1 files changed, 115 insertions, 3 deletions

diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c
index befb41bc4d37..419707b07248 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);
+}