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| author |   Jason A. Donenfeld <Jason@zx2c4.com> | 2018-03-02 03:59:48 +0100 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2018-03-02 03:59:48 +0100 |
| commit | 903d255f48e66535bf27ef29897e1e65836f2296 (patch) | |
| tree | 1c11be08d91995b0cebe8f901f83182f13b066f3 | |
| parent | Precomp changes from upstream (diff) | |
| download | kbench9000-903d255f48e66535bf27ef29897e1e65836f2296.tar.xz kbench9000-903d255f48e66535bf27ef29897e1e65836f2296.zip | |
precomp: use asm cselect
| -rw-r--r-- | curve25519-precomp.c | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/curve25519-precomp.c b/curve25519-precomp.c index a794bf9..457b428 100644 --- a/curve25519-precomp.c +++ b/curve25519-precomp.c @@ -1647,16 +1647,18 @@ static __always_inline void fred_eltfp25519_1w(u64 *const c) : "memory", "cc", "%rax", "%rbx", "%rcx", "%rdx"); } -static __always_inline void cswap(u64 bit, u64 *const px, u64 *const py) +static __always_inline void cselect(u8 bit, u64 *const px, u64 *const py) { - int i; - u64 mask = 0ULL - bit; - - for (i = 0; i < NUM_WORDS_ELTFP25519; ++i) { - u64 t = mask & (px[i] ^ py[i]); - px[i] = px[i] ^ t; - py[i] = py[i] ^ t; - } + __asm__ __volatile__ ( + "test %4, %4 ;" + "cmovnzq %5, %0 ;" + "cmovnzq %6, %1 ;" + "cmovnzq %7, %2 ;" + "cmovnzq %8, %3 ;" + : "+r"(px[0]), "+r"(px[1]), "+r"(px[2]), "+r"(px[3]) + : "r"(bit), "rm"(py[0]), "rm"(py[1]), "rm"(py[2]), "rm"(py[3]) + : "cc" + ); } bool curve25519_precomp_adx(u8 shared[CURVE25519_POINT_SIZE], const u8 private_key[CURVE25519_POINT_SIZE], const u8 session_key[CURVE25519_POINT_SIZE]) @@ -1732,8 +1734,8 @@ bool curve25519_precomp_adx(u8 shared[CURVE25519_POINT_SIZE], const u8 private_k sub_eltfp25519_1w(D, X3, Z3); /* D = (X3-Z3) */ mul_eltfp25519_2w_adx(DACB, AB, DC); /* [DA|CB] = [A|B]*[D|C] */ - cswap(swap, A, C); - cswap(swap, B, D); + cselect(swap, A, C); + cselect(swap, B, D); sqr_eltfp25519_2w_adx(AB); /* [AA|BB] = [A^2|B^2] */ add_eltfp25519_1w_adx(X3, DA, CB); /* X3 = (DA+CB) */ @@ -1832,8 +1834,8 @@ bool curve25519_precomp_bmi2(u8 shared[CURVE25519_POINT_SIZE], const u8 private_ sub_eltfp25519_1w(D, X3, Z3); /* D = (X3-Z3) */ mul_eltfp25519_2w_bmi2(DACB, AB, DC); /* [DA|CB] = [A|B]*[D|C] */ - cswap(swap, A, C); - cswap(swap, B, D); + cselect(swap, A, C); + cselect(swap, B, D); sqr_eltfp25519_2w_bmi2(AB); /* [AA|BB] = [A^2|B^2] */ add_eltfp25519_1w_bmi2(X3, DA, CB); /* X3 = (DA+CB) */ |