5 files changed, 172 insertions, 131 deletions

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index ea27c019655a..f900dc9f6822 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1805,6 +1805,30 @@ asmlinkage int printk_emit(int facility, int level,
 }
 EXPORT_SYMBOL(printk_emit);
 
+int vprintk_default(const char *fmt, va_list args)
+{
+        int r;
+
+#ifdef CONFIG_KGDB_KDB
+        if (unlikely(kdb_trap_printk)) {
+                r = vkdb_printf(fmt, args);
+                return r;
+        }
+#endif
+        r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
+
+        return r;
+}
+EXPORT_SYMBOL_GPL(vprintk_default);
+
+/*
+ * This allows printk to be diverted to another function per cpu.
+ * This is useful for calling printk functions from within NMI
+ * without worrying about race conditions that can lock up the
+ * box.
+ */
+DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default;
+
 /**
  * printk - print a kernel message
  * @fmt: format string
@@ -1828,19 +1852,15 @@ EXPORT_SYMBOL(printk_emit);
  */
 asmlinkage __visible int printk(const char *fmt, ...)
 {
+        printk_func_t vprintk_func;
         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_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
+        preempt_disable();
+        vprintk_func = this_cpu_read(printk_func);
+        r = vprintk_func(fmt, args);
+        preempt_enable();
         va_end(args);
 
         return r;
@@ -1874,6 +1894,9 @@ static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev,
                              bool syslog, char *buf, size_t size) { return 0; }
 static size_t cont_print_text(char *text, size_t size) { return 0; }
 
+/* Still needs to be defined for users */
+DEFINE_PER_CPU(printk_func_t, printk_func);
+
 #endif /* CONFIG_PRINTK */
 
 #ifdef CONFIG_EARLY_PRINTK
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ce11fa50a2f0..1af4f8f2ab5d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -939,19 +939,20 @@ out:
         return ret;
 }
 
+/* TODO add a seq_buf_to_buffer() */
 static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 {
         int len;
 
-        if (s->len <= s->readpos)
+        if (trace_seq_used(s) <= s->seq.readpos)
                 return -EBUSY;
 
-        len = s->len - s->readpos;
+        len = trace_seq_used(s) - s->seq.readpos;
         if (cnt > len)
                 cnt = len;
-        memcpy(buf, s->buffer + s->readpos, cnt);
+        memcpy(buf, s->buffer + s->seq.readpos, cnt);
 
-        s->readpos += cnt;
+        s->seq.readpos += cnt;
         return cnt;
 }
 
@@ -4313,6 +4314,8 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
                 goto out;
         }
 
+        trace_seq_init(&iter->seq);
+
         /*
          * We make a copy of the current tracer to avoid concurrent
          * changes on it while we are reading.
@@ -4506,18 +4509,18 @@ waitagain:
         trace_access_lock(iter->cpu_file);
         while (trace_find_next_entry_inc(iter) != NULL) {
                 enum print_line_t ret;
-                int len = iter->seq.len;
+                int save_len = iter->seq.seq.len;
 
                 ret = print_trace_line(iter);
                 if (ret == TRACE_TYPE_PARTIAL_LINE) {
                         /* don't print partial lines */
-                        iter->seq.len = len;
+                        iter->seq.seq.len = save_len;
                         break;
                 }
                 if (ret != TRACE_TYPE_NO_CONSUME)
                         trace_consume(iter);
 
-                if (iter->seq.len >= cnt)
+                if (trace_seq_used(&iter->seq) >= cnt)
                         break;
 
                 /*
@@ -4533,7 +4536,7 @@ waitagain:
 
         /* Now copy what we have to the user */
         sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
-        if (iter->seq.readpos >= iter->seq.len)
+        if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
                 trace_seq_init(&iter->seq);
 
         /*
@@ -4567,20 +4570,33 @@ static size_t
 tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 {
         size_t count;
+        int save_len;
         int ret;
 
         /* Seq buffer is page-sized, exactly what we need. */
         for (;;) {
-                count = iter->seq.len;
+                save_len = iter->seq.seq.len;
                 ret = print_trace_line(iter);
-                count = iter->seq.len - count;
-                if (rem < count) {
-                        rem = 0;
-                        iter->seq.len -= count;
+
+                if (trace_seq_has_overflowed(&iter->seq)) {
+                        iter->seq.seq.len = save_len;
                         break;
                 }
+
+                /*
+                 * This should not be hit, because it should only
+                 * be set if the iter->seq overflowed. But check it
+                 * anyway to be safe.
+                 */
                 if (ret == TRACE_TYPE_PARTIAL_LINE) {
-                        iter->seq.len -= count;
+                        iter->seq.seq.len = save_len;
+                        break;
+                }
+
+                count = trace_seq_used(&iter->seq) - save_len;
+                if (rem < count) {
+                        rem = 0;
+                        iter->seq.seq.len = save_len;
                         break;
                 }
 
@@ -4661,13 +4677,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
                 /* Copy the data into the page, so we can start over. */
                 ret = trace_seq_to_buffer(&iter->seq,
                                           page_address(spd.pages[i]),
-                                          iter->seq.len);
+                                          trace_seq_used(&iter->seq));
                 if (ret < 0) {
                         __free_page(spd.pages[i]);
                         break;
                 }
                 spd.partial[i].offset = 0;
-                spd.partial[i].len = iter->seq.len;
+                spd.partial[i].len = trace_seq_used(&iter->seq);
 
                 trace_seq_init(&iter->seq);
         }
@@ -5667,7 +5683,8 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
         cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
         trace_seq_printf(s, "read events: %ld\n", cnt);
 
-        count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
+        count = simple_read_from_buffer(ubuf, count, ppos,
+                                        s->buffer, trace_seq_used(s));
 
         kfree(s);
 
@@ -6630,11 +6647,19 @@ void
 trace_printk_seq(struct trace_seq *s)
 {
         /* Probably should print a warning here. */
-        if (s->len >= TRACE_MAX_PRINT)
-                s->len = TRACE_MAX_PRINT;
+        if (s->seq.len >= TRACE_MAX_PRINT)
+                s->seq.len = TRACE_MAX_PRINT;
+
+        /*
+         * More paranoid code. Although the buffer size is set to
+         * PAGE_SIZE, and TRACE_MAX_PRINT is 1000, this is just
+         * an extra layer of protection.
+         */
+        if (WARN_ON_ONCE(s->seq.len >= s->seq.size))
+                s->seq.len = s->seq.size - 1;
 
         /* should be zero ended, but we are paranoid. */
-        s->buffer[s->len] = 0;
+        s->buffer[s->seq.len] = 0;
 
         printk(KERN_TRACE "%s", s->buffer);
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 139716bcef7a..d0e4f92b5eb6 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1044,7 +1044,8 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
         mutex_unlock(&event_mutex);
 
         if (file)
-                r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+                r = simple_read_from_buffer(ubuf, cnt, ppos,
+                                            s->buffer, trace_seq_used(s));
 
         kfree(s);
 
@@ -1210,7 +1211,8 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
         trace_seq_init(s);
 
         print_subsystem_event_filter(system, s);
-        r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+        r = simple_read_from_buffer(ubuf, cnt, ppos,
+                                    s->buffer, trace_seq_used(s));
 
         kfree(s);
 
@@ -1265,7 +1267,8 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
         trace_seq_init(s);
 
         func(s);
-        r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+        r = simple_read_from_buffer(ubuf, cnt, ppos,
+                                    s->buffer, trace_seq_used(s));
 
         kfree(s);
 
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 6c2ab955018c..ba476009e5de 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1136,14 +1136,17 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
                         return ret;
         }
 
+        if (trace_seq_has_overflowed(s))
+                goto out;
+
         /* Strip ending newline */
-        if (s->buffer[s->len - 1] == '\n') {
-                s->buffer[s->len - 1] = '\0';
-                s->len--;
+        if (s->buffer[s->seq.len - 1] == '\n') {
+                s->buffer[s->seq.len - 1] = '\0';
+                s->seq.len--;
         }
 
         trace_seq_puts(s, " */\n");
-
+ out:
         return trace_handle_return(s);
 }
 
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index fabfa0f190a3..f8b45d8792f9 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -27,10 +27,19 @@
 #include <linux/trace_seq.h>
 
 /* How much buffer is left on the trace_seq? */
-#define TRACE_SEQ_BUF_LEFT(s) ((PAGE_SIZE - 1) - (s)->len)
+#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
 
 /* How much buffer is written? */
-#define TRACE_SEQ_BUF_USED(s) min((s)->len, (unsigned int)(PAGE_SIZE - 1))
+#define TRACE_SEQ_BUF_USED(s) seq_buf_used(&(s)->seq)
+
+/*
+ * trace_seq should work with being initialized with 0s.
+ */
+static inline void __trace_seq_init(struct trace_seq *s)
+{
+        if (unlikely(!s->seq.size))
+                trace_seq_init(s);
+}
 
 /**
  * trace_print_seq - move the contents of trace_seq into a seq_file
@@ -43,10 +52,11 @@
  */
 int trace_print_seq(struct seq_file *m, struct trace_seq *s)
 {
-        unsigned int len = TRACE_SEQ_BUF_USED(s);
         int ret;
 
-        ret = seq_write(m, s->buffer, len);
+        __trace_seq_init(s);
+
+        ret = seq_buf_print_seq(m, &s->seq);
 
         /*
          * Only reset this buffer if we successfully wrote to the
@@ -72,24 +82,23 @@ int trace_print_seq(struct seq_file *m, struct trace_seq *s)
  */
 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 {
-        unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+        unsigned int save_len = s->seq.len;
         va_list ap;
-        int ret;
 
-        if (s->full || !len)
+        if (s->full)
                 return;
 
+        __trace_seq_init(s);
+
         va_start(ap, fmt);
-        ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
+        seq_buf_vprintf(&s->seq, fmt, ap);
         va_end(ap);
 
         /* If we can't write it all, don't bother writing anything */
-        if (ret >= len) {
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
                 s->full = 1;
-                return;
         }
-
-        s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
 
@@ -104,14 +113,19 @@ EXPORT_SYMBOL_GPL(trace_seq_printf);
 void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
                       int nmaskbits)
 {
-        unsigned int len = TRACE_SEQ_BUF_LEFT(s);
-        int ret;
+        unsigned int save_len = s->seq.len;
 
-        if (s->full || !len)
+        if (s->full)
                 return;
 
-        ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
-        s->len += ret;
+        __trace_seq_init(s);
+
+        seq_buf_bitmask(&s->seq, maskp, nmaskbits);
+
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
+                s->full = 1;
+        }
 }
 EXPORT_SYMBOL_GPL(trace_seq_bitmask);
 
@@ -128,21 +142,20 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask);
  */
 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
 {
-        unsigned int len = TRACE_SEQ_BUF_LEFT(s);
-        int ret;
+        unsigned int save_len = s->seq.len;
 
-        if (s->full || !len)
+        if (s->full)
                 return;
 
-        ret = vsnprintf(s->buffer + s->len, len, fmt, args);
+        __trace_seq_init(s);
+
+        seq_buf_vprintf(&s->seq, fmt, args);
 
         /* If we can't write it all, don't bother writing anything */
-        if (ret >= len) {
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
                 s->full = 1;
-                return;
         }
-
-        s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_vprintf);
 
@@ -163,21 +176,21 @@ EXPORT_SYMBOL_GPL(trace_seq_vprintf);
  */
 void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 {
-        unsigned int len = TRACE_SEQ_BUF_LEFT(s);
-        int ret;
+        unsigned int save_len = s->seq.len;
 
-        if (s->full || !len)
+        if (s->full)
                 return;
 
-        ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+        __trace_seq_init(s);
+
+        seq_buf_bprintf(&s->seq, fmt, binary);
 
         /* If we can't write it all, don't bother writing anything */
-        if (ret >= len) {
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
                 s->full = 1;
                 return;
         }
-
-        s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_bprintf);
 
@@ -198,13 +211,14 @@ void trace_seq_puts(struct trace_seq *s, const char *str)
         if (s->full)
                 return;
 
+        __trace_seq_init(s);
+
         if (len > TRACE_SEQ_BUF_LEFT(s)) {
                 s->full = 1;
                 return;
         }
 
-        memcpy(s->buffer + s->len, str, len);
-        s->len += len;
+        seq_buf_putmem(&s->seq, str, len);
 }
 EXPORT_SYMBOL_GPL(trace_seq_puts);
 
@@ -223,12 +237,14 @@ void trace_seq_putc(struct trace_seq *s, unsigned char c)
         if (s->full)
                 return;
 
+        __trace_seq_init(s);
+
         if (TRACE_SEQ_BUF_LEFT(s) < 1) {
                 s->full = 1;
                 return;
         }
 
-        s->buffer[s->len++] = c;
+        seq_buf_putc(&s->seq, c);
 }
 EXPORT_SYMBOL_GPL(trace_seq_putc);
 
@@ -247,19 +263,17 @@ void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
         if (s->full)
                 return;
 
+        __trace_seq_init(s);
+
         if (len > TRACE_SEQ_BUF_LEFT(s)) {
                 s->full = 1;
                 return;
         }
 
-        memcpy(s->buffer + s->len, mem, len);
-        s->len += len;
+        seq_buf_putmem(&s->seq, mem, len);
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem);
 
-#define MAX_MEMHEX_BYTES        8U
-#define HEX_CHARS               (MAX_MEMHEX_BYTES*2 + 1)
-
 /**
  * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex
  * @s: trace sequence descriptor
@@ -273,32 +287,26 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem);
 void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
                          unsigned int len)
 {
-        unsigned char hex[HEX_CHARS];
-        const unsigned char *data = mem;
-        unsigned int start_len;
-        int i, j;
+        unsigned int save_len = s->seq.len;
 
         if (s->full)
                 return;
 
-        while (len) {
-                start_len = min(len, HEX_CHARS - 1);
-#ifdef __BIG_ENDIAN
-                for (i = 0, j = 0; i < start_len; i++) {
-#else
-                for (i = start_len-1, j = 0; i >= 0; i--) {
-#endif
-                        hex[j++] = hex_asc_hi(data[i]);
-                        hex[j++] = hex_asc_lo(data[i]);
-                }
-                if (WARN_ON_ONCE(j == 0 || j/2 > len))
-                        break;
-
-                /* j increments twice per loop */
-                len -= j / 2;
-                hex[j++] = ' ';
-
-                trace_seq_putmem(s, hex, j);
+        __trace_seq_init(s);
+
+        /* Each byte is represented by two chars */
+        if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) {
+                s->full = 1;
+                return;
+        }
+
+        /* The added spaces can still cause an overflow */
+        seq_buf_putmem_hex(&s->seq, mem, len);
+
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
+                s->full = 1;
+                return;
         }
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
@@ -317,30 +325,27 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
  */
 int trace_seq_path(struct trace_seq *s, const struct path *path)
 {
-        unsigned char *p;
+        unsigned int save_len = s->seq.len;
 
         if (s->full)
                 return 0;
 
+        __trace_seq_init(s);
+
         if (TRACE_SEQ_BUF_LEFT(s) < 1) {
                 s->full = 1;
                 return 0;
         }
 
-        p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
-        if (!IS_ERR(p)) {
-                p = mangle_path(s->buffer + s->len, p, "\n");
-                if (p) {
-                        s->len = p - s->buffer;
-                        return 1;
-                }
-        } else {
-                s->buffer[s->len++] = '?';
-                return 1;
+        seq_buf_path(&s->seq, path, "\n");
+
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
+                s->full = 1;
+                return 0;
         }
 
-        s->full = 1;
-        return 0;
+        return 1;
 }
 EXPORT_SYMBOL_GPL(trace_seq_path);
 
@@ -366,25 +371,7 @@ EXPORT_SYMBOL_GPL(trace_seq_path);
  */
 int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
 {
-        int len;
-        int ret;
-
-        if (!cnt)
-                return 0;
-
-        if (s->len <= s->readpos)
-                return -EBUSY;
-
-        len = s->len - s->readpos;
-        if (cnt > len)
-                cnt = len;
-        ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
-        if (ret == cnt)
-                return -EFAULT;
-
-        cnt -= ret;
-
-        s->readpos += cnt;
-        return cnt;
+        __trace_seq_init(s);
+        return seq_buf_to_user(&s->seq, ubuf, cnt);
 }
 EXPORT_SYMBOL_GPL(trace_seq_to_user);