rump: Reduce startup latency

Since rump now requires large buffers of random numbers (>= 512 bytes), use the
jitterentropy library instead of the slow timer pseudo random number generation.

Fixes #1393

repos/dde_rump/lib/mk/rump_base.inc

@@ -12,6 +12,11 @@ RMAKE       = $(RUMP_TOOLS)/rumpmake
 #
 VERBOSE_LEVEL ?= 0
 
+#
+# Libraries
+#
+LIBS += jitterentropy
+
 #
 # Sources
 #

repos/dde_rump/src/lib/rump/bootstrap.cc

@@ -166,7 +166,7 @@ struct Sym_tab
 			/* set absolute value */
 			sym_tab[out_cnt].st_value += map->addr;
 			if (verbose)
-				PDBG("Read symbol %s val: %zx", name, sym_tab[out_cnt].st_value);
+				PDBG("Read symbol %s val: %lx", name, sym_tab[out_cnt].st_value);
 			out_cnt++;
 		}
 	}

repos/dde_rump/src/lib/rump/hypercall.cc

@@ -21,6 +21,11 @@
 #include <util/allocator_fap.h>
 #include <util/string.h>
 
+extern "C" {
+	namespace Jitter {
+		#include <jitterentropy.h>
+	}
+}
 
 extern "C" void wait_for_continue();
 enum { SUPPORTED_RUMP_VERSION = 17 };
@@ -31,6 +36,38 @@ static bool verbose = false;
 struct rumpuser_hyperup _rump_upcalls;
 
 
+/***********************************
+ ** Jitter entropy for randomness **
+ ***********************************/
+
+struct Entropy
+{
+	struct Jitter::rand_data *ec_stir;
+
+	Entropy()
+	{
+		Jitter::jent_entropy_init();
+		ec_stir = Jitter::jent_entropy_collector_alloc(0, 0);
+	}
+
+	static Entropy *e()
+	{
+		static Entropy _e;
+		return &_e;
+	}
+
+	size_t read(char *buf, size_t len)
+	{
+		int err;
+		if ((err = Jitter::jent_read_entropy(ec_stir, buf, len) < 0)) {
+			PERR("Failed to read entropy: %d", err);
+			return 0;
+		}
+
+		return len;
+	}
+};
+
 /********************
  ** Initialization **
  ********************/
@@ -53,6 +90,9 @@ int rumpuser_init(int version, const struct rumpuser_hyperup *hyp)
 	 */
 	Genode::Timeout_thread::alarm_timer();
 
+	/* initialize jitter entropy */
+	Entropy::e();
+
 	return 0;
 }
 
@@ -296,14 +336,7 @@ int rumpuser_clock_sleep(int enum_rumpclock, int64_t sec, long nsec)
 
 int rumpuser_getrandom(void *buf, size_t buflen, int flags, size_t *retp)
 {
-	Timer::Connection *timer = myself()->timer();
+	*retp = Entropy::e()->read((char *)buf, buflen);
-
-	uint8_t *rndbuf;
-	for (*retp = 0, rndbuf = (uint8_t *)buf; *retp < buflen; (*retp)++) {
-		*rndbuf++ = timer->elapsed_ms() & 0xff;
-		timer->msleep(timer->elapsed_ms() & 0xf);
-	}
-
 	return 0;
 }
 

repos/dde_rump/src/lib/rump/misc.cc

@@ -15,15 +15,6 @@
 #include <util/string.h>
 
 
-/*
- * On some platforms (namely ARM) we end-up pulling in string.h prototypes
- */
-extern "C" void *memcpy(void *d, void *s, Genode::size_t n)
-{
-	return Genode::memcpy(d, s, n);
-}
-
-
 extern "C" void *memset(void *s, int c, Genode::size_t n)
 {
 	return Genode::memset(s, c, n);