This is a squashed commit of the printk_persist changes.
- Add PRINTK_PERSIST support to new kernel.
- Port over BOOTLOG_COPY from oldkernel.
- Change the magic number for the new kernel.
- Fix build error when CONFIG_PRINTK_PERSIST=y is removed
- Use crc for printk_persist corruption check
- Fixed b/20084294 printk data validation problem
- armada printk_persist: this seems to work
- Copy physmem_reserve change from kernel/mindspeed.
Change-Id: I2ff04cb6986df39fa830c869d8bb00d2d91ba079
diff --git a/init/Kconfig b/init/Kconfig
index 8b9521a..d7a54a9 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1343,6 +1343,27 @@
very difficult to diagnose system problems, saying N here is
strongly discouraged.
+config PRINTK_PERSIST
+ default n
+ bool "printk log persists across reboots" if PRINTK
+ help
+ This option tries to keep the printk memory buffer in a well-known
+ location in physical memory. It isn't cleared on reboot (unless RAM
+ is wiped by your boot loader or BIOS) so if your system crashes
+ or panics, you might get to examine all the log messages next time you
+ boot. The persisted log messages show up in your 'dmesg' output.
+ Note: you must supply the log_buf_len= kernel parameter to
+ activate this feature.
+
+config BOOTLOG_COPY
+ default n
+ bool "copy boot log to printk log" if PRINTK
+ help
+ This option copies the boot log stored in bootlog memory and save it
+ in the printk log.
+ Note: you must supply the bootlog= and log_buf_len= kernel parameters
+ to activate this feature.
+
config BUG
bool "BUG() support" if EXPERT
default y
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 8c086e6..ff9937c 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -45,6 +45,8 @@
#include <linux/poll.h>
#include <linux/irq_work.h>
#include <linux/utsname.h>
+#include <linux/ctype.h>
+#include <linux/crc32.h>
#include <asm/uaccess.h>
@@ -201,6 +203,9 @@
u16 text_len; /* length of text buffer */
u16 dict_len; /* length of dictionary buffer */
u8 facility; /* syslog facility */
+#ifdef CONFIG_PRINTK_PERSIST
+ u32 crc; /* the flags may change, so don't include them */
+#endif
u8 flags:5; /* internal record flags */
u8 level:3; /* syslog level */
};
@@ -213,6 +218,99 @@
#ifdef CONFIG_PRINTK
DECLARE_WAIT_QUEUE_HEAD(log_wait);
+
+#define PREFIX_MAX 32
+#define LOG_LINE_MAX 1024 - PREFIX_MAX
+
+/* record buffer */
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+#define LOG_ALIGN 4
+#else
+#define LOG_ALIGN __alignof__(struct printk_log)
+#endif
+#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
+static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
+static char *log_buf = __log_buf;
+
+static int log_make_free_space(u32 msg_size);
+static void log_store(int facility, int level,
+ enum log_flags flags, u64 ts_nsec,
+ const char *dict, u16 dict_len,
+ const char *text, u16 text_len);
+
+#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);
+
+static __init 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;
+ }
+ printk(KERN_INFO "bootlog: bootlog_size was 0.\n");
+ return NULL;
+}
+
+#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
+
+static inline void __init copy_bootlog(struct bloghdr *blog_hdr)
+{
+ if (blog_hdr) {
+ char *blog_buf = (char *)(blog_hdr + 1);
+ int i,j;
+ char *tmp;
+ /* Strip out nonprintable characters from the bootlog. */
+ for (i=0,j=0; i < blog_hdr->offset; i++) {
+ if (printable(blog_buf[i])) {
+ blog_buf[j++] = blog_buf[i];
+ }
+ }
+ /* Loop over each line in the boot loader log, and insert them into the
+ * kernel log one at a time. Attempting to insert the entire thing fails due
+ * to some logic that truncates long messages.
+ */
+ tmp = &blog_buf[0];
+ for (i=0; i < j; i++) {
+ if (blog_buf[i] == '\n') {
+ /* Insert with facility=0, level=INFO, time=0, No dict. */
+ log_store(0, 6, LOG_NEWLINE, 0,
+ NULL, 0, tmp, &blog_buf[i] - tmp);
+ tmp = &blog_buf[i+1];
+ }
+ }
+
+ /* Insert any trailing line into the kernel buffer. */
+ if (tmp != &blog_buf[i]) {
+ log_store(0, 6, 0, 0,
+ NULL, 0, tmp, &blog_buf[i] - tmp);
+ }
+ }
+}
+
+static inline void __init free_bootlog(void)
+{
+ free_bootmem(bootlog_get_addr(), bootlog_get_size());
+}
+#endif
+
+#ifndef CONFIG_PRINTK_PERSIST
/* the next printk record to read by syslog(READ) or /proc/kmsg */
static u64 syslog_seq;
static u32 syslog_idx;
@@ -236,20 +334,197 @@
static u64 clear_seq;
static u32 clear_idx;
-#define PREFIX_MAX 32
-#define LOG_LINE_MAX 1024 - PREFIX_MAX
-
-/* record buffer */
-#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
-#define LOG_ALIGN 4
-#else
-#define LOG_ALIGN __alignof__(struct printk_log)
-#endif
-#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
-static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
-static char *log_buf = __log_buf;
static u32 log_buf_len = __LOG_BUF_LEN;
+#else /* CONFIG_PRINTK_PERSIST */
+
+struct logbits {
+ int magic; /* needed to verify the memory across reboots */
+ u32 _log_buf_len;
+ u64 _syslog_seq; /* leading _ so they aren't replaced by #define */
+ u32 _syslog_idx;
+ enum log_flags _syslog_prev;
+ size_t _syslog_partial;
+
+/* index and sequence number of the first record stored in the buffer */
+ u64 _log_first_seq;
+ u32 _log_first_idx;
+
+/* index and sequence number of the next record to store in the buffer */
+ u64 _log_next_seq;
+ u32 _log_next_idx;
+
+/* the next printk record to write to the console */
+ u64 _console_seq;
+ u32 _console_idx;
+ enum log_flags _console_prev;
+
+/* the next printk record to read after the last 'clear' command */
+ u64 _clear_seq;
+ u32 _clear_idx;
+};
+
+static struct logbits __logbits = {
+ ._log_buf_len = __LOG_BUF_LEN,
+};
+static struct logbits *logbits = &__logbits;
+
+#define log_buf_len logbits->_log_buf_len
+#define syslog_seq logbits->_syslog_seq
+#define syslog_idx logbits->_syslog_idx
+#define syslog_prev logbits->_syslog_prev
+#define syslog_partial logbits->_syslog_partial
+#define log_first_seq logbits->_log_first_seq
+#define log_first_idx logbits->_log_first_idx
+#define log_next_seq logbits->_log_next_seq
+#define log_next_idx logbits->_log_next_idx
+#define console_seq logbits->_console_seq
+#define console_idx logbits->_console_idx
+#define console_prev logbits->_console_prev
+#define clear_seq logbits->_clear_seq
+#define clear_idx logbits->_clear_idx
+
+#define PERSIST_SEARCH_START 0
+#ifdef CONFIG_NO_BOOTMEM
+#define PERSIST_SEARCH_END 0x5e000000
+#else
+#define PERSIST_SEARCH_END 0xfe000000
+#endif
+#define PERSIST_SEARCH_JUMP (16*1024*1024)
+#define PERSIST_MAGIC 0xba5eba11
+
+/*
+ * arm uses one memory model, mips uses another
+ */
+static __init phys_addr_t physmem_reserve(phys_addr_t size) {
+#ifdef CONFIG_NO_BOOTMEM
+ phys_addr_t alloc;
+ alloc = memblock_find_in_range_node(size, SMP_CACHE_BYTES,
+ PERSIST_SEARCH_START, PERSIST_SEARCH_END,
+ NUMA_NO_NODE);
+ if (!alloc) return alloc;
+ if (memblock_reserve(alloc, size)) {
+ pr_err("printk_persist: memblock_reserve failed\n");
+ return 0;
+ }
+ return alloc;
+#else
+ unsigned long where;
+ for (where = PERSIST_SEARCH_END - size;
+ where >= PERSIST_SEARCH_START && where <= PERSIST_SEARCH_END - size;
+ where -= PERSIST_SEARCH_JUMP) {
+ if (reserve_bootmem(where, size, BOOTMEM_EXCLUSIVE))
+ continue;
+ else
+ return where;
+ }
+ return 0;
+#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 struct logbits *log_buf_alloc(unsigned long size, char **new_logbuf)
+{
+ char *buf;
+ phys_addr_t alloc;
+ unsigned long full_size = size + sizeof(struct logbits);
+ struct logbits *new_logbits;
+ u64 seq;
+ int idx, lost_entries;
+ struct printk_log *prlog;
+ u32 curr_crc;
+
+ alloc = physmem_reserve(full_size);
+ if (alloc) {
+ buf = phys_to_virt(alloc);
+ *new_logbuf = buf;
+ new_logbits = (void*)buf + size;
+ printk(KERN_INFO "printk_persist: memory reserved @ 0x%08llx\n",
+ alloc);
+ if ((new_logbits->magic != PERSIST_MAGIC) ||
+ (new_logbits->_log_buf_len != size) ||
+ (new_logbits->_log_first_seq >
+ new_logbits->_log_next_seq) ||
+ (new_logbits->_log_first_idx > size) ||
+ (new_logbits->_syslog_idx > size) ||
+ (new_logbits->_syslog_seq >
+ new_logbits->_log_next_seq) ||
+ (new_logbits->_log_next_idx > size) ||
+ (new_logbits->_console_seq >
+ new_logbits->_log_next_seq) ||
+ (new_logbits->_console_idx > size) ||
+ (new_logbits->_clear_seq >
+ new_logbits->_log_next_seq) ||
+ (new_logbits->_clear_idx > size)) {
+ printk(KERN_INFO "printk_persist: header invalid, "
+ "cleared.\n");
+ memset(buf, 0, full_size);
+ memset(new_logbits, 0, sizeof(*new_logbits));
+ new_logbits->magic = PERSIST_MAGIC;
+ new_logbits->_log_buf_len = size;
+ } else {
+ printk(KERN_INFO "printk_persist: header valid; "
+ "log_first_idx=%d\n"
+ "log_next_idx=%d\n"
+ "log_first_seq=%lld\n"
+ "log_next_seq=%lld\n"
+ "console_seq=%lld\n"
+ "console_idx=%d\n"
+ "syslog_seq=%lld\n"
+ "syslog_idx=%d\n",
+ new_logbits->_log_first_idx,
+ new_logbits->_log_next_idx,
+ new_logbits->_log_first_seq,
+ new_logbits->_log_next_seq,
+ new_logbits->_console_seq,
+ new_logbits->_console_idx,
+ new_logbits->_syslog_seq,
+ new_logbits->_syslog_idx);
+ printk(KERN_INFO "printk_persist: validating records\n");
+ for (seq = new_logbits->_log_first_seq, idx = new_logbits->_log_first_idx;
+ seq < new_logbits->_log_next_seq; ++seq) {
+ prlog = (struct printk_log *) &buf[idx];
+ // Verify validity of this record. If its bad, then move the next
+ // pointer to be where this record is at.
+ curr_crc = crc32(~0, prlog, offsetof(struct printk_log, crc));
+ if (prlog->crc != curr_crc) {
+ lost_entries = (int)(new_logbits->_log_next_seq - seq);
+ printk(KERN_INFO "printk_persist: corruption found, lost %d entries\n",
+ lost_entries);
+ new_logbits->_log_next_seq = seq;
+ new_logbits->_log_next_idx = idx;
+ break;
+ }
+ if (prlog->len == 0) {
+ idx = 0;
+ // Do not increment the sequence counter for the
+ // record that's used to indicate wrapping. We
+ // do still want to verify its CRC above though.
+ --seq;
+ }
+ else
+ idx += prlog->len;
+ }
+ }
+ return new_logbits;
+ } else {
+ /* replace the buffer, but don't bother to swap struct logbits */
+ printk(KERN_ERR "printk_persist: failed to reserve bootmem "
+ "area. disabled.\n");
+ buf = alloc_bootmem(full_size);
+ *new_logbuf = buf;
+ new_logbits = (struct logbits*)(buf + size);
+ memset(buf, 0, full_size);
+ }
+
+ return new_logbits;
+}
+#endif
+
/* cpu currently holding logbuf_lock */
static volatile unsigned int logbuf_cpu = UINT_MAX;
@@ -297,6 +572,48 @@
return idx + msg->len;
}
+/*
+ * Check whether there is enough free space for the given message.
+ *
+ * The same values of first_idx and next_idx mean that the buffer
+ * is either empty or full.
+ *
+ * If the buffer is empty, we must respect the position of the indexes.
+ * They cannot be reset to the beginning of the buffer.
+ */
+static int logbuf_has_space(u32 msg_size, bool empty)
+{
+ u32 free;
+
+ if (log_next_idx > log_first_idx || empty)
+ free = max(log_buf_len - log_next_idx, log_first_idx);
+ else
+ free = log_first_idx - log_next_idx;
+
+ /*
+ * We need space also for an empty header that signalizes wrapping
+ * of the buffer.
+ */
+ return free >= msg_size + sizeof(struct printk_log);
+}
+
+static int log_make_free_space(u32 msg_size)
+{
+ while (log_first_seq < log_next_seq) {
+ if (logbuf_has_space(msg_size, false))
+ return 0;
+ /* drop old messages until we have enough contiguous space */
+ log_first_idx = log_next(log_first_idx);
+ log_first_seq++;
+ }
+
+ /* sequence numbers are equal, so the log buffer is empty */
+ if (logbuf_has_space(msg_size, true))
+ return 0;
+
+ return -ENOMEM;
+}
+
/* insert record into the buffer, discard old ones, update heads */
static void log_store(int facility, int level,
enum log_flags flags, u64 ts_nsec,
@@ -334,6 +651,10 @@
* to signify a wrap around.
*/
memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));
+#ifdef CONFIG_PRINTK_PERSIST
+ ((struct printk_log*) (log_buf + log_next_idx))->crc =
+ crc32(~0, log_buf + log_next_idx, offsetof(struct printk_log, crc));
+#endif
log_next_idx = 0;
}
@@ -352,6 +673,9 @@
msg->ts_nsec = local_clock();
memset(log_dict(msg) + dict_len, 0, pad_len);
msg->len = sizeof(struct printk_log) + text_len + dict_len + pad_len;
+#ifdef CONFIG_PRINTK_PERSIST
+ msg->crc = crc32(~0, msg, offsetof(struct printk_log, crc));
+#endif
/* insert message */
log_next_idx += msg->len;
@@ -752,16 +1076,30 @@
unsigned long flags;
char *new_log_buf;
int free;
+#ifdef CONFIG_PRINTK_PERSIST
+ struct logbits *new_logbits;
+ struct logbits *old_logbits;
+ struct printk_log *prlog;
+ int seq, idx;
+ int console_found=0, syslog_found=0;
+#endif
+#ifdef CONFIG_BOOTLOG_COPY
+ struct bloghdr *blog_hdr = NULL;
+#endif
if (!new_log_buf_len)
return;
+#ifndef CONFIG_PRINTK_PERSIST
if (early) {
new_log_buf =
memblock_virt_alloc(new_log_buf_len, PAGE_SIZE);
} else {
new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len, 0);
}
+#else
+ new_logbits = log_buf_alloc(new_log_buf_len, &new_log_buf);
+#endif
if (unlikely(!new_log_buf)) {
pr_err("log_buf_len: %ld bytes not available\n",
@@ -769,14 +1107,93 @@
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;
new_log_buf_len = 0;
free = __LOG_BUF_LEN - log_next_idx;
+
+#ifndef CONFIG_PRINTK_PERSIST
memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
+#else
+ /* We have to copy over entries one at a time from the old
+ * buffer to the new buffer.
+ */
+ old_logbits = logbits;
+ logbits = new_logbits;
+
+#ifdef CONFIG_BOOTLOG_COPY
+ copy_bootlog(blog_hdr);
+#endif
+
+ for (seq = old_logbits->_log_first_seq, idx = old_logbits->_log_first_idx;
+ seq < old_logbits->_log_next_seq; ++seq) {
+ prlog = (struct printk_log *)&__log_buf[idx];
+ if (prlog->len == 0) {
+ idx = 0;
+ prlog = (struct printk_log *)&__log_buf[0];
+ }
+
+ if (log_make_free_space(prlog->len)) {
+ pr_err("not copying entry due to it being too huge\n");
+ idx += prlog->len;
+ continue;
+ }
+
+ if (log_next_idx + prlog->len + sizeof(struct printk_log) > log_buf_len) {
+ /*
+ * This message + an additional empty header does not fit
+ * at the end of the buffer. Add an empty header with len == 0
+ * to signify a wrap around.
+ */
+ memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));
+#ifdef CONFIG_PRINTK_PERSIST
+ ((struct printk_log*) (log_buf + log_next_idx))->crc =
+ crc32(~0, log_buf + log_next_idx, offsetof(struct printk_log, crc));
+#endif
+ log_next_idx = 0;
+ }
+ memcpy(&log_buf[log_next_idx], &__log_buf[idx], prlog->len);
+
+ if (old_logbits->_syslog_seq == seq) {
+ syslog_seq = log_next_seq;
+ syslog_idx = log_next_idx;
+ syslog_found = 1;
+ }
+
+ if (old_logbits->_console_seq == seq) {
+ console_seq = log_next_seq;
+ console_idx = log_next_idx;
+ console_found = 1;
+ }
+
+ idx += prlog->len;
+ log_next_seq++;
+ log_next_idx += prlog->len;
+ }
+
+ if (!syslog_found) {
+ syslog_seq = log_next_seq;
+ syslog_idx = log_next_idx;
+ }
+
+ if (!console_found) {
+ console_seq = log_next_seq;
+ console_idx = log_next_idx;
+ }
+#endif
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);
