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: 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>hifive-unleashed-5.1
Aruna Balakrishnaiah
Benjamin Herrenschmidt
parent
126746101e
commit
d7563c94f7
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@ -18,6 +18,7 @@
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#include <linux/spinlock.h>
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#include <linux/slab.h>
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#include <linux/kmsg_dump.h>
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#include <linux/pstore.h>
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#include <linux/ctype.h>
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#include <linux/zlib.h>
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#include <asm/uaccess.h>
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@ -127,6 +128,14 @@ static size_t oops_data_sz;
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#define MEM_LEVEL 4
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static struct z_stream_s stream;
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#ifdef CONFIG_PSTORE
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static enum pstore_type_id nvram_type_ids[] = {
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PSTORE_TYPE_DMESG,
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-1
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};
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static int read_type;
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#endif
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static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
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{
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unsigned int i;
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@ -430,6 +439,149 @@ static int __init pseries_nvram_init_os_partition(struct nvram_os_partition
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return 0;
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}
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/*
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* Are we using the ibm,rtas-log for oops/panic reports? And if so,
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* would logging this oops/panic overwrite an RTAS event that rtas_errd
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* hasn't had a chance to read and process? Return 1 if so, else 0.
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*
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* We assume that if rtas_errd hasn't read the RTAS event in
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* NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.
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*/
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static int clobbering_unread_rtas_event(void)
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{
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return (oops_log_partition.index == rtas_log_partition.index
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&& last_unread_rtas_event
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&& get_seconds() - last_unread_rtas_event <=
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NVRAM_RTAS_READ_TIMEOUT);
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}
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#ifdef CONFIG_PSTORE
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static int nvram_pstore_open(struct pstore_info *psi)
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{
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/* Reset the iterator to start reading partitions again */
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read_type = -1;
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return 0;
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}
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/**
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* nvram_pstore_write - pstore write callback for nvram
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* @type: Type of message logged
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* @reason: reason behind dump (oops/panic)
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* @id: identifier to indicate the write performed
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* @part: pstore writes data to registered buffer in parts,
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* part number will indicate the same.
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* @count: Indicates oops count
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* @size: number of bytes written to the registered buffer
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* @psi: registered pstore_info structure
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*
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* Called by pstore_dump() when an oops or panic report is logged in the
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* printk buffer.
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* Returns 0 on successful write.
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*/
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static int nvram_pstore_write(enum pstore_type_id type,
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enum kmsg_dump_reason reason,
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u64 *id, unsigned int part, int count,
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size_t size, struct pstore_info *psi)
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{
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int rc;
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struct oops_log_info *oops_hdr = (struct oops_log_info *) oops_buf;
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/* part 1 has the recent messages from printk buffer */
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if (part > 1 || type != PSTORE_TYPE_DMESG ||
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clobbering_unread_rtas_event())
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return -1;
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oops_hdr->version = OOPS_HDR_VERSION;
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oops_hdr->report_length = (u16) size;
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oops_hdr->timestamp = get_seconds();
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rc = nvram_write_os_partition(&oops_log_partition, oops_buf,
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(int) (sizeof(*oops_hdr) + size), ERR_TYPE_KERNEL_PANIC,
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count);
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if (rc != 0)
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return rc;
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*id = part;
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return 0;
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}
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/*
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* Reads the oops/panic report.
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* Returns the length of the data we read from each partition.
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* Returns 0 if we've been called before.
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*/
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static ssize_t nvram_pstore_read(u64 *id, enum pstore_type_id *type,
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int *count, struct timespec *time, char **buf,
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struct pstore_info *psi)
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{
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struct oops_log_info *oops_hdr;
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unsigned int err_type, id_no;
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struct nvram_os_partition *part = NULL;
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char *buff = NULL;
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read_type++;
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switch (nvram_type_ids[read_type]) {
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case PSTORE_TYPE_DMESG:
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part = &oops_log_partition;
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*type = PSTORE_TYPE_DMESG;
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break;
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default:
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return 0;
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}
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buff = kmalloc(part->size, GFP_KERNEL);
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if (!buff)
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return -ENOMEM;
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if (nvram_read_partition(part, buff, part->size, &err_type, &id_no)) {
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kfree(buff);
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return 0;
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}
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*count = 0;
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*id = id_no;
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oops_hdr = (struct oops_log_info *)buff;
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*buf = buff + sizeof(*oops_hdr);
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time->tv_sec = oops_hdr->timestamp;
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time->tv_nsec = 0;
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return oops_hdr->report_length;
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}
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static struct pstore_info nvram_pstore_info = {
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.owner = THIS_MODULE,
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.name = "nvram",
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.open = nvram_pstore_open,
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.read = nvram_pstore_read,
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.write = nvram_pstore_write,
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};
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static int nvram_pstore_init(void)
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{
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int rc = 0;
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nvram_pstore_info.buf = oops_data;
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nvram_pstore_info.bufsize = oops_data_sz;
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rc = pstore_register(&nvram_pstore_info);
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if (rc != 0)
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pr_err("nvram: pstore_register() failed, defaults to "
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"kmsg_dump; returned %d\n", rc);
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else
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/*TODO: Support compression when pstore is configured */
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pr_info("nvram: Compression of oops text supported only when "
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"pstore is not configured");
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return rc;
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}
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#else
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static int nvram_pstore_init(void)
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{
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return -1;
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}
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#endif
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static void __init nvram_init_oops_partition(int rtas_partition_exists)
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{
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int rc;
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@ -453,6 +605,11 @@ static void __init nvram_init_oops_partition(int rtas_partition_exists)
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oops_data = oops_buf + sizeof(struct oops_log_info);
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oops_data_sz = oops_log_partition.size - sizeof(struct oops_log_info);
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rc = nvram_pstore_init();
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if (!rc)
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return;
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/*
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* Figure compression (preceded by elimination of each line's <n>
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* severity prefix) will reduce the oops/panic report to at most
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@ -525,21 +682,6 @@ int __init pSeries_nvram_init(void)
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return 0;
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}
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/*
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* Are we using the ibm,rtas-log for oops/panic reports? And if so,
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* would logging this oops/panic overwrite an RTAS event that rtas_errd
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* hasn't had a chance to read and process? Return 1 if so, else 0.
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*
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* We assume that if rtas_errd hasn't read the RTAS event in
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* NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.
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*/
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static int clobbering_unread_rtas_event(void)
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{
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return (oops_log_partition.index == rtas_log_partition.index
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&& last_unread_rtas_event
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&& get_seconds() - last_unread_rtas_event <=
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NVRAM_RTAS_READ_TIMEOUT);
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}
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/* Derived from logfs_compress() */
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static int nvram_compress(const void *in, void *out, size_t inlen,
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