From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- lib/crypto/mpi/mpi-bit.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 177 insertions(+) create mode 100644 lib/crypto/mpi/mpi-bit.c (limited to 'lib/crypto/mpi/mpi-bit.c') diff --git a/lib/crypto/mpi/mpi-bit.c b/lib/crypto/mpi/mpi-bit.c new file mode 100644 index 000000000..b3d0e7ddb --- /dev/null +++ b/lib/crypto/mpi/mpi-bit.c @@ -0,0 +1,177 @@ +/* mpi-bit.c - MPI bit level functions + * Copyright (C) 1998, 1999 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 + */ + +#include + +#include "mpi-internal.h" +#include "longlong.h" + +#define A_LIMB_1 ((mpi_limb_t) 1) + +/**************** + * Sometimes we have MSL (most significant limbs) which are 0; + * this is for some reasons not good, so this function removes them. + */ +void mpi_normalize(MPI a) +{ + for (; a->nlimbs && !a->d[a->nlimbs - 1]; a->nlimbs--) + ; +} + +/**************** + * Return the number of bits in A. + */ +unsigned mpi_get_nbits(MPI a) +{ + unsigned n; + + mpi_normalize(a); + + if (a->nlimbs) { + mpi_limb_t alimb = a->d[a->nlimbs - 1]; + if (alimb) + n = count_leading_zeros(alimb); + else + n = BITS_PER_MPI_LIMB; + n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB; + } else + n = 0; + return n; +} +EXPORT_SYMBOL_GPL(mpi_get_nbits); + +/**************** + * Test whether bit N is set. + */ +int mpi_test_bit(MPI a, unsigned int n) +{ + unsigned int limbno, bitno; + mpi_limb_t limb; + + limbno = n / BITS_PER_MPI_LIMB; + bitno = n % BITS_PER_MPI_LIMB; + + if (limbno >= a->nlimbs) + return 0; /* too far left: this is a 0 */ + limb = a->d[limbno]; + return (limb & (A_LIMB_1 << bitno)) ? 1 : 0; +} +EXPORT_SYMBOL_GPL(mpi_test_bit); + +/**************** + * Set bit N of A. + */ +int mpi_set_bit(MPI a, unsigned int n) +{ + unsigned int i, limbno, bitno; + int err; + + limbno = n / BITS_PER_MPI_LIMB; + bitno = n % BITS_PER_MPI_LIMB; + + if (limbno >= a->nlimbs) { + for (i = a->nlimbs; i < a->alloced; i++) + a->d[i] = 0; + err = mpi_resize(a, limbno+1); + if (err) + return err; + a->nlimbs = limbno+1; + } + a->d[limbno] |= (A_LIMB_1<= x->nlimbs) { + x->nlimbs = 0; + return 0; + } + + if (nlimbs) { + for (i = 0; i < x->nlimbs - nlimbs; i++) + x->d[i] = x->d[i+nlimbs]; + x->d[i] = 0; + x->nlimbs -= nlimbs; + } + if (x->nlimbs && nbits) + mpihelp_rshift(x->d, x->d, x->nlimbs, nbits); + } else if (nlimbs) { + /* Copy and shift by more or equal bits than in a limb. */ + xsize = a->nlimbs; + x->sign = a->sign; + err = RESIZE_IF_NEEDED(x, xsize); + if (err) + return err; + x->nlimbs = xsize; + for (i = 0; i < a->nlimbs; i++) + x->d[i] = a->d[i]; + x->nlimbs = i; + + if (nlimbs >= x->nlimbs) { + x->nlimbs = 0; + return 0; + } + + for (i = 0; i < x->nlimbs - nlimbs; i++) + x->d[i] = x->d[i+nlimbs]; + x->d[i] = 0; + x->nlimbs -= nlimbs; + + if (x->nlimbs && nbits) + mpihelp_rshift(x->d, x->d, x->nlimbs, nbits); + } else { + /* Copy and shift by less than bits in a limb. */ + xsize = a->nlimbs; + x->sign = a->sign; + err = RESIZE_IF_NEEDED(x, xsize); + if (err) + return err; + x->nlimbs = xsize; + + if (xsize) { + if (nbits) + mpihelp_rshift(x->d, a->d, x->nlimbs, nbits); + else { + /* The rshift helper function is not specified for + * NBITS==0, thus we do a plain copy here. + */ + for (i = 0; i < x->nlimbs; i++) + x->d[i] = a->d[i]; + } + } + } + MPN_NORMALIZE(x->d, x->nlimbs); + + return 0; +} +EXPORT_SYMBOL_GPL(mpi_rshift); -- cgit v1.3.1