From d7563c94f728d8c9228cfddbb044c843b2e243e8 Mon Sep 17 00:00:00 2001 From: Aruna Balakrishnaiah Date: Thu, 6 Jun 2013 00:21:32 +0530 Subject: [PATCH] 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 Signed-off-by: Aruna Balakrishnaiah Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/platforms/pseries/nvram.c | 172 ++++++++++++++++++++++--- 1 file changed, 157 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c index 088f023d8f25..9edec8ee02ef 100644 --- a/arch/powerpc/platforms/pseries/nvram.c +++ b/arch/powerpc/platforms/pseries/nvram.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -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 * 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, -- GitLab