Add software STB "ROM" implementation for Mambo

Pass SKIBOOT_ENABLE_MAMBO_STB=1 as environment variable to skiboot.tcl
and the tcl will enable the /ibm,secureboot node, enabling hash and
signature "verification" for that mambo session.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

6 files changed, 726 insertions, 1 deletions

diff --git a/libstb/drivers/Makefile.inc b/libstb/drivers/Makefile.inc
index 2817378..d0f88ea 100644
--- a/libstb/drivers/Makefile.inc
+++ b/libstb/drivers/Makefile.inc
@@ -4,7 +4,7 @@ DRIVERS_DIR = libstb/drivers
 
 SUBDIRS += $(DRIVERS_DIR)
 
-DRIVERS_SRCS = romcode.c tpm_i2c_interface.c tpm_i2c_nuvoton.c
+DRIVERS_SRCS = romcode.c tpm_i2c_interface.c tpm_i2c_nuvoton.c sw_driver.c sha512.c
 DRIVERS_OBJS = $(DRIVERS_SRCS:%.c=%.o)
 DRIVERS = $(DRIVERS_DIR)/built-in.o
 
diff --git a/libstb/drivers/sha512.c b/libstb/drivers/sha512.c
new file mode 100644
index 0000000..a133795
--- /dev/null
+++ b/libstb/drivers/sha512.c
@@ -0,0 +1,480 @@
+/*
+ *  FIPS-180-2 compliant SHA-384/512 implementation
+ *
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+/*
+ *  The SHA-512 Secure Hash Standard was published by NIST in 2002.
+ *
+ *  http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
+ */
+
+#include "sha512.h"
+
+#define UL64(x) x
+
+#include <string.h>
+#include <stdio.h>
+#define mbedtls_printf printf
+
+#if !defined(MBEDTLS_SHA512_ALT)
+
+/* Implementation that should never be optimized out by the compiler */
+static void mbedtls_zeroize( void *v, size_t n ) {
+    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
+}
+
+/*
+ * 64-bit integer manipulation macros (big endian)
+ */
+#ifndef GET_UINT64_BE
+#define GET_UINT64_BE(n,b,i)                            \
+{                                                       \
+    (n) = ( (uint64_t) (b)[(i)    ] << 56 )       \
+        | ( (uint64_t) (b)[(i) + 1] << 48 )       \
+        | ( (uint64_t) (b)[(i) + 2] << 40 )       \
+        | ( (uint64_t) (b)[(i) + 3] << 32 )       \
+        | ( (uint64_t) (b)[(i) + 4] << 24 )       \
+        | ( (uint64_t) (b)[(i) + 5] << 16 )       \
+        | ( (uint64_t) (b)[(i) + 6] <<  8 )       \
+        | ( (uint64_t) (b)[(i) + 7]       );      \
+}
+#endif /* GET_UINT64_BE */
+
+#ifndef PUT_UINT64_BE
+#define PUT_UINT64_BE(n,b,i)                            \
+{                                                       \
+    (b)[(i)    ] = (unsigned char) ( (n) >> 56 );       \
+    (b)[(i) + 1] = (unsigned char) ( (n) >> 48 );       \
+    (b)[(i) + 2] = (unsigned char) ( (n) >> 40 );       \
+    (b)[(i) + 3] = (unsigned char) ( (n) >> 32 );       \
+    (b)[(i) + 4] = (unsigned char) ( (n) >> 24 );       \
+    (b)[(i) + 5] = (unsigned char) ( (n) >> 16 );       \
+    (b)[(i) + 6] = (unsigned char) ( (n) >>  8 );       \
+    (b)[(i) + 7] = (unsigned char) ( (n)       );       \
+}
+#endif /* PUT_UINT64_BE */
+
+void mbedtls_sha512_init( mbedtls_sha512_context *ctx )
+{
+    memset( ctx, 0, sizeof( mbedtls_sha512_context ) );
+}
+
+void mbedtls_sha512_free( mbedtls_sha512_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    mbedtls_zeroize( ctx, sizeof( mbedtls_sha512_context ) );
+}
+
+void mbedtls_sha512_clone( mbedtls_sha512_context *dst,
+                           const mbedtls_sha512_context *src )
+{
+    *dst = *src;
+}
+
+/*
+ * SHA-512 context setup
+ */
+void mbedtls_sha512_starts( mbedtls_sha512_context *ctx, int is384 )
+{
+    ctx->total[0] = 0;
+    ctx->total[1] = 0;
+
+    if( is384 == 0 )
+    {
+        /* SHA-512 */
+        ctx->state[0] = UL64(0x6A09E667F3BCC908);
+        ctx->state[1] = UL64(0xBB67AE8584CAA73B);
+        ctx->state[2] = UL64(0x3C6EF372FE94F82B);
+        ctx->state[3] = UL64(0xA54FF53A5F1D36F1);
+        ctx->state[4] = UL64(0x510E527FADE682D1);
+        ctx->state[5] = UL64(0x9B05688C2B3E6C1F);
+        ctx->state[6] = UL64(0x1F83D9ABFB41BD6B);
+        ctx->state[7] = UL64(0x5BE0CD19137E2179);
+    }
+    else
+    {
+        /* SHA-384 */
+        ctx->state[0] = UL64(0xCBBB9D5DC1059ED8);
+        ctx->state[1] = UL64(0x629A292A367CD507);
+        ctx->state[2] = UL64(0x9159015A3070DD17);
+        ctx->state[3] = UL64(0x152FECD8F70E5939);
+        ctx->state[4] = UL64(0x67332667FFC00B31);
+        ctx->state[5] = UL64(0x8EB44A8768581511);
+        ctx->state[6] = UL64(0xDB0C2E0D64F98FA7);
+        ctx->state[7] = UL64(0x47B5481DBEFA4FA4);
+    }
+
+    ctx->is384 = is384;
+}
+
+#if !defined(MBEDTLS_SHA512_PROCESS_ALT)
+
+/*
+ * Round constants
+ */
+static const uint64_t K[80] =
+{
+    UL64(0x428A2F98D728AE22),  UL64(0x7137449123EF65CD),
+    UL64(0xB5C0FBCFEC4D3B2F),  UL64(0xE9B5DBA58189DBBC),
+    UL64(0x3956C25BF348B538),  UL64(0x59F111F1B605D019),
+    UL64(0x923F82A4AF194F9B),  UL64(0xAB1C5ED5DA6D8118),
+    UL64(0xD807AA98A3030242),  UL64(0x12835B0145706FBE),
+    UL64(0x243185BE4EE4B28C),  UL64(0x550C7DC3D5FFB4E2),
+    UL64(0x72BE5D74F27B896F),  UL64(0x80DEB1FE3B1696B1),
+    UL64(0x9BDC06A725C71235),  UL64(0xC19BF174CF692694),
+    UL64(0xE49B69C19EF14AD2),  UL64(0xEFBE4786384F25E3),
+    UL64(0x0FC19DC68B8CD5B5),  UL64(0x240CA1CC77AC9C65),
+    UL64(0x2DE92C6F592B0275),  UL64(0x4A7484AA6EA6E483),
+    UL64(0x5CB0A9DCBD41FBD4),  UL64(0x76F988DA831153B5),
+    UL64(0x983E5152EE66DFAB),  UL64(0xA831C66D2DB43210),
+    UL64(0xB00327C898FB213F),  UL64(0xBF597FC7BEEF0EE4),
+    UL64(0xC6E00BF33DA88FC2),  UL64(0xD5A79147930AA725),
+    UL64(0x06CA6351E003826F),  UL64(0x142929670A0E6E70),
+    UL64(0x27B70A8546D22FFC),  UL64(0x2E1B21385C26C926),
+    UL64(0x4D2C6DFC5AC42AED),  UL64(0x53380D139D95B3DF),
+    UL64(0x650A73548BAF63DE),  UL64(0x766A0ABB3C77B2A8),
+    UL64(0x81C2C92E47EDAEE6),  UL64(0x92722C851482353B),
+    UL64(0xA2BFE8A14CF10364),  UL64(0xA81A664BBC423001),
+    UL64(0xC24B8B70D0F89791),  UL64(0xC76C51A30654BE30),
+    UL64(0xD192E819D6EF5218),  UL64(0xD69906245565A910),
+    UL64(0xF40E35855771202A),  UL64(0x106AA07032BBD1B8),
+    UL64(0x19A4C116B8D2D0C8),  UL64(0x1E376C085141AB53),
+    UL64(0x2748774CDF8EEB99),  UL64(0x34B0BCB5E19B48A8),
+    UL64(0x391C0CB3C5C95A63),  UL64(0x4ED8AA4AE3418ACB),
+    UL64(0x5B9CCA4F7763E373),  UL64(0x682E6FF3D6B2B8A3),
+    UL64(0x748F82EE5DEFB2FC),  UL64(0x78A5636F43172F60),
+    UL64(0x84C87814A1F0AB72),  UL64(0x8CC702081A6439EC),
+    UL64(0x90BEFFFA23631E28),  UL64(0xA4506CEBDE82BDE9),
+    UL64(0xBEF9A3F7B2C67915),  UL64(0xC67178F2E372532B),
+    UL64(0xCA273ECEEA26619C),  UL64(0xD186B8C721C0C207),
+    UL64(0xEADA7DD6CDE0EB1E),  UL64(0xF57D4F7FEE6ED178),
+    UL64(0x06F067AA72176FBA),  UL64(0x0A637DC5A2C898A6),
+    UL64(0x113F9804BEF90DAE),  UL64(0x1B710B35131C471B),
+    UL64(0x28DB77F523047D84),  UL64(0x32CAAB7B40C72493),
+    UL64(0x3C9EBE0A15C9BEBC),  UL64(0x431D67C49C100D4C),
+    UL64(0x4CC5D4BECB3E42B6),  UL64(0x597F299CFC657E2A),
+    UL64(0x5FCB6FAB3AD6FAEC),  UL64(0x6C44198C4A475817)
+};
+
+void mbedtls_sha512_process( mbedtls_sha512_context *ctx, const unsigned char data[128] )
+{
+    int i;
+    uint64_t temp1, temp2, W[80];
+    uint64_t A, B, C, D, E, F, G, H;
+
+#define  SHR(x,n) (x >> n)
+#define ROTR(x,n) (SHR(x,n) | (x << (64 - n)))
+
+#define S0(x) (ROTR(x, 1) ^ ROTR(x, 8) ^  SHR(x, 7))
+#define S1(x) (ROTR(x,19) ^ ROTR(x,61) ^  SHR(x, 6))
+
+#define S2(x) (ROTR(x,28) ^ ROTR(x,34) ^ ROTR(x,39))
+#define S3(x) (ROTR(x,14) ^ ROTR(x,18) ^ ROTR(x,41))
+
+#define F0(x,y,z) ((x & y) | (z & (x | y)))
+#define F1(x,y,z) (z ^ (x & (y ^ z)))
+
+#define P(a,b,c,d,e,f,g,h,x,K)                  \
+{                                               \
+    temp1 = h + S3(e) + F1(e,f,g) + K + x;      \
+    temp2 = S2(a) + F0(a,b,c);                  \
+    d += temp1; h = temp1 + temp2;              \
+}
+
+    for( i = 0; i < 16; i++ )
+    {
+        GET_UINT64_BE( W[i], data, i << 3 );
+    }
+
+    for( ; i < 80; i++ )
+    {
+        W[i] = S1(W[i -  2]) + W[i -  7] +
+               S0(W[i - 15]) + W[i - 16];
+    }
+
+    A = ctx->state[0];
+    B = ctx->state[1];
+    C = ctx->state[2];
+    D = ctx->state[3];
+    E = ctx->state[4];
+    F = ctx->state[5];
+    G = ctx->state[6];
+    H = ctx->state[7];
+    i = 0;
+
+    do
+    {
+        P( A, B, C, D, E, F, G, H, W[i], K[i] ); i++;
+        P( H, A, B, C, D, E, F, G, W[i], K[i] ); i++;
+        P( G, H, A, B, C, D, E, F, W[i], K[i] ); i++;
+        P( F, G, H, A, B, C, D, E, W[i], K[i] ); i++;
+        P( E, F, G, H, A, B, C, D, W[i], K[i] ); i++;
+        P( D, E, F, G, H, A, B, C, W[i], K[i] ); i++;
+        P( C, D, E, F, G, H, A, B, W[i], K[i] ); i++;
+        P( B, C, D, E, F, G, H, A, W[i], K[i] ); i++;
+    }
+    while( i < 80 );
+
+    ctx->state[0] += A;
+    ctx->state[1] += B;
+    ctx->state[2] += C;
+    ctx->state[3] += D;
+    ctx->state[4] += E;
+    ctx->state[5] += F;
+    ctx->state[6] += G;
+    ctx->state[7] += H;
+}
+#endif /* !MBEDTLS_SHA512_PROCESS_ALT */
+
+/*
+ * SHA-512 process buffer
+ */
+void mbedtls_sha512_update( mbedtls_sha512_context *ctx, const unsigned char *input,
+                    size_t ilen )
+{
+    size_t fill;
+    unsigned int left;
+
+    if( ilen == 0 )
+        return;
+
+    left = (unsigned int) (ctx->total[0] & 0x7F);
+    fill = 128 - left;
+
+    ctx->total[0] += (uint64_t) ilen;
+
+    if( ctx->total[0] < (uint64_t) ilen )
+        ctx->total[1]++;
+
+    if( left && ilen >= fill )
+    {
+        memcpy( (void *) (ctx->buffer + left), input, fill );
+        mbedtls_sha512_process( ctx, ctx->buffer );
+        input += fill;
+        ilen  -= fill;
+        left = 0;
+    }
+
+    while( ilen >= 128 )
+    {
+        mbedtls_sha512_process( ctx, input );
+        input += 128;
+        ilen  -= 128;
+    }
+
+    if( ilen > 0 )
+        memcpy( (void *) (ctx->buffer + left), input, ilen );
+}
+
+static const unsigned char sha512_padding[128] =
+{
+ 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+/*
+ * SHA-512 final digest
+ */
+void mbedtls_sha512_finish( mbedtls_sha512_context *ctx, unsigned char output[64] )
+{
+    size_t last, padn;
+    uint64_t high, low;
+    unsigned char msglen[16];
+
+    high = ( ctx->total[0] >> 61 )
+         | ( ctx->total[1] <<  3 );
+    low  = ( ctx->total[0] <<  3 );
+
+    PUT_UINT64_BE( high, msglen, 0 );
+    PUT_UINT64_BE( low,  msglen, 8 );
+
+    last = (size_t)( ctx->total[0] & 0x7F );
+    padn = ( last < 112 ) ? ( 112 - last ) : ( 240 - last );
+
+    mbedtls_sha512_update( ctx, sha512_padding, padn );
+    mbedtls_sha512_update( ctx, msglen, 16 );
+
+    PUT_UINT64_BE( ctx->state[0], output,  0 );
+    PUT_UINT64_BE( ctx->state[1], output,  8 );
+    PUT_UINT64_BE( ctx->state[2], output, 16 );
+    PUT_UINT64_BE( ctx->state[3], output, 24 );
+    PUT_UINT64_BE( ctx->state[4], output, 32 );
+    PUT_UINT64_BE( ctx->state[5], output, 40 );
+
+    if( ctx->is384 == 0 )
+    {
+        PUT_UINT64_BE( ctx->state[6], output, 48 );
+        PUT_UINT64_BE( ctx->state[7], output, 56 );
+    }
+}
+
+#endif /* !MBEDTLS_SHA512_ALT */
+
+/*
+ * output = SHA-512( input buffer )
+ */
+void mbedtls_sha512( const unsigned char *input, size_t ilen,
+             unsigned char output[64], int is384 )
+{
+    mbedtls_sha512_context ctx;
+
+    mbedtls_sha512_init( &ctx );
+    mbedtls_sha512_starts( &ctx, is384 );
+    mbedtls_sha512_update( &ctx, input, ilen );
+    mbedtls_sha512_finish( &ctx, output );
+    mbedtls_sha512_free( &ctx );
+}
+
+#if defined(MBEDTLS_SELF_TEST)
+
+/*
+ * FIPS-180-2 test vectors
+ */
+static const unsigned char sha512_test_buf[3][113] =
+{
+    { "abc" },
+    { "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmn"
+      "hijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu" },
+    { "" }
+};
+
+static const int sha512_test_buflen[3] =
+{
+    3, 112, 1000
+};
+
+static const unsigned char sha512_test_sum[6][64] =
+{
+    /*
+     * SHA-384 test vectors
+     */
+    { 0xCB, 0x00, 0x75, 0x3F, 0x45, 0xA3, 0x5E, 0x8B,
+      0xB5, 0xA0, 0x3D, 0x69, 0x9A, 0xC6, 0x50, 0x07,
+      0x27, 0x2C, 0x32, 0xAB, 0x0E, 0xDE, 0xD1, 0x63,
+      0x1A, 0x8B, 0x60, 0x5A, 0x43, 0xFF, 0x5B, 0xED,
+      0x80, 0x86, 0x07, 0x2B, 0xA1, 0xE7, 0xCC, 0x23,
+      0x58, 0xBA, 0xEC, 0xA1, 0x34, 0xC8, 0x25, 0xA7 },
+    { 0x09, 0x33, 0x0C, 0x33, 0xF7, 0x11, 0x47, 0xE8,
+      0x3D, 0x19, 0x2F, 0xC7, 0x82, 0xCD, 0x1B, 0x47,
+      0x53, 0x11, 0x1B, 0x17, 0x3B, 0x3B, 0x05, 0xD2,
+      0x2F, 0xA0, 0x80, 0x86, 0xE3, 0xB0, 0xF7, 0x12,
+      0xFC, 0xC7, 0xC7, 0x1A, 0x55, 0x7E, 0x2D, 0xB9,
+      0x66, 0xC3, 0xE9, 0xFA, 0x91, 0x74, 0x60, 0x39 },
+    { 0x9D, 0x0E, 0x18, 0x09, 0x71, 0x64, 0x74, 0xCB,
+      0x08, 0x6E, 0x83, 0x4E, 0x31, 0x0A, 0x4A, 0x1C,
+      0xED, 0x14, 0x9E, 0x9C, 0x00, 0xF2, 0x48, 0x52,
+      0x79, 0x72, 0xCE, 0xC5, 0x70, 0x4C, 0x2A, 0x5B,
+      0x07, 0xB8, 0xB3, 0xDC, 0x38, 0xEC, 0xC4, 0xEB,
+      0xAE, 0x97, 0xDD, 0xD8, 0x7F, 0x3D, 0x89, 0x85 },
+
+    /*
+     * SHA-512 test vectors
+     */
+    { 0xDD, 0xAF, 0x35, 0xA1, 0x93, 0x61, 0x7A, 0xBA,
+      0xCC, 0x41, 0x73, 0x49, 0xAE, 0x20, 0x41, 0x31,
+      0x12, 0xE6, 0xFA, 0x4E, 0x89, 0xA9, 0x7E, 0xA2,
+      0x0A, 0x9E, 0xEE, 0xE6, 0x4B, 0x55, 0xD3, 0x9A,
+      0x21, 0x92, 0x99, 0x2A, 0x27, 0x4F, 0xC1, 0xA8,
+      0x36, 0xBA, 0x3C, 0x23, 0xA3, 0xFE, 0xEB, 0xBD,
+      0x45, 0x4D, 0x44, 0x23, 0x64, 0x3C, 0xE8, 0x0E,
+      0x2A, 0x9A, 0xC9, 0x4F, 0xA5, 0x4C, 0xA4, 0x9F },
+    { 0x8E, 0x95, 0x9B, 0x75, 0xDA, 0xE3, 0x13, 0xDA,
+      0x8C, 0xF4, 0xF7, 0x28, 0x14, 0xFC, 0x14, 0x3F,
+      0x8F, 0x77, 0x79, 0xC6, 0xEB, 0x9F, 0x7F, 0xA1,
+      0x72, 0x99, 0xAE, 0xAD, 0xB6, 0x88, 0x90, 0x18,
+      0x50, 0x1D, 0x28, 0x9E, 0x49, 0x00, 0xF7, 0xE4,
+      0x33, 0x1B, 0x99, 0xDE, 0xC4, 0xB5, 0x43, 0x3A,
+      0xC7, 0xD3, 0x29, 0xEE, 0xB6, 0xDD, 0x26, 0x54,
+      0x5E, 0x96, 0xE5, 0x5B, 0x87, 0x4B, 0xE9, 0x09 },
+    { 0xE7, 0x18, 0x48, 0x3D, 0x0C, 0xE7, 0x69, 0x64,
+      0x4E, 0x2E, 0x42, 0xC7, 0xBC, 0x15, 0xB4, 0x63,
+      0x8E, 0x1F, 0x98, 0xB1, 0x3B, 0x20, 0x44, 0x28,
+      0x56, 0x32, 0xA8, 0x03, 0xAF, 0xA9, 0x73, 0xEB,
+      0xDE, 0x0F, 0xF2, 0x44, 0x87, 0x7E, 0xA6, 0x0A,
+      0x4C, 0xB0, 0x43, 0x2C, 0xE5, 0x77, 0xC3, 0x1B,
+      0xEB, 0x00, 0x9C, 0x5C, 0x2C, 0x49, 0xAA, 0x2E,
+      0x4E, 0xAD, 0xB2, 0x17, 0xAD, 0x8C, 0xC0, 0x9B }
+};
+
+/*
+ * Checkup routine
+ */
+int mbedtls_sha512_self_test( int verbose )
+{
+    int i, j, k, buflen, ret = 0;
+    unsigned char buf[1024];
+    unsigned char sha512sum[64];
+    mbedtls_sha512_context ctx;
+
+    mbedtls_sha512_init( &ctx );
+
+    for( i = 0; i < 6; i++ )
+    {
+        j = i % 3;
+        k = i < 3;
+
+        if( verbose != 0 )
+            mbedtls_printf( "  SHA-%d test #%d: ", 512 - k * 128, j + 1 );
+
+        mbedtls_sha512_starts( &ctx, k );
+
+        if( j == 2 )
+        {
+            memset( buf, 'a', buflen = 1000 );
+
+            for( j = 0; j < 1000; j++ )
+                mbedtls_sha512_update( &ctx, buf, buflen );
+        }
+        else
+            mbedtls_sha512_update( &ctx, sha512_test_buf[j],
+                                 sha512_test_buflen[j] );
+
+        mbedtls_sha512_finish( &ctx, sha512sum );
+
+        if( memcmp( sha512sum, sha512_test_sum[i], 64 - k * 16 ) != 0 )
+        {
+            if( verbose != 0 )
+                mbedtls_printf( "failed\n" );
+
+            ret = 1;
+            goto exit;
+        }
+
+        if( verbose != 0 )
+            mbedtls_printf( "passed\n" );
+    }
+
+    if( verbose != 0 )
+        mbedtls_printf( "\n" );
+
+exit:
+    mbedtls_sha512_free( &ctx );
+
+    return( ret );
+}
+
+#endif /* MBEDTLS_SELF_TEST */
diff --git a/libstb/drivers/sha512.h b/libstb/drivers/sha512.h
new file mode 100644
index 0000000..627694f
--- /dev/null
+++ b/libstb/drivers/sha512.h
@@ -0,0 +1,141 @@
+/**
+ * \file sha512.h
+ *
+ * \brief SHA-384 and SHA-512 cryptographic hash function
+ *
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+#ifndef MBEDTLS_SHA512_H
+#define MBEDTLS_SHA512_H
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#include <stddef.h>
+#include <stdint.h>
+
+#if !defined(MBEDTLS_SHA512_ALT)
+// Regular implementation
+//
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief          SHA-512 context structure
+ */
+typedef struct
+{
+    uint64_t total[2];          /*!< number of bytes processed  */
+    uint64_t state[8];          /*!< intermediate digest state  */
+    unsigned char buffer[128];  /*!< data block being processed */
+    int is384;                  /*!< 0 => SHA-512, else SHA-384 */
+}
+mbedtls_sha512_context;
+
+/**
+ * \brief          Initialize SHA-512 context
+ *
+ * \param ctx      SHA-512 context to be initialized
+ */
+void mbedtls_sha512_init( mbedtls_sha512_context *ctx );
+
+/**
+ * \brief          Clear SHA-512 context
+ *
+ * \param ctx      SHA-512 context to be cleared
+ */
+void mbedtls_sha512_free( mbedtls_sha512_context *ctx );
+
+/**
+ * \brief          Clone (the state of) a SHA-512 context
+ *
+ * \param dst      The destination context
+ * \param src      The context to be cloned
+ */
+void mbedtls_sha512_clone( mbedtls_sha512_context *dst,
+                           const mbedtls_sha512_context *src );
+
+/**
+ * \brief          SHA-512 context setup
+ *
+ * \param ctx      context to be initialized
+ * \param is384    0 = use SHA512, 1 = use SHA384
+ */
+void mbedtls_sha512_starts( mbedtls_sha512_context *ctx, int is384 );
+
+/**
+ * \brief          SHA-512 process buffer
+ *
+ * \param ctx      SHA-512 context
+ * \param input    buffer holding the  data
+ * \param ilen     length of the input data
+ */
+void mbedtls_sha512_update( mbedtls_sha512_context *ctx, const unsigned char *input,
+                    size_t ilen );
+
+/**
+ * \brief          SHA-512 final digest
+ *
+ * \param ctx      SHA-512 context
+ * \param output   SHA-384/512 checksum result
+ */
+void mbedtls_sha512_finish( mbedtls_sha512_context *ctx, unsigned char output[64] );
+
+#ifdef __cplusplus
+}
+#endif
+
+#else  /* MBEDTLS_SHA512_ALT */
+#include "sha512_alt.h"
+#endif /* MBEDTLS_SHA512_ALT */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief          Output = SHA-512( input buffer )
+ *
+ * \param input    buffer holding the  data
+ * \param ilen     length of the input data
+ * \param output   SHA-384/512 checksum result
+ * \param is384    0 = use SHA512, 1 = use SHA384
+ */
+void mbedtls_sha512( const unsigned char *input, size_t ilen,
+             unsigned char output[64], int is384 );
+
+/**
+ * \brief          Checkup routine
+ *
+ * \return         0 if successful, or 1 if the test failed
+ */
+int mbedtls_sha512_self_test( int verbose );
+
+/* Internal use */
+void mbedtls_sha512_process( mbedtls_sha512_context *ctx, const unsigned char data[128] );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* mbedtls_sha512.h */
diff --git a/libstb/drivers/sw_driver.c b/libstb/drivers/sw_driver.c
new file mode 100644
index 0000000..e7f3740
--- /dev/null
+++ b/libstb/drivers/sw_driver.c
@@ -0,0 +1,76 @@
+/* Copyright 2013-2016 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <chip.h>
+#include <string.h>
+#include <skiboot.h>
+#include "../rom.h"
+#include "sha512.h"
+#include "sw_driver.h"
+
+static sha2_hash_t *hw_key_hash = NULL;
+
+static int stb_software_verify(void *container __unused)
+{
+	return -100;
+}
+
+static void stb_software_sha512(const uint8_t *data, size_t len, uint8_t *digest)
+{
+	mbedtls_sha512_context ctx;
+	mbedtls_sha512_init(&ctx);
+	memset(digest, 0, sizeof(sha2_hash_t));
+	mbedtls_sha512_starts(&ctx, 0); // SHA512 = 0
+	mbedtls_sha512_update(&ctx, data, len);
+	mbedtls_sha512_finish(&ctx, digest);
+	mbedtls_sha512_free(&ctx);
+}
+
+static void stb_software_cleanup(void)
+{
+	return;
+}
+
+static struct rom_driver_ops sw_driver = {
+	.name    = "software",
+	.verify  = stb_software_verify,
+	.sha512  = stb_software_sha512,
+	.cleanup = stb_software_cleanup
+};
+
+void stb_software_probe(const struct dt_node *node)
+{
+	const char* hash_algo;
+
+	if (!dt_node_is_compatible(node, "ibm,secureboot-v1-softrom")) {
+		return;
+	}
+
+	hash_algo = dt_prop_get(node, "hash-algo");
+	if (strcmp(hash_algo, "sha512")) {
+		/**
+		 * @fwts-label ROMHashAlgorithmInvalid
+		 * @fwts-advice Hostboot creates the ibm,secureboot node and
+		 * the hash-algo property. Check that the ibm,secureboot node
+		 * layout has not changed.
+		 */
+		prlog(PR_ERR, "ROM: hash-algo=%s not expected\n", hash_algo);
+		return;
+	}
+	hw_key_hash = (sha2_hash_t*) dt_prop_get(node, "hw-key-hash");
+
+	rom_set_driver(&sw_driver);
+}
diff --git a/libstb/drivers/sw_driver.h b/libstb/drivers/sw_driver.h
new file mode 100644
index 0000000..73adabf
--- /dev/null
+++ b/libstb/drivers/sw_driver.h
@@ -0,0 +1,24 @@
+/* Copyright 2013-2016 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __SW_DRIVER_H
+#define __SW_DRIVER_H
+
+#include <device.h>
+
+extern void stb_software_probe(const struct dt_node *node);
+
+#endif /* __ROMCODE_H */
diff --git a/libstb/rom.c b/libstb/rom.c
index 217ef13..5f9abd2 100644
--- a/libstb/rom.c
+++ b/libstb/rom.c
@@ -17,6 +17,7 @@
 #include <skiboot.h>
 #include "rom.h"
 #include "drivers/romcode.h"
+#include "drivers/sw_driver.h"
 
 static struct rom_driver_ops *rom_driver = NULL;
 
@@ -29,6 +30,9 @@ struct rom_driver_ops* rom_init(const struct dt_node *node __unused)
 	romcode_probe(node);
 
 	if (!rom_driver)
+		stb_software_probe(node);
+
+	if (!rom_driver)
 		prlog(PR_NOTICE, "ROM: no rom driver found\n");
 end:
 	return rom_driver;