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Merge branch 'printk-rework' into for-linus

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This commit is contained in:
Petr Mladek 2021-04-27 14:32:09 +02:00
commit c8dbea6df3
11 changed files with 316 additions and 309 deletions
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8
arch/powerpc/kernel/nvram_64.c
View File

@ -647,6 +647,7 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
{
struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
static unsigned int oops_count = 0;
static struct kmsg_dump_iter iter;
static bool panicking = false;
static DEFINE_SPINLOCK(lock);
unsigned long flags;
@ -681,13 +682,14 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
return;
if (big_oops_buf) {
kmsg_dump_get_buffer(dumper, false,
kmsg_dump_rewind(&iter);
kmsg_dump_get_buffer(&iter, false,
big_oops_buf, big_oops_buf_sz, &text_len);
rc = zip_oops(text_len);
}
if (rc != 0) {
kmsg_dump_rewind(dumper);
kmsg_dump_get_buffer(dumper, false,
kmsg_dump_rewind(&iter);
kmsg_dump_get_buffer(&iter, false,
oops_data, oops_data_sz, &text_len);
err_type = ERR_TYPE_KERNEL_PANIC;
oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION);

6
arch/powerpc/xmon/xmon.c
View File

@ -3005,7 +3005,7 @@ print_address(unsigned long addr)
static void
dump_log_buf(void)
{
struct kmsg_dumper dumper = { .active = 1 };
struct kmsg_dump_iter iter;
unsigned char buf[128];
size_t len;
@ -3017,9 +3017,9 @@ dump_log_buf(void)
catch_memory_errors = 1;
sync();
kmsg_dump_rewind_nolock(&dumper);
kmsg_dump_rewind(&iter);
xmon_start_pagination();
while (kmsg_dump_get_line_nolock(&dumper, false, buf, sizeof(buf), &len)) {
while (kmsg_dump_get_line(&iter, false, buf, sizeof(buf), &len)) {
buf[len] = '\0';
printf("%s", buf);
}

13
arch/um/kernel/kmsg_dump.c
View File

@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/kmsg_dump.h>
#include <linux/spinlock.h>
#include <linux/console.h>
#include <linux/string.h>
#include <shared/init.h>
@ -9,8 +10,11 @@
static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason)
{
static struct kmsg_dump_iter iter;
static DEFINE_SPINLOCK(lock);
static char line[1024];
struct console *con;
unsigned long flags;
size_t len = 0;
/* only dump kmsg when no console is available */
@ -29,11 +33,18 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
if (con)
return;
if (!spin_trylock_irqsave(&lock, flags))
return;
kmsg_dump_rewind(&iter);
printf("kmsg_dump:\n");
while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len)) {
while (kmsg_dump_get_line(&iter, true, line, sizeof(line), &len)) {
line[len] = '\0';
printf("%s", line);
}
spin_unlock_irqrestore(&lock, flags);
}
static struct kmsg_dumper kmsg_dumper = {

4
drivers/hv/vmbus_drv.c
View File

@ -1391,6 +1391,7 @@ static void vmbus_isr(void)
static void hv_kmsg_dump(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason)
{
struct kmsg_dump_iter iter;
size_t bytes_written;
phys_addr_t panic_pa;
@ -1404,7 +1405,8 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper,
* Write dump contents to the page. No need to synchronize; panic should
* be single-threaded.
*/
kmsg_dump_get_buffer(dumper, false, hv_panic_page, HV_HYP_PAGE_SIZE,
kmsg_dump_rewind(&iter);
kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE,
&bytes_written);
if (bytes_written)
hyperv_report_panic_msg(panic_pa, bytes_written);

17
drivers/mtd/mtdoops.c
View File

@ -52,6 +52,7 @@ static struct mtdoops_context {
int nextcount;
unsigned long *oops_page_used;
unsigned long oops_buf_busy;
void *oops_buf;
} oops_cxt;
@ -180,6 +181,9 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
u32 *hdr;
int ret;
if (test_and_set_bit(0, &cxt->oops_buf_busy))
return;
/* Add mtdoops header to the buffer */
hdr = cxt->oops_buf;
hdr[0] = cxt->nextcount;
@ -190,7 +194,7 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
record_size, &retlen, cxt->oops_buf);
if (ret == -EOPNOTSUPP) {
printk(KERN_ERR "mtdoops: Cannot write from panic without panic_write\n");
return;
goto out;
}
} else
ret = mtd_write(mtd, cxt->nextpage * record_size,
@ -203,6 +207,8 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
memset(cxt->oops_buf, 0xff, record_size);
mtdoops_inc_counter(cxt);
out:
clear_bit(0, &cxt->oops_buf_busy);
}
static void mtdoops_workfunc_write(struct work_struct *work)
@ -271,13 +277,19 @@ static void mtdoops_do_dump(struct kmsg_dumper *dumper,
{
struct mtdoops_context *cxt = container_of(dumper,
struct mtdoops_context, dump);
struct kmsg_dump_iter iter;
/* Only dump oopses if dump_oops is set */
if (reason == KMSG_DUMP_OOPS && !dump_oops)
return;
kmsg_dump_get_buffer(dumper, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
kmsg_dump_rewind(&iter);
if (test_and_set_bit(0, &cxt->oops_buf_busy))
return;
kmsg_dump_get_buffer(&iter, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
record_size - MTDOOPS_HEADER_SIZE, NULL);
clear_bit(0, &cxt->oops_buf_busy);
if (reason != KMSG_DUMP_OOPS) {
/* Panics must be written immediately */
@ -394,6 +406,7 @@ static int __init mtdoops_init(void)
return -ENOMEM;
}
memset(cxt->oops_buf, 0xff, record_size);
cxt->oops_buf_busy = 0;
INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);

5
fs/pstore/platform.c
View File

@ -385,6 +385,7 @@ void pstore_record_init(struct pstore_record *record,
static void pstore_dump(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason)
{
struct kmsg_dump_iter iter;
unsigned long total = 0;
const char *why;
unsigned int part = 1;
@ -405,6 +406,8 @@ static void pstore_dump(struct kmsg_dumper *dumper,
}
}
kmsg_dump_rewind(&iter);
oopscount++;
while (total < kmsg_bytes) {
char *dst;
@ -435,7 +438,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
dst_size -= header_size;
/* Write dump contents. */
if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
dst_size, &dump_size))
break;

47
include/linux/kmsg_dump.h
View File

@ -29,6 +29,16 @@ enum kmsg_dump_reason {
KMSG_DUMP_MAX
};
/**
* struct kmsg_dump_iter - iterator for retrieving kernel messages
* @cur_seq: Points to the oldest message to dump
* @next_seq: Points after the newest message to dump
*/
struct kmsg_dump_iter {
u64 cur_seq;
u64 next_seq;
};
/**
* struct kmsg_dumper - kernel crash message dumper structure
* @list: Entry in the dumper list (private)
@ -41,31 +51,19 @@ struct kmsg_dumper {
struct list_head list;
void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason);
enum kmsg_dump_reason max_reason;
bool active;
bool registered;
/* private state of the kmsg iterator */
u32 cur_idx;
u32 next_idx;
u64 cur_seq;
u64 next_seq;
};
#ifdef CONFIG_PRINTK
void kmsg_dump(enum kmsg_dump_reason reason);
bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
char *line, size_t size, size_t *len);
bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
char *line, size_t size, size_t *len);
bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
char *buf, size_t size, size_t *len);
bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog,
char *buf, size_t size, size_t *len_out);
void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper);
void kmsg_dump_rewind(struct kmsg_dumper *dumper);
void kmsg_dump_rewind(struct kmsg_dump_iter *iter);
int kmsg_dump_register(struct kmsg_dumper *dumper);
@ -77,30 +75,19 @@ static inline void kmsg_dump(enum kmsg_dump_reason reason)
{
}
static inline bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper,
bool syslog, const char *line,
size_t size, size_t *len)
{
return false;
}
static inline bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
static inline bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
const char *line, size_t size, size_t *len)
{
return false;
}
static inline bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
static inline bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog,
char *buf, size_t size, size_t *len)
{
return false;
}
static inline void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
{
}
static inline void kmsg_dump_rewind(struct kmsg_dumper *dumper)
static inline void kmsg_dump_rewind(struct kmsg_dump_iter *iter)
{
}

10
kernel/debug/kdb/kdb_main.c
View File

@ -2101,7 +2101,7 @@ static int kdb_dmesg(int argc, const char **argv)
int adjust = 0;
int n = 0;
int skip = 0;
struct kmsg_dumper dumper = { .active = 1 };
struct kmsg_dump_iter iter;
size_t len;
char buf[201];
@ -2126,8 +2126,8 @@ static int kdb_dmesg(int argc, const char **argv)
kdb_set(2, setargs);
}
kmsg_dump_rewind_nolock(&dumper);
while (kmsg_dump_get_line_nolock(&dumper, 1, NULL, 0, NULL))
kmsg_dump_rewind(&iter);
while (kmsg_dump_get_line(&iter, 1, NULL, 0, NULL))
n++;
if (lines < 0) {
@ -2159,8 +2159,8 @@ static int kdb_dmesg(int argc, const char **argv)
if (skip >= n || skip < 0)
return 0;
kmsg_dump_rewind_nolock(&dumper);
while (kmsg_dump_get_line_nolock(&dumper, 1, buf, sizeof(buf), &len)) {
kmsg_dump_rewind(&iter);
while (kmsg_dump_get_line(&iter, 1, buf, sizeof(buf), &len)) {
if (skip) {
skip--;
continue;

7
kernel/printk/internal.h
View File

@ -12,8 +12,6 @@
#define PRINTK_NMI_CONTEXT_OFFSET 0x010000000
extern raw_spinlock_t logbuf_lock;
__printf(4, 0)
int vprintk_store(int facility, int level,
const struct dev_printk_info *dev_info,
@ -21,7 +19,6 @@ int vprintk_store(int facility, int level,
__printf(1, 0) int vprintk_default(const char *fmt, va_list args);
__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
__printf(1, 0) int vprintk_func(const char *fmt, va_list args);
void __printk_safe_enter(void);
void __printk_safe_exit(void);
@ -56,10 +53,8 @@ void defer_console_output(void);
#else
__printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; }
/*
* In !PRINTK builds we still export logbuf_lock spin_lock, console_sem
* In !PRINTK builds we still export console_sem
* semaphore and some of console functions (console_unlock()/etc.), so
* printk-safe must preserve the existing local IRQ guarantees.
*/

478
kernel/printk/printk.c
View File

@ -262,7 +262,7 @@ static void __up_console_sem(unsigned long ip)
* definitely not the perfect debug tool (we don't know if _WE_
* hold it and are racing, but it helps tracking those weird code
* paths in the console code where we end up in places I want
* locked without the console sempahore held).
* locked without the console semaphore held).
*/
static int console_locked, console_suspended;
@ -355,62 +355,50 @@ enum log_flags {
LOG_CONT = 8, /* text is a fragment of a continuation line */
};
/*
* The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
* within the scheduler's rq lock. It must be released before calling
* console_unlock() or anything else that might wake up a process.
*/
DEFINE_RAW_SPINLOCK(logbuf_lock);
/*
* Helper macros to lock/unlock logbuf_lock and switch between
* printk-safe/unsafe modes.
*/
#define logbuf_lock_irq() \
do { \
printk_safe_enter_irq(); \
raw_spin_lock(&logbuf_lock); \
} while (0)
#define logbuf_unlock_irq() \
do { \
raw_spin_unlock(&logbuf_lock); \
printk_safe_exit_irq(); \
} while (0)
#define logbuf_lock_irqsave(flags) \
do { \
printk_safe_enter_irqsave(flags); \
raw_spin_lock(&logbuf_lock); \
} while (0)
#define logbuf_unlock_irqrestore(flags) \
do { \
raw_spin_unlock(&logbuf_lock); \
printk_safe_exit_irqrestore(flags); \
} while (0)
/* syslog_lock protects syslog_* variables and write access to clear_seq. */
static DEFINE_RAW_SPINLOCK(syslog_lock);
#ifdef CONFIG_PRINTK
DECLARE_WAIT_QUEUE_HEAD(log_wait);
/* All 3 protected by @syslog_lock. */
/* the next printk record to read by syslog(READ) or /proc/kmsg */
static u64 syslog_seq;
static size_t syslog_partial;
static bool syslog_time;
/* All 3 protected by @console_sem. */
/* the next printk record to write to the console */
static u64 console_seq;
static u64 exclusive_console_stop_seq;
static unsigned long console_dropped;
/* the next printk record to read after the last 'clear' command */
static u64 clear_seq;
struct latched_seq {
seqcount_latch_t latch;
u64 val[2];
};
/*
* The next printk record to read after the last 'clear' command. There are
* two copies (updated with seqcount_latch) so that reads can locklessly
* access a valid value. Writers are synchronized by @syslog_lock.
*/
static struct latched_seq clear_seq = {
.latch = SEQCNT_LATCH_ZERO(clear_seq.latch),
.val[0] = 0,
.val[1] = 0,
};
#ifdef CONFIG_PRINTK_CALLER
#define PREFIX_MAX 48
#else
#define PREFIX_MAX 32
#endif
#define LOG_LINE_MAX (1024 - PREFIX_MAX)
/* the maximum size of a formatted record (i.e. with prefix added per line) */
#define CONSOLE_LOG_MAX 1024
/* the maximum size allowed to be reserved for a record */
#define LOG_LINE_MAX (CONSOLE_LOG_MAX - PREFIX_MAX)
#define LOG_LEVEL(v) ((v) & 0x07)
#define LOG_FACILITY(v) ((v) >> 3 & 0xff)
@ -452,6 +440,31 @@ bool printk_percpu_data_ready(void)
return __printk_percpu_data_ready;
}
/* Must be called under syslog_lock. */
static void latched_seq_write(struct latched_seq *ls, u64 val)
{
raw_write_seqcount_latch(&ls->latch);
ls->val[0] = val;
raw_write_seqcount_latch(&ls->latch);
ls->val[1] = val;
}
/* Can be called from any context. */
static u64 latched_seq_read_nolock(struct latched_seq *ls)
{
unsigned int seq;
unsigned int idx;
u64 val;
do {
seq = raw_read_seqcount_latch(&ls->latch);
idx = seq & 0x1;
val = ls->val[idx];
} while (read_seqcount_latch_retry(&ls->latch, seq));
return val;
}
/* Return log buffer address */
char *log_buf_addr_get(void)
{
@ -619,7 +632,7 @@ out:
/* /dev/kmsg - userspace message inject/listen interface */
struct devkmsg_user {
u64 seq;
atomic64_t seq;
struct ratelimit_state rs;
struct mutex lock;
char buf[CONSOLE_EXT_LOG_MAX];
@ -719,27 +732,27 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
if (ret)
return ret;
logbuf_lock_irq();
if (!prb_read_valid(prb, user->seq, r)) {
printk_safe_enter_irq();
if (!prb_read_valid(prb, atomic64_read(&user->seq), r)) {
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
logbuf_unlock_irq();
printk_safe_exit_irq();
goto out;
}
logbuf_unlock_irq();
printk_safe_exit_irq();
ret = wait_event_interruptible(log_wait,
prb_read_valid(prb, user->seq, r));
prb_read_valid(prb, atomic64_read(&user->seq), r));
if (ret)
goto out;
logbuf_lock_irq();
printk_safe_enter_irq();
}
if (r->info->seq != user->seq) {
if (r->info->seq != atomic64_read(&user->seq)) {
/* our last seen message is gone, return error and reset */
user->seq = r->info->seq;
atomic64_set(&user->seq, r->info->seq);
ret = -EPIPE;
logbuf_unlock_irq();
printk_safe_exit_irq();
goto out;
}
@ -748,8 +761,8 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
&r->text_buf[0], r->info->text_len,
&r->info->dev_info);
user->seq = r->info->seq + 1;
logbuf_unlock_irq();
atomic64_set(&user->seq, r->info->seq + 1);
printk_safe_exit_irq();
if (len > count) {
ret = -EINVAL;
@ -784,11 +797,11 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
if (offset)
return -ESPIPE;
logbuf_lock_irq();
printk_safe_enter_irq();
switch (whence) {
case SEEK_SET:
/* the first record */
user->seq = prb_first_valid_seq(prb);
atomic64_set(&user->seq, prb_first_valid_seq(prb));
break;
case SEEK_DATA:
/*
@ -796,16 +809,16 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
* like issued by 'dmesg -c'. Reading /dev/kmsg itself
* changes no global state, and does not clear anything.
*/
user->seq = clear_seq;
atomic64_set(&user->seq, latched_seq_read_nolock(&clear_seq));
break;
case SEEK_END:
/* after the last record */
user->seq = prb_next_seq(prb);
atomic64_set(&user->seq, prb_next_seq(prb));
break;
default:
ret = -EINVAL;
}
logbuf_unlock_irq();
printk_safe_exit_irq();
return ret;
}
@ -820,15 +833,15 @@ static __poll_t devkmsg_poll(struct file *file, poll_table *wait)
poll_wait(file, &log_wait, wait);
logbuf_lock_irq();
if (prb_read_valid_info(prb, user->seq, &info, NULL)) {
printk_safe_enter_irq();
if (prb_read_valid_info(prb, atomic64_read(&user->seq), &info, NULL)) {
/* return error when data has vanished underneath us */
if (info.seq != user->seq)
if (info.seq != atomic64_read(&user->seq))
ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
else
ret = EPOLLIN|EPOLLRDNORM;
}
logbuf_unlock_irq();
printk_safe_exit_irq();
return ret;
}
@ -861,9 +874,9 @@ 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));
logbuf_lock_irq();
user->seq = prb_first_valid_seq(prb);
logbuf_unlock_irq();
printk_safe_enter_irq();
atomic64_set(&user->seq, prb_first_valid_seq(prb));
printk_safe_exit_irq();
file->private_data = user;
return 0;
@ -955,6 +968,9 @@ void log_buf_vmcoreinfo_setup(void)
VMCOREINFO_SIZE(atomic_long_t);
VMCOREINFO_TYPE_OFFSET(atomic_long_t, counter);
VMCOREINFO_STRUCT_SIZE(latched_seq);
VMCOREINFO_OFFSET(latched_seq, val);
}
#endif
@ -1421,6 +1437,50 @@ static size_t get_record_print_text_size(struct printk_info *info,
return ((prefix_len * line_count) + info->text_len + 1);
}
/*
* Beginning with @start_seq, find the first record where it and all following
* records up to (but not including) @max_seq fit into @size.
*
* @max_seq is simply an upper bound and does not need to exist. If the caller
* does not require an upper bound, -1 can be used for @max_seq.
*/
static u64 find_first_fitting_seq(u64 start_seq, u64 max_seq, size_t size,
bool syslog, bool time)
{
struct printk_info info;
unsigned int line_count;
size_t len = 0;
u64 seq;
/* Determine the size of the records up to @max_seq. */
prb_for_each_info(start_seq, prb, seq, &info, &line_count) {
if (info.seq >= max_seq)
break;
len += get_record_print_text_size(&info, line_count, syslog, time);
}
/*
* Adjust the upper bound for the next loop to avoid subtracting
* lengths that were never added.
*/
if (seq < max_seq)
max_seq = seq;
/*
* Move first record forward until length fits into the buffer. Ignore
* newest messages that were not counted in the above cycle. Messages
* might appear and get lost in the meantime. This is a best effort
* that prevents an infinite loop that could occur with a retry.
*/
prb_for_each_info(start_seq, prb, seq, &info, &line_count) {
if (len <= size || info.seq >= max_seq)
break;
len -= get_record_print_text_size(&info, line_count, syslog, time);
}
return seq;
}
static int syslog_print(char __user *buf, int size)
{
struct printk_info info;
@ -1428,19 +1488,21 @@ static int syslog_print(char __user *buf, int size)
char *text;
int len = 0;
text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
prb_rec_init_rd(&r, &info, text, LOG_LINE_MAX + PREFIX_MAX);
prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
while (size > 0) {
size_t n;
size_t skip;
logbuf_lock_irq();
printk_safe_enter_irq();
raw_spin_lock(&syslog_lock);
if (!prb_read_valid(prb, syslog_seq, &r)) {
logbuf_unlock_irq();
raw_spin_unlock(&syslog_lock);
printk_safe_exit_irq();
break;
}
if (r.info->seq != syslog_seq) {
@ -1469,7 +1531,8 @@ static int syslog_print(char __user *buf, int size)
syslog_partial += n;
} else
n = 0;
logbuf_unlock_irq();
raw_spin_unlock(&syslog_lock);
printk_safe_exit_irq();
if (!n)
break;
@ -1492,34 +1555,26 @@ static int syslog_print(char __user *buf, int size)
static int syslog_print_all(char __user *buf, int size, bool clear)
{
struct printk_info info;
unsigned int line_count;
struct printk_record r;
char *text;
int len = 0;
u64 seq;
bool time;
text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
time = printk_time;
logbuf_lock_irq();
printk_safe_enter_irq();
/*
* Find first record that fits, including all following records,
* into the user-provided buffer for this dump.
*/
prb_for_each_info(clear_seq, prb, seq, &info, &line_count)
len += get_record_print_text_size(&info, line_count, true, time);
seq = find_first_fitting_seq(latched_seq_read_nolock(&clear_seq), -1,
size, true, time);
/* move first record forward until length fits into the buffer */
prb_for_each_info(clear_seq, prb, seq, &info, &line_count) {
if (len <= size)
break;
len -= get_record_print_text_size(&info, line_count, true, time);
}
prb_rec_init_rd(&r, &info, text, LOG_LINE_MAX + PREFIX_MAX);
prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
len = 0;
prb_for_each_record(seq, prb, seq, &r) {
@ -1532,20 +1587,23 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
break;
}
logbuf_unlock_irq();
printk_safe_exit_irq();
if (copy_to_user(buf + len, text, textlen))
len = -EFAULT;
else
len += textlen;
logbuf_lock_irq();
printk_safe_enter_irq();
if (len < 0)
break;
}
if (clear)
clear_seq = seq;
logbuf_unlock_irq();
if (clear) {
raw_spin_lock(&syslog_lock);
latched_seq_write(&clear_seq, seq);
raw_spin_unlock(&syslog_lock);
}
printk_safe_exit_irq();
kfree(text);
return len;
@ -1553,9 +1611,23 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
static void syslog_clear(void)
{
logbuf_lock_irq();
clear_seq = prb_next_seq(prb);
logbuf_unlock_irq();
printk_safe_enter_irq();
raw_spin_lock(&syslog_lock);
latched_seq_write(&clear_seq, prb_next_seq(prb));
raw_spin_unlock(&syslog_lock);
printk_safe_exit_irq();
}
/* Return a consistent copy of @syslog_seq. */
static u64 read_syslog_seq_irq(void)
{
u64 seq;
raw_spin_lock_irq(&syslog_lock);
seq = syslog_seq;
raw_spin_unlock_irq(&syslog_lock);
return seq;
}
int do_syslog(int type, char __user *buf, int len, int source)
@ -1581,8 +1653,9 @@ int do_syslog(int type, char __user *buf, int len, int source)
return 0;
if (!access_ok(buf, len))
return -EFAULT;
error = wait_event_interruptible(log_wait,
prb_read_valid(prb, syslog_seq, NULL));
prb_read_valid(prb, read_syslog_seq_irq(), NULL));
if (error)
return error;
error = syslog_print(buf, len);
@ -1630,10 +1703,12 @@ int do_syslog(int type, char __user *buf, int len, int source)
break;
/* Number of chars in the log buffer */
case SYSLOG_ACTION_SIZE_UNREAD:
logbuf_lock_irq();
printk_safe_enter_irq();
raw_spin_lock(&syslog_lock);
if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) {
/* No unread messages. */
logbuf_unlock_irq();
raw_spin_unlock(&syslog_lock);
printk_safe_exit_irq();
return 0;
}
if (info.seq != syslog_seq) {
@ -1661,7 +1736,8 @@ int do_syslog(int type, char __user *buf, int len, int source)
}
error -= syslog_partial;
}
logbuf_unlock_irq();
raw_spin_unlock(&syslog_lock);
printk_safe_exit_irq();
break;
/* Size of the log buffer */
case SYSLOG_ACTION_SIZE_BUFFER:
@ -2104,12 +2180,6 @@ asmlinkage int vprintk_emit(int facility, int level,
}
EXPORT_SYMBOL(vprintk_emit);
asmlinkage int vprintk(const char *fmt, va_list args)
{
return vprintk_func(fmt, args);
}
EXPORT_SYMBOL(vprintk);
int vprintk_default(const char *fmt, va_list args)
{
return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
@ -2143,7 +2213,7 @@ asmlinkage __visible int printk(const char *fmt, ...)
int r;
va_start(args, fmt);
r = vprintk_func(fmt, args);
r = vprintk(fmt, args);
va_end(args);
return r;
@ -2152,8 +2222,7 @@ EXPORT_SYMBOL(printk);
#else /* CONFIG_PRINTK */
#define LOG_LINE_MAX 0
#define PREFIX_MAX 0
#define CONSOLE_LOG_MAX 0
#define printk_time false
#define prb_read_valid(rb, seq, r) false
@ -2262,7 +2331,7 @@ static int __init console_setup(char *str)
/*
* console="" or console=null have been suggested as a way to
* disable console output. Use ttynull that has been created
* for exacly this purpose.
* for exactly this purpose.
*/
if (str[0] == 0 || strcmp(str, "null") == 0) {
__add_preferred_console("ttynull", 0, NULL, NULL, true);
@ -2471,7 +2540,7 @@ static inline int can_use_console(void)
void console_unlock(void)
{
static char ext_text[CONSOLE_EXT_LOG_MAX];
static char text[LOG_LINE_MAX + PREFIX_MAX];
static char text[CONSOLE_LOG_MAX];
unsigned long flags;
bool do_cond_resched, retry;
struct printk_info info;
@ -2518,7 +2587,6 @@ again:
size_t len;
printk_safe_enter_irqsave(flags);
raw_spin_lock(&logbuf_lock);
skip:
if (!prb_read_valid(prb, console_seq, &r))
break;
@ -2562,7 +2630,6 @@ skip:
console_msg_format & MSG_FORMAT_SYSLOG,
printk_time);
console_seq++;
raw_spin_unlock(&logbuf_lock);
/*
* While actively printing out messages, if another printk()
@ -2589,8 +2656,6 @@ skip:
console_locked = 0;
raw_spin_unlock(&logbuf_lock);
up_console_sem();
/*
@ -2599,9 +2664,7 @@ skip:
* there's a new owner and the console_unlock() from them will do the
* flush, no worries.
*/
raw_spin_lock(&logbuf_lock);
retry = prb_read_valid(prb, console_seq, NULL);
raw_spin_unlock(&logbuf_lock);
printk_safe_exit_irqrestore(flags);
if (retry && console_trylock())
@ -2668,9 +2731,9 @@ void console_flush_on_panic(enum con_flush_mode mode)
if (mode == CONSOLE_REPLAY_ALL) {
unsigned long flags;
logbuf_lock_irqsave(flags);
printk_safe_enter_irqsave(flags);
console_seq = prb_first_valid_seq(prb);
logbuf_unlock_irqrestore(flags);
printk_safe_exit_irqrestore(flags);
}
console_unlock();
}
@ -2898,9 +2961,7 @@ void register_console(struct console *newcon)
/*
* console_unlock(); will print out the buffered messages
* for us.
*/
logbuf_lock_irqsave(flags);
/*
*
* We're about to replay the log buffer. Only do this to the
* just-registered console to avoid excessive message spam to
* the already-registered consoles.
@ -2911,8 +2972,11 @@ void register_console(struct console *newcon)
*/
exclusive_console = newcon;
exclusive_console_stop_seq = console_seq;
/* Get a consistent copy of @syslog_seq. */
raw_spin_lock_irqsave(&syslog_lock, flags);
console_seq = syslog_seq;
logbuf_unlock_irqrestore(flags);
raw_spin_unlock_irqrestore(&syslog_lock, flags);
}
console_unlock();
console_sysfs_notify();
@ -3042,7 +3106,7 @@ void __init console_init(void)
*
* To mitigate this problem somewhat, only unregister consoles whose memory
* intersects with the init section. Note that all other boot consoles will
* get unregistred when the real preferred console is registered.
* get unregistered when the real preferred console is registered.
*/
static int __init printk_late_init(void)
{
@ -3276,7 +3340,6 @@ EXPORT_SYMBOL_GPL(kmsg_dump_reason_str);
void kmsg_dump(enum kmsg_dump_reason reason)
{
struct kmsg_dumper *dumper;
unsigned long flags;
rcu_read_lock();
list_for_each_entry_rcu(dumper, &dump_list, list) {
@ -3293,26 +3356,15 @@ void kmsg_dump(enum kmsg_dump_reason reason)
if (reason > max_reason)
continue;
/* initialize iterator with data about the stored records */
dumper->active = true;
logbuf_lock_irqsave(flags);
dumper->cur_seq = clear_seq;
dumper->next_seq = prb_next_seq(prb);
logbuf_unlock_irqrestore(flags);
/* invoke dumper which will iterate over records */
dumper->dump(dumper, reason);
/* reset iterator */
dumper->active = false;
}
rcu_read_unlock();
}
/**
* kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
* @dumper: registered kmsg dumper
* kmsg_dump_get_line - retrieve one kmsg log line
* @iter: kmsg dump iterator
* @syslog: include the "<4>" prefixes
* @line: buffer to copy the line to
* @size: maximum size of the buffer
@ -3326,30 +3378,31 @@ void kmsg_dump(enum kmsg_dump_reason reason)
*
* A return value of FALSE indicates that there are no more records to
* read.
*
* The function is similar to kmsg_dump_get_line(), but grabs no locks.
*/
bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
char *line, size_t size, size_t *len)
bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
char *line, size_t size, size_t *len)
{
u64 min_seq = latched_seq_read_nolock(&clear_seq);
struct printk_info info;
unsigned int line_count;
struct printk_record r;
unsigned long flags;
size_t l = 0;
bool ret = false;
prb_rec_init_rd(&r, &info, line, size);
if (iter->cur_seq < min_seq)
iter->cur_seq = min_seq;
if (!dumper->active)
goto out;
printk_safe_enter_irqsave(flags);
prb_rec_init_rd(&r, &info, line, size);
/* Read text or count text lines? */
if (line) {
if (!prb_read_valid(prb, dumper->cur_seq, &r))
if (!prb_read_valid(prb, iter->cur_seq, &r))
goto out;
l = record_print_text(&r, syslog, printk_time);
} else {
if (!prb_read_valid_info(prb, dumper->cur_seq,
if (!prb_read_valid_info(prb, iter->cur_seq,
&info, &line_count)) {
goto out;
}
@ -3358,52 +3411,23 @@ bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
}
dumper->cur_seq = r.info->seq + 1;
iter->cur_seq = r.info->seq + 1;
ret = true;
out:
printk_safe_exit_irqrestore(flags);
if (len)
*len = l;
return ret;
}
/**
* kmsg_dump_get_line - retrieve one kmsg log line
* @dumper: registered kmsg dumper
* @syslog: include the "<4>" prefixes
* @line: buffer to copy the line to
* @size: maximum size of the buffer
* @len: length of line placed into buffer
*
* Start at the beginning of the kmsg buffer, with the oldest kmsg
* record, and copy one record into the provided buffer.
*
* Consecutive calls will return the next available record moving
* towards the end of the buffer with the youngest messages.
*
* A return value of FALSE indicates that there are no more records to
* read.
*/
bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
char *line, size_t size, size_t *len)
{
unsigned long flags;
bool ret;
logbuf_lock_irqsave(flags);
ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
logbuf_unlock_irqrestore(flags);
return ret;
}
EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
/**
* kmsg_dump_get_buffer - copy kmsg log lines
* @dumper: registered kmsg dumper
* @iter: kmsg dump iterator
* @syslog: include the "<4>" prefixes
* @buf: buffer to copy the line to
* @size: maximum size of the buffer
* @len: length of line placed into buffer
* @len_out: length of line placed into buffer
*
* Start at the end of the kmsg buffer and fill the provided buffer
* with as many of the *youngest* kmsg records that fit into it.
@ -3416,115 +3440,93 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
* A return value of FALSE indicates that there are no more records to
* read.
*/
bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
char *buf, size_t size, size_t *len)
bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog,
char *buf, size_t size, size_t *len_out)
{
u64 min_seq = latched_seq_read_nolock(&clear_seq);
struct printk_info info;
unsigned int line_count;
struct printk_record r;
unsigned long flags;
u64 seq;
u64 next_seq;
size_t l = 0;
size_t len = 0;
bool ret = false;
bool time = printk_time;
prb_rec_init_rd(&r, &info, buf, size);
if (!dumper->active || !buf || !size)
if (!buf || !size)
goto out;
logbuf_lock_irqsave(flags);
if (prb_read_valid_info(prb, dumper->cur_seq, &info, NULL)) {
if (info.seq != dumper->cur_seq) {
if (iter->cur_seq < min_seq)
iter->cur_seq = min_seq;
printk_safe_enter_irqsave(flags);
if (prb_read_valid_info(prb, iter->cur_seq, &info, NULL)) {
if (info.seq != iter->cur_seq) {
/* messages are gone, move to first available one */
dumper->cur_seq = info.seq;
iter->cur_seq = info.seq;
}
}
/* last entry */
if (dumper->cur_seq >= dumper->next_seq) {
logbuf_unlock_irqrestore(flags);
if (iter->cur_seq >= iter->next_seq) {
printk_safe_exit_irqrestore(flags);
goto out;
}
/* calculate length of entire buffer */
seq = dumper->cur_seq;
while (prb_read_valid_info(prb, seq, &info, &line_count)) {
if (r.info->seq >= dumper->next_seq)
break;
l += get_record_print_text_size(&info, line_count, syslog, time);
seq = r.info->seq + 1;
}
/*
* Find first record that fits, including all following records,
* into the user-provided buffer for this dump. Pass in size-1
* because this function (by way of record_print_text()) will
* not write more than size-1 bytes of text into @buf.
*/
seq = find_first_fitting_seq(iter->cur_seq, iter->next_seq,
size - 1, syslog, time);
/* move first record forward until length fits into the buffer */
seq = dumper->cur_seq;
while (l >= size && prb_read_valid_info(prb, seq,
&info, &line_count)) {
if (r.info->seq >= dumper->next_seq)
break;
l -= get_record_print_text_size(&info, line_count, syslog, time);
seq = r.info->seq + 1;
}
/* last message in next interation */
/*
* Next kmsg_dump_get_buffer() invocation will dump block of
* older records stored right before this one.
*/
next_seq = seq;
/* actually read text into the buffer now */
l = 0;
while (prb_read_valid(prb, seq, &r)) {
if (r.info->seq >= dumper->next_seq)
prb_rec_init_rd(&r, &info, buf, size);
len = 0;
prb_for_each_record(seq, prb, seq, &r) {
if (r.info->seq >= iter->next_seq)
break;
l += record_print_text(&r, syslog, time);
len += record_print_text(&r, syslog, time);
/* adjust record to store to remaining buffer space */
prb_rec_init_rd(&r, &info, buf + l, size - l);
seq = r.info->seq + 1;
/* Adjust record to store to remaining buffer space. */
prb_rec_init_rd(&r, &info, buf + len, size - len);
}
dumper->next_seq = next_seq;
iter->next_seq = next_seq;
ret = true;
logbuf_unlock_irqrestore(flags);
printk_safe_exit_irqrestore(flags);
out:
if (len)
*len = l;
if (len_out)
*len_out = len;
return ret;
}
EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
/**
* kmsg_dump_rewind_nolock - reset the iterator (unlocked version)
* @dumper: registered kmsg dumper
*
* Reset the dumper's iterator so that kmsg_dump_get_line() and
* kmsg_dump_get_buffer() can be called again and used multiple
* times within the same dumper.dump() callback.
*
* The function is similar to kmsg_dump_rewind(), but grabs no locks.
*/
void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
{
dumper->cur_seq = clear_seq;
dumper->next_seq = prb_next_seq(prb);
}
/**
* kmsg_dump_rewind - reset the iterator
* @dumper: registered kmsg dumper
* @iter: kmsg dump iterator
*
* Reset the dumper's iterator so that kmsg_dump_get_line() and
* kmsg_dump_get_buffer() can be called again and used multiple
* times within the same dumper.dump() callback.
*/
void kmsg_dump_rewind(struct kmsg_dumper *dumper)
void kmsg_dump_rewind(struct kmsg_dump_iter *iter)
{
unsigned long flags;
logbuf_lock_irqsave(flags);
kmsg_dump_rewind_nolock(dumper);
logbuf_unlock_irqrestore(flags);
printk_safe_enter_irqsave(flags);
iter->cur_seq = latched_seq_read_nolock(&clear_seq);
iter->next_seq = prb_next_seq(prb);
printk_safe_exit_irqrestore(flags);
}
EXPORT_SYMBOL_GPL(kmsg_dump_rewind);

30
kernel/printk/printk_safe.c
View File

@ -16,7 +16,7 @@
#include "internal.h"
/*
* printk() could not take logbuf_lock in NMI context. Instead,
* In NMI and safe mode, printk() avoids taking locks. Instead,
* it uses an alternative implementation that temporary stores
* the strings into a per-CPU buffer. The content of the buffer
* is later flushed into the main ring buffer via IRQ work.
@ -267,17 +267,9 @@ void printk_safe_flush(void)
void printk_safe_flush_on_panic(void)
{
/*
* Make sure that we could access the main ring buffer.
* Make sure that we could access the safe buffers.
* Do not risk a double release when more CPUs are up.
*/
if (raw_spin_is_locked(&logbuf_lock)) {
if (num_online_cpus() > 1)
return;
debug_locks_off();
raw_spin_lock_init(&logbuf_lock);
}
if (raw_spin_is_locked(&safe_read_lock)) {
if (num_online_cpus() > 1)
return;
@ -319,9 +311,7 @@ void noinstr printk_nmi_exit(void)
* reordering.
*
* It has effect only when called in NMI context. Then printk()
* will try to store the messages into the main logbuf directly
* and use the per-CPU buffers only as a fallback when the lock
* is not available.
* will store the messages into the main logbuf directly.
*/
void printk_nmi_direct_enter(void)
{
@ -367,7 +357,7 @@ void __printk_safe_exit(void)
this_cpu_dec(printk_context);
}
__printf(1, 0) int vprintk_func(const char *fmt, va_list args)
asmlinkage int vprintk(const char *fmt, va_list args)
{
#ifdef CONFIG_KGDB_KDB
/* Allow to pass printk() to kdb but avoid a recursion. */
@ -376,20 +366,21 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args)
#endif
/*
* Try to use the main logbuf even in NMI. But avoid calling console
* Use the main logbuf even in NMI. But avoid calling console
* drivers that might have their own locks.
*/
if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK) &&
raw_spin_trylock(&logbuf_lock)) {
if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK)) {
unsigned long flags;
int len;
printk_safe_enter_irqsave(flags);
len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
raw_spin_unlock(&logbuf_lock);
printk_safe_exit_irqrestore(flags);
defer_console_output();
return len;
}
/* Use extra buffer in NMI when logbuf_lock is taken or in safe mode. */
/* Use extra buffer in NMI. */
if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK)
return vprintk_nmi(fmt, args);
@ -420,3 +411,4 @@ void __init printk_safe_init(void)
/* Flush pending messages that did not have scheduled IRQ works. */
printk_safe_flush();
}
EXPORT_SYMBOL(vprintk);