4 files changed, 90 insertions, 5 deletions

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 0339f5c14bf9..f8adefca71dc 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -110,11 +110,16 @@ void __show_regs(struct pt_regs *regs, int all)
         get_debugreg(d1, 1);
         get_debugreg(d2, 2);
         get_debugreg(d3, 3);
-        printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
-                        d0, d1, d2, d3);
-
         get_debugreg(d6, 6);
         get_debugreg(d7, 7);
+
+        /* Only print out debug registers if they are in their non-default state. */
+        if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) &&
+            (d6 == DR6_RESERVED) && (d7 == 0x400))
+                return;
+
+        printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
+                        d0, d1, d2, d3);
         printk(KERN_DEFAULT "DR6: %08lx DR7: %08lx\n",
                         d6, d7);
 }
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index f99a242730e9..05646bab4ca6 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -105,11 +105,18 @@ void __show_regs(struct pt_regs *regs, int all)
         get_debugreg(d0, 0);
         get_debugreg(d1, 1);
         get_debugreg(d2, 2);
-        printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
         get_debugreg(d3, 3);
         get_debugreg(d6, 6);
         get_debugreg(d7, 7);
+
+        /* Only print out debug registers if they are in their non-default state. */
+        if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) &&
+            (d6 == DR6_RESERVED) && (d7 == 0x400))
+                return;
+
+        printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
         printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
+
 }
 
 void release_thread(struct task_struct *dead_task)
diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index f84fe00fad48..3ff42d2f046d 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -31,6 +31,7 @@
 #include <linux/pfn.h>
 #include <linux/mm.h>
 #include <linux/tboot.h>
+#include <linux/debugfs.h>
 
 #include <asm/realmode.h>
 #include <asm/processor.h>
@@ -338,6 +339,73 @@ static struct notifier_block tboot_cpu_notifier __cpuinitdata =
         .notifier_call = tboot_cpu_callback,
 };
 
+#ifdef CONFIG_DEBUG_FS
+
+#define TBOOT_LOG_UUID  { 0x26, 0x25, 0x19, 0xc0, 0x30, 0x6b, 0xb4, 0x4d, \
+                          0x4c, 0x84, 0xa3, 0xe9, 0x53, 0xb8, 0x81, 0x74 }
+
+#define TBOOT_SERIAL_LOG_ADDR   0x60000
+#define TBOOT_SERIAL_LOG_SIZE   0x08000
+#define LOG_MAX_SIZE_OFF        16
+#define LOG_BUF_OFF             24
+
+static uint8_t tboot_log_uuid[16] = TBOOT_LOG_UUID;
+
+static ssize_t tboot_log_read(struct file *file, char __user *user_buf, size_t count, loff_t *ppos)
+{
+        void __iomem *log_base;
+        u8 log_uuid[16];
+        u32 max_size;
+        void *kbuf;
+        int ret = -EFAULT;
+
+        log_base = ioremap_nocache(TBOOT_SERIAL_LOG_ADDR, TBOOT_SERIAL_LOG_SIZE);
+        if (!log_base)
+                return ret;
+
+        memcpy_fromio(log_uuid, log_base, sizeof(log_uuid));
+        if (memcmp(&tboot_log_uuid, log_uuid, sizeof(log_uuid)))
+                goto err_iounmap;
+
+        max_size = readl(log_base + LOG_MAX_SIZE_OFF);
+        if (*ppos >= max_size) {
+                ret = 0;
+                goto err_iounmap;
+        }
+
+        if (*ppos + count > max_size)
+                count = max_size - *ppos;
+
+        kbuf = kmalloc(count, GFP_KERNEL);
+        if (!kbuf) {
+                ret = -ENOMEM;
+                goto err_iounmap;
+        }
+
+        memcpy_fromio(kbuf, log_base + LOG_BUF_OFF + *ppos, count);
+        if (copy_to_user(user_buf, kbuf, count))
+                goto err_kfree;
+
+        *ppos += count;
+
+        ret = count;
+
+err_kfree:
+        kfree(kbuf);
+
+err_iounmap:
+        iounmap(log_base);
+
+        return ret;
+}
+
+static const struct file_operations tboot_log_fops = {
+        .read   = tboot_log_read,
+        .llseek = default_llseek,
+};
+
+#endif /* CONFIG_DEBUG_FS */
+
 static __init int tboot_late_init(void)
 {
         if (!tboot_enabled())
@@ -348,6 +416,11 @@ static __init int tboot_late_init(void)
         atomic_set(&ap_wfs_count, 0);
         register_hotcpu_notifier(&tboot_cpu_notifier);
 
+#ifdef CONFIG_DEBUG_FS
+        debugfs_create_file("tboot_log", S_IRUSR,
+                        arch_debugfs_dir, NULL, &tboot_log_fops);
+#endif
+
         acpi_os_set_prepare_sleep(&tboot_sleep);
         return 0;
 }
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 167d481c5fd3..ee3d8e510504 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -440,7 +440,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
         /* Store the virtualized DR6 value */
         tsk->thread.debugreg6 = dr6;
 
-        if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
+        if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
                                                         SIGTRAP) == NOTIFY_STOP)
                 goto exit;