random: add tracepoints for easier debugging and verification

commit 00ce1db1a634746040ace24c09a4e3a7949a3145 upstream.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 156 insertions, 4 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index f4dc6d81889..e70701ec3b0 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -266,6 +266,9 @@
 #include <asm/irq_regs.h>
 #include <asm/io.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/random.h>
+
 /*
  * Configuration information
  */
@@ -478,8 +481,8 @@ static __u32 const twist_table[8] = {
  * it's cheap to do so and helps slightly in the expected case where
  * the entropy is concentrated in the low-order bits.
  */
-static void __mix_pool_bytes(struct entropy_store *r, const void *in,
-                             int nbytes, __u8 out[64])
+static void _mix_pool_bytes(struct entropy_store *r, const void *in,
+                            int nbytes, __u8 out[64])
 {
         unsigned long i, j, tap1, tap2, tap3, tap4, tap5;
         int input_rotate;
@@ -531,13 +534,21 @@ static void __mix_pool_bytes(struct entropy_store *r, const void *in,
                         ((__u32 *)out)[j] = r->pool[(i - j) & wordmask];
 }
 
-static void mix_pool_bytes(struct entropy_store *r, const void *in,
+static void __mix_pool_bytes(struct entropy_store *r, const void *in,
                              int nbytes, __u8 out[64])
 {
+        trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
+        _mix_pool_bytes(r, in, nbytes, out);
+}
+
+static void mix_pool_bytes(struct entropy_store *r, const void *in,
+                           int nbytes, __u8 out[64])
+{
         unsigned long flags;
 
+        trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
         spin_lock_irqsave(&r->lock, flags);
-        __mix_pool_bytes(r, in, nbytes, out);
+        _mix_pool_bytes(r, in, nbytes, out);
         spin_unlock_irqrestore(&r->lock, flags);
 }
 
@@ -585,6 +596,7 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 retry:
         entropy_count = orig = ACCESS_ONCE(r->entropy_count);
         entropy_count += nbits;
+
         if (entropy_count < 0) {
                 DEBUG_ENT("negative entropy/overflow\n");
                 entropy_count = 0;
@@ -599,6 +611,9 @@ retry:
                         r->initialized = 1;
         }
 
+        trace_credit_entropy_bits(r->name, nbits, entropy_count,
+                                  r->entropy_total, _RET_IP_);
+
         /* should we wake readers? */
         if (r == &input_pool && entropy_count >= random_read_wakeup_thresh) {
                 wake_up_interruptible(&random_read_wait);
@@ -971,6 +986,7 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
         ssize_t ret = 0, i;
         __u8 tmp[EXTRACT_SIZE];
 
+        trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
         xfer_secondary_pool(r, nbytes);
         nbytes = account(r, nbytes, min, reserved);
 
@@ -1005,6 +1021,7 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
         ssize_t ret = 0, i;
         __u8 tmp[EXTRACT_SIZE];
 
+        trace_extract_entropy_user(r->name, nbytes, r->entropy_count, _RET_IP_);
         xfer_secondary_pool(r, nbytes);
         nbytes = account(r, nbytes, 0, 0);
 
@@ -1062,6 +1079,7 @@ void get_random_bytes_arch(void *buf, int nbytes)
 {
         char *p = buf;
 
+        trace_get_random_bytes(nbytes, _RET_IP_);
         while (nbytes) {
                 unsigned long v;
                 int chunk = min(nbytes, (int)sizeof(unsigned long));
diff --git a/include/trace/events/random.h b/include/trace/events/random.h
new file mode 100644
index 00000000000..422df19de73
--- /dev/null
+++ b/include/trace/events/random.h
@@ -0,0 +1,134 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM random
+
+#if !defined(_TRACE_RANDOM_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_RANDOM_H
+
+#include <linux/writeback.h>
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(random__mix_pool_bytes,
+        TP_PROTO(const char *pool_name, int bytes, unsigned long IP),
+
+        TP_ARGS(pool_name, bytes, IP),
+
+        TP_STRUCT__entry(
+                __field( const char *,  pool_name               )
+                __field(          int,  bytes                   )
+                __field(unsigned long,  IP                      )
+        ),
+
+        TP_fast_assign(
+                __entry->pool_name      = pool_name;
+                __entry->bytes          = bytes;
+                __entry->IP             = IP;
+        ),
+
+        TP_printk("%s pool: bytes %d caller %pF",
+                  __entry->pool_name, __entry->bytes, (void *)__entry->IP)
+);
+
+DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes,
+        TP_PROTO(const char *pool_name, int bytes, unsigned long IP),
+
+        TP_ARGS(pool_name, bytes, IP)
+);
+
+DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes_nolock,
+        TP_PROTO(const char *pool_name, int bytes, unsigned long IP),
+
+        TP_ARGS(pool_name, bytes, IP)
+);
+
+TRACE_EVENT(credit_entropy_bits,
+        TP_PROTO(const char *pool_name, int bits, int entropy_count,
+                 int entropy_total, unsigned long IP),
+
+        TP_ARGS(pool_name, bits, entropy_count, entropy_total, IP),
+
+        TP_STRUCT__entry(
+                __field( const char *,  pool_name               )
+                __field(          int,  bits                    )
+                __field(          int,  entropy_count           )
+                __field(          int,  entropy_total           )
+                __field(unsigned long,  IP                      )
+        ),
+
+        TP_fast_assign(
+                __entry->pool_name      = pool_name;
+                __entry->bits           = bits;
+                __entry->entropy_count  = entropy_count;
+                __entry->entropy_total  = entropy_total;
+                __entry->IP             = IP;
+        ),
+
+        TP_printk("%s pool: bits %d entropy_count %d entropy_total %d "
+                  "caller %pF", __entry->pool_name, __entry->bits,
+                  __entry->entropy_count, __entry->entropy_total,
+                  (void *)__entry->IP)
+);
+
+TRACE_EVENT(get_random_bytes,
+        TP_PROTO(int nbytes, unsigned long IP),
+
+        TP_ARGS(nbytes, IP),
+
+        TP_STRUCT__entry(
+                __field(          int,  nbytes                  )
+                __field(unsigned long,  IP                      )
+        ),
+
+        TP_fast_assign(
+                __entry->nbytes         = nbytes;
+                __entry->IP             = IP;
+        ),
+
+        TP_printk("nbytes %d caller %pF", __entry->nbytes, (void *)__entry->IP)
+);
+
+DECLARE_EVENT_CLASS(random__extract_entropy,
+        TP_PROTO(const char *pool_name, int nbytes, int entropy_count,
+                 unsigned long IP),
+
+        TP_ARGS(pool_name, nbytes, entropy_count, IP),
+
+        TP_STRUCT__entry(
+                __field( const char *,  pool_name               )
+                __field(          int,  nbytes                  )
+                __field(          int,  entropy_count           )
+                __field(unsigned long,  IP                      )
+        ),
+
+        TP_fast_assign(
+                __entry->pool_name      = pool_name;
+                __entry->nbytes         = nbytes;
+                __entry->entropy_count  = entropy_count;
+                __entry->IP             = IP;
+        ),
+
+        TP_printk("%s pool: nbytes %d entropy_count %d caller %pF",
+                  __entry->pool_name, __entry->nbytes, __entry->entropy_count,
+                  (void *)__entry->IP)
+);
+
+
+DEFINE_EVENT(random__extract_entropy, extract_entropy,
+        TP_PROTO(const char *pool_name, int nbytes, int entropy_count,
+                 unsigned long IP),
+
+        TP_ARGS(pool_name, nbytes, entropy_count, IP)
+);
+
+DEFINE_EVENT(random__extract_entropy, extract_entropy_user,
+        TP_PROTO(const char *pool_name, int nbytes, int entropy_count,
+                 unsigned long IP),
+
+        TP_ARGS(pool_name, nbytes, entropy_count, IP)
+);
+
+
+
+#endif /* _TRACE_RANDOM_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>