On Mon, 2011-02-07 at 16:01 +1100, Benjamin Herrenschmidt wrote:
> On Sat, 2010-11-13 at 20:15 -0800, Jim Keniston wrote:
> > Create the ibm,oops-log NVRAM partition, and capture the end of the printk
> > buffer in it when there's an oops or panic. If we can't create the
> > ibm,oops-log partition, capture the oops/panic report in ibm,rtas-log.
I've appended an updated patch that addresses your comments and applies
to 2.6.38-rc4.
>
> Won't the parsing tools choke on the oops log in the RTAS log
> partition ?
I don't think that that will be a problem, because pSeries_log_error()
doesn't log errors that aren't of type ERR_TYPE_RTAS_LOG.
However, I did add code to ensure that even if ibm,rtas-log is used for
both RTAS errors and oops reports, an oops report won't overwrite a
recently captured RTAS event that hasn't yet been read into the
filesystem (e.g., by rtas_errd).
>
> Also, maybe remove the "ibm," prefix on the nvram partition, make it
> "lnx," instead.
Done.
>
> Then, if you move the rest of the code out of pseries, you can move that
> out too, just make pseries platform code call the init code for it, that
> way other platforms can re-use that as-is.
>
> But that later part can wait a separate patch series,
Agreed.
> just make sure you
> change the partition name now.
Still done.
>
> Cheers,
> Ben.
Here's my revised patch.
Jim
=====
Capture oops/panic reports in lnx,oops-log partition
Create the lnx,oops-log NVRAM partition, and capture the end of the printk
buffer in it when there's an oops or panic. If we can't create the
lnx,oops-log partition, capture the oops/panic report in ibm,rtas-log.
Signed-off-by: Jim Keniston <jkeni...@us.ibm.com>
---
arch/powerpc/platforms/pseries/nvram.c | 118 +++++++++++++++++++++++++++++++-
1 files changed, 115 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/nvram.c
b/arch/powerpc/platforms/pseries/nvram.c
index befb41b..419707b 100644
--- a/arch/powerpc/platforms/pseries/nvram.c
+++ b/arch/powerpc/platforms/pseries/nvram.c
@@ -16,6 +16,8 @@
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/kmsg_dump.h>
#include <asm/uaccess.h>
#include <asm/nvram.h>
#include <asm/rtas.h>
@@ -39,7 +41,7 @@ struct nvram_os_partition {
const char *name;
int req_size; /* desired size, in bytes */
int min_size; /* minimum acceptable size (0 means req_size) */
- long size; /* size of data portion of partition */
+ long size; /* size of data portion (excluding err_log_info) */
long index; /* offset of data portion of partition */
};
@@ -50,11 +52,35 @@ static struct nvram_os_partition rtas_log_partition = {
.index = -1
};
+static struct nvram_os_partition oops_log_partition = {
+ .name = "lnx,oops-log",
+ .req_size = 4000,
+ .min_size = 2000,
+ .index = -1
+};
+
static const char *pseries_nvram_os_partitions[] = {
"ibm,rtas-log",
+ "lnx,oops-log",
NULL
};
+static void oops_to_nvram(struct kmsg_dumper *dumper,
+ enum kmsg_dump_reason reason,
+ const char *old_msgs, unsigned long old_len,
+ const char *new_msgs, unsigned long new_len);
+
+static struct kmsg_dumper nvram_kmsg_dumper = {
+ .dump = oops_to_nvram
+};
+
+/* See clobbering_unread_rtas_event() */
+#define NVRAM_RTAS_READ_TIMEOUT 5 /* seconds */
+static unsigned long last_unread_rtas_event; /* timestamp */
+
+/* We preallocate oops_buf during init to avoid kmalloc during oops/panic. */
+static char *oops_buf;
+
static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
{
unsigned int i;
@@ -214,8 +240,11 @@ int nvram_write_os_partition(struct nvram_os_partition
*part, char * buff,
int nvram_write_error_log(char * buff, int length,
unsigned int err_type, unsigned int error_log_cnt)
{
- return nvram_write_os_partition(&rtas_log_partition, buff, length,
+ int rc = nvram_write_os_partition(&rtas_log_partition, buff, length,
err_type, error_log_cnt);
+ if (!rc)
+ last_unread_rtas_event = get_seconds();
+ return rc;
}
/* nvram_read_error_log
@@ -274,6 +303,7 @@ int nvram_clear_error_log(void)
printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write
(%d)\n", rc);
return rc;
}
+ last_unread_rtas_event = 0;
return 0;
}
@@ -342,9 +372,35 @@ static int __init pseries_nvram_init_os_partition(struct
nvram_os_partition
return 0;
}
+static void __init nvram_init_oops_partition(int rtas_partition_exists)
+{
+ int rc;
+
+ rc = pseries_nvram_init_os_partition(&oops_log_partition);
+ if (rc != 0) {
+ if (!rtas_partition_exists)
+ 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));
+ }
+ oops_buf = kmalloc(oops_log_partition.size, GFP_KERNEL);
+ rc = kmsg_dump_register(&nvram_kmsg_dumper);
+ if (rc != 0) {
+ pr_err("nvram: kmsg_dump_register() failed; returned %d\n", rc);
+ kfree(oops_buf);
+ return;
+ }
+}
+
static int __init pseries_nvram_init_log_partitions(void)
{
- (void) pseries_nvram_init_os_partition(&rtas_log_partition);
+ int rc;
+
+ rc = pseries_nvram_init_os_partition(&rtas_log_partition);
+ nvram_init_oops_partition(rc == 0);
return 0;
}
machine_arch_initcall(pseries, pseries_nvram_init_log_partitions);
@@ -378,3 +434,59 @@ int __init pSeries_nvram_init(void)
return 0;
}
+
+/*
+ * Try to capture the last capture_len bytes of the printk buffer. Return
+ * the amount actually captured.
+ */
+static size_t capture_last_msgs(const char *old_msgs, size_t old_len,
+ const char *new_msgs, size_t new_len,
+ char *captured, size_t capture_len)
+{
+ if (new_len >= capture_len) {
+ memcpy(captured, new_msgs + (new_len - capture_len),
+ capture_len);
+ return capture_len;
+ } else {
+ /* Grab the end of old_msgs. */
+ size_t old_tail_len = min(old_len, capture_len - new_len);
+ memcpy(captured, old_msgs + (old_len - old_tail_len),
+ old_tail_len);
+ memcpy(captured + old_tail_len, new_msgs, new_len);
+ return old_tail_len + new_len;
+ }
+}
+
+/*
+ * 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);
+}
+
+/* our kmsg_dump callback */
+static void oops_to_nvram(struct kmsg_dumper *dumper,
+ enum kmsg_dump_reason reason,
+ const char *old_msgs, unsigned long old_len,
+ const char *new_msgs, unsigned long new_len)
+{
+ static unsigned int oops_count = 0;
+ size_t text_len;
+
+ if (clobbering_unread_rtas_event())
+ return;
+
+ text_len = capture_last_msgs(old_msgs, old_len, new_msgs, new_len,
+ oops_buf, oops_log_partition.size);
+ (void) nvram_write_os_partition(&oops_log_partition, oops_buf,
+ (int) text_len, ERR_TYPE_KERNEL_PANIC, ++oops_count);
+}
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