summaryrefslogtreecommitdiffstats
path: root/kernel/printk
diff options
context:
space:
mode:
authorJiri Kosina <jkosina@suse.cz>2020-09-01 14:19:48 +0200
committerJiri Kosina <jkosina@suse.cz>2020-09-01 14:19:48 +0200
commitead5d1f4d877e92c051e1a1ade623d0d30e71619 (patch)
treecb9db5698a546e7b96f7d5bef5ce544629dd37a2 /kernel/printk
parentf53fa968a7344970b8f8a5707c39cdcf17a6f367 (diff)
parentb51594df17d0ce80b9f9f35394a1f42d7ac94472 (diff)
downloadlinux-ead5d1f4d877e92c051e1a1ade623d0d30e71619.tar.gz
linux-ead5d1f4d877e92c051e1a1ade623d0d30e71619.tar.bz2
linux-ead5d1f4d877e92c051e1a1ade623d0d30e71619.zip
Merge branch 'master' into for-next
Sync with Linus' branch in order to be able to apply fixups of more recent patches.
Diffstat (limited to 'kernel/printk')
-rw-r--r--kernel/printk/console_cmdline.h1
-rw-r--r--kernel/printk/internal.h13
-rw-r--r--kernel/printk/printk.c274
-rw-r--r--kernel/printk/printk_safe.c27
4 files changed, 211 insertions, 104 deletions
diff --git a/kernel/printk/console_cmdline.h b/kernel/printk/console_cmdline.h
index 11f19c466af5..3ca74ad391d6 100644
--- a/kernel/printk/console_cmdline.h
+++ b/kernel/printk/console_cmdline.h
@@ -6,6 +6,7 @@ struct console_cmdline
{
char name[16]; /* Name of the driver */
int index; /* Minor dev. to use */
+ bool user_specified; /* Specified by command line vs. platform */
char *options; /* Options for the driver */
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
char *brl_options; /* Options for braille driver */
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index c8e6ab689d42..660f9a6bf73a 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -6,9 +6,11 @@
#ifdef CONFIG_PRINTK
-#define PRINTK_SAFE_CONTEXT_MASK 0x3fffffff
-#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x40000000
-#define PRINTK_NMI_CONTEXT_MASK 0x80000000
+#define PRINTK_SAFE_CONTEXT_MASK 0x007ffffff
+#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x008000000
+#define PRINTK_NMI_CONTEXT_MASK 0xff0000000
+
+#define PRINTK_NMI_CONTEXT_OFFSET 0x010000000
extern raw_spinlock_t logbuf_lock;
@@ -23,6 +25,9 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args);
void __printk_safe_enter(void);
void __printk_safe_exit(void);
+void printk_safe_init(void);
+bool printk_percpu_data_ready(void);
+
#define printk_safe_enter_irqsave(flags) \
do { \
local_irq_save(flags); \
@@ -64,4 +69,6 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; }
#define printk_safe_enter_irq() local_irq_disable()
#define printk_safe_exit_irq() local_irq_enable()
+static inline void printk_safe_init(void) { }
+static inline bool printk_percpu_data_ready(void) { return false; }
#endif /* CONFIG_PRINTK */
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fada22dc4ab6..9b75f6bfc333 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -35,7 +35,6 @@
#include <linux/memblock.h>
#include <linux/syscalls.h>
#include <linux/crash_core.h>
-#include <linux/kdb.h>
#include <linux/ratelimit.h>
#include <linux/kmsg_dump.h>
#include <linux/syslog.h>
@@ -173,7 +172,7 @@ __setup("printk.devkmsg=", control_devkmsg);
char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit";
int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
- void __user *buffer, size_t *lenp, loff_t *ppos)
+ void *buffer, size_t *lenp, loff_t *ppos)
{
char old_str[DEVKMSG_STR_MAX_SIZE];
unsigned int old;
@@ -280,6 +279,7 @@ static struct console *exclusive_console;
static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
static int preferred_console = -1;
+static bool has_preferred_console;
int console_set_on_cmdline;
EXPORT_SYMBOL(console_set_on_cmdline);
@@ -460,6 +460,18 @@ static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
static char *log_buf = __log_buf;
static u32 log_buf_len = __LOG_BUF_LEN;
+/*
+ * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before
+ * per_cpu_areas are initialised. This variable is set to true when
+ * it's safe to access per-CPU data.
+ */
+static bool __printk_percpu_data_ready __read_mostly;
+
+bool printk_percpu_data_ready(void)
+{
+ return __printk_percpu_data_ready;
+}
+
/* Return log buffer address */
char *log_buf_addr_get(void)
{
@@ -931,6 +943,14 @@ out:
return ret;
}
+/*
+ * Be careful when modifying this function!!!
+ *
+ * Only few operations are supported because the device works only with the
+ * entire variable length messages (records). Non-standard values are
+ * returned in the other cases and has been this way for quite some time.
+ * User space applications might depend on this behavior.
+ */
static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
{
struct devkmsg_user *user = file->private_data;
@@ -1146,12 +1166,28 @@ static void __init log_buf_add_cpu(void)
static inline void log_buf_add_cpu(void) {}
#endif /* CONFIG_SMP */
+static void __init set_percpu_data_ready(void)
+{
+ printk_safe_init();
+ /* Make sure we set this flag only after printk_safe() init is done */
+ barrier();
+ __printk_percpu_data_ready = true;
+}
+
void __init setup_log_buf(int early)
{
unsigned long flags;
char *new_log_buf;
unsigned int free;
+ /*
+ * Some archs call setup_log_buf() multiple times - first is very
+ * early, e.g. from setup_arch(), and second - when percpu_areas
+ * are initialised.
+ */
+ if (!early)
+ set_percpu_data_ready();
+
if (log_buf != __log_buf)
return;
@@ -1772,9 +1808,6 @@ static void call_console_drivers(const char *ext_text, size_t ext_len,
trace_console_rcuidle(text, len);
- if (!console_drivers)
- return;
-
for_each_console(con) {
if (exclusive_console && con != exclusive_console)
continue;
@@ -2011,18 +2044,7 @@ EXPORT_SYMBOL(vprintk);
int vprintk_default(const char *fmt, va_list args)
{
- int r;
-
-#ifdef CONFIG_KGDB_KDB
- /* Allow to pass printk() to kdb but avoid a recursion. */
- if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) {
- r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
- return r;
- }
-#endif
- r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
-
- return r;
+ return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
}
EXPORT_SYMBOL_GPL(vprintk_default);
@@ -2115,7 +2137,7 @@ asmlinkage __visible void early_printk(const char *fmt, ...)
#endif
static int __add_preferred_console(char *name, int idx, char *options,
- char *brl_options)
+ char *brl_options, bool user_specified)
{
struct console_cmdline *c;
int i;
@@ -2130,6 +2152,8 @@ static int __add_preferred_console(char *name, int idx, char *options,
if (strcmp(c->name, name) == 0 && c->index == idx) {
if (!brl_options)
preferred_console = i;
+ if (user_specified)
+ c->user_specified = true;
return 0;
}
}
@@ -2139,6 +2163,7 @@ static int __add_preferred_console(char *name, int idx, char *options,
preferred_console = i;
strlcpy(c->name, name, sizeof(c->name));
c->options = options;
+ c->user_specified = user_specified;
braille_set_options(c, brl_options);
c->index = idx;
@@ -2165,6 +2190,9 @@ static int __init console_setup(char *str)
char *s, *options, *brl_options = NULL;
int idx;
+ if (str[0] == 0)
+ return 1;
+
if (_braille_console_setup(&str, &brl_options))
return 1;
@@ -2193,7 +2221,7 @@ static int __init console_setup(char *str)
idx = simple_strtoul(s, NULL, 10);
*s = 0;
- __add_preferred_console(buf, idx, options, brl_options);
+ __add_preferred_console(buf, idx, options, brl_options, true);
console_set_on_cmdline = 1;
return 1;
}
@@ -2214,7 +2242,7 @@ __setup("console=", console_setup);
*/
int add_preferred_console(char *name, int idx, char *options)
{
- return __add_preferred_console(name, idx, options, NULL);
+ return __add_preferred_console(name, idx, options, NULL, false);
}
bool console_suspend_enabled = true;
@@ -2413,9 +2441,9 @@ again:
printk_safe_enter_irqsave(flags);
raw_spin_lock(&logbuf_lock);
if (console_seq < log_first_seq) {
- len = sprintf(text,
- "** %llu printk messages dropped **\n",
- log_first_seq - console_seq);
+ len = snprintf(text, sizeof(text),
+ "** %llu printk messages dropped **\n",
+ log_first_seq - console_seq);
/* messages are gone, move to first one */
console_seq = log_first_seq;
@@ -2627,6 +2655,63 @@ static int __init keep_bootcon_setup(char *str)
early_param("keep_bootcon", keep_bootcon_setup);
/*
+ * This is called by register_console() to try to match
+ * the newly registered console with any of the ones selected
+ * by either the command line or add_preferred_console() and
+ * setup/enable it.
+ *
+ * Care need to be taken with consoles that are statically
+ * enabled such as netconsole
+ */
+static int try_enable_new_console(struct console *newcon, bool user_specified)
+{
+ struct console_cmdline *c;
+ int i, err;
+
+ for (i = 0, c = console_cmdline;
+ i < MAX_CMDLINECONSOLES && c->name[0];
+ i++, c++) {
+ if (c->user_specified != user_specified)
+ continue;
+ if (!newcon->match ||
+ newcon->match(newcon, c->name, c->index, c->options) != 0) {
+ /* default matching */
+ BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
+ if (strcmp(c->name, newcon->name) != 0)
+ continue;
+ if (newcon->index >= 0 &&
+ newcon->index != c->index)
+ continue;
+ if (newcon->index < 0)
+ newcon->index = c->index;
+
+ if (_braille_register_console(newcon, c))
+ return 0;
+
+ if (newcon->setup &&
+ (err = newcon->setup(newcon, c->options)) != 0)
+ return err;
+ }
+ newcon->flags |= CON_ENABLED;
+ if (i == preferred_console) {
+ newcon->flags |= CON_CONSDEV;
+ has_preferred_console = true;
+ }
+ return 0;
+ }
+
+ /*
+ * Some consoles, such as pstore and netconsole, can be enabled even
+ * without matching. Accept the pre-enabled consoles only when match()
+ * and setup() had a chance to be called.
+ */
+ if (newcon->flags & CON_ENABLED && c->user_specified == user_specified)
+ return 0;
+
+ return -ENOENT;
+}
+
+/*
* The console driver calls this routine during kernel initialization
* to register the console printing procedure with printk() and to
* print any messages that were printed by the kernel before the
@@ -2647,25 +2732,21 @@ early_param("keep_bootcon", keep_bootcon_setup);
*/
void register_console(struct console *newcon)
{
- int i;
unsigned long flags;
struct console *bcon = NULL;
- struct console_cmdline *c;
- static bool has_preferred;
+ int err;
- if (console_drivers)
- for_each_console(bcon)
- if (WARN(bcon == newcon,
- "console '%s%d' already registered\n",
- bcon->name, bcon->index))
- return;
+ for_each_console(bcon) {
+ if (WARN(bcon == newcon, "console '%s%d' already registered\n",
+ bcon->name, bcon->index))
+ return;
+ }
/*
* before we register a new CON_BOOT console, make sure we don't
* already have a valid console
*/
- if (console_drivers && newcon->flags & CON_BOOT) {
- /* find the last or real console */
+ if (newcon->flags & CON_BOOT) {
for_each_console(bcon) {
if (!(bcon->flags & CON_BOOT)) {
pr_info("Too late to register bootconsole %s%d\n",
@@ -2678,15 +2759,15 @@ void register_console(struct console *newcon)
if (console_drivers && console_drivers->flags & CON_BOOT)
bcon = console_drivers;
- if (!has_preferred || bcon || !console_drivers)
- has_preferred = preferred_console >= 0;
+ if (!has_preferred_console || bcon || !console_drivers)
+ has_preferred_console = preferred_console >= 0;
/*
* See if we want to use this console driver. If we
* didn't select a console we take the first one
* that registers here.
*/
- if (!has_preferred) {
+ if (!has_preferred_console) {
if (newcon->index < 0)
newcon->index = 0;
if (newcon->setup == NULL ||
@@ -2694,47 +2775,20 @@ void register_console(struct console *newcon)
newcon->flags |= CON_ENABLED;
if (newcon->device) {
newcon->flags |= CON_CONSDEV;
- has_preferred = true;
+ has_preferred_console = true;
}
}
}
- /*
- * See if this console matches one we selected on
- * the command line.
- */
- for (i = 0, c = console_cmdline;
- i < MAX_CMDLINECONSOLES && c->name[0];
- i++, c++) {
- if (!newcon->match ||
- newcon->match(newcon, c->name, c->index, c->options) != 0) {
- /* default matching */
- BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
- if (strcmp(c->name, newcon->name) != 0)
- continue;
- if (newcon->index >= 0 &&
- newcon->index != c->index)
- continue;
- if (newcon->index < 0)
- newcon->index = c->index;
-
- if (_braille_register_console(newcon, c))
- return;
+ /* See if this console matches one we selected on the command line */
+ err = try_enable_new_console(newcon, true);
- if (newcon->setup &&
- newcon->setup(newcon, c->options) != 0)
- break;
- }
+ /* If not, try to match against the platform default(s) */
+ if (err == -ENOENT)
+ err = try_enable_new_console(newcon, false);
- newcon->flags |= CON_ENABLED;
- if (i == preferred_console) {
- newcon->flags |= CON_CONSDEV;
- has_preferred = true;
- }
- break;
- }
-
- if (!(newcon->flags & CON_ENABLED))
+ /* printk() messages are not printed to the Braille console. */
+ if (err || newcon->flags & CON_BRL)
return;
/*
@@ -2756,6 +2810,8 @@ void register_console(struct console *newcon)
console_drivers = newcon;
if (newcon->next)
newcon->next->flags &= ~CON_CONSDEV;
+ /* Ensure this flag is always set for the head of the list */
+ newcon->flags |= CON_CONSDEV;
} else {
newcon->next = console_drivers->next;
console_drivers->next = newcon;
@@ -2813,7 +2869,7 @@ EXPORT_SYMBOL(register_console);
int unregister_console(struct console *console)
{
- struct console *a, *b;
+ struct console *con;
int res;
pr_info("%sconsole [%s%d] disabled\n",
@@ -2821,26 +2877,30 @@ int unregister_console(struct console *console)
console->name, console->index);
res = _braille_unregister_console(console);
- if (res)
+ if (res < 0)
return res;
+ if (res > 0)
+ return 0;
- res = 1;
+ res = -ENODEV;
console_lock();
if (console_drivers == console) {
console_drivers=console->next;
res = 0;
- } else if (console_drivers) {
- for (a=console_drivers->next, b=console_drivers ;
- a; b=a, a=b->next) {
- if (a == console) {
- b->next = a->next;
+ } else {
+ for_each_console(con) {
+ if (con->next == console) {
+ con->next = console->next;
res = 0;
break;
}
}
}
- if (!res && (console->flags & CON_EXTENDED))
+ if (res)
+ goto out_disable_unlock;
+
+ if (console->flags & CON_EXTENDED)
nr_ext_console_drivers--;
/*
@@ -2853,6 +2913,16 @@ int unregister_console(struct console *console)
console->flags &= ~CON_ENABLED;
console_unlock();
console_sysfs_notify();
+
+ if (console->exit)
+ res = console->exit(console);
+
+ return res;
+
+out_disable_unlock:
+ console->flags &= ~CON_ENABLED;
+ console_unlock();
+
return res;
}
EXPORT_SYMBOL(unregister_console);
@@ -2966,6 +3036,9 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
void wake_up_klogd(void)
{
+ if (!printk_percpu_data_ready())
+ return;
+
preempt_disable();
if (waitqueue_active(&log_wait)) {
this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
@@ -2976,6 +3049,9 @@ void wake_up_klogd(void)
void defer_console_output(void)
{
+ if (!printk_percpu_data_ready())
+ return;
+
preempt_disable();
__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
@@ -3101,6 +3177,23 @@ EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
static bool always_kmsg_dump;
module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
+const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason)
+{
+ switch (reason) {
+ case KMSG_DUMP_PANIC:
+ return "Panic";
+ case KMSG_DUMP_OOPS:
+ return "Oops";
+ case KMSG_DUMP_EMERG:
+ return "Emergency";
+ case KMSG_DUMP_SHUTDOWN:
+ return "Shutdown";
+ default:
+ return "Unknown";
+ }
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_reason_str);
+
/**
* kmsg_dump - dump kernel log to kernel message dumpers.
* @reason: the reason (oops, panic etc) for dumping
@@ -3114,12 +3207,19 @@ void kmsg_dump(enum kmsg_dump_reason reason)
struct kmsg_dumper *dumper;
unsigned long flags;
- if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
- return;
-
rcu_read_lock();
list_for_each_entry_rcu(dumper, &dump_list, list) {
- if (dumper->max_reason && reason > dumper->max_reason)
+ enum kmsg_dump_reason max_reason = dumper->max_reason;
+
+ /*
+ * If client has not provided a specific max_reason, default
+ * to KMSG_DUMP_OOPS, unless always_kmsg_dump was set.
+ */
+ if (max_reason == KMSG_DUMP_UNDEF) {
+ max_reason = always_kmsg_dump ? KMSG_DUMP_MAX :
+ KMSG_DUMP_OOPS;
+ }
+ if (reason > max_reason)
continue;
/* initialize iterator with data about the stored records */
@@ -3317,7 +3417,7 @@ out:
EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
/**
- * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
+ * 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
@@ -3335,7 +3435,7 @@ void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
}
/**
- * kmsg_dump_rewind - reset the interator
+ * kmsg_dump_rewind - reset the iterator
* @dumper: registered kmsg dumper
*
* Reset the dumper's iterator so that kmsg_dump_get_line() and
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index 08a8bf778990..e95d2a517244 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -6,10 +6,12 @@
#include <linux/preempt.h>
#include <linux/spinlock.h>
#include <linux/debug_locks.h>
+#include <linux/kdb.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/irq_work.h>
#include <linux/printk.h>
+#include <linux/kprobes.h>
#include "internal.h"
@@ -27,7 +29,6 @@
* There are situations when we want to make sure that all buffers
* were handled or when IRQs are blocked.
*/
-static int printk_safe_irq_ready __read_mostly;
#define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \
sizeof(atomic_t) - \
@@ -51,7 +52,7 @@ static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq);
/* Get flushed in a more safe context. */
static void queue_flush_work(struct printk_safe_seq_buf *s)
{
- if (printk_safe_irq_ready)
+ if (printk_percpu_data_ready())
irq_work_queue(&s->work);
}
@@ -294,14 +295,14 @@ static __printf(1, 0) int vprintk_nmi(const char *fmt, va_list args)
return printk_safe_log_store(s, fmt, args);
}
-void notrace printk_nmi_enter(void)
+void noinstr printk_nmi_enter(void)
{
- this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK);
+ this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET);
}
-void notrace printk_nmi_exit(void)
+void noinstr printk_nmi_exit(void)
{
- this_cpu_and(printk_context, ~PRINTK_NMI_CONTEXT_MASK);
+ this_cpu_sub(printk_context, PRINTK_NMI_CONTEXT_OFFSET);
}
/*
@@ -360,6 +361,12 @@ void __printk_safe_exit(void)
__printf(1, 0) int vprintk_func(const char *fmt, va_list args)
{
+#ifdef CONFIG_KGDB_KDB
+ /* Allow to pass printk() to kdb but avoid a recursion. */
+ if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0))
+ return vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
+#endif
+
/*
* Try to use the main logbuf even in NMI. But avoid calling console
* drivers that might have their own locks.
@@ -402,14 +409,6 @@ void __init printk_safe_init(void)
#endif
}
- /*
- * In the highly unlikely event that a NMI were to trigger at
- * this moment. Make sure IRQ work is set up before this
- * variable is set.
- */
- barrier();
- printk_safe_irq_ready = 1;
-
/* Flush pending messages that did not have scheduled IRQ works. */
printk_safe_flush();
}