mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-18 06:40:49 +07:00
aacf29bf1b
Provide count_leading/trailing_zeros() macros based on extant arch bit scanning functions rather than reimplementing from scratch in MPILIB. Whilst we're at it, turn count_foo_zeros(n, x) into n = count_foo_zeros(x). Also move the definition to asm-generic as other people may be interested in using it. Signed-off-by: David Howells <dhowells@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Cc: Arnd Bergmann <arnd@arndb.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
324 lines
8.3 KiB
C
324 lines
8.3 KiB
C
/* mpi-pow.c - MPI functions
|
|
* Copyright (C) 1994, 1996, 1998, 2000 Free Software Foundation, Inc.
|
|
*
|
|
* This file is part of GnuPG.
|
|
*
|
|
* GnuPG is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* GnuPG is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
|
|
*
|
|
* Note: This code is heavily based on the GNU MP Library.
|
|
* Actually it's the same code with only minor changes in the
|
|
* way the data is stored; this is to support the abstraction
|
|
* of an optional secure memory allocation which may be used
|
|
* to avoid revealing of sensitive data due to paging etc.
|
|
* The GNU MP Library itself is published under the LGPL;
|
|
* however I decided to publish this code under the plain GPL.
|
|
*/
|
|
|
|
#include <linux/string.h>
|
|
#include "mpi-internal.h"
|
|
#include "longlong.h"
|
|
|
|
/****************
|
|
* RES = BASE ^ EXP mod MOD
|
|
*/
|
|
int mpi_powm(MPI res, MPI base, MPI exp, MPI mod)
|
|
{
|
|
mpi_ptr_t mp_marker = NULL, bp_marker = NULL, ep_marker = NULL;
|
|
mpi_ptr_t xp_marker = NULL;
|
|
mpi_ptr_t tspace = NULL;
|
|
mpi_ptr_t rp, ep, mp, bp;
|
|
mpi_size_t esize, msize, bsize, rsize;
|
|
int esign, msign, bsign, rsign;
|
|
mpi_size_t size;
|
|
int mod_shift_cnt;
|
|
int negative_result;
|
|
int assign_rp = 0;
|
|
mpi_size_t tsize = 0; /* to avoid compiler warning */
|
|
/* fixme: we should check that the warning is void */
|
|
int rc = -ENOMEM;
|
|
|
|
esize = exp->nlimbs;
|
|
msize = mod->nlimbs;
|
|
size = 2 * msize;
|
|
esign = exp->sign;
|
|
msign = mod->sign;
|
|
|
|
rp = res->d;
|
|
ep = exp->d;
|
|
|
|
if (!msize)
|
|
return -EINVAL;
|
|
|
|
if (!esize) {
|
|
/* Exponent is zero, result is 1 mod MOD, i.e., 1 or 0
|
|
* depending on if MOD equals 1. */
|
|
rp[0] = 1;
|
|
res->nlimbs = (msize == 1 && mod->d[0] == 1) ? 0 : 1;
|
|
res->sign = 0;
|
|
goto leave;
|
|
}
|
|
|
|
/* Normalize MOD (i.e. make its most significant bit set) as required by
|
|
* mpn_divrem. This will make the intermediate values in the calculation
|
|
* slightly larger, but the correct result is obtained after a final
|
|
* reduction using the original MOD value. */
|
|
mp = mp_marker = mpi_alloc_limb_space(msize);
|
|
if (!mp)
|
|
goto enomem;
|
|
mod_shift_cnt = count_leading_zeros(mod->d[msize - 1]);
|
|
if (mod_shift_cnt)
|
|
mpihelp_lshift(mp, mod->d, msize, mod_shift_cnt);
|
|
else
|
|
MPN_COPY(mp, mod->d, msize);
|
|
|
|
bsize = base->nlimbs;
|
|
bsign = base->sign;
|
|
if (bsize > msize) { /* The base is larger than the module. Reduce it. */
|
|
/* Allocate (BSIZE + 1) with space for remainder and quotient.
|
|
* (The quotient is (bsize - msize + 1) limbs.) */
|
|
bp = bp_marker = mpi_alloc_limb_space(bsize + 1);
|
|
if (!bp)
|
|
goto enomem;
|
|
MPN_COPY(bp, base->d, bsize);
|
|
/* We don't care about the quotient, store it above the remainder,
|
|
* at BP + MSIZE. */
|
|
mpihelp_divrem(bp + msize, 0, bp, bsize, mp, msize);
|
|
bsize = msize;
|
|
/* Canonicalize the base, since we are going to multiply with it
|
|
* quite a few times. */
|
|
MPN_NORMALIZE(bp, bsize);
|
|
} else
|
|
bp = base->d;
|
|
|
|
if (!bsize) {
|
|
res->nlimbs = 0;
|
|
res->sign = 0;
|
|
goto leave;
|
|
}
|
|
|
|
if (res->alloced < size) {
|
|
/* We have to allocate more space for RES. If any of the input
|
|
* parameters are identical to RES, defer deallocation of the old
|
|
* space. */
|
|
if (rp == ep || rp == mp || rp == bp) {
|
|
rp = mpi_alloc_limb_space(size);
|
|
if (!rp)
|
|
goto enomem;
|
|
assign_rp = 1;
|
|
} else {
|
|
if (mpi_resize(res, size) < 0)
|
|
goto enomem;
|
|
rp = res->d;
|
|
}
|
|
} else { /* Make BASE, EXP and MOD not overlap with RES. */
|
|
if (rp == bp) {
|
|
/* RES and BASE are identical. Allocate temp. space for BASE. */
|
|
BUG_ON(bp_marker);
|
|
bp = bp_marker = mpi_alloc_limb_space(bsize);
|
|
if (!bp)
|
|
goto enomem;
|
|
MPN_COPY(bp, rp, bsize);
|
|
}
|
|
if (rp == ep) {
|
|
/* RES and EXP are identical. Allocate temp. space for EXP. */
|
|
ep = ep_marker = mpi_alloc_limb_space(esize);
|
|
if (!ep)
|
|
goto enomem;
|
|
MPN_COPY(ep, rp, esize);
|
|
}
|
|
if (rp == mp) {
|
|
/* RES and MOD are identical. Allocate temporary space for MOD. */
|
|
BUG_ON(mp_marker);
|
|
mp = mp_marker = mpi_alloc_limb_space(msize);
|
|
if (!mp)
|
|
goto enomem;
|
|
MPN_COPY(mp, rp, msize);
|
|
}
|
|
}
|
|
|
|
MPN_COPY(rp, bp, bsize);
|
|
rsize = bsize;
|
|
rsign = bsign;
|
|
|
|
{
|
|
mpi_size_t i;
|
|
mpi_ptr_t xp;
|
|
int c;
|
|
mpi_limb_t e;
|
|
mpi_limb_t carry_limb;
|
|
struct karatsuba_ctx karactx;
|
|
|
|
xp = xp_marker = mpi_alloc_limb_space(2 * (msize + 1));
|
|
if (!xp)
|
|
goto enomem;
|
|
|
|
memset(&karactx, 0, sizeof karactx);
|
|
negative_result = (ep[0] & 1) && base->sign;
|
|
|
|
i = esize - 1;
|
|
e = ep[i];
|
|
c = count_leading_zeros(e);
|
|
e = (e << c) << 1; /* shift the exp bits to the left, lose msb */
|
|
c = BITS_PER_MPI_LIMB - 1 - c;
|
|
|
|
/* Main loop.
|
|
*
|
|
* Make the result be pointed to alternately by XP and RP. This
|
|
* helps us avoid block copying, which would otherwise be necessary
|
|
* with the overlap restrictions of mpihelp_divmod. With 50% probability
|
|
* the result after this loop will be in the area originally pointed
|
|
* by RP (==RES->d), and with 50% probability in the area originally
|
|
* pointed to by XP.
|
|
*/
|
|
|
|
for (;;) {
|
|
while (c) {
|
|
mpi_ptr_t tp;
|
|
mpi_size_t xsize;
|
|
|
|
/*if (mpihelp_mul_n(xp, rp, rp, rsize) < 0) goto enomem */
|
|
if (rsize < KARATSUBA_THRESHOLD)
|
|
mpih_sqr_n_basecase(xp, rp, rsize);
|
|
else {
|
|
if (!tspace) {
|
|
tsize = 2 * rsize;
|
|
tspace =
|
|
mpi_alloc_limb_space(tsize);
|
|
if (!tspace)
|
|
goto enomem;
|
|
} else if (tsize < (2 * rsize)) {
|
|
mpi_free_limb_space(tspace);
|
|
tsize = 2 * rsize;
|
|
tspace =
|
|
mpi_alloc_limb_space(tsize);
|
|
if (!tspace)
|
|
goto enomem;
|
|
}
|
|
mpih_sqr_n(xp, rp, rsize, tspace);
|
|
}
|
|
|
|
xsize = 2 * rsize;
|
|
if (xsize > msize) {
|
|
mpihelp_divrem(xp + msize, 0, xp, xsize,
|
|
mp, msize);
|
|
xsize = msize;
|
|
}
|
|
|
|
tp = rp;
|
|
rp = xp;
|
|
xp = tp;
|
|
rsize = xsize;
|
|
|
|
if ((mpi_limb_signed_t) e < 0) {
|
|
/*mpihelp_mul( xp, rp, rsize, bp, bsize ); */
|
|
if (bsize < KARATSUBA_THRESHOLD) {
|
|
mpi_limb_t tmp;
|
|
if (mpihelp_mul
|
|
(xp, rp, rsize, bp, bsize,
|
|
&tmp) < 0)
|
|
goto enomem;
|
|
} else {
|
|
if (mpihelp_mul_karatsuba_case
|
|
(xp, rp, rsize, bp, bsize,
|
|
&karactx) < 0)
|
|
goto enomem;
|
|
}
|
|
|
|
xsize = rsize + bsize;
|
|
if (xsize > msize) {
|
|
mpihelp_divrem(xp + msize, 0,
|
|
xp, xsize, mp,
|
|
msize);
|
|
xsize = msize;
|
|
}
|
|
|
|
tp = rp;
|
|
rp = xp;
|
|
xp = tp;
|
|
rsize = xsize;
|
|
}
|
|
e <<= 1;
|
|
c--;
|
|
}
|
|
|
|
i--;
|
|
if (i < 0)
|
|
break;
|
|
e = ep[i];
|
|
c = BITS_PER_MPI_LIMB;
|
|
}
|
|
|
|
/* We shifted MOD, the modulo reduction argument, left MOD_SHIFT_CNT
|
|
* steps. Adjust the result by reducing it with the original MOD.
|
|
*
|
|
* Also make sure the result is put in RES->d (where it already
|
|
* might be, see above).
|
|
*/
|
|
if (mod_shift_cnt) {
|
|
carry_limb =
|
|
mpihelp_lshift(res->d, rp, rsize, mod_shift_cnt);
|
|
rp = res->d;
|
|
if (carry_limb) {
|
|
rp[rsize] = carry_limb;
|
|
rsize++;
|
|
}
|
|
} else {
|
|
MPN_COPY(res->d, rp, rsize);
|
|
rp = res->d;
|
|
}
|
|
|
|
if (rsize >= msize) {
|
|
mpihelp_divrem(rp + msize, 0, rp, rsize, mp, msize);
|
|
rsize = msize;
|
|
}
|
|
|
|
/* Remove any leading zero words from the result. */
|
|
if (mod_shift_cnt)
|
|
mpihelp_rshift(rp, rp, rsize, mod_shift_cnt);
|
|
MPN_NORMALIZE(rp, rsize);
|
|
|
|
mpihelp_release_karatsuba_ctx(&karactx);
|
|
}
|
|
|
|
if (negative_result && rsize) {
|
|
if (mod_shift_cnt)
|
|
mpihelp_rshift(mp, mp, msize, mod_shift_cnt);
|
|
mpihelp_sub(rp, mp, msize, rp, rsize);
|
|
rsize = msize;
|
|
rsign = msign;
|
|
MPN_NORMALIZE(rp, rsize);
|
|
}
|
|
res->nlimbs = rsize;
|
|
res->sign = rsign;
|
|
|
|
leave:
|
|
rc = 0;
|
|
enomem:
|
|
if (assign_rp)
|
|
mpi_assign_limb_space(res, rp, size);
|
|
if (mp_marker)
|
|
mpi_free_limb_space(mp_marker);
|
|
if (bp_marker)
|
|
mpi_free_limb_space(bp_marker);
|
|
if (ep_marker)
|
|
mpi_free_limb_space(ep_marker);
|
|
if (xp_marker)
|
|
mpi_free_limb_space(xp_marker);
|
|
if (tspace)
|
|
mpi_free_limb_space(tspace);
|
|
return rc;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_powm);
|