| /* |
| * linux/kernel/printk.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| * |
| * Modified to make sys_syslog() more flexible: added commands to |
| * return the last 4k of kernel messages, regardless of whether |
| * they've been read or not. Added option to suppress kernel printk's |
| * to the console. Added hook for sending the console messages |
| * elsewhere, in preparation for a serial line console (someday). |
| * Ted Ts'o, 2/11/93. |
| * Modified for sysctl support, 1/8/97, Chris Horn. |
| * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
| * manfred@colorfullife.com |
| * Rewrote bits to get rid of console_lock |
| * 01Mar01 Andrew Morton |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/mm.h> |
| #include <linux/tty.h> |
| #include <linux/tty_driver.h> |
| #include <linux/console.h> |
| #include <linux/init.h> |
| #include <linux/jiffies.h> |
| #include <linux/nmi.h> |
| #include <linux/module.h> |
| #include <linux/moduleparam.h> |
| #include <linux/interrupt.h> /* For in_interrupt() */ |
| #include <linux/delay.h> |
| #include <linux/smp.h> |
| #include <linux/security.h> |
| #include <linux/bootmem.h> |
| #include <linux/memblock.h> |
| #include <linux/syscalls.h> |
| #include <linux/kexec.h> |
| #include <linux/kdb.h> |
| #include <linux/ratelimit.h> |
| #include <linux/kmsg_dump.h> |
| #include <linux/syslog.h> |
| #include <linux/cpu.h> |
| #include <linux/notifier.h> |
| #include <linux/rculist.h> |
| |
| #include <asm/uaccess.h> |
| #include <asm/cacheflush.h> |
| |
| /* |
| * Architectures can override it: |
| */ |
| void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
| { |
| } |
| |
| #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
| |
| /* printk's without a loglevel use this.. */ |
| #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL |
| |
| /* We show everything that is MORE important than this.. */ |
| #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ |
| #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ |
| |
| DECLARE_WAIT_QUEUE_HEAD(log_wait); |
| |
| int console_printk[4] = { |
| DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ |
| DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ |
| MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ |
| DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ |
| }; |
| |
| /* |
| * Low level drivers may need that to know if they can schedule in |
| * their unblank() callback or not. So let's export it. |
| */ |
| int oops_in_progress; |
| EXPORT_SYMBOL(oops_in_progress); |
| |
| /* |
| * console_sem protects the console_drivers list, and also |
| * provides serialisation for access to the entire console |
| * driver system. |
| */ |
| static DEFINE_SEMAPHORE(console_sem); |
| struct console *console_drivers; |
| EXPORT_SYMBOL_GPL(console_drivers); |
| |
| /* |
| * This is used for debugging the mess that is the VT code by |
| * keeping track if we have the console semaphore held. It's |
| * definitely not the perfect debug tool (we don't know if _WE_ |
| * hold it are racing, but it helps tracking those weird code |
| * path in the console code where we end up in places I want |
| * locked without the console sempahore held |
| */ |
| static int console_locked, console_suspended; |
| |
| /* |
| * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars |
| * It is also used in interesting ways to provide interlocking in |
| * console_unlock();. |
| */ |
| static DEFINE_RAW_SPINLOCK(logbuf_lock); |
| |
| #define LOG_BUF_MASK (log_buf_len-1) |
| #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
| |
| /* |
| * The indices into log_buf are not constrained to log_buf_len - they |
| * must be masked before subscripting |
| */ |
| static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
| static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ |
| |
| #ifdef CONFIG_PRINTK_PERSIST |
| #define log_end logbits->_log_end |
| #else |
| static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ |
| #endif |
| |
| /* |
| * If exclusive_console is non-NULL then only this console is to be printed to. |
| */ |
| static struct console *exclusive_console; |
| |
| /* |
| * Array of consoles built from command line options (console=) |
| */ |
| struct console_cmdline |
| { |
| char name[8]; /* Name of the driver */ |
| int index; /* Minor dev. to use */ |
| char *options; /* Options for the driver */ |
| #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| char *brl_options; /* Options for braille driver */ |
| #endif |
| }; |
| |
| #define MAX_CMDLINECONSOLES 8 |
| |
| static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; |
| static int selected_console = -1; |
| static int preferred_console = -1; |
| int console_set_on_cmdline; |
| EXPORT_SYMBOL(console_set_on_cmdline); |
| |
| /* Flag: console code may call schedule() */ |
| static int console_may_schedule; |
| |
| #ifdef CONFIG_PRINTK |
| |
| #ifdef CONFIG_KEXEC |
| /* |
| * This appends the listed symbols to /proc/vmcoreinfo |
| * |
| * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to |
| * obtain access to symbols that are otherwise very difficult to locate. These |
| * symbols are specifically used so that utilities can access and extract the |
| * dmesg log from a vmcore file after a crash. |
| */ |
| void log_buf_kexec_setup(void) |
| { |
| VMCOREINFO_SYMBOL(log_buf); |
| VMCOREINFO_SYMBOL(log_end); |
| VMCOREINFO_SYMBOL(log_buf_len); |
| VMCOREINFO_SYMBOL(logged_chars); |
| } |
| #endif |
| |
| static int saved_console_loglevel = -1; |
| static char __log_buf[__LOG_BUF_LEN]; |
| static char *log_buf = __log_buf; |
| |
| #ifndef CONFIG_PRINTK_PERSIST |
| |
| static int log_buf_len = __LOG_BUF_LEN; |
| static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
| |
| static __init char *log_buf_alloc(unsigned long size, unsigned *dest_offset) |
| { |
| return alloc_bootmem(size); |
| } |
| |
| #else /* CONFIG_PRINTK_PERSIST */ |
| |
| struct logbits { |
| int magic; /* needed to verify the memory across reboots */ |
| int _log_buf_len; /* leading _ so they aren't replaced by #define */ |
| unsigned _logged_chars; |
| unsigned _log_end; |
| }; |
| static struct logbits __logbits = { |
| ._log_buf_len = __LOG_BUF_LEN, |
| }; |
| static struct logbits *logbits = &__logbits; |
| #define log_buf_len logbits->_log_buf_len |
| #define logged_chars logbits->_logged_chars |
| |
| #define PERSIST_SEARCH_START 0 |
| #define PERSIST_SEARCH_END 0xfe000000 |
| #define PERSIST_SEARCH_JUMP (16*1024*1024) |
| #define PERSIST_MAGIC 0xbabb1e |
| |
| #ifdef CONFIG_BOOTLOG_COPY |
| #define BOOTLOG_MAGIC (0x1090091e) |
| struct bloghdr { |
| unsigned int magic; /* for kernel verification */ |
| unsigned int offset; /* current log offset */ |
| }; |
| |
| extern unsigned long bootlog_get_addr(void); |
| extern unsigned long bootlog_get_size(void); |
| extern void bootlog_free(void); |
| |
| static inline struct bloghdr *get_bootlog_hdr(void) |
| { |
| unsigned long bootlog_size = bootlog_get_size(); |
| if (bootlog_size) { |
| struct bloghdr *blog_hdr = (struct bloghdr *) |
| phys_to_virt(bootlog_get_addr()); |
| if (BOOTLOG_MAGIC != blog_hdr->magic || |
| (blog_hdr->offset + sizeof(struct bloghdr) > |
| bootlog_size)) { |
| printk(KERN_INFO "bootlog: header invalid m:0x%08x " |
| "o:0x%08x s:0x%08lx\n", blog_hdr->magic, |
| blog_hdr->offset, bootlog_size); |
| return NULL; |
| } |
| return blog_hdr; |
| } |
| return NULL; |
| } |
| |
| static inline unsigned copy_bootlog(struct bloghdr *blog_hdr, |
| unsigned dest_offset) |
| { |
| if (blog_hdr) { |
| unsigned idx = dest_offset; |
| char *blog_buf = (char *)(blog_hdr + 1); |
| unsigned i; |
| |
| for (i = 0; i < blog_hdr->offset; ++i) { |
| LOG_BUF(idx) = blog_buf[i]; |
| ++idx; |
| } |
| if (logged_chars + blog_hdr->offset <= log_buf_len) |
| logged_chars += blog_hdr->offset; |
| else |
| logged_chars = log_buf_len; |
| dest_offset = idx; |
| } |
| return dest_offset; |
| } |
| |
| static inline void free_bootlog(void) |
| { |
| bootlog_free(); |
| } |
| |
| #endif |
| |
| /* |
| * size is a power of 2 so that the printk offset mask will work. We'll add |
| * a bit more space to the end of the buffer for our extra data, but that |
| * won't change the offset of the buffers. |
| */ |
| static __init char *log_buf_alloc(unsigned long size, unsigned *dest_offset) |
| { |
| unsigned long where; |
| char *buf; |
| unsigned long full_size = size + sizeof(struct logbits); |
| struct logbits *new_logbits; |
| |
| for (where = PERSIST_SEARCH_END - size; |
| where >= PERSIST_SEARCH_START; |
| where -= PERSIST_SEARCH_JUMP) { |
| if (reserve_bootmem(where, full_size, BOOTMEM_EXCLUSIVE)) |
| continue; |
| |
| buf = phys_to_virt(where); |
| new_logbits = phys_to_virt(where + size); |
| printk(KERN_INFO "printk_persist: memory reserved @ 0x%08lx\n", |
| where); |
| if (new_logbits->magic != PERSIST_MAGIC || |
| new_logbits->_log_buf_len != size || |
| new_logbits->_logged_chars > size) { |
| printk(KERN_INFO "printk_persist: header invalid, " |
| "cleared.\n"); |
| memset(buf, 0, full_size); |
| new_logbits->magic = PERSIST_MAGIC; |
| new_logbits->_log_buf_len = size; |
| new_logbits->_logged_chars = 0; |
| new_logbits->_log_end = 0; |
| } else { |
| printk(KERN_INFO "printk_persist: header valid; " |
| "logged=%d next=%d\n", |
| new_logbits->_logged_chars, |
| new_logbits->_log_end); |
| } |
| *dest_offset = new_logbits->_log_end; |
| new_logbits->_log_end = log_end; |
| if (new_logbits->_logged_chars + logged_chars <= size) |
| new_logbits->_logged_chars += logged_chars; |
| else |
| new_logbits->_logged_chars = size; |
| logbits = new_logbits; |
| return buf; |
| } |
| goto error; |
| |
| error: |
| /* replace the buffer, but don't bother to swap struct logbits */ |
| printk(KERN_ERR "printk_persist: failed to reserve bootmem " |
| "area. disabled.\n"); |
| return alloc_bootmem(full_size); |
| } |
| #endif /* CONFIG_PRINTK_PERSIST */ |
| |
| /* requested log_buf_len from kernel cmdline */ |
| static unsigned long __initdata new_log_buf_len = |
| #ifdef CONFIG_PRINTK_PERSIST_BUF_SHIFT |
| (1 << CONFIG_PRINTK_PERSIST_BUF_SHIFT) |
| #else |
| 0 |
| #endif |
| ; |
| |
| /* save requested log_buf_len since it's too early to process it */ |
| static int __init log_buf_len_setup(char *str) |
| { |
| unsigned size = memparse(str, &str); |
| |
| if (size) |
| size = roundup_pow_of_two(size); |
| if (size > log_buf_len || size == 0) |
| new_log_buf_len = size; |
| |
| return 0; |
| } |
| early_param("log_buf_len", log_buf_len_setup); |
| |
| void __init setup_log_buf(int early) |
| { |
| unsigned long flags; |
| unsigned start, dest_offset = 0, dest_idx, offset; |
| char *new_log_buf = NULL; |
| int free; |
| #ifdef CONFIG_BOOTLOG_COPY |
| struct bloghdr *blog_hdr = NULL; |
| #endif |
| |
| if (!new_log_buf_len) |
| return; |
| |
| if (early) { |
| unsigned long mem; |
| |
| mem = memblock_alloc(new_log_buf_len, PAGE_SIZE); |
| if (mem == MEMBLOCK_ERROR) |
| return; |
| new_log_buf = __va(mem); |
| } else { |
| new_log_buf = log_buf_alloc(new_log_buf_len, &dest_offset); |
| } |
| |
| if (unlikely(!new_log_buf)) { |
| pr_err("log_buf_len: %ld bytes not available\n", |
| new_log_buf_len); |
| return; |
| } |
| |
| #ifdef CONFIG_BOOTLOG_COPY |
| /* Read out the blog_hdr before logbuf is locked in case print |
| * is needed. */ |
| blog_hdr = get_bootlog_hdr(); |
| #endif |
| |
| raw_spin_lock_irqsave(&logbuf_lock, flags); |
| log_buf_len = new_log_buf_len; |
| log_buf = new_log_buf; |
| free = __LOG_BUF_LEN - log_end; |
| |
| #ifdef CONFIG_BOOTLOG_COPY |
| dest_offset = copy_bootlog(blog_hdr, dest_offset); |
| #endif |
| offset = start = min(con_start, log_start); |
| dest_idx = dest_offset; |
| while (start != log_end) { |
| unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1); |
| unsigned dest_idx_mask = dest_idx & (new_log_buf_len - 1); |
| |
| log_buf[dest_idx_mask] = __log_buf[log_idx_mask]; |
| start++; |
| dest_idx++; |
| } |
| log_start += dest_offset - offset; |
| con_start += dest_offset - offset; |
| log_end += dest_offset - offset; |
| raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| |
| #ifdef CONFIG_BOOTLOG_COPY |
| free_bootlog(); |
| #endif |
| |
| pr_info("log_buf_len: %d\n", log_buf_len); |
| pr_info("early log buf free: %d(%d%%)\n", |
| free, (free * 100) / __LOG_BUF_LEN); |
| } |
| |
| #ifdef CONFIG_BOOT_PRINTK_DELAY |
| |
| static int boot_delay; /* msecs delay after each printk during bootup */ |
| static unsigned long long loops_per_msec; /* based on boot_delay */ |
| |
| static int __init boot_delay_setup(char *str) |
| { |
| unsigned long lpj; |
| |
| lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ |
| loops_per_msec = (unsigned long long)lpj / 1000 * HZ; |
| |
| get_option(&str, &boot_delay); |
| if (boot_delay > 10 * 1000) |
| boot_delay = 0; |
| |
| pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
| "HZ: %d, loops_per_msec: %llu\n", |
| boot_delay, preset_lpj, lpj, HZ, loops_per_msec); |
| return 1; |
| } |
| __setup("boot_delay=", boot_delay_setup); |
| |
| static void boot_delay_msec(void) |
| { |
| unsigned long long k; |
| unsigned long timeout; |
| |
| if (boot_delay == 0 || system_state != SYSTEM_BOOTING) |
| return; |
| |
| k = (unsigned long long)loops_per_msec * boot_delay; |
| |
| timeout = jiffies + msecs_to_jiffies(boot_delay); |
| while (k) { |
| k--; |
| cpu_relax(); |
| /* |
| * use (volatile) jiffies to prevent |
| * compiler reduction; loop termination via jiffies |
| * is secondary and may or may not happen. |
| */ |
| if (time_after(jiffies, timeout)) |
| break; |
| touch_nmi_watchdog(); |
| } |
| } |
| #else |
| static inline void boot_delay_msec(void) |
| { |
| } |
| #endif |
| |
| #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
| int dmesg_restrict = 1; |
| #else |
| int dmesg_restrict; |
| #endif |
| |
| static int syslog_action_restricted(int type) |
| { |
| if (dmesg_restrict) |
| return 1; |
| /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ |
| return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; |
| } |
| |
| static int check_syslog_permissions(int type, bool from_file) |
| { |
| /* |
| * If this is from /proc/kmsg and we've already opened it, then we've |
| * already done the capabilities checks at open time. |
| */ |
| if (from_file && type != SYSLOG_ACTION_OPEN) |
| return 0; |
| |
| if (syslog_action_restricted(type)) { |
| if (capable(CAP_SYSLOG)) |
| return 0; |
| /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ |
| if (capable(CAP_SYS_ADMIN)) { |
| printk_once(KERN_WARNING "%s (%d): " |
| "Attempt to access syslog with CAP_SYS_ADMIN " |
| "but no CAP_SYSLOG (deprecated).\n", |
| current->comm, task_pid_nr(current)); |
| return 0; |
| } |
| return -EPERM; |
| } |
| return 0; |
| } |
| |
| #define COPY_SIZE 4096 |
| |
| int do_syslog(int type, char __user *buf, int len, bool from_file) |
| { |
| char *copybuf; |
| unsigned i, j, limit, count; |
| int do_clear = 0; |
| char c; |
| int error; |
| |
| error = check_syslog_permissions(type, from_file); |
| if (error) |
| goto out; |
| |
| error = security_syslog(type); |
| if (error) |
| return error; |
| |
| switch (type) { |
| case SYSLOG_ACTION_CLOSE: /* Close log */ |
| break; |
| case SYSLOG_ACTION_OPEN: /* Open log */ |
| break; |
| case SYSLOG_ACTION_READ: /* Read from log */ |
| error = -EINVAL; |
| if (!buf || len < 0) |
| goto out; |
| error = 0; |
| if (!len) |
| goto out; |
| if (!access_ok(VERIFY_WRITE, buf, len)) { |
| error = -EFAULT; |
| goto out; |
| } |
| error = wait_event_interruptible(log_wait, |
| (log_start - log_end)); |
| if (error) |
| goto out; |
| i = 0; |
| raw_spin_lock_irq(&logbuf_lock); |
| while (!error && (log_start != log_end) && i < len) { |
| c = LOG_BUF(log_start); |
| log_start++; |
| raw_spin_unlock_irq(&logbuf_lock); |
| error = __put_user(c,buf); |
| buf++; |
| i++; |
| cond_resched(); |
| raw_spin_lock_irq(&logbuf_lock); |
| } |
| raw_spin_unlock_irq(&logbuf_lock); |
| if (!error) |
| error = i; |
| break; |
| /* Read/clear last kernel messages */ |
| case SYSLOG_ACTION_READ_CLEAR: |
| do_clear = 1; |
| /* FALL THRU */ |
| /* Read last kernel messages */ |
| case SYSLOG_ACTION_READ_ALL: |
| error = -EINVAL; |
| if (!buf || len < 0) |
| goto out; |
| error = 0; |
| if (!len) |
| goto out; |
| if (!access_ok(VERIFY_WRITE, buf, len)) { |
| error = -EFAULT; |
| goto out; |
| } |
| copybuf = kmalloc(COPY_SIZE, GFP_KERNEL); |
| if (!copybuf) { |
| error = -ENOMEM; |
| goto out; |
| } |
| count = len; |
| if (count > log_buf_len) |
| count = log_buf_len; |
| raw_spin_lock_irq(&logbuf_lock); |
| if (count > logged_chars) |
| count = logged_chars; |
| if (do_clear) |
| logged_chars = 0; |
| limit = log_end; |
| /* |
| * copy_to_user() could sleep, and while we sleep |
| * printk() could overwrite the messages |
| * we try to copy to user space. Therefore |
| * the messages are copied in reverse. <manfreds> |
| */ |
| for (i = 0; i < count && !error; i++) { |
| j = limit-1-i; |
| if (j + log_buf_len < log_end) |
| break; |
| c = LOG_BUF(j); |
| copybuf[COPY_SIZE-1-(i % COPY_SIZE)] = c; |
| if ((i+1) % COPY_SIZE == 0) { |
| raw_spin_unlock_irq(&logbuf_lock); |
| error = copy_to_user(&buf[count-1-i], |
| copybuf, COPY_SIZE); |
| cond_resched(); |
| raw_spin_lock_irq(&logbuf_lock); |
| } |
| } |
| raw_spin_unlock_irq(&logbuf_lock); |
| if (!error) { |
| /* in case copybuf was only partially filled */ |
| error = copy_to_user(&buf[count-i], |
| copybuf + COPY_SIZE - (i % COPY_SIZE), |
| i % COPY_SIZE); |
| } |
| if (error) { |
| error = -EFAULT; |
| goto copy_done; |
| } |
| error = i; |
| if (i != count) { |
| int offset = count-error; |
| /* buffer overflow during copy, correct user buffer. */ |
| for (i = 0; i < error; i++) { |
| if (__get_user(c,&buf[i+offset]) || |
| __put_user(c,&buf[i])) { |
| error = -EFAULT; |
| break; |
| } |
| cond_resched(); |
| } |
| } |
| copy_done: |
| kfree(copybuf); |
| break; |
| /* Clear ring buffer */ |
| case SYSLOG_ACTION_CLEAR: |
| logged_chars = 0; |
| break; |
| /* Disable logging to console */ |
| case SYSLOG_ACTION_CONSOLE_OFF: |
| if (saved_console_loglevel == -1) |
| saved_console_loglevel = console_loglevel; |
| console_loglevel = minimum_console_loglevel; |
| break; |
| /* Enable logging to console */ |
| case SYSLOG_ACTION_CONSOLE_ON: |
| if (saved_console_loglevel != -1) { |
| console_loglevel = saved_console_loglevel; |
| saved_console_loglevel = -1; |
| } |
| break; |
| /* Set level of messages printed to console */ |
| case SYSLOG_ACTION_CONSOLE_LEVEL: |
| error = -EINVAL; |
| if (len < 1 || len > 8) |
| goto out; |
| if (len < minimum_console_loglevel) |
| len = minimum_console_loglevel; |
| console_loglevel = len; |
| /* Implicitly re-enable logging to console */ |
| saved_console_loglevel = -1; |
| error = 0; |
| break; |
| /* Number of chars in the log buffer */ |
| case SYSLOG_ACTION_SIZE_UNREAD: |
| error = log_end - log_start; |
| break; |
| /* Size of the log buffer */ |
| case SYSLOG_ACTION_SIZE_BUFFER: |
| error = log_buf_len; |
| break; |
| default: |
| error = -EINVAL; |
| break; |
| } |
| out: |
| return error; |
| } |
| |
| SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
| { |
| return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
| } |
| |
| #ifdef CONFIG_KGDB_KDB |
| /* kdb dmesg command needs access to the syslog buffer. do_syslog() |
| * uses locks so it cannot be used during debugging. Just tell kdb |
| * where the start and end of the physical and logical logs are. This |
| * is equivalent to do_syslog(3). |
| */ |
| void kdb_syslog_data(char *syslog_data[4]) |
| { |
| syslog_data[0] = log_buf; |
| syslog_data[1] = log_buf + log_buf_len; |
| syslog_data[2] = log_buf + log_end - |
| (logged_chars < log_buf_len ? logged_chars : log_buf_len); |
| syslog_data[3] = log_buf + log_end; |
| } |
| #endif /* CONFIG_KGDB_KDB */ |
| |
| /* |
| * Call the console drivers on a range of log_buf |
| */ |
| static void __call_console_drivers(unsigned start, unsigned end) |
| { |
| struct console *con; |
| |
| for_each_console(con) { |
| if (exclusive_console && con != exclusive_console) |
| continue; |
| if ((con->flags & CON_ENABLED) && con->write && |
| (cpu_online(smp_processor_id()) || |
| (con->flags & CON_ANYTIME))) |
| con->write(con, &LOG_BUF(start), end - start); |
| } |
| } |
| |
| static int __read_mostly ignore_loglevel; |
| |
| static int __init ignore_loglevel_setup(char *str) |
| { |
| ignore_loglevel = 1; |
| printk(KERN_INFO "debug: ignoring loglevel setting.\n"); |
| |
| return 0; |
| } |
| |
| early_param("ignore_loglevel", ignore_loglevel_setup); |
| module_param_named(ignore_loglevel, ignore_loglevel, bool, S_IRUGO | S_IWUSR); |
| MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to" |
| "print all kernel messages to the console."); |
| |
| /* |
| * Write out chars from start to end - 1 inclusive |
| */ |
| static void _call_console_drivers(unsigned start, |
| unsigned end, int msg_log_level) |
| { |
| if ((msg_log_level < console_loglevel || ignore_loglevel) && |
| console_drivers && start != end) { |
| if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { |
| /* wrapped write */ |
| __call_console_drivers(start & LOG_BUF_MASK, |
| log_buf_len); |
| __call_console_drivers(0, end & LOG_BUF_MASK); |
| } else { |
| __call_console_drivers(start, end); |
| } |
| } |
| } |
| |
| /* |
| * Parse the syslog header <[0-9]*>. The decimal value represents 32bit, the |
| * lower 3 bit are the log level, the rest are the log facility. In case |
| * userspace passes usual userspace syslog messages to /dev/kmsg or |
| * /dev/ttyprintk, the log prefix might contain the facility. Printk needs |
| * to extract the correct log level for in-kernel processing, and not mangle |
| * the original value. |
| * |
| * If a prefix is found, the length of the prefix is returned. If 'level' is |
| * passed, it will be filled in with the log level without a possible facility |
| * value. If 'special' is passed, the special printk prefix chars are accepted |
| * and returned. If no valid header is found, 0 is returned and the passed |
| * variables are not touched. |
| */ |
| static size_t log_prefix(const char *p, unsigned int *level, char *special) |
| { |
| unsigned int lev = 0; |
| char sp = '\0'; |
| size_t len; |
| |
| if (p[0] != '<' || !p[1]) |
| return 0; |
| if (p[2] == '>') { |
| /* usual single digit level number or special char */ |
| switch (p[1]) { |
| case '0' ... '7': |
| lev = p[1] - '0'; |
| break; |
| case 'c': /* KERN_CONT */ |
| case 'd': /* KERN_DEFAULT */ |
| sp = p[1]; |
| break; |
| default: |
| return 0; |
| } |
| len = 3; |
| } else { |
| /* multi digit including the level and facility number */ |
| char *endp = NULL; |
| |
| lev = (simple_strtoul(&p[1], &endp, 10) & 7); |
| if (endp == NULL || endp[0] != '>') |
| return 0; |
| len = (endp + 1) - p; |
| } |
| |
| /* do not accept special char if not asked for */ |
| if (sp && !special) |
| return 0; |
| |
| if (special) { |
| *special = sp; |
| /* return special char, do not touch level */ |
| if (sp) |
| return len; |
| } |
| |
| if (level) |
| *level = lev; |
| return len; |
| } |
| |
| /* |
| * Call the console drivers, asking them to write out |
| * log_buf[start] to log_buf[end - 1]. |
| * The console_lock must be held. |
| */ |
| static void call_console_drivers(unsigned start, unsigned end) |
| { |
| unsigned cur_index, start_print; |
| static int msg_level = -1; |
| |
| BUG_ON(((int)(start - end)) > 0); |
| |
| cur_index = start; |
| start_print = start; |
| while (cur_index != end) { |
| if (msg_level < 0 && ((end - cur_index) > 2)) { |
| /* strip log prefix */ |
| cur_index += log_prefix(&LOG_BUF(cur_index), &msg_level, NULL); |
| start_print = cur_index; |
| } |
| while (cur_index != end) { |
| char c = LOG_BUF(cur_index); |
| |
| cur_index++; |
| if (c == '\n') { |
| if (msg_level < 0) { |
| /* |
| * printk() has already given us loglevel tags in |
| * the buffer. This code is here in case the |
| * log buffer has wrapped right round and scribbled |
| * on those tags |
| */ |
| msg_level = default_message_loglevel; |
| } |
| _call_console_drivers(start_print, cur_index, msg_level); |
| msg_level = -1; |
| start_print = cur_index; |
| break; |
| } |
| } |
| } |
| _call_console_drivers(start_print, end, msg_level); |
| } |
| |
| static void emit_log_char(char c) |
| { |
| LOG_BUF(log_end) = c; |
| log_end++; |
| if (log_end - log_start > log_buf_len) |
| log_start = log_end - log_buf_len; |
| if (log_end - con_start > log_buf_len) |
| con_start = log_end - log_buf_len; |
| if (logged_chars < log_buf_len) |
| logged_chars++; |
| } |
| |
| /* |
| * Zap console related locks when oopsing. Only zap at most once |
| * every 10 seconds, to leave time for slow consoles to print a |
| * full oops. |
| */ |
| static void zap_locks(void) |
| { |
| static unsigned long oops_timestamp; |
| |
| if (time_after_eq(jiffies, oops_timestamp) && |
| !time_after(jiffies, oops_timestamp + 30 * HZ)) |
| return; |
| |
| oops_timestamp = jiffies; |
| |
| /* If a crash is occurring, make sure we can't deadlock */ |
| raw_spin_lock_init(&logbuf_lock); |
| /* And make sure that we print immediately */ |
| sema_init(&console_sem, 1); |
| } |
| |
| #if defined(CONFIG_PRINTK_TIME) |
| static int printk_time = 1; |
| #else |
| static int printk_time = 0; |
| #endif |
| module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
| |
| /* Check if we have any console registered that can be called early in boot. */ |
| static int have_callable_console(void) |
| { |
| struct console *con; |
| |
| for_each_console(con) |
| if (con->flags & CON_ANYTIME) |
| return 1; |
| |
| return 0; |
| } |
| |
| /** |
| * printk - print a kernel message |
| * @fmt: format string |
| * |
| * This is printk(). It can be called from any context. We want it to work. |
| * |
| * We try to grab the console_lock. If we succeed, it's easy - we log the output and |
| * call the console drivers. If we fail to get the semaphore we place the output |
| * into the log buffer and return. The current holder of the console_sem will |
| * notice the new output in console_unlock(); and will send it to the |
| * consoles before releasing the lock. |
| * |
| * One effect of this deferred printing is that code which calls printk() and |
| * then changes console_loglevel may break. This is because console_loglevel |
| * is inspected when the actual printing occurs. |
| * |
| * See also: |
| * printf(3) |
| * |
| * See the vsnprintf() documentation for format string extensions over C99. |
| */ |
| |
| asmlinkage int printk(const char *fmt, ...) |
| { |
| va_list args; |
| int r; |
| |
| #ifdef CONFIG_KGDB_KDB |
| if (unlikely(kdb_trap_printk)) { |
| va_start(args, fmt); |
| r = vkdb_printf(fmt, args); |
| va_end(args); |
| return r; |
| } |
| #endif |
| va_start(args, fmt); |
| r = vprintk(fmt, args); |
| va_end(args); |
| |
| return r; |
| } |
| |
| /* cpu currently holding logbuf_lock */ |
| static volatile unsigned int printk_cpu = UINT_MAX; |
| |
| /* |
| * Can we actually use the console at this time on this cpu? |
| * |
| * Console drivers may assume that per-cpu resources have |
| * been allocated. So unless they're explicitly marked as |
| * being able to cope (CON_ANYTIME) don't call them until |
| * this CPU is officially up. |
| */ |
| static inline int can_use_console(unsigned int cpu) |
| { |
| return cpu_online(cpu) || have_callable_console(); |
| } |
| |
| /* |
| * Try to get console ownership to actually show the kernel |
| * messages from a 'printk'. Return true (and with the |
| * console_lock held, and 'console_locked' set) if it |
| * is successful, false otherwise. |
| * |
| * This gets called with the 'logbuf_lock' spinlock held and |
| * interrupts disabled. It should return with 'lockbuf_lock' |
| * released but interrupts still disabled. |
| */ |
| static int console_trylock_for_printk(unsigned int cpu) |
| __releases(&logbuf_lock) |
| { |
| int retval = 0, wake = 0; |
| |
| if (console_trylock()) { |
| retval = 1; |
| |
| /* |
| * If we can't use the console, we need to release |
| * the console semaphore by hand to avoid flushing |
| * the buffer. We need to hold the console semaphore |
| * in order to do this test safely. |
| */ |
| if (!can_use_console(cpu)) { |
| console_locked = 0; |
| wake = 1; |
| retval = 0; |
| } |
| } |
| printk_cpu = UINT_MAX; |
| if (wake) |
| up(&console_sem); |
| raw_spin_unlock(&logbuf_lock); |
| return retval; |
| } |
| static const char recursion_bug_msg [] = |
| KERN_CRIT "BUG: recent printk recursion!\n"; |
| static int recursion_bug; |
| static int new_text_line = 1; |
| static char printk_buf[1024]; |
| |
| int printk_delay_msec __read_mostly; |
| |
| static inline void printk_delay(void) |
| { |
| if (unlikely(printk_delay_msec)) { |
| int m = printk_delay_msec; |
| |
| while (m--) { |
| mdelay(1); |
| touch_nmi_watchdog(); |
| } |
| } |
| } |
| |
| static inline void flush_persist(void *ptr, size_t len) { |
| #ifdef CONFIG_PRINTK_PERSIST |
| /* |
| * If PRINTK_PERSIST, we need to make sure log messages are fully |
| * flushed all the way to RAM in case the system gets reset |
| * suddenly (eg. by a watchdog). Such a case is exactly when |
| * PRINTK_PERSIST is most useful. |
| */ |
| if (cpu_cache.flush_kern_dcache_area) |
| cpu_cache.flush_kern_dcache_area(ptr, len); |
| outer_flush_range(virt_to_phys(ptr), |
| virt_to_phys(ptr) + len); |
| #endif |
| } |
| |
| asmlinkage int vprintk(const char *fmt, va_list args) |
| { |
| int printed_len = 0; |
| int current_log_level = default_message_loglevel; |
| unsigned long flags; |
| int this_cpu; |
| unsigned orig_end = log_end & LOG_BUF_MASK, new_end; |
| char *p; |
| size_t plen; |
| char special; |
| |
| boot_delay_msec(); |
| printk_delay(); |
| |
| preempt_disable(); |
| /* This stops the holder of console_sem just where we want him */ |
| raw_local_irq_save(flags); |
| this_cpu = smp_processor_id(); |
| |
| /* |
| * Ouch, printk recursed into itself! |
| */ |
| if (unlikely(printk_cpu == this_cpu)) { |
| /* |
| * If a crash is occurring during printk() on this CPU, |
| * then try to get the crash message out but make sure |
| * we can't deadlock. Otherwise just return to avoid the |
| * recursion and return - but flag the recursion so that |
| * it can be printed at the next appropriate moment: |
| */ |
| if (!oops_in_progress) { |
| recursion_bug = 1; |
| goto out_restore_irqs; |
| } |
| zap_locks(); |
| } |
| |
| lockdep_off(); |
| raw_spin_lock(&logbuf_lock); |
| printk_cpu = this_cpu; |
| |
| if (recursion_bug) { |
| recursion_bug = 0; |
| strcpy(printk_buf, recursion_bug_msg); |
| printed_len = strlen(recursion_bug_msg); |
| } |
| /* Emit the output into the temporary buffer */ |
| printed_len += vscnprintf(printk_buf + printed_len, |
| sizeof(printk_buf) - printed_len, fmt, args); |
| |
| p = printk_buf; |
| |
| /* Read log level and handle special printk prefix */ |
| plen = log_prefix(p, ¤t_log_level, &special); |
| if (plen) { |
| p += plen; |
| |
| switch (special) { |
| case 'c': /* Strip <c> KERN_CONT, continue line */ |
| plen = 0; |
| break; |
| case 'd': /* Strip <d> KERN_DEFAULT, start new line */ |
| plen = 0; |
| default: |
| if (!new_text_line) { |
| emit_log_char('\n'); |
| new_text_line = 1; |
| } |
| } |
| } |
| |
| /* |
| * Copy the output into log_buf. If the caller didn't provide |
| * the appropriate log prefix, we insert them here |
| */ |
| for (; *p; p++) { |
| if (new_text_line) { |
| new_text_line = 0; |
| |
| if (plen) { |
| /* Copy original log prefix */ |
| int i; |
| |
| for (i = 0; i < plen; i++) |
| emit_log_char(printk_buf[i]); |
| } else { |
| /* Add log prefix */ |
| emit_log_char('<'); |
| emit_log_char(current_log_level + '0'); |
| emit_log_char('>'); |
| } |
| |
| if (printk_time) { |
| /* Add the current time stamp */ |
| char tbuf[50], *tp; |
| unsigned tlen; |
| unsigned long long t; |
| unsigned long nanosec_rem; |
| |
| t = cpu_clock(printk_cpu); |
| nanosec_rem = do_div(t, 1000000000); |
| tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
| (unsigned long) t, |
| nanosec_rem / 1000); |
| |
| for (tp = tbuf; tp < tbuf + tlen; tp++) |
| emit_log_char(*tp); |
| } |
| |
| if (!*p) |
| break; |
| } |
| |
| emit_log_char(*p); |
| if (*p == '\n') |
| new_text_line = 1; |
| } |
| |
| /* |
| * Try to acquire and then immediately release the |
| * console semaphore. The release will do all the |
| * actual magic (print out buffers, wake up klogd, |
| * etc). |
| * |
| * The console_trylock_for_printk() function |
| * will release 'logbuf_lock' regardless of whether it |
| * actually gets the semaphore or not. |
| */ |
| if (console_trylock_for_printk(this_cpu)) |
| console_unlock(); |
| |
| lockdep_on(); |
| out_restore_irqs: |
| new_end = log_end & LOG_BUF_MASK; |
| if (new_end >= orig_end) { |
| flush_persist(log_buf + orig_end, new_end - orig_end); |
| } else { |
| flush_persist(log_buf + orig_end, log_buf_len - orig_end); |
| flush_persist(log_buf, new_end); |
| } |
| flush_persist(logbits, sizeof(*logbits)); |
| raw_local_irq_restore(flags); |
| |
| preempt_enable(); |
| return printed_len; |
| } |
| EXPORT_SYMBOL(printk); |
| EXPORT_SYMBOL(vprintk); |
| |
| #else |
| |
| static void call_console_drivers(unsigned start, unsigned end) |
| { |
| } |
| |
| #endif |
| |
| static int __add_preferred_console(char *name, int idx, char *options, |
| char *brl_options) |
| { |
| struct console_cmdline *c; |
| int i; |
| |
| /* |
| * See if this tty is not yet registered, and |
| * if we have a slot free. |
| */ |
| for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
| if (strcmp(console_cmdline[i].name, name) == 0 && |
| console_cmdline[i].index == idx) { |
| if (!brl_options) |
| selected_console = i; |
| return 0; |
| } |
| if (i == MAX_CMDLINECONSOLES) |
| return -E2BIG; |
| if (!brl_options) |
| selected_console = i; |
| c = &console_cmdline[i]; |
| strlcpy(c->name, name, sizeof(c->name)); |
| c->options = options; |
| #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| c->brl_options = brl_options; |
| #endif |
| c->index = idx; |
| return 0; |
| } |
| /* |
| * Set up a list of consoles. Called from init/main.c |
| */ |
| static int __init console_setup(char *str) |
| { |
| char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
| char *s, *options, *brl_options = NULL; |
| int idx; |
| |
| #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| if (!memcmp(str, "brl,", 4)) { |
| brl_options = ""; |
| str += 4; |
| } else if (!memcmp(str, "brl=", 4)) { |
| brl_options = str + 4; |
| str = strchr(brl_options, ','); |
| if (!str) { |
| printk(KERN_ERR "need port name after brl=\n"); |
| return 1; |
| } |
| *(str++) = 0; |
| } |
| #endif |
| |
| /* |
| * Decode str into name, index, options. |
| */ |
| if (str[0] >= '0' && str[0] <= '9') { |
| strcpy(buf, "ttyS"); |
| strncpy(buf + 4, str, sizeof(buf) - 5); |
| } else { |
| strncpy(buf, str, sizeof(buf) - 1); |
| } |
| buf[sizeof(buf) - 1] = 0; |
| if ((options = strchr(str, ',')) != NULL) |
| *(options++) = 0; |
| #ifdef __sparc__ |
| if (!strcmp(str, "ttya")) |
| strcpy(buf, "ttyS0"); |
| if (!strcmp(str, "ttyb")) |
| strcpy(buf, "ttyS1"); |
| #endif |
| for (s = buf; *s; s++) |
| if ((*s >= '0' && *s <= '9') || *s == ',') |
| break; |
| idx = simple_strtoul(s, NULL, 10); |
| *s = 0; |
| |
| __add_preferred_console(buf, idx, options, brl_options); |
| console_set_on_cmdline = 1; |
| return 1; |
| } |
| __setup("console=", console_setup); |
| |
| /** |
| * add_preferred_console - add a device to the list of preferred consoles. |
| * @name: device name |
| * @idx: device index |
| * @options: options for this console |
| * |
| * The last preferred console added will be used for kernel messages |
| * and stdin/out/err for init. Normally this is used by console_setup |
| * above to handle user-supplied console arguments; however it can also |
| * be used by arch-specific code either to override the user or more |
| * commonly to provide a default console (ie from PROM variables) when |
| * the user has not supplied one. |
| */ |
| int add_preferred_console(char *name, int idx, char *options) |
| { |
| return __add_preferred_console(name, idx, options, NULL); |
| } |
| |
| int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
| { |
| struct console_cmdline *c; |
| int i; |
| |
| for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
| if (strcmp(console_cmdline[i].name, name) == 0 && |
| console_cmdline[i].index == idx) { |
| c = &console_cmdline[i]; |
| strlcpy(c->name, name_new, sizeof(c->name)); |
| c->name[sizeof(c->name) - 1] = 0; |
| c->options = options; |
| c->index = idx_new; |
| return i; |
| } |
| /* not found */ |
| return -1; |
| } |
| |
| int console_suspend_enabled = 1; |
| EXPORT_SYMBOL(console_suspend_enabled); |
| |
| static int __init console_suspend_disable(char *str) |
| { |
| console_suspend_enabled = 0; |
| return 1; |
| } |
| __setup("no_console_suspend", console_suspend_disable); |
| module_param_named(console_suspend, console_suspend_enabled, |
| bool, S_IRUGO | S_IWUSR); |
| MODULE_PARM_DESC(console_suspend, "suspend console during suspend" |
| " and hibernate operations"); |
| |
| /** |
| * suspend_console - suspend the console subsystem |
| * |
| * This disables printk() while we go into suspend states |
| */ |
| void suspend_console(void) |
| { |
| if (!console_suspend_enabled) |
| return; |
| printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
| console_lock(); |
| console_suspended = 1; |
| up(&console_sem); |
| } |
| |
| void resume_console(void) |
| { |
| if (!console_suspend_enabled) |
| return; |
| down(&console_sem); |
| console_suspended = 0; |
| console_unlock(); |
| } |
| |
| /** |
| * console_cpu_notify - print deferred console messages after CPU hotplug |
| * @self: notifier struct |
| * @action: CPU hotplug event |
| * @hcpu: unused |
| * |
| * If printk() is called from a CPU that is not online yet, the messages |
| * will be spooled but will not show up on the console. This function is |
| * called when a new CPU comes online (or fails to come up), and ensures |
| * that any such output gets printed. |
| */ |
| static int __cpuinit console_cpu_notify(struct notifier_block *self, |
| unsigned long action, void *hcpu) |
| { |
| switch (action) { |
| case CPU_ONLINE: |
| case CPU_DEAD: |
| case CPU_DYING: |
| case CPU_DOWN_FAILED: |
| case CPU_UP_CANCELED: |
| console_lock(); |
| console_unlock(); |
| } |
| return NOTIFY_OK; |
| } |
| |
| /** |
| * console_lock - lock the console system for exclusive use. |
| * |
| * Acquires a lock which guarantees that the caller has |
| * exclusive access to the console system and the console_drivers list. |
| * |
| * Can sleep, returns nothing. |
| */ |
| void console_lock(void) |
| { |
| BUG_ON(in_interrupt()); |
| down(&console_sem); |
| if (console_suspended) |
| return; |
| console_locked = 1; |
| console_may_schedule = 1; |
| } |
| EXPORT_SYMBOL(console_lock); |
| |
| /** |
| * console_trylock - try to lock the console system for exclusive use. |
| * |
| * Tried to acquire a lock which guarantees that the caller has |
| * exclusive access to the console system and the console_drivers list. |
| * |
| * returns 1 on success, and 0 on failure to acquire the lock. |
| */ |
| int console_trylock(void) |
| { |
| if (down_trylock(&console_sem)) |
| return 0; |
| if (console_suspended) { |
| up(&console_sem); |
| return 0; |
| } |
| console_locked = 1; |
| console_may_schedule = 0; |
| return 1; |
| } |
| EXPORT_SYMBOL(console_trylock); |
| |
| int is_console_locked(void) |
| { |
| return console_locked; |
| } |
| |
| static DEFINE_PER_CPU(int, printk_pending); |
| |
| void printk_tick(void) |
| { |
| if (__this_cpu_read(printk_pending)) { |
| __this_cpu_write(printk_pending, 0); |
| wake_up_interruptible(&log_wait); |
| } |
| } |
| |
| int printk_needs_cpu(int cpu) |
| { |
| if (cpu_is_offline(cpu)) |
| printk_tick(); |
| return __this_cpu_read(printk_pending); |
| } |
| |
| void wake_up_klogd(void) |
| { |
| if (waitqueue_active(&log_wait)) |
| this_cpu_write(printk_pending, 1); |
| } |
| |
| /** |
| * console_unlock - unlock the console system |
| * |
| * Releases the console_lock which the caller holds on the console system |
| * and the console driver list. |
| * |
| * While the console_lock was held, console output may have been buffered |
| * by printk(). If this is the case, console_unlock(); emits |
| * the output prior to releasing the lock. |
| * |
| * If there is output waiting for klogd, we wake it up. |
| * |
| * console_unlock(); may be called from any context. |
| */ |
| void console_unlock(void) |
| { |
| unsigned long flags; |
| unsigned _con_start, _log_end; |
| unsigned wake_klogd = 0, retry = 0; |
| |
| if (console_suspended) { |
| up(&console_sem); |
| return; |
| } |
| |
| console_may_schedule = 0; |
| |
| again: |
| for ( ; ; ) { |
| raw_spin_lock_irqsave(&logbuf_lock, flags); |
| wake_klogd |= log_start - log_end; |
| if (con_start == log_end) |
| break; /* Nothing to print */ |
| _con_start = con_start; |
| _log_end = log_end; |
| con_start = log_end; /* Flush */ |
| raw_spin_unlock(&logbuf_lock); |
| stop_critical_timings(); /* don't trace print latency */ |
| call_console_drivers(_con_start, _log_end); |
| start_critical_timings(); |
| local_irq_restore(flags); |
| } |
| console_locked = 0; |
| |
| /* Release the exclusive_console once it is used */ |
| if (unlikely(exclusive_console)) |
| exclusive_console = NULL; |
| |
| raw_spin_unlock(&logbuf_lock); |
| |
| up(&console_sem); |
| |
| /* |
| * Someone could have filled up the buffer again, so re-check if there's |
| * something to flush. In case we cannot trylock the console_sem again, |
| * there's a new owner and the console_unlock() from them will do the |
| * flush, no worries. |
| */ |
| raw_spin_lock(&logbuf_lock); |
| if (con_start != log_end) |
| retry = 1; |
| raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| |
| if (retry && console_trylock()) |
| goto again; |
| |
| if (wake_klogd) |
| wake_up_klogd(); |
| } |
| EXPORT_SYMBOL(console_unlock); |
| |
| /** |
| * console_conditional_schedule - yield the CPU if required |
| * |
| * If the console code is currently allowed to sleep, and |
| * if this CPU should yield the CPU to another task, do |
| * so here. |
| * |
| * Must be called within console_lock();. |
| */ |
| void __sched console_conditional_schedule(void) |
| { |
| if (console_may_schedule) |
| cond_resched(); |
| } |
| EXPORT_SYMBOL(console_conditional_schedule); |
| |
| void console_unblank(void) |
| { |
| struct console *c; |
| |
| /* |
| * console_unblank can no longer be called in interrupt context unless |
| * oops_in_progress is set to 1.. |
| */ |
| if (oops_in_progress) { |
| if (down_trylock(&console_sem) != 0) |
| return; |
| } else |
| console_lock(); |
| |
| console_locked = 1; |
| console_may_schedule = 0; |
| for_each_console(c) |
| if ((c->flags & CON_ENABLED) && c->unblank) |
| c->unblank(); |
| console_unlock(); |
| } |
| |
| /* |
| * Return the console tty driver structure and its associated index |
| */ |
| struct tty_driver *console_device(int *index) |
| { |
| struct console *c; |
| struct tty_driver *driver = NULL; |
| |
| console_lock(); |
| for_each_console(c) { |
| if (!c->device) |
| continue; |
| driver = c->device(c, index); |
| if (driver) |
| break; |
| } |
| console_unlock(); |
| return driver; |
| } |
| |
| /* |
| * Prevent further output on the passed console device so that (for example) |
| * serial drivers can disable console output before suspending a port, and can |
| * re-enable output afterwards. |
| */ |
| void console_stop(struct console *console) |
| { |
| console_lock(); |
| console->flags &= ~CON_ENABLED; |
| console_unlock(); |
| } |
| EXPORT_SYMBOL(console_stop); |
| |
| void console_start(struct console *console) |
| { |
| console_lock(); |
| console->flags |= CON_ENABLED; |
| console_unlock(); |
| } |
| EXPORT_SYMBOL(console_start); |
| |
| static int __read_mostly keep_bootcon; |
| |
| static int __init keep_bootcon_setup(char *str) |
| { |
| keep_bootcon = 1; |
| printk(KERN_INFO "debug: skip boot console de-registration.\n"); |
| |
| return 0; |
| } |
| |
| early_param("keep_bootcon", keep_bootcon_setup); |
| |
| /* |
| * 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 |
| * console driver was initialized. |
| * |
| * This can happen pretty early during the boot process (because of |
| * early_printk) - sometimes before setup_arch() completes - be careful |
| * of what kernel features are used - they may not be initialised yet. |
| * |
| * There are two types of consoles - bootconsoles (early_printk) and |
| * "real" consoles (everything which is not a bootconsole) which are |
| * handled differently. |
| * - Any number of bootconsoles can be registered at any time. |
| * - As soon as a "real" console is registered, all bootconsoles |
| * will be unregistered automatically. |
| * - Once a "real" console is registered, any attempt to register a |
| * bootconsoles will be rejected |
| */ |
| void register_console(struct console *newcon) |
| { |
| int i; |
| unsigned long flags; |
| struct console *bcon = NULL; |
| |
| /* |
| * 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 */ |
| for_each_console(bcon) { |
| if (!(bcon->flags & CON_BOOT)) { |
| printk(KERN_INFO "Too late to register bootconsole %s%d\n", |
| newcon->name, newcon->index); |
| return; |
| } |
| } |
| } |
| |
| if (console_drivers && console_drivers->flags & CON_BOOT) |
| bcon = console_drivers; |
| |
| if (preferred_console < 0 || bcon || !console_drivers) |
| preferred_console = selected_console; |
| |
| if (newcon->early_setup) |
| newcon->early_setup(); |
| |
| /* |
| * 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 (preferred_console < 0) { |
| if (newcon->index < 0) |
| newcon->index = 0; |
| if (newcon->setup == NULL || |
| newcon->setup(newcon, NULL) == 0) { |
| newcon->flags |= CON_ENABLED; |
| if (newcon->device) { |
| newcon->flags |= CON_CONSDEV; |
| preferred_console = 0; |
| } |
| } |
| } |
| |
| /* |
| * See if this console matches one we selected on |
| * the command line. |
| */ |
| for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
| i++) { |
| if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
| continue; |
| if (newcon->index >= 0 && |
| newcon->index != console_cmdline[i].index) |
| continue; |
| if (newcon->index < 0) |
| newcon->index = console_cmdline[i].index; |
| #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| if (console_cmdline[i].brl_options) { |
| newcon->flags |= CON_BRL; |
| braille_register_console(newcon, |
| console_cmdline[i].index, |
| console_cmdline[i].options, |
| console_cmdline[i].brl_options); |
| return; |
| } |
| #endif |
| if (newcon->setup && |
| newcon->setup(newcon, console_cmdline[i].options) != 0) |
| break; |
| newcon->flags |= CON_ENABLED; |
| newcon->index = console_cmdline[i].index; |
| if (i == selected_console) { |
| newcon->flags |= CON_CONSDEV; |
| preferred_console = selected_console; |
| } |
| break; |
| } |
| |
| if (!(newcon->flags & CON_ENABLED)) |
| return; |
| |
| /* |
| * If we have a bootconsole, and are switching to a real console, |
| * don't print everything out again, since when the boot console, and |
| * the real console are the same physical device, it's annoying to |
| * see the beginning boot messages twice |
| */ |
| if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) |
| newcon->flags &= ~CON_PRINTBUFFER; |
| |
| /* |
| * Put this console in the list - keep the |
| * preferred driver at the head of the list. |
| */ |
| console_lock(); |
| if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
| newcon->next = console_drivers; |
| console_drivers = newcon; |
| if (newcon->next) |
| newcon->next->flags &= ~CON_CONSDEV; |
| } else { |
| newcon->next = console_drivers->next; |
| console_drivers->next = newcon; |
| } |
| if (newcon->flags & CON_PRINTBUFFER) { |
| /* |
| * console_unlock(); will print out the buffered messages |
| * for us. |
| */ |
| raw_spin_lock_irqsave(&logbuf_lock, flags); |
| con_start = log_start; |
| raw_spin_unlock_irqrestore(&logbuf_lock, 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. |
| */ |
| exclusive_console = newcon; |
| } |
| console_unlock(); |
| console_sysfs_notify(); |
| |
| /* |
| * By unregistering the bootconsoles after we enable the real console |
| * we get the "console xxx enabled" message on all the consoles - |
| * boot consoles, real consoles, etc - this is to ensure that end |
| * users know there might be something in the kernel's log buffer that |
| * went to the bootconsole (that they do not see on the real console) |
| */ |
| if (bcon && |
| ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && |
| !keep_bootcon) { |
| /* we need to iterate through twice, to make sure we print |
| * everything out, before we unregister the console(s) |
| */ |
| printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", |
| newcon->name, newcon->index); |
| for_each_console(bcon) |
| if (bcon->flags & CON_BOOT) |
| unregister_console(bcon); |
| } else { |
| printk(KERN_INFO "%sconsole [%s%d] enabled\n", |
| (newcon->flags & CON_BOOT) ? "boot" : "" , |
| newcon->name, newcon->index); |
| } |
| } |
| EXPORT_SYMBOL(register_console); |
| |
| int unregister_console(struct console *console) |
| { |
| struct console *a, *b; |
| int res = 1; |
| |
| #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| if (console->flags & CON_BRL) |
| return braille_unregister_console(console); |
| #endif |
| |
| 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; |
| res = 0; |
| break; |
| } |
| } |
| } |
| |
| /* |
| * If this isn't the last console and it has CON_CONSDEV set, we |
| * need to set it on the next preferred console. |
| */ |
| if (console_drivers != NULL && console->flags & CON_CONSDEV) |
| console_drivers->flags |= CON_CONSDEV; |
| |
| console_unlock(); |
| console_sysfs_notify(); |
| return res; |
| } |
| EXPORT_SYMBOL(unregister_console); |
| |
| static int __init printk_late_init(void) |
| { |
| struct console *con; |
| |
| for_each_console(con) { |
| if (!keep_bootcon && con->flags & CON_BOOT) { |
| printk(KERN_INFO "turn off boot console %s%d\n", |
| con->name, con->index); |
| unregister_console(con); |
| } |
| } |
| hotcpu_notifier(console_cpu_notify, 0); |
| return 0; |
| } |
| late_initcall(printk_late_init); |
| |
| #if defined CONFIG_PRINTK |
| |
| /* |
| * printk rate limiting, lifted from the networking subsystem. |
| * |
| * This enforces a rate limit: not more than 10 kernel messages |
| * every 5s to make a denial-of-service attack impossible. |
| */ |
| DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
| |
| int __printk_ratelimit(const char *func) |
| { |
| return ___ratelimit(&printk_ratelimit_state, func); |
| } |
| EXPORT_SYMBOL(__printk_ratelimit); |
| |
| /** |
| * printk_timed_ratelimit - caller-controlled printk ratelimiting |
| * @caller_jiffies: pointer to caller's state |
| * @interval_msecs: minimum interval between prints |
| * |
| * printk_timed_ratelimit() returns true if more than @interval_msecs |
| * milliseconds have elapsed since the last time printk_timed_ratelimit() |
| * returned true. |
| */ |
| bool printk_timed_ratelimit(unsigned long *caller_jiffies, |
| unsigned int interval_msecs) |
| { |
| if (*caller_jiffies == 0 |
| || !time_in_range(jiffies, *caller_jiffies, |
| *caller_jiffies |
| + msecs_to_jiffies(interval_msecs))) { |
| *caller_jiffies = jiffies; |
| return true; |
| } |
| return false; |
| } |
| EXPORT_SYMBOL(printk_timed_ratelimit); |
| |
| static DEFINE_SPINLOCK(dump_list_lock); |
| static LIST_HEAD(dump_list); |
| |
| /** |
| * kmsg_dump_register - register a kernel log dumper. |
| * @dumper: pointer to the kmsg_dumper structure |
| * |
| * Adds a kernel log dumper to the system. The dump callback in the |
| * structure will be called when the kernel oopses or panics and must be |
| * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. |
| */ |
| int kmsg_dump_register(struct kmsg_dumper *dumper) |
| { |
| unsigned long flags; |
| int err = -EBUSY; |
| |
| /* The dump callback needs to be set */ |
| if (!dumper->dump) |
| return -EINVAL; |
| |
| spin_lock_irqsave(&dump_list_lock, flags); |
| /* Don't allow registering multiple times */ |
| if (!dumper->registered) { |
| dumper->registered = 1; |
| list_add_tail_rcu(&dumper->list, &dump_list); |
| err = 0; |
| } |
| spin_unlock_irqrestore(&dump_list_lock, flags); |
| |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(kmsg_dump_register); |
| |
| /** |
| * kmsg_dump_unregister - unregister a kmsg dumper. |
| * @dumper: pointer to the kmsg_dumper structure |
| * |
| * Removes a dump device from the system. Returns zero on success and |
| * %-EINVAL otherwise. |
| */ |
| int kmsg_dump_unregister(struct kmsg_dumper *dumper) |
| { |
| unsigned long flags; |
| int err = -EINVAL; |
| |
| spin_lock_irqsave(&dump_list_lock, flags); |
| if (dumper->registered) { |
| dumper->registered = 0; |
| list_del_rcu(&dumper->list); |
| err = 0; |
| } |
| spin_unlock_irqrestore(&dump_list_lock, flags); |
| synchronize_rcu(); |
| |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(kmsg_dump_unregister); |
| |
| /** |
| * kmsg_dump - dump kernel log to kernel message dumpers. |
| * @reason: the reason (oops, panic etc) for dumping |
| * |
| * Iterate through each of the dump devices and call the oops/panic |
| * callbacks with the log buffer. |
| */ |
| void kmsg_dump(enum kmsg_dump_reason reason) |
| { |
| unsigned long end; |
| unsigned chars; |
| struct kmsg_dumper *dumper; |
| const char *s1, *s2; |
| unsigned long l1, l2; |
| unsigned long flags; |
| |
| /* Theoretically, the log could move on after we do this, but |
| there's not a lot we can do about that. The new messages |
| will overwrite the start of what we dump. */ |
| raw_spin_lock_irqsave(&logbuf_lock, flags); |
| end = log_end & LOG_BUF_MASK; |
| chars = logged_chars; |
| raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| |
| if (chars > end) { |
| s1 = log_buf + log_buf_len - chars + end; |
| l1 = chars - end; |
| |
| s2 = log_buf; |
| l2 = end; |
| } else { |
| s1 = ""; |
| l1 = 0; |
| |
| s2 = log_buf + end - chars; |
| l2 = chars; |
| } |
| |
| rcu_read_lock(); |
| list_for_each_entry_rcu(dumper, &dump_list, list) |
| dumper->dump(dumper, reason, s1, l1, s2, l2); |
| rcu_read_unlock(); |
| } |
| #endif |