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Commit d7563c94 authored by Aruna Balakrishnaiah's avatar Aruna Balakrishnaiah Committed by Benjamin Herrenschmidt
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powerpc/pseries: Read/Write oops nvram partition via pstore 



IBM's p series machines provide persistent storage for LPARs through NVRAM.
NVRAM's lnx,oops-log partition is used to log oops messages.
Currently the kernel provides the contents of p-series NVRAM only as a
simple stream of bytes via /dev/nvram, which must be interpreted in user
space by the nvram command in the powerpc-utils package.

This patch set exploits the pstore subsystem to expose oops partition in
NVRAM as a separate file in /dev/pstore. For instance, Oops messages will be
stored in a file named [dmesg-nvram-2]. In case pstore registration fails it
will fall back to kmsg_dump mechanism.

This patch will read/write the oops messages from/to this partition via pstore.

Signed-off-by: default avatarJim Keniston <jkenisto@us.ibm.com>
Signed-off-by: default avatarAruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 12674610

arch/powerpc/platforms/pseries/nvram.c

+157 −15
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/spinlock.h>

#include <linux/slab.h>

#include <linux/kmsg_dump.h>

#include <linux/pstore.h>

#include <linux/ctype.h>

#include <linux/zlib.h>

#include <asm/uaccess.h>
@@ -127,6 +128,14 @@ static size_t oops_data_sz; 
#define MEM_LEVEL 4

static struct z_stream_s stream;



#ifdef CONFIG_PSTORE

static enum pstore_type_id nvram_type_ids[] = {

	PSTORE_TYPE_DMESG,

	-1

};

static int read_type;

#endif



static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)

{

	unsigned int i;
@@ -430,6 +439,149 @@ static int __init pseries_nvram_init_os_partition(struct nvram_os_partition 
	return 0;

}



/*

 * Are we using the ibm,rtas-log for oops/panic reports?  And if so,

 * would logging this oops/panic overwrite an RTAS event that rtas_errd

 * hasn't had a chance to read and process?  Return 1 if so, else 0.

 *

 * We assume that if rtas_errd hasn't read the RTAS event in

 * NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.

 */

static int clobbering_unread_rtas_event(void)

{

	return (oops_log_partition.index == rtas_log_partition.index

		&& last_unread_rtas_event

		&& get_seconds() - last_unread_rtas_event <=

						NVRAM_RTAS_READ_TIMEOUT);

}



#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;

}



/**

 * nvram_pstore_write - pstore write callback for nvram

 * @type:               Type of message logged

 * @reason:             reason behind dump (oops/panic)

 * @id:                 identifier to indicate the write performed

 * @part:               pstore writes data to registered buffer in parts,

 *                      part number will indicate the same.

 * @count:              Indicates oops count

 * @size:               number of bytes written to the registered buffer

 * @psi:                registered pstore_info structure

 *

 * 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(enum pstore_type_id type,

				enum kmsg_dump_reason reason,

				u64 *id, unsigned int part, int count,

				size_t size, struct pstore_info *psi)

{

	int rc;

	struct oops_log_info *oops_hdr = (struct oops_log_info *) oops_buf;



	/* part 1 has the recent messages from printk buffer */

	if (part > 1 || type != PSTORE_TYPE_DMESG ||

				clobbering_unread_rtas_event())

		return -1;



	oops_hdr->version = OOPS_HDR_VERSION;

	oops_hdr->report_length = (u16) size;

	oops_hdr->timestamp = get_seconds();

	rc = nvram_write_os_partition(&oops_log_partition, oops_buf,

		(int) (sizeof(*oops_hdr) + size), ERR_TYPE_KERNEL_PANIC,

		count);



	if (rc != 0)

		return rc;



	*id = part;

	return 0;

}



/*

 * Reads the oops/panic report.

 * 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(u64 *id, enum pstore_type_id *type,

				int *count, struct timespec *time, char **buf,

				struct pstore_info *psi)

{

	struct oops_log_info *oops_hdr;

	unsigned int err_type, id_no;

	struct nvram_os_partition *part = NULL;

	char *buff = NULL;



	read_type++;



	switch (nvram_type_ids[read_type]) {

	case PSTORE_TYPE_DMESG:

		part = &oops_log_partition;

		*type = PSTORE_TYPE_DMESG;

		break;

	default:

		return 0;

	}



	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;

	}



	*count = 0;

	*id = id_no;

	oops_hdr = (struct oops_log_info *)buff;

	*buf = buff + sizeof(*oops_hdr);

	time->tv_sec = oops_hdr->timestamp;

	time->tv_nsec = 0;

	return oops_hdr->report_length;

}



static struct pstore_info nvram_pstore_info = {

	.owner = THIS_MODULE,

	.name = "nvram",

	.open = nvram_pstore_open,

	.read = nvram_pstore_read,

	.write = nvram_pstore_write,

};



static int nvram_pstore_init(void)

{

	int rc = 0;



	nvram_pstore_info.buf = oops_data;

	nvram_pstore_info.bufsize = oops_data_sz;



	rc = pstore_register(&nvram_pstore_info);

	if (rc != 0)

		pr_err("nvram: pstore_register() failed, defaults to "

				"kmsg_dump; returned %d\n", rc);

	else

		/*TODO: Support compression when pstore is configured */

		pr_info("nvram: Compression of oops text supported only when "

				"pstore is not configured");



	return rc;

}

#else

static int nvram_pstore_init(void)

{

	return -1;

}

#endif



static void __init nvram_init_oops_partition(int rtas_partition_exists)

{

	int rc;
@@ -453,6 +605,11 @@ static void __init nvram_init_oops_partition(int rtas_partition_exists) 
	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
@@ -525,21 +682,6 @@ int __init pSeries_nvram_init(void) 
	return 0;

}



/*

 * Are we using the ibm,rtas-log for oops/panic reports?  And if so,

 * would logging this oops/panic overwrite an RTAS event that rtas_errd

 * hasn't had a chance to read and process?  Return 1 if so, else 0.

 *

 * We assume that if rtas_errd hasn't read the RTAS event in

 * NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.

 */

static int clobbering_unread_rtas_event(void)

{

	return (oops_log_partition.index == rtas_log_partition.index

		&& last_unread_rtas_event

		&& get_seconds() - last_unread_rtas_event <=

						NVRAM_RTAS_READ_TIMEOUT);

}



/* Derived from logfs_compress() */

static int nvram_compress(const void *in, void *out, size_t inlen,