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39db721f9a
This function will be used to generate some entropy using the
Clock Recovery System.
BRANCH=none
BUG=b:38486828
TEST=make BOARD=hammer -j tests
./util/flash_ec --board=hammer --image=build/hammer/test-entropy.bin
EC console: runtest
TEST=Test fails when no USB connection is active
TEST=Test passes when USB connection is active
TEST=Pasting the values into:
tr ';' '\n' | awk 'BEGIN { e = 0; tot=16384.0 }
{ p = $1/tot; if (p > 0) { e -= p*log(p)/log(2) } }
END { print e }'
shows an entropy > 4 bits per sample.
Change-Id: I2363c7bce42c72c33ef0bf3f099d709ee9c13d13
Reviewed-on: https://chromium-review.googlesource.com/518608
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
61 lines
1.3 KiB
C
61 lines
1.3 KiB
C
/* Copyright 2017 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*
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* Tests entropy source.
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*/
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#include "console.h"
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#include "common.h"
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#include "rollback.h"
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#include "test_util.h"
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#include "timer.h"
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#include "util.h"
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#include "watchdog.h"
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static int buckets[256];
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void run_test(void)
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{
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const int loopcount = 512;
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uint8_t buffer[32];
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timestamp_t t0, t1;
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int i, j;
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memset(buckets, 0, sizeof(buckets));
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for (i = 0; i < loopcount; i++) {
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t0 = get_time();
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if (!board_get_entropy(buffer, sizeof(buffer))) {
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ccprintf("Cannot get entropy\n");
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test_fail();
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return;
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}
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t1 = get_time();
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if (i == 0)
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ccprintf("Got %d bytes in %ld us\n",
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sizeof(buffer), t1.val - t0.val);
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for (j = 0; j < sizeof(buffer); j++)
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buckets[buffer[j]]++;
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watchdog_reload();
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}
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ccprintf("Total count: %d\n", loopcount * sizeof(buffer));
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ccprintf("Buckets: ");
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for (j = 0; j < 256; j++) {
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ccprintf("%d;", buckets[j]);
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cflush();
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}
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ccprintf("\n");
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/*
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* From the data above, entropy can be obtained with this command:
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* tr ';' '\n' | awk 'BEGIN { e = 0; tot=16384.0 }
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{ p = $1/tot; if (p > 0) { e -= p*log(p)/log(2) } }
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END { print e }'
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*/
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test_pass();
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}
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