kdump: fix dmesg gdbmacro to work with record based printk

Commit 7ff9554bb578 ("printk: convert byte-buffer to variable-length
record buffer") introduced a record based printk buffer.  Modify
gdbmacros.txt to parse this new structure so dmesg will work properly.

Link: http://lkml.kernel.org/r/1463515794-1599-1-git-send-email-minyard@acm.org
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 82 insertions, 11 deletions

diff --git a/Documentation/kdump/gdbmacros.txt b/Documentation/kdump/gdbmacros.txt
index 35f6a982a0d5..220d0a80ca2c 100644
--- a/Documentation/kdump/gdbmacros.txt
+++ b/Documentation/kdump/gdbmacros.txt
@@ -170,21 +170,92 @@ document trapinfo
         address the kernel panicked.
 end
 
+define dump_log_idx
+        set $idx = $arg0
+        if ($argc > 1)
+                set $prev_flags = $arg1
+        else
+                set $prev_flags = 0
+        end
+        set $msg = ((struct printk_log *) (log_buf + $idx))
+        set $prefix = 1
+        set $newline = 1
+        set $log = log_buf + $idx + sizeof(*$msg)
 
-define dmesg
-        set $i = 0
-        set $end_idx = (log_end - 1) & (log_buf_len - 1)
+        # prev & LOG_CONT && !(msg->flags & LOG_PREIX)
+        if (($prev_flags & 8) && !($msg->flags & 4))
+                set $prefix = 0
+        end
+
+        # msg->flags & LOG_CONT
+        if ($msg->flags & 8)
+                # (prev & LOG_CONT && !(prev & LOG_NEWLINE))
+                if (($prev_flags & 8) && !($prev_flags & 2))
+                        set $prefix = 0
+                end
+                # (!(msg->flags & LOG_NEWLINE))
+                if (!($msg->flags & 2))
+                        set $newline = 0
+                end
+        end
+
+        if ($prefix)
+                printf "[%5lu.%06lu] ", $msg->ts_nsec / 1000000000, $msg->ts_nsec % 1000000000
+        end
+        if ($msg->text_len != 0)
+                eval "printf \"%%%d.%ds\", $log", $msg->text_len, $msg->text_len
+        end
+        if ($newline)
+                printf "\n"
+        end
+        if ($msg->dict_len > 0)
+                set $dict = $log + $msg->text_len
+                set $idx = 0
+                set $line = 1
+                while ($idx < $msg->dict_len)
+                        if ($line)
+                                printf " "
+                                set $line = 0
+                        end
+                        set $c = $dict[$idx]
+                        if ($c == '\0')
+                                printf "\n"
+                                set $line = 1
+                        else
+                                if ($c < ' ' || $c >= 127 || $c == '\\')
+                                        printf "\\x%02x", $c
+                                else
+                                        printf "%c", $c
+                                end
+                        end
+                        set $idx = $idx + 1
+                end
+                printf "\n"
+        end
+end
+document dump_log_idx
+        Dump a single log given its index in the log buffer.  The first
+        parameter is the index into log_buf, the second is optional and
+        specified the previous log buffer's flags, used for properly
+        formatting continued lines.
+end
 
-        while ($i < logged_chars)
-                set $idx = (log_end - 1 - logged_chars + $i) & (log_buf_len - 1)
+define dmesg
+        set $i = log_first_idx
+        set $end_idx = log_first_idx
+        set $prev_flags = 0
 
-                if ($idx + 100 <= $end_idx) || \
-                   ($end_idx <= $idx && $idx + 100 < log_buf_len)
-                        printf "%.100s", &log_buf[$idx]
-                        set $i = $i + 100
+        while (1)
+                set $msg = ((struct printk_log *) (log_buf + $i))
+                if ($msg->len == 0)
+                        set $i = 0
                 else
-                        printf "%c", log_buf[$idx]
-                        set $i = $i + 1
+                        dump_log_idx $i $prev_flags
+                        set $i = $i + $msg->len
+                        set $prev_flags = $msg->flags
+                end
+                if ($i == $end_idx)
+                        loop_break
                 end
         end
 end