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printk: move dictionary keys to dev_printk_info 

Dictionaries are only used for SUBSYSTEM and DEVICE properties. The
current implementation stores the property names each time they are
used. This requires more space than otherwise necessary. Also,
because the dictionary entries are currently considered optional,
it cannot be relied upon that they are always available, even if the
writer wanted to store them. These issues will increase should new
dictionary properties be introduced.

Rather than storing the subsystem and device properties in the
dict ring, introduce a struct dev_printk_info with separate fields
to store only the property values. Embed this struct within the
struct printk_info to provide guaranteed availability.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/87mu1jl6ne.fsf@jogness.linutronix.de
This commit is contained in:
John Ogness 2020-09-21 13:24:45 +02:06 committed by Petr Mladek
parent cfe2790b16
commit 74caba7f2a
9 changed files with 172 additions and 168 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
Documentation/admin-guide/kdump/gdbmacros.txt
View File

@ -172,13 +172,13 @@ end
define dump_record
set var $desc = $arg0
if ($argc > 1)
set var $prev_flags = $arg1
set var $info = $arg1
if ($argc > 2)
set var $prev_flags = $arg2
else
set var $prev_flags = 0
end
set var $info = &$desc->info
set var $prefix = 1
set var $newline = 1
@ -237,44 +237,36 @@ define dump_record
# handle dictionary data
set var $begin = $desc->dict_blk_lpos.begin % (1U << prb->dict_data_ring.size_bits)
set var $next = $desc->dict_blk_lpos.next % (1U << prb->dict_data_ring.size_bits)
# handle data-less record
if ($begin & 1)
set var $dict_len = 0
set var $dict = ""
else
# handle wrapping data block
if ($begin > $next)
set var $begin = 0
end
# skip over descriptor id
set var $begin = $begin + sizeof(long)
# handle truncated message
if ($next - $begin < $info->dict_len)
set var $dict_len = $next - $begin
else
set var $dict_len = $info->dict_len
end
set var $dict = &prb->dict_data_ring.data[$begin]
end
if ($dict_len > 0)
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
set var $line = 1
while ($idx < $dict_len)
if ($line)
printf " "
set var $line = 0
end
set var $c = $dict[$idx]
if ($c == '\0')
printf "\n"
set var $line = 1
loop_break
else
if ($c < ' ' || $c >= 127 || $c == '\\')
printf "\\x%02x", $c
else
printf "%c", $c
end
end
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 ($c == '\0')
loop_break
else
if ($c < ' ' || $c >= 127 || $c == '\\')
printf "\\x%02x", $c
@ -288,10 +280,10 @@ define dump_record
end
end
document dump_record
Dump a single record. The first parameter is the descriptor
sequence number, the second is optional and specifies the
previous record's flags, used for properly formatting
continued lines.
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
@ -311,12 +303,13 @@ define dmesg
while (1)
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 $prev_flags
set var $prev_flags = $desc->info.flags
dump_record $desc $info $prev_flags
set var $prev_flags = $info->flags
end
set var $id = ($id + 1) & $id_mask

46
drivers/base/core.c
View File

@ -3815,22 +3815,21 @@ void device_shutdown(void)
*/
#ifdef CONFIG_PRINTK
static int
create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
static void
set_dev_info(const struct device *dev, struct dev_printk_info *dev_info)
{
const char *subsys;
size_t pos = 0;
memset(dev_info, 0, sizeof(*dev_info));
if (dev->class)
subsys = dev->class->name;
else if (dev->bus)
subsys = dev->bus->name;
else
return 0;
return;
pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys);
if (pos >= hdrlen)
goto overflow;
strscpy(dev_info->subsystem, subsys, sizeof(dev_info->subsystem));
/*
* Add device identifier DEVICE=:
@ -3846,41 +3845,28 @@ create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
c = 'b';
else
c = 'c';
pos++;
pos += snprintf(hdr + pos, hdrlen - pos,
"DEVICE=%c%u:%u",
c, MAJOR(dev->devt), MINOR(dev->devt));
snprintf(dev_info->device, sizeof(dev_info->device),
"%c%u:%u", c, MAJOR(dev->devt), MINOR(dev->devt));
} else if (strcmp(subsys, "net") == 0) {
struct net_device *net = to_net_dev(dev);
pos++;
pos += snprintf(hdr + pos, hdrlen - pos,
"DEVICE=n%u", net->ifindex);
snprintf(dev_info->device, sizeof(dev_info->device),
"n%u", net->ifindex);
} else {
pos++;
pos += snprintf(hdr + pos, hdrlen - pos,
"DEVICE=+%s:%s", subsys, dev_name(dev));
snprintf(dev_info->device, sizeof(dev_info->device),
"+%s:%s", subsys, dev_name(dev));
}
if (pos >= hdrlen)
goto overflow;
return pos;
overflow:
dev_WARN(dev, "device/subsystem name too long");
return 0;
}
int dev_vprintk_emit(int level, const struct device *dev,
const char *fmt, va_list args)
{
char hdr[128];
size_t hdrlen;
struct dev_printk_info dev_info;
hdrlen = create_syslog_header(dev, hdr, sizeof(hdr));
set_dev_info(dev, &dev_info);
return vprintk_emit(0, level, hdrlen ? hdr : NULL, hdrlen, fmt, args);
return vprintk_emit(0, level, &dev_info, fmt, args);
}
EXPORT_SYMBOL(dev_vprintk_emit);

8
include/linux/dev_printk.h
View File

@ -21,6 +21,14 @@
struct device;
#define PRINTK_INFO_SUBSYSTEM_LEN 16
#define PRINTK_INFO_DEVICE_LEN 48
struct dev_printk_info {
char subsystem[PRINTK_INFO_SUBSYSTEM_LEN];
char device[PRINTK_INFO_DEVICE_LEN];
};
#ifdef CONFIG_PRINTK
__printf(3, 0) __cold

6
include/linux/printk.h
View File

@ -158,10 +158,12 @@ static inline void printk_nmi_direct_enter(void) { }
static inline void printk_nmi_direct_exit(void) { }
#endif /* PRINTK_NMI */
struct dev_printk_info;
#ifdef CONFIG_PRINTK
asmlinkage __printf(5, 0)
asmlinkage __printf(4, 0)
int vprintk_emit(int facility, int level,
const char *dict, size_t dictlen,
const struct dev_printk_info *dev_info,
const char *fmt, va_list args);
asmlinkage __printf(1, 0)

4
kernel/printk/internal.h
View File

@ -14,9 +14,9 @@
extern raw_spinlock_t logbuf_lock;
__printf(5, 0)
__printf(4, 0)
int vprintk_store(int facility, int level,
const char *dict, size_t dictlen,
const struct dev_printk_info *dev_info,
const char *fmt, va_list args);
__printf(1, 0) int vprintk_default(const char *fmt, va_list args);

176
kernel/printk/printk.c
View File

@ -296,8 +296,8 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
/*
* The printk log buffer consists of a sequenced collection of records, each
* containing variable length message and dictionary text. Every record
* also contains its own meta-data (@info).
* containing variable length message text. Every record also contains its
* own meta-data (@info).
*
* Every record meta-data carries the timestamp in microseconds, as well as
* the standard userspace syslog level and syslog facility. The usual kernel
@ -310,9 +310,7 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
* terminated.
*
* Optionally, a record can carry a dictionary of properties (key/value
* pairs), to provide userspace with a machine-readable message context. The
* length of the dictionary is available in @dict_len. The dictionary is not
* terminated.
* pairs), to provide userspace with a machine-readable message context.
*
* Examples for well-defined, commonly used property names are:
* DEVICE=b12:8 device identifier
@ -322,21 +320,20 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
* +sound:card0 subsystem:devname
* SUBSYSTEM=pci driver-core subsystem name
*
* Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
* follows directly after a '=' character. Every property is terminated by
* a '\0' character. The last property is not terminated.
* Valid characters in property names are [a-zA-Z0-9.-_]. Property names
* and values are terminated by a '\0' character.
*
* Example of record values:
* record.text_buf = "it's a line" (unterminated)
* record.dict_buf = "DEVICE=b8:2\0DRIVER=bug" (unterminated)
* record.info.seq = 56
* record.info.ts_nsec = 36863
* record.info.text_len = 11
* record.info.dict_len = 22
* record.info.facility = 0 (LOG_KERN)
* record.info.flags = 0
* record.info.level = 3 (LOG_ERR)
* record.info.caller_id = 299 (task 299)
* record.text_buf = "it's a line" (unterminated)
* record.info.seq = 56
* record.info.ts_nsec = 36863
* record.info.text_len = 11
* record.info.facility = 0 (LOG_KERN)
* record.info.flags = 0
* record.info.level = 3 (LOG_ERR)
* record.info.caller_id = 299 (task 299)
* record.info.dev_info.subsystem = "pci" (terminated)
* record.info.dev_info.device = "+pci:0000:00:01.0" (terminated)
*
* The 'struct printk_info' buffer must never be directly exported to
* userspace, it is a kernel-private implementation detail that might
@ -498,19 +495,19 @@ static void truncate_msg(u16 *text_len, u16 *trunc_msg_len)
/* insert record into the buffer, discard old ones, update heads */
static int log_store(u32 caller_id, int facility, int level,
enum log_flags flags, u64 ts_nsec,
const char *dict, u16 dict_len,
const struct dev_printk_info *dev_info,
const char *text, u16 text_len)
{
struct prb_reserved_entry e;
struct printk_record r;
u16 trunc_msg_len = 0;
prb_rec_init_wr(&r, text_len, dict_len);
prb_rec_init_wr(&r, text_len, 0);
if (!prb_reserve(&e, prb, &r)) {
/* truncate the message if it is too long for empty buffer */
truncate_msg(&text_len, &trunc_msg_len);
prb_rec_init_wr(&r, text_len + trunc_msg_len, dict_len);
prb_rec_init_wr(&r, text_len + trunc_msg_len, 0);
/* survive when the log buffer is too small for trunc_msg */
if (!prb_reserve(&e, prb, &r))
return 0;
@ -521,10 +518,6 @@ static int log_store(u32 caller_id, int facility, int level,
if (trunc_msg_len)
memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len);
r.info->text_len = text_len + trunc_msg_len;
if (r.dict_buf) {
memcpy(&r.dict_buf[0], dict, dict_len);
r.info->dict_len = dict_len;
}
r.info->facility = facility;
r.info->level = level & 7;
r.info->flags = flags & 0x1f;
@ -533,6 +526,8 @@ static int log_store(u32 caller_id, int facility, int level,
else
r.info->ts_nsec = local_clock();
r.info->caller_id = caller_id;
if (dev_info)
memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info));
/* insert message */
if ((flags & LOG_CONT) || !(flags & LOG_NEWLINE))
@ -613,9 +608,9 @@ static ssize_t info_print_ext_header(char *buf, size_t size,
ts_usec, info->flags & LOG_CONT ? 'c' : '-', caller);
}
static ssize_t msg_print_ext_body(char *buf, size_t size,
char *dict, size_t dict_len,
char *text, size_t text_len)
static ssize_t msg_add_ext_text(char *buf, size_t size,
const char *text, size_t text_len,
unsigned char endc)
{
char *p = buf, *e = buf + size;
size_t i;
@ -629,38 +624,46 @@ static ssize_t msg_print_ext_body(char *buf, size_t size,
else
append_char(&p, e, c);
}
append_char(&p, e, '\n');
if (dict_len) {
bool line = true;
for (i = 0; i < dict_len; i++) {
unsigned char c = dict[i];
if (line) {
append_char(&p, e, ' ');
line = false;
}
if (c == '\0') {
append_char(&p, e, '\n');
line = true;
continue;
}
if (c < ' ' || c >= 127 || c == '\\') {
p += scnprintf(p, e - p, "\\x%02x", c);
continue;
}
append_char(&p, e, c);
}
append_char(&p, e, '\n');
}
append_char(&p, e, endc);
return p - buf;
}
static ssize_t msg_add_dict_text(char *buf, size_t size,
const char *key, const char *val)
{
size_t val_len = strlen(val);
ssize_t len;
if (!val_len)
return 0;
len = msg_add_ext_text(buf, size, "", 0, ' '); /* dict prefix */
len += msg_add_ext_text(buf + len, size - len, key, strlen(key), '=');
len += msg_add_ext_text(buf + len, size - len, val, val_len, '\n');
return len;
}
static ssize_t msg_print_ext_body(char *buf, size_t size,
char *text, size_t text_len,
struct dev_printk_info *dev_info)
{
ssize_t len;
len = msg_add_ext_text(buf, size, text, text_len, '\n');
if (!dev_info)
goto out;
len += msg_add_dict_text(buf + len, size - len, "SUBSYSTEM",
dev_info->subsystem);
len += msg_add_dict_text(buf + len, size - len, "DEVICE",
dev_info->device);
out:
return len;
}
/* /dev/kmsg - userspace message inject/listen interface */
struct devkmsg_user {
u64 seq;
@ -670,7 +673,6 @@ struct devkmsg_user {
struct printk_info info;
char text_buf[CONSOLE_EXT_LOG_MAX];
char dict_buf[CONSOLE_EXT_LOG_MAX];
struct printk_record record;
};
@ -681,7 +683,7 @@ int devkmsg_emit(int facility, int level, const char *fmt, ...)
int r;
va_start(args, fmt);
r = vprintk_emit(facility, level, NULL, 0, fmt, args);
r = vprintk_emit(facility, level, NULL, fmt, args);
va_end(args);
return r;
@ -791,8 +793,8 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
len = info_print_ext_header(user->buf, sizeof(user->buf), r->info);
len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
&r->dict_buf[0], r->info->dict_len,
&r->text_buf[0], r->info->text_len);
&r->text_buf[0], r->info->text_len,
&r->info->dev_info);
user->seq = r->info->seq + 1;
logbuf_unlock_irq();
@ -897,7 +899,7 @@ static int devkmsg_open(struct inode *inode, struct file *file)
prb_rec_init_rd(&user->record, &user->info,
&user->text_buf[0], sizeof(user->text_buf),
&user->dict_buf[0], sizeof(user->dict_buf));
NULL, 0);
logbuf_lock_irq();
user->seq = prb_first_valid_seq(prb);
@ -941,6 +943,8 @@ const struct file_operations kmsg_fops = {
*/
void log_buf_vmcoreinfo_setup(void)
{
struct dev_printk_info *dev_info = NULL;
VMCOREINFO_SYMBOL(prb);
VMCOREINFO_SYMBOL(printk_rb_static);
VMCOREINFO_SYMBOL(clear_seq);
@ -978,6 +982,13 @@ void log_buf_vmcoreinfo_setup(void)
VMCOREINFO_OFFSET(printk_info, text_len);
VMCOREINFO_OFFSET(printk_info, dict_len);
VMCOREINFO_OFFSET(printk_info, caller_id);
VMCOREINFO_OFFSET(printk_info, dev_info);
VMCOREINFO_STRUCT_SIZE(dev_printk_info);
VMCOREINFO_OFFSET(dev_printk_info, subsystem);
VMCOREINFO_LENGTH(printk_info_subsystem, sizeof(dev_info->subsystem));
VMCOREINFO_OFFSET(dev_printk_info, device);
VMCOREINFO_LENGTH(printk_info_device, sizeof(dev_info->device));
VMCOREINFO_STRUCT_SIZE(prb_data_ring);
VMCOREINFO_OFFSET(prb_data_ring, size_bits);
@ -1070,22 +1081,19 @@ static unsigned int __init add_to_rb(struct printk_ringbuffer *rb,
struct prb_reserved_entry e;
struct printk_record dest_r;
prb_rec_init_wr(&dest_r, r->info->text_len, r->info->dict_len);
prb_rec_init_wr(&dest_r, r->info->text_len, 0);
if (!prb_reserve(&e, rb, &dest_r))
return 0;
memcpy(&dest_r.text_buf[0], &r->text_buf[0], r->info->text_len);
dest_r.info->text_len = r->info->text_len;
if (dest_r.dict_buf) {
memcpy(&dest_r.dict_buf[0], &r->dict_buf[0], r->info->dict_len);
dest_r.info->dict_len = r->info->dict_len;
}
dest_r.info->facility = r->info->facility;
dest_r.info->level = r->info->level;
dest_r.info->flags = r->info->flags;
dest_r.info->ts_nsec = r->info->ts_nsec;
dest_r.info->caller_id = r->info->caller_id;
memcpy(&dest_r.info->dev_info, &r->info->dev_info, sizeof(dest_r.info->dev_info));
prb_final_commit(&e);
@ -1093,7 +1101,6 @@ static unsigned int __init add_to_rb(struct printk_ringbuffer *rb,
}
static char setup_text_buf[CONSOLE_EXT_LOG_MAX] __initdata;
static char setup_dict_buf[CONSOLE_EXT_LOG_MAX] __initdata;
void __init setup_log_buf(int early)
{
@ -1165,7 +1172,7 @@ void __init setup_log_buf(int early)
prb_rec_init_rd(&r, &info,
&setup_text_buf[0], sizeof(setup_text_buf),
&setup_dict_buf[0], sizeof(setup_dict_buf));
NULL, 0);
prb_init(&printk_rb_dynamic,
new_log_buf, ilog2(new_log_buf_len),
@ -1903,7 +1910,9 @@ static inline u32 printk_caller_id(void)
0x80000000 + raw_smp_processor_id();
}
static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len)
static size_t log_output(int facility, int level, enum log_flags lflags,
const struct dev_printk_info *dev_info,
char *text, size_t text_len)
{
const u32 caller_id = printk_caller_id();
@ -1927,12 +1936,12 @@ static size_t log_output(int facility, int level, enum log_flags lflags, const c
/* Store it in the record log */
return log_store(caller_id, facility, level, lflags, 0,
dict, dictlen, text, text_len);
dev_info, text, text_len);
}
/* Must be called under logbuf_lock. */
int vprintk_store(int facility, int level,
const char *dict, size_t dictlen,
const struct dev_printk_info *dev_info,
const char *fmt, va_list args)
{
static char textbuf[LOG_LINE_MAX];
@ -1974,15 +1983,14 @@ int vprintk_store(int facility, int level,
if (level == LOGLEVEL_DEFAULT)
level = default_message_loglevel;
if (dict)
if (dev_info)
lflags |= LOG_NEWLINE;
return log_output(facility, level, lflags,
dict, dictlen, text, text_len);
return log_output(facility, level, lflags, dev_info, text, text_len);
}
asmlinkage int vprintk_emit(int facility, int level,
const char *dict, size_t dictlen,
const struct dev_printk_info *dev_info,
const char *fmt, va_list args)
{
int printed_len;
@ -2003,7 +2011,7 @@ asmlinkage int vprintk_emit(int facility, int level,
/* This stops the holder of console_sem just where we want him */
logbuf_lock_irqsave(flags);
printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args);
printed_len = vprintk_store(facility, level, dev_info, fmt, args);
logbuf_unlock_irqrestore(flags);
/* If called from the scheduler, we can not call up(). */
@ -2037,7 +2045,7 @@ EXPORT_SYMBOL(vprintk);
int vprintk_default(const char *fmt, va_list args)
{
return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
}
EXPORT_SYMBOL_GPL(vprintk_default);
@ -2100,8 +2108,8 @@ static ssize_t info_print_ext_header(char *buf, size_t size,
return 0;
}
static ssize_t msg_print_ext_body(char *buf, size_t size,
char *dict, size_t dict_len,
char *text, size_t text_len) { return 0; }
char *text, size_t text_len,
struct dev_printk_info *dev_info) { return 0; }
static void console_lock_spinning_enable(void) { }
static int console_lock_spinning_disable_and_check(void) { return 0; }
static void call_console_drivers(const char *ext_text, size_t ext_len,
@ -2390,7 +2398,6 @@ void console_unlock(void)
{
static char ext_text[CONSOLE_EXT_LOG_MAX];
static char text[LOG_LINE_MAX + PREFIX_MAX];
static char dict[LOG_LINE_MAX];
unsigned long flags;
bool do_cond_resched, retry;
struct printk_info info;
@ -2401,7 +2408,7 @@ void console_unlock(void)
return;
}
prb_rec_init_rd(&r, &info, text, sizeof(text), dict, sizeof(dict));
prb_rec_init_rd(&r, &info, text, sizeof(text), NULL, 0);
/*
* Console drivers are called with interrupts disabled, so
@ -2473,10 +2480,9 @@ skip:
r.info);
ext_len += msg_print_ext_body(ext_text + ext_len,
sizeof(ext_text) - ext_len,
&r.dict_buf[0],
r.info->dict_len,
&r.text_buf[0],
r.info->text_len);
r.info->text_len,
&r.info->dev_info);
}
len = record_print_text(&r,
console_msg_format & MSG_FORMAT_SYSLOG,
@ -3055,7 +3061,7 @@ int vprintk_deferred(const char *fmt, va_list args)
{
int r;
r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, fmt, args);
defer_console_output();
return r;

3
kernel/printk/printk_ringbuffer.h
View File

@ -4,6 +4,7 @@
#define _KERNEL_PRINTK_RINGBUFFER_H
#include <linux/atomic.h>
#include <linux/dev_printk.h>
/*
* Meta information about each stored message.
@ -21,6 +22,8 @@ struct printk_info {
u8 flags:5; /* internal record flags */
u8 level:3; /* syslog level */
u32 caller_id; /* thread id or processor id */
struct dev_printk_info dev_info;
};
/*

2
kernel/printk/printk_safe.c
View File

@ -375,7 +375,7 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args)
raw_spin_trylock(&logbuf_lock)) {
int len;
len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
raw_spin_unlock(&logbuf_lock);
defer_console_output();
return len;

16
scripts/gdb/linux/dmesg.py
View File

@ -52,6 +52,12 @@ class LxDmesg(gdb.Command):
addr = utils.read_ulong(desc_ring, off)
descs = utils.read_memoryview(inf, addr, desc_sz * desc_ring_count).tobytes()
# read in info array
info_sz = printk_info_type.get_type().sizeof
off = prb_desc_ring_type.get_type()['infos'].bitpos // 8
addr = utils.read_ulong(desc_ring, off)
infos = utils.read_memoryview(inf, addr, info_sz * desc_ring_count).tobytes()
# read in text data ring structure
off = printk_ringbuffer_type.get_type()['text_data_ring'].bitpos // 8
addr = prb_addr + off
@ -73,9 +79,8 @@ class LxDmesg(gdb.Command):
begin_off = off + (prb_data_blk_lpos_type.get_type()['begin'].bitpos // 8)
next_off = off + (prb_data_blk_lpos_type.get_type()['next'].bitpos // 8)
off = prb_desc_type.get_type()['info'].bitpos // 8
ts_off = off + printk_info_type.get_type()['ts_nsec'].bitpos // 8
len_off = off + printk_info_type.get_type()['text_len'].bitpos // 8
ts_off = printk_info_type.get_type()['ts_nsec'].bitpos // 8
len_off = printk_info_type.get_type()['text_len'].bitpos // 8
# definitions from kernel/printk/printk_ringbuffer.h
desc_committed = 1
@ -95,6 +100,7 @@ class LxDmesg(gdb.Command):
while True:
ind = did % desc_ring_count
desc_off = desc_sz * ind
info_off = info_sz * ind
# skip non-committed record
state = 3 & (utils.read_u64(descs, desc_off + sv_off +
@ -119,7 +125,7 @@ class LxDmesg(gdb.Command):
# skip over descriptor id
text_start = begin + utils.get_long_type().sizeof
text_len = utils.read_u16(descs, desc_off + len_off)
text_len = utils.read_u16(infos, info_off + len_off)
# handle truncated message
if end - text_start < text_len:
@ -128,7 +134,7 @@ class LxDmesg(gdb.Command):
text = text_data[text_start:text_start + text_len].decode(
encoding='utf8', errors='replace')
time_stamp = utils.read_u64(descs, desc_off + ts_off)
time_stamp = utils.read_u64(infos, info_off + ts_off)
for line in text.splitlines():
msg = u"[{time:12.6f}] {line}\n".format(