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authorPetr Mladek <pmladek@suse.com>2020-10-12 14:01:37 +0300
committerPetr Mladek <pmladek@suse.com>2020-10-12 14:01:37 +0300
commit70333f4ff9c16dd82a2667080c3ae48fe30a3cb4 (patch)
treedf9a785cca8bd73c1a1962c2cc66b1702d9a4ebd /Documentation/admin-guide
parent4e797e6ec79c0705791c14f3e60f38b01c78ea1d (diff)
parent0463d04ea03a12d8a5aad42197a5945dfd78d7d6 (diff)
downloadlinux-70333f4ff9c16dd82a2667080c3ae48fe30a3cb4.tar.xz
Merge branch 'printk-rework' into for-linus
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/kdump/gdbmacros.txt159
-rw-r--r--Documentation/admin-guide/kdump/vmcoreinfo.rst131
2 files changed, 211 insertions, 79 deletions
diff --git a/Documentation/admin-guide/kdump/gdbmacros.txt b/Documentation/admin-guide/kdump/gdbmacros.txt
index 220d0a80ca2c..82aecdcae8a6 100644
--- a/Documentation/admin-guide/kdump/gdbmacros.txt
+++ b/Documentation/admin-guide/kdump/gdbmacros.txt
@@ -170,57 +170,103 @@ document trapinfo
address the kernel panicked.
end
-define dump_log_idx
- set $idx = $arg0
- if ($argc > 1)
- set $prev_flags = $arg1
+define dump_record
+ set var $desc = $arg0
+ set var $info = $arg1
+ if ($argc > 2)
+ set var $prev_flags = $arg2
else
- set $prev_flags = 0
+ set var $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)
-
- # prev & LOG_CONT && !(msg->flags & LOG_PREIX)
- if (($prev_flags & 8) && !($msg->flags & 4))
- set $prefix = 0
+
+ set var $prefix = 1
+ set var $newline = 1
+
+ set var $begin = $desc->text_blk_lpos.begin % (1U << prb->text_data_ring.size_bits)
+ set var $next = $desc->text_blk_lpos.next % (1U << prb->text_data_ring.size_bits)
+
+ # handle data-less record
+ if ($begin & 1)
+ set var $text_len = 0
+ set var $log = ""
+ else
+ # handle wrapping data block
+ if ($begin > $next)
+ set var $begin = 0
+ end
+
+ # skip over descriptor id
+ set var $begin = $begin + sizeof(long)
+
+ # handle truncated message
+ if ($next - $begin < $info->text_len)
+ set var $text_len = $next - $begin
+ else
+ set var $text_len = $info->text_len
+ end
+
+ set var $log = &prb->text_data_ring.data[$begin]
+ end
+
+ # prev & LOG_CONT && !(info->flags & LOG_PREIX)
+ if (($prev_flags & 8) && !($info->flags & 4))
+ set var $prefix = 0
end
- # msg->flags & LOG_CONT
- if ($msg->flags & 8)
+ # info->flags & LOG_CONT
+ if ($info->flags & 8)
# (prev & LOG_CONT && !(prev & LOG_NEWLINE))
if (($prev_flags & 8) && !($prev_flags & 2))
- set $prefix = 0
+ set var $prefix = 0
end
- # (!(msg->flags & LOG_NEWLINE))
- if (!($msg->flags & 2))
- set $newline = 0
+ # (!(info->flags & LOG_NEWLINE))
+ if (!($info->flags & 2))
+ set var $newline = 0
end
end
if ($prefix)
- printf "[%5lu.%06lu] ", $msg->ts_nsec / 1000000000, $msg->ts_nsec % 1000000000
+ printf "[%5lu.%06lu] ", $info->ts_nsec / 1000000000, $info->ts_nsec % 1000000000
end
- if ($msg->text_len != 0)
- eval "printf \"%%%d.%ds\", $log", $msg->text_len, $msg->text_len
+ if ($text_len)
+ eval "printf \"%%%d.%ds\", $log", $text_len, $text_len
end
if ($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
+
+ # handle dictionary data
+
+ set var $dict = &$info->dev_info.subsystem[0]
+ set var $dict_len = sizeof($info->dev_info.subsystem)
+ if ($dict[0] != '\0')
+ printf " SUBSYSTEM="
+ set var $idx = 0
+ while ($idx < $dict_len)
+ set var $c = $dict[$idx]
+ if ($c == '\0')
+ loop_break
+ else
+ if ($c < ' ' || $c >= 127 || $c == '\\')
+ printf "\\x%02x", $c
+ else
+ printf "%c", $c
+ end
end
- set $c = $dict[$idx]
+ set var $idx = $idx + 1
+ end
+ printf "\n"
+ end
+
+ set var $dict = &$info->dev_info.device[0]
+ set var $dict_len = sizeof($info->dev_info.device)
+ if ($dict[0] != '\0')
+ printf " DEVICE="
+ set var $idx = 0
+ while ($idx < $dict_len)
+ set var $c = $dict[$idx]
if ($c == '\0')
- printf "\n"
- set $line = 1
+ loop_break
else
if ($c < ' ' || $c >= 127 || $c == '\\')
printf "\\x%02x", $c
@@ -228,33 +274,46 @@ define dump_log_idx
printf "%c", $c
end
end
- set $idx = $idx + 1
+ set var $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.
+document dump_record
+ Dump a single record. The first parameter is the descriptor,
+ the second parameter is the info, the third parameter is
+ optional and specifies the previous record's flags, used for
+ properly formatting continued lines.
end
define dmesg
- set $i = log_first_idx
- set $end_idx = log_first_idx
- set $prev_flags = 0
+ # definitions from kernel/printk/printk_ringbuffer.h
+ set var $desc_committed = 1
+ set var $desc_finalized = 2
+ set var $desc_sv_bits = sizeof(long) * 8
+ set var $desc_flags_shift = $desc_sv_bits - 2
+ set var $desc_flags_mask = 3 << $desc_flags_shift
+ set var $id_mask = ~$desc_flags_mask
+
+ set var $desc_count = 1U << prb->desc_ring.count_bits
+ set var $prev_flags = 0
+
+ set var $id = prb->desc_ring.tail_id.counter
+ set var $end_id = prb->desc_ring.head_id.counter
while (1)
- set $msg = ((struct printk_log *) (log_buf + $i))
- if ($msg->len == 0)
- set $i = 0
- else
- dump_log_idx $i $prev_flags
- set $i = $i + $msg->len
- set $prev_flags = $msg->flags
+ set var $desc = &prb->desc_ring.descs[$id % $desc_count]
+ set var $info = &prb->desc_ring.infos[$id % $desc_count]
+
+ # skip non-committed record
+ set var $state = 3 & ($desc->state_var.counter >> $desc_flags_shift)
+ if ($state == $desc_committed || $state == $desc_finalized)
+ dump_record $desc $info $prev_flags
+ set var $prev_flags = $info->flags
end
- if ($i == $end_idx)
+
+ set var $id = ($id + 1) & $id_mask
+ if ($id == $end_id)
loop_break
end
end
diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst
index 2baad0bfb09d..e44a6c01f336 100644
--- a/Documentation/admin-guide/kdump/vmcoreinfo.rst
+++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst
@@ -189,50 +189,123 @@ from this.
Free areas descriptor. User-space tools use this value to iterate the
free_area ranges. MAX_ORDER is used by the zone buddy allocator.
-log_first_idx
+prb
+---
+
+A pointer to the printk ringbuffer (struct printk_ringbuffer). This
+may be pointing to the static boot ringbuffer or the dynamically
+allocated ringbuffer, depending on when the the core dump occurred.
+Used by user-space tools to read the active kernel log buffer.
+
+printk_rb_static
+----------------
+
+A pointer to the static boot printk ringbuffer. If @prb has a
+different value, this is useful for viewing the initial boot messages,
+which may have been overwritten in the dynamically allocated
+ringbuffer.
+
+clear_seq
+---------
+
+The sequence number of the printk() record after the last clear
+command. It indicates the first record after the last
+SYSLOG_ACTION_CLEAR, like issued by 'dmesg -c'. Used by user-space
+tools to dump a subset of the dmesg log.
+
+printk_ringbuffer
+-----------------
+
+The size of a printk_ringbuffer structure. This structure contains all
+information required for accessing the various components of the
+kernel log buffer.
+
+(printk_ringbuffer, desc_ring|text_data_ring|dict_data_ring|fail)
+-----------------------------------------------------------------
+
+Offsets for the various components of the printk ringbuffer. Used by
+user-space tools to view the kernel log buffer without requiring the
+declaration of the structure.
+
+prb_desc_ring
-------------
-Index of the first record stored in the buffer log_buf. Used by
-user-space tools to read the strings in the log_buf.
+The size of the prb_desc_ring structure. This structure contains
+information about the set of record descriptors.
-log_buf
--------
+(prb_desc_ring, count_bits|descs|head_id|tail_id)
+-------------------------------------------------
+
+Offsets for the fields describing the set of record descriptors. Used
+by user-space tools to be able to traverse the descriptors without
+requiring the declaration of the structure.
+
+prb_desc
+--------
+
+The size of the prb_desc structure. This structure contains
+information about a single record descriptor.
+
+(prb_desc, info|state_var|text_blk_lpos|dict_blk_lpos)
+------------------------------------------------------
+
+Offsets for the fields describing a record descriptors. Used by
+user-space tools to be able to read descriptors without requiring
+the declaration of the structure.
+
+prb_data_blk_lpos
+-----------------
+
+The size of the prb_data_blk_lpos structure. This structure contains
+information about where the text or dictionary data (data block) is
+located within the respective data ring.
+
+(prb_data_blk_lpos, begin|next)
+-------------------------------
-Console output is written to the ring buffer log_buf at index
-log_first_idx. Used to get the kernel log.
+Offsets for the fields describing the location of a data block. Used
+by user-space tools to be able to locate data blocks without
+requiring the declaration of the structure.
-log_buf_len
+printk_info
-----------
-log_buf's length.
+The size of the printk_info structure. This structure contains all
+the meta-data for a record.
-clear_idx
----------
+(printk_info, seq|ts_nsec|text_len|dict_len|caller_id)
+------------------------------------------------------
-The index that the next printk() record to read after the last clear
-command. It indicates the first record after the last SYSLOG_ACTION
-_CLEAR, like issued by 'dmesg -c'. Used by user-space tools to dump
-the dmesg log.
+Offsets for the fields providing the meta-data for a record. Used by
+user-space tools to be able to read the information without requiring
+the declaration of the structure.
-log_next_idx
-------------
+prb_data_ring
+-------------
-The index of the next record to store in the buffer log_buf. Used to
-compute the index of the current buffer position.
+The size of the prb_data_ring structure. This structure contains
+information about a set of data blocks.
-printk_log
-----------
+(prb_data_ring, size_bits|data|head_lpos|tail_lpos)
+---------------------------------------------------
-The size of a structure printk_log. Used to compute the size of
-messages, and extract dmesg log. It encapsulates header information for
-log_buf, such as timestamp, syslog level, etc.
+Offsets for the fields describing a set of data blocks. Used by
+user-space tools to be able to access the data blocks without
+requiring the declaration of the structure.
-(printk_log, ts_nsec|len|text_len|dict_len)
--------------------------------------------
+atomic_long_t
+-------------
+
+The size of the atomic_long_t structure. Used by user-space tools to
+be able to copy the full structure, regardless of its
+architecture-specific implementation.
+
+(atomic_long_t, counter)
+------------------------
-It represents field offsets in struct printk_log. User space tools
-parse it and check whether the values of printk_log's members have been
-changed.
+Offset for the long value of an atomic_long_t variable. Used by
+user-space tools to access the long value without requiring the
+architecture-specific declaration.
(free_area.free_list, MIGRATE_TYPES)
------------------------------------