3 files changed, 170 insertions, 0 deletions

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index e21175be25d0..f09fc0e2062d 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -1121,5 +1121,12 @@ config DEVPORT
 
 source "drivers/s390/char/Kconfig"
 
+config RAMOOPS
+        tristate "Log panic/oops to a RAM buffer"
+        default n
+        help
+          This enables panic and oops messages to be logged to a circular
+          buffer in RAM where it can be read back at some later point.
+
 endmenu
 
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index d39be4cf1f5d..88d6eac69754 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -108,6 +108,7 @@ obj-$(CONFIG_HANGCHECK_TIMER)	+= hangcheck-timer.o
 obj-$(CONFIG_TCG_TPM)           += tpm/
 
 obj-$(CONFIG_PS3_FLASH)         += ps3flash.o
+obj-$(CONFIG_RAMOOPS)           += ramoops.o
 
 obj-$(CONFIG_JS_RTC)            += js-rtc.o
 js-rtc-y = rtc.o
diff --git a/drivers/char/ramoops.c b/drivers/char/ramoops.c
new file mode 100644
index 000000000000..74f00b5ffa36
--- /dev/null
+++ b/drivers/char/ramoops.c
@@ -0,0 +1,162 @@
+/*
+ * RAM Oops/Panic logger
+ *
+ * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kmsg_dump.h>
+#include <linux/time.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+
+#define RAMOOPS_KERNMSG_HDR "===="
+#define RAMOOPS_HEADER_SIZE   (5 + sizeof(struct timeval))
+
+#define RECORD_SIZE 4096
+
+static ulong mem_address;
+module_param(mem_address, ulong, 0400);
+MODULE_PARM_DESC(mem_address,
+                "start of reserved RAM used to store oops/panic logs");
+
+static ulong mem_size;
+module_param(mem_size, ulong, 0400);
+MODULE_PARM_DESC(mem_size,
+                "size of reserved RAM used to store oops/panic logs");
+
+static int dump_oops = 1;
+module_param(dump_oops, int, 0600);
+MODULE_PARM_DESC(dump_oops,
+                "set to 1 to dump oopses, 0 to only dump panics (default 1)");
+
+static struct ramoops_context {
+        struct kmsg_dumper dump;
+        void *virt_addr;
+        phys_addr_t phys_addr;
+        unsigned long size;
+        int count;
+        int max_count;
+} oops_cxt;
+
+static void ramoops_do_dump(struct kmsg_dumper *dumper,
+                enum kmsg_dump_reason reason, const char *s1, unsigned long l1,
+                const char *s2, unsigned long l2)
+{
+        struct ramoops_context *cxt = container_of(dumper,
+                        struct ramoops_context, dump);
+        unsigned long s1_start, s2_start;
+        unsigned long l1_cpy, l2_cpy;
+        int res;
+        char *buf;
+        struct timeval timestamp;
+
+        /* Only dump oopses if dump_oops is set */
+        if (reason == KMSG_DUMP_OOPS && !dump_oops)
+                return;
+
+        buf = (char *)(cxt->virt_addr + (cxt->count * RECORD_SIZE));
+        memset(buf, '\0', RECORD_SIZE);
+        res = sprintf(buf, "%s", RAMOOPS_KERNMSG_HDR);
+        buf += res;
+        do_gettimeofday(&timestamp);
+        res = sprintf(buf, "%lu.%lu\n", (long)timestamp.tv_sec, (long)timestamp.tv_usec);
+        buf += res;
+
+        l2_cpy = min(l2, (unsigned long)(RECORD_SIZE - RAMOOPS_HEADER_SIZE));
+        l1_cpy = min(l1, (unsigned long)(RECORD_SIZE - RAMOOPS_HEADER_SIZE) - l2_cpy);
+
+        s2_start = l2 - l2_cpy;
+        s1_start = l1 - l1_cpy;
+
+        memcpy(buf, s1 + s1_start, l1_cpy);
+        memcpy(buf + l1_cpy, s2 + s2_start, l2_cpy);
+
+        cxt->count = (cxt->count + 1) % cxt->max_count;
+}
+
+static int __init ramoops_init(void)
+{
+        struct ramoops_context *cxt = &oops_cxt;
+        int err = -EINVAL;
+
+        if (!mem_size) {
+                printk(KERN_ERR "ramoops: invalid size specification");
+                goto fail3;
+        }
+
+        rounddown_pow_of_two(mem_size);
+
+        if (mem_size < RECORD_SIZE) {
+                printk(KERN_ERR "ramoops: size too small");
+                goto fail3;
+        }
+
+        cxt->max_count = mem_size / RECORD_SIZE;
+        cxt->count = 0;
+        cxt->size = mem_size;
+        cxt->phys_addr = mem_address;
+
+        if (!request_mem_region(cxt->phys_addr, cxt->size, "ramoops")) {
+                printk(KERN_ERR "ramoops: request mem region failed");
+                err = -EINVAL;
+                goto fail3;
+        }
+
+        cxt->virt_addr = ioremap(cxt->phys_addr,  cxt->size);
+        if (!cxt->virt_addr) {
+                printk(KERN_ERR "ramoops: ioremap failed");
+                goto fail2;
+        }
+
+        cxt->dump.dump = ramoops_do_dump;
+        err = kmsg_dump_register(&cxt->dump);
+        if (err) {
+                printk(KERN_ERR "ramoops: registering kmsg dumper failed");
+                goto fail1;
+        }
+
+        return 0;
+
+fail1:
+        iounmap(cxt->virt_addr);
+fail2:
+        release_mem_region(cxt->phys_addr, cxt->size);
+fail3:
+        return err;
+}
+
+static void __exit ramoops_exit(void)
+{
+        struct ramoops_context *cxt = &oops_cxt;
+
+        if (kmsg_dump_unregister(&cxt->dump) < 0)
+                printk(KERN_WARNING "ramoops: could not unregister kmsg_dumper");
+
+        iounmap(cxt->virt_addr);
+        release_mem_region(cxt->phys_addr, cxt->size);
+}
+
+
+module_init(ramoops_init);
+module_exit(ramoops_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marco Stornelli <marco.stornelli@gmail.com>");
+MODULE_DESCRIPTION("RAM Oops/Panic logger/driver");