cr50: move several few static inline functions into dcrypto/internal.hstabilize-14238.B-cr50_stab

Several functions like lo32(), hi32(), clz() were defined into bn.c,
but clz and ctz are used in fips_rand.c. Move these functions into
internal.h to allow reuse.

Both __builtin_ctz() and __builtin_clz() have undefined behavior for
argument which is zero. Explicitly set result to 32 in such case. It
was the case for __builtin_clz() in bn.c, but not for variants used
in TRNG health tests.

BUG=None
TEST=make BOARD=cr50 CRYPTO_TEST=1; TCG tests

Signed-off-by: Vadim Sukhomlinov <sukhomlinov@google.com>
Change-Id: Ifc6fa7f820080bdad0f14fc079163f4976369724
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3174592
Reviewed-by: Vadim Sukhomlinov <sukhomlinov@chromium.org>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>
Tested-by: Vadim Sukhomlinov <sukhomlinov@chromium.org>
Commit-Queue: Vadim Sukhomlinov <sukhomlinov@chromium.org>

3 files changed, 43 insertions, 35 deletions

diff --git a/board/cr50/dcrypto/bn.c b/board/cr50/dcrypto/bn.c
index 446d2b98eb..4fecca8295 100644
--- a/board/cr50/dcrypto/bn.c
+++ b/board/cr50/dcrypto/bn.c
@@ -503,35 +503,6 @@ static void bn_mul_ex(struct LITE_BIGNUM *c,
 	BN_DIGIT(c, i + b->dmax - 1) = carry;
 }
 
-/* Functions to convert between uint32_t and uint64_t */
-static inline uint32_t lo32(uint64_t v)
-{
-	return (uint32_t)v;
-}
-static inline uint32_t hi32(uint64_t v)
-{
-	return (uint32_t)(v >> 32);
-}
-static inline uint64_t make64(uint32_t hi, uint32_t lo)
-{
-	return (((uint64_t)hi) << 32) | lo;
-}
-
-static inline uint32_t lo16(uint32_t v)
-{
-	return (uint32_t)(v)&0xffff;
-}
-
-static inline uint32_t hi16(uint32_t v)
-{
-	return (uint32_t)(v >> 16);
-}
-
-/* make Clang's host behavior of clz match Soteria and avoid UBSAN error */
-static inline int clz(unsigned int x)
-{
-	return (x) ? __builtin_clz(x) : 32;
-}
 
 /**
  * Unsigned division of 64-bit integer with 32-bit divisor, used to implement
@@ -590,7 +561,7 @@ uint64_t udiv32(uint64_t n, uint32_t d0)
 	if (d0 == 0 || n1 == 0)
 		return n0 / d0;
 
-	bm = clz(d0);
+	bm = count_leading_zeros(d0);
 	if (d0 > n1) { /* 0q = nn / 0D */
 		/* make the most significant bit of the denominator set. */
 		if (bm != 0) {
@@ -671,7 +642,7 @@ static int bn_div_ex(struct LITE_BIGNUM *q,
 		return bn_div_word_ex(q, r, u, m, vtop);
 
 	/* Compute shift factor to make v have high bit set */
-	s = clz(vtop);
+	s = count_leading_zeros(vtop);
 	vtop <<= s;
 
 	/* Normalize u and v into un and vn.
diff --git a/board/cr50/dcrypto/fips_rand.c b/board/cr50/dcrypto/fips_rand.c
index 4529a1cfbf..e3dcf4d298 100644
--- a/board/cr50/dcrypto/fips_rand.c
+++ b/board/cr50/dcrypto/fips_rand.c
@@ -63,11 +63,12 @@ static struct {
 static bool repetition_count_test(uint32_t rnd)
 {
 	uint32_t clz, ctz, clo, cto;
+
 	/* count repeating 0 and 1 bits from each side */
-	clz = __builtin_clz(rnd);  /* # of leading 0s */
-	ctz = __builtin_ctz(rnd);  /* # of trailing 0s */
-	clo = __builtin_clz(~rnd); /* # of leading 1s */
-	cto = __builtin_ctz(~rnd); /* # of trailing 1s */
+	clz = count_leading_zeros(rnd);  /* # of leading 0s */
+	ctz = count_trailing_zeros(rnd);  /* # of trailing 0s */
+	clo = count_leading_zeros(~rnd); /* # of leading 1s */
+	cto = count_trailing_zeros(~rnd); /* # of trailing 1s */
 
 	/**
 	 * check that number of trailing 0/1 in current sample added to
diff --git a/board/cr50/dcrypto/internal.h b/board/cr50/dcrypto/internal.h
index e07389542c..7d64fc69b3 100644
--- a/board/cr50/dcrypto/internal.h
+++ b/board/cr50/dcrypto/internal.h
@@ -340,6 +340,42 @@ static inline uint64_t rol64(uint64_t value, int bits)
 	return (value << bits) | (value >> (64 - bits));
 }
 
+/* Functions to convert between uint32_t and uint64_t */
+static inline uint32_t lo32(uint64_t v)
+{
+	return (uint32_t)v;
+}
+static inline uint32_t hi32(uint64_t v)
+{
+	return (uint32_t)(v >> 32);
+}
+static inline uint64_t make64(uint32_t hi, uint32_t lo)
+{
+	return (((uint64_t)hi) << 32) | lo;
+}
+
+static inline uint32_t lo16(uint32_t v)
+{
+	return (uint32_t)(v)&0xffff;
+}
+
+static inline uint32_t hi16(uint32_t v)
+{
+	return (uint32_t)(v >> 16);
+}
+
+static inline int count_leading_zeros(uint32_t x)
+{
+	/* __builtin_clz(0) is undefined, so explicitly return bit size. */
+	return (x) ? __builtin_clz(x) : 32;
+}
+
+static inline int count_trailing_zeros(uint32_t x)
+{
+	/* __builtin_ctz(0) is undefined, so explicitly return bit size. */
+	return (x) ? __builtin_ctz(x) : 32;
+}
+
 /* stack based allocation */
 #ifndef alloca
 #define alloca __builtin_alloca