Juno: Introduce juno_getentropy(void *buf, size_t len)

This function fills the buffer (first argument) with the specified
number of bytes (second argument) from the trusted entropy source.

This function will be used to initialize the stack protector canary.

Change-Id: Iff15aaf4778c13fa883ecb5528fcf9b8479d4489
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>

plat/arm/board/juno/juno_decl.h

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __JUNO_DECL_H__
+#define __JUNO_DECL_H__
+
+int juno_getentropy(void *buf, size_t len);
+
+#endif /* __JUNO_DECL_H__ */

plat/arm/board/juno/juno_def.h

 /*
- * Copyright (c) 2014-2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2017, ARM Limited and Contributors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -74,6 +74,16 @@
 #define TZC400_NSAID_SCP		11
 #define TZC400_NSAID_CORESIGHT		12
 
+/*******************************************************************************
+ * TRNG related constants
+ ******************************************************************************/
+#define TRNG_BASE	0x7FE60000ULL
+#define TRNG_NOUTPUTS	4
+#define TRNG_STATUS	0x10
+#define TRNG_INTMASK	0x14
+#define TRNG_CONFIG	0x18
+#define TRNG_CONTROL	0x1C
+
 /*******************************************************************************
  * MMU-401 related constants
  ******************************************************************************/

plat/arm/board/juno/juno_trng.c

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <assert.h>
+#include <mmio.h>
+#include <string.h>
+#include <utils.h>
+#include "juno_def.h"
+
+#define NSAMPLE_CLOCKS	1 /* min 1 cycle, max 231 cycles */
+#define NRETRIES	5
+
+static inline int output_valid(void)
+{
+	int i;
+
+	for (i = 0; i < NRETRIES; i++) {
+		uint32_t val;
+
+		val = mmio_read_32(TRNG_BASE + TRNG_STATUS);
+		if (val & 1U)
+			break;
+	}
+	if (i >= NRETRIES)
+		return 0; /* No output data available. */
+	return 1;
+}
+
+/*
+ * This function fills `buf` with `len` bytes of entropy.
+ * It uses the Trusted Entropy Source peripheral on Juno.
+ * Returns 0 when the buffer has been filled with entropy
+ * successfully and -1 otherwise.
+ */
+int juno_getentropy(void *buf, size_t len)
+{
+	uint8_t *bp = buf;
+
+	assert(buf);
+	assert(len);
+	assert(!check_uptr_overflow((uintptr_t)bp, len));
+
+	/* Disable interrupt mode. */
+	mmio_write_32(TRNG_BASE + TRNG_INTMASK, 0);
+	/* Program TRNG to sample for `NSAMPLE_CLOCKS`. */
+	mmio_write_32(TRNG_BASE + TRNG_CONFIG, NSAMPLE_CLOCKS);
+
+	while (len > 0) {
+		int i;
+
+		/* Start TRNG. */
+		mmio_write_32(TRNG_BASE + TRNG_CONTROL, 1);
+
+		/* Check if output is valid. */
+		if (!output_valid())
+			return -1;
+
+		/* Fill entropy buffer. */
+		for (i = 0; i < TRNG_NOUTPUTS; i++) {
+			size_t n;
+			uint32_t val;
+
+			val = mmio_read_32(TRNG_BASE + i * sizeof(uint32_t));
+			n = MIN(len, sizeof(uint32_t));
+			memcpy(bp, &val, n);
+			bp += n;
+			len -= n;
+			if (len == 0)
+				break;
+		}
+
+		/* Reset TRNG outputs. */
+		mmio_write_32(TRNG_BASE + TRNG_STATUS, 1);
+	}
+
+	return 0;
+}

plat/arm/board/juno/platform.mk

 #
-# Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are met:
@@ -39,6 +39,7 @@ JUNO_INTERCONNECT_SOURCES	:=	drivers/arm/cci/cci.c		\
 
 JUNO_SECURITY_SOURCES	:=	drivers/arm/tzc/tzc400.c		\
 				plat/arm/board/juno/juno_security.c	\
+				plat/arm/board/juno/juno_trng.c		\
 				plat/arm/common/arm_tzc400.c