in the
 * printk buffer.
 * Returns 0 on successful write.
 */


static int nvram_pstore_write(struct pstore_record *record)
{
	int rc;
	unsigned int err_type = ERR_TYPE_KERNEL_PANIC;
	struct oops_log_info *oops_hdr = (struct oops_log_info *) oops_buf;

	/* part 1 has the recent messages from printk buffer */
	if (record->part > 1 || (record->type != PSTORE_TYPE_DMESG))
		return -1;

	if (clobbering_unread_rtas_event())
		return -1;

	oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION);
	oops_hdr->report_length = cpu_to_be16(record->size);
	oops_hdr->timestamp = cpu_to_be64(ktime_get_real_seconds());

	if (record->compressed)
		err_type = ERR_TYPE_KERNEL_PANIC_GZ;

	rc = nvram_write_os_partition(&oops_log_partition, oops_buf,
		(int) (sizeof(*oops_hdr) + record->size), err_type,
		record->count);

	if (rc != 0)
		return rc;

	record->id = record->part;
	return 0;
}

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/*
 * Reads the oops/panic report, rtas, of-config and common partition.
 * Returns the length of the data we read from each partition.
 * Returns 0 if we've been called before.
 */


static ssize_t nvram_pstore_read(struct pstore_record *record)
{
	struct oops_log_info *oops_hdr;
	unsigned int err_type, id_no, size = 0;
	struct nvram_os_partition *part = NULL;
	char *buff = NULL;
	int sig = 0;
	loff_t p;

	read_type++;

	switch (nvram_type_ids[read_type]) {
	case PSTORE_TYPE_DMESG:
		part = &oops_log_partition;
		record->type = PSTORE_TYPE_DMESG;
		break;
	case PSTORE_TYPE_PPC_COMMON:
		sig = NVRAM_SIG_SYS;
		part = &common_partition;
		record->type = PSTORE_TYPE_PPC_COMMON;
		record->id = PSTORE_TYPE_PPC_COMMON;
		record->time.tv_sec = 0;
		record->time.tv_nsec = 0;
		break;
#ifdef CONFIG_PPC_PSERIES
	case PSTORE_TYPE_PPC_RTAS:
		part = &rtas_log_partition;
		record->type = PSTORE_TYPE_PPC_RTAS;
		record->time.tv_sec = last_rtas_event;
		record->time.tv_nsec = 0;
		break;
	case PSTORE_TYPE_PPC_OF:
		sig = NVRAM_SIG_OF;
		part = &of_config_partition;
		record->type = PSTORE_TYPE_PPC_OF;
		record->id = PSTORE_TYPE_PPC_OF;
		record->time.tv_sec = 0;
		record->time.tv_nsec = 0;
		break;
#endif
#ifdef CONFIG_PPC_POWERNV
	case PSTORE_TYPE_PPC_OPAL:
		sig = NVRAM_SIG_FW;
		part = &skiboot_partition;
		record->type = PSTORE_TYPE_PPC_OPAL;
		record->id = PSTORE_TYPE_PPC_OPAL;
		record->time.tv_sec = 0;
		record->time.tv_nsec = 0;
		break;
#endif
	default:
		return 0;
	}

	if (!part->os_partition) {
		p = nvram_find_partition(part->name, sig, &size);
		if (p <= 0) {
			pr_err("nvram: Failed to find partition %s, "
				"err %d\n", part->name, (int)p);
			return 0;
		}
		part->index = p;
		part->size = size;
	}

	buff = kmalloc(part->size, GFP_KERNEL);

	if (!buff)
		return -ENOMEM;

	if (nvram_read_partition(part, buff, part->size, &err_type, &id_no)) {
		kfree(buff);
		return 0;
	}

	record->count = 0;

	if (part->os_partition)
		record->id = id_no;

	if (nvram_type_ids[read_type] == PSTORE_TYPE_DMESG) {
		size_t length, hdr_size;

		oops_hdr = (struct oops_log_info *)buff;
		if (be16_to_cpu(oops_hdr->version) < OOPS_HDR_VERSION) {
			/* Old format oops header had 2-byte record size */
			hdr_size = sizeof(u16);
			length = be16_to_cpu(oops_hdr->version);
			record->time.tv_sec = 0;
			record->time.tv_nsec = 0;
		} else {
			hdr_size = sizeof(*oops_hdr);
			length = be16_to_cpu(oops_hdr->report_length);
			record->time.tv_sec = be64_to_cpu(oops_hdr->timestamp);
			record->time.tv_nsec = 0;
		}
		record->buf = kmemdup(buff + hdr_size, length, GFP_KERNEL);
		kfree(buff);
		if (record->buf == NULL)
			return -ENOMEM;

		record->ecc_notice_size = 0;
		if (err_type == ERR_TYPE_KERNEL_PANIC_GZ)
			record->compressed = true;
		else
			record->compressed = false;
		return length;
	}

	record->buf = buff;
	return part->size;
}

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static struct pstore_info nvram_pstore_info = {
	.owner = THIS_MODULE,
	.name = "nvram",
	.flags = PSTORE_FLAGS_DMESG,
	.open = nvram_pstore_open,
	.read = nvram_pstore_read,
	.write = nvram_pstore_write,
};



static int nvram_pstore_init(void)
{
	int rc = 0;

	if (machine_is(pseries)) {
		nvram_type_ids[2] = PSTORE_TYPE_PPC_RTAS;
		nvram_type_ids[3] = PSTORE_TYPE_PPC_OF;
	} else
		nvram_type_ids[2] = PSTORE_TYPE_PPC_OPAL;

	nvram_pstore_info.buf = oops_data;
	nvram_pstore_info.bufsize = oops_data_sz;

	spin_lock_init(&nvram_pstore_info.buf_lock);

	rc = pstore_register(&nvram_pstore_info);
	if (rc && (rc != -EPERM))
		/* Print error only when pstore.backend == nvram */
		pr_err("nvram: pstore_register() failed, returned %d. "
				"Defaults to kmsg_dump\n", rc);

	return rc;
}
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#else


static int nvram_pstore_init(void)
{
	return -1;
}
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#endif



void __init nvram_init_oops_partition(int rtas_partition_exists)
{
	int rc;

	rc = nvram_init_os_partition(&oops_log_partition);
	if (rc != 0) {
#ifdef CONFIG_PPC_PSERIES
		if (!rtas_partition_exists) {
			pr_err("nvram: Failed to initialize oops partition!");
			return;
		}
		pr_notice("nvram: Using %s partition to log both"
			" RTAS errors and oops/panic reports\n",
			rtas_log_partition.name);
		memcpy(&oops_log_partition, &rtas_log_partition,
						sizeof(rtas_log_partition));
#else
		pr_err("nvram: Failed to initialize oops partition!");
		return;
#endif
	}
	oops_buf = kmalloc(oops_log_partition.size, GFP_KERNEL);
	if (!oops_buf) {
		pr_err("nvram: No memory for %s partition\n",
						oops_log_partition.name);
		return;
	}
	oops_data = oops_buf + sizeof(struct oops_log_info);
	oops_data_sz = oops_log_partition.size - sizeof(struct oops_log_info);

	rc = nvram_pstore_init();

	if (!rc)
		return;

	/*
         * Figure compression (preceded by elimination of each line's <n>
         * severity prefix) will reduce the oops/panic report to at most
         * 45% of its original size.
         */
	big_oops_buf_sz = (oops_data_sz * 100) / 45;
	big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
	if (big_oops_buf) {
		stream.workspace =  kmalloc(zlib_deflate_workspacesize(
					WINDOW_BITS, MEM_LEVEL), GFP_KERNEL);
		if (!stream.workspace) {
			pr_err("nvram: No memory for compression workspace; "
				"skipping compression of %s partition data\n",
				oops_log_partition.name);
			kfree(big_oops_buf);
			big_oops_buf = NULL;
		}
	} else {
		pr_err("No memory for uncompressed %s data; "
			"skipping compression\n", oops_log_partition.name);
		stream.workspace = NULL;
	}

	rc = kmsg_dump_register(&nvram_kmsg_dumper);
	if (rc != 0) {
		pr_err("nvram: kmsg_dump_register() failed; returned %d\n", rc);
		kfree(oops_buf);
		kfree(big_oops_buf);
		kfree(stream.workspace);
	}
}

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/*
 * This is our kmsg_dump callback, called after an oops or panic report
 * has been written to the printk buffer.  We want to capture as much
 * of the printk buffer as possible.  First, capture as much as we can
 * that we think will compress sufficiently to fit in the lnx,oops-log
 * partition.  If that's too much, go back and capture uncompressed text.
 */


static void oops_to_nvram(struct kmsg_dumper *dumper,
			  enum kmsg_dump_reason reason)
{
	struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
	static unsigned int oops_count = 0;
	static bool panicking = false;
	static DEFINE_SPINLOCK(lock);
	unsigned long flags;
	size_t text_len;
	unsigned int err_type = ERR_TYPE_KERNEL_PANIC_GZ;
	int rc = -1;

	switch (reason) {
	case KMSG_DUMP_RESTART:
	case KMSG_DUMP_HALT:
	case KMSG_DUMP_POWEROFF:
		/* These are almost always orderly shutdowns. */
		return;
	case KMSG_DUMP_OOPS:
		break;
	case KMSG_DUMP_PANIC:
		panicking = true;
		break;
	case KMSG_DUMP_EMERG:
		if (panicking)
			/* Panic report already captured. */
			return;
		break;
	default:
		pr_err("%s: ignoring unrecognized KMSG_DUMP_* reason %d\n",
		       __func__, (int) reason);
		return;
	}

	if (clobbering_unread_rtas_event())
		return;

	if (!spin_trylock_irqsave(&lock, flags))
		return;

	if (big_oops_buf) {
		kmsg_dump_get_buffer(dumper, false,
				     big_oops_buf, big_oops_buf_sz, &text_len);
		rc = zip_oops(text_len);
	}
	if (rc != 0) {
		kmsg_dump_rewind(dumper);
		kmsg_dump_get_buffer(dumper, false,
				     oops_data, oops_data_sz, &text_len);
		err_type = ERR_TYPE_KERNEL_PANIC;
		oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION);
		oops_hdr->report_length = cpu_to_be16(text_len);
		oops_hdr->timestamp = cpu_to_be64(ktime_get_real_seconds());
	}

	(void) nvram_write_os_partition(&oops_log_partition, oops_buf,
		(int) (sizeof(*oops_hdr) + text_len), err_type,
		++oops_count);

	spin_unlock_irqrestore(&lock, flags);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Hari Bathini
259
100.00%
2
100.00%
Total
259
100.00%
2
100.00%



static loff_t dev_nvram_llseek(struct file *file, loff_t offset, int origin)
{
	if (ppc_md.nvram_size == NULL)
		return -ENODEV;
	return generic_file_llseek_size(file, offset, origin, MAX_LFS_FILESIZE,
					ppc_md.nvram_size());
}


Contributors
Person
Tokens
Prop
Commits
CommitProp
Anton Blanchard
17
36.96%
1
25.00%
Benjamin Herrenschmidt
16
34.78%
1
25.00%
Al Viro
12
26.09%
1
25.00%
Andrew Morton
1
2.17%
1
25.00%
Total
46
100.00%
4
100.00%



static ssize_t dev_nvram_read(struct file *file, char __user *buf,
			  size_t count, loff_t *ppos)
{
	ssize_t ret;
	char *tmp = NULL;
	ssize_t size;

	if (!ppc_md.nvram_size) {
		ret = -ENODEV;
		goto out;
	}

	size = ppc_md.nvram_size();
	if (size < 0) {
		ret = size;
		goto out;
	}

	if (*ppos >= size) {
		ret = 0;
		goto out;
	}

	count = min_t(size_t, count, size - *ppos);
	count = min(count, PAGE_SIZE);

	tmp = kmalloc(count, GFP_KERNEL);
	if (!tmp) {
		ret = -ENOMEM;
		goto out;
	}

	ret = ppc_md.nvram_read(tmp, count, ppos);
	if (ret <= 0)
		goto out;

	if (copy_to_user(buf, tmp, ret))
		ret = -EFAULT;

out:
	kfree(tmp);
	return ret;

}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Arnd Bergmann
51
27.57%
1
16.67%
Anton Blanchard
47
25.41%
1
16.67%
Chen Gang S
35
18.92%
1
16.67%
Andrew Morton
34
18.38%
1
16.67%
Benjamin Herrenschmidt
17
9.19%
1
16.67%
David Gibson
1
0.54%
1
16.67%
Total
185
100.00%
6
100.00%



static ssize_t dev_nvram_write(struct file *file, const char __user *buf,
			  size_t count, loff_t *ppos)
{
	ssize_t ret;
	char *tmp = NULL;
	ssize_t size;

	ret = -ENODEV;
	if (!ppc_md.nvram_size)
		goto out;

	ret = 0;
	size = ppc_md.nvram_size();
	if (*ppos >= size || size < 0)
		goto out;

	count = min_t(size_t, count, size - *ppos);
	count = min(count, PAGE_SIZE);

	tmp = memdup_user(buf, count);
	if (IS_ERR(tmp)) {
		ret = PTR_ERR(tmp);
		goto out;
	}

	ret = ppc_md.nvram_write(tmp, count, ppos);

	kfree(tmp);
out:
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Arnd Bergmann
55
36.67%
1
16.67%
Anton Blanchard
42
28.00%
1
16.67%
Andrew Morton
22
14.67%
1
16.67%
Benjamin Herrenschmidt
18
12.00%
1
16.67%
Geliang Tang