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powerpc/pseries: Read/Write oops nvram partition via pstore

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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: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Aruna Balakrishnaiah 2013-06-06 00:21:32 +05:30 committed by Benjamin Herrenschmidt
parent 126746101e
commit d7563c94f7
1 changed files with 157 additions and 15 deletions
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172
arch/powerpc/platforms/pseries/nvram.c
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@ -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,