diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-01-10 21:51:23 -0800 | 
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-01-10 21:51:23 -0800 | 
| commit | e7691a1ce341c80ed9504244a36b31c025217391 (patch) | |
| tree | e9941bb350f64a726130e299c411821da6f41a53 /lib/mpi/mpih-div.c | |
| parent | 5cd9599bba428762025db6027764f1c59d0b1e1b (diff) | |
| parent | 8fcc99549522fc7a0bbaeb5755855ab0d9a59ce8 (diff) | |
Merge branch 'for-linus' of git://selinuxproject.org/~jmorris/linux-security
* 'for-linus' of git://selinuxproject.org/~jmorris/linux-security: (32 commits)
  ima: fix invalid memory reference
  ima: free duplicate measurement memory
  security: update security_file_mmap() docs
  selinux: Casting (void *) value returned by kmalloc is useless
  apparmor: fix module parameter handling
  Security: tomoyo: add .gitignore file
  tomoyo: add missing rcu_dereference()
  apparmor: add missing rcu_dereference()
  evm: prevent racing during tfm allocation
  evm: key must be set once during initialization
  mpi/mpi-mpow: NULL dereference on allocation failure
  digsig: build dependency fix
  KEYS: Give key types their own lockdep class for key->sem
  TPM: fix transmit_cmd error logic
  TPM: NSC and TIS drivers X86 dependency fix
  TPM: Export wait_for_stat for other vendor specific drivers
  TPM: Use vendor specific function for status probe
  tpm_tis: add delay after aborting command
  tpm_tis: Check return code from getting timeouts/durations
  tpm: Introduce function to poll for result of self test
  ...
Fix up trivial conflict in lib/Makefile due to addition of CONFIG_MPI
and SIGSIG next to CONFIG_DQL addition.
Diffstat (limited to 'lib/mpi/mpih-div.c')
| -rw-r--r-- | lib/mpi/mpih-div.c | 541 | 
1 files changed, 541 insertions, 0 deletions
diff --git a/lib/mpi/mpih-div.c b/lib/mpi/mpih-div.c new file mode 100644 index 000000000000..87ede162dfab --- /dev/null +++ b/lib/mpi/mpih-div.c @@ -0,0 +1,541 @@ +/* mpihelp-div.c  -  MPI helper functions + *	Copyright (C) 1994, 1996 Free Software Foundation, Inc. + *	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 + * + * 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 "mpi-internal.h" +#include "longlong.h" + +#ifndef UMUL_TIME +#define UMUL_TIME 1 +#endif +#ifndef UDIV_TIME +#define UDIV_TIME UMUL_TIME +#endif + +/* FIXME: We should be using invert_limb (or invert_normalized_limb) + * here (not udiv_qrnnd). + */ + +mpi_limb_t +mpihelp_mod_1(mpi_ptr_t dividend_ptr, mpi_size_t dividend_size, +	      mpi_limb_t divisor_limb) +{ +	mpi_size_t i; +	mpi_limb_t n1, n0, r; +	int dummy; + +	/* Botch: Should this be handled at all?  Rely on callers?  */ +	if (!dividend_size) +		return 0; + +	/* If multiplication is much faster than division, and the +	 * dividend is large, pre-invert the divisor, and use +	 * only multiplications in the inner loop. +	 * +	 * This test should be read: +	 *   Does it ever help to use udiv_qrnnd_preinv? +	 *     && Does what we save compensate for the inversion overhead? +	 */ +	if (UDIV_TIME > (2 * UMUL_TIME + 6) +	    && (UDIV_TIME - (2 * UMUL_TIME + 6)) * dividend_size > UDIV_TIME) { +		int normalization_steps; + +		count_leading_zeros(normalization_steps, divisor_limb); +		if (normalization_steps) { +			mpi_limb_t divisor_limb_inverted; + +			divisor_limb <<= normalization_steps; + +			/* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB.  The +			 * result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the +			 * most significant bit (with weight 2**N) implicit. +			 * +			 * Special case for DIVISOR_LIMB == 100...000. +			 */ +			if (!(divisor_limb << 1)) +				divisor_limb_inverted = ~(mpi_limb_t) 0; +			else +				udiv_qrnnd(divisor_limb_inverted, dummy, +					   -divisor_limb, 0, divisor_limb); + +			n1 = dividend_ptr[dividend_size - 1]; +			r = n1 >> (BITS_PER_MPI_LIMB - normalization_steps); + +			/* Possible optimization: +			 * if (r == 0 +			 * && divisor_limb > ((n1 << normalization_steps) +			 *                 | (dividend_ptr[dividend_size - 2] >> ...))) +			 * ...one division less... +			 */ +			for (i = dividend_size - 2; i >= 0; i--) { +				n0 = dividend_ptr[i]; +				UDIV_QRNND_PREINV(dummy, r, r, +						  ((n1 << normalization_steps) +						   | (n0 >> +						      (BITS_PER_MPI_LIMB - +						       normalization_steps))), +						  divisor_limb, +						  divisor_limb_inverted); +				n1 = n0; +			} +			UDIV_QRNND_PREINV(dummy, r, r, +					  n1 << normalization_steps, +					  divisor_limb, divisor_limb_inverted); +			return r >> normalization_steps; +		} else { +			mpi_limb_t divisor_limb_inverted; + +			/* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB.  The +			 * result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the +			 * most significant bit (with weight 2**N) implicit. +			 * +			 * Special case for DIVISOR_LIMB == 100...000. +			 */ +			if (!(divisor_limb << 1)) +				divisor_limb_inverted = ~(mpi_limb_t) 0; +			else +				udiv_qrnnd(divisor_limb_inverted, dummy, +					   -divisor_limb, 0, divisor_limb); + +			i = dividend_size - 1; +			r = dividend_ptr[i]; + +			if (r >= divisor_limb) +				r = 0; +			else +				i--; + +			for (; i >= 0; i--) { +				n0 = dividend_ptr[i]; +				UDIV_QRNND_PREINV(dummy, r, r, +						  n0, divisor_limb, +						  divisor_limb_inverted); +			} +			return r; +		} +	} else { +		if (UDIV_NEEDS_NORMALIZATION) { +			int normalization_steps; + +			count_leading_zeros(normalization_steps, divisor_limb); +			if (normalization_steps) { +				divisor_limb <<= normalization_steps; + +				n1 = dividend_ptr[dividend_size - 1]; +				r = n1 >> (BITS_PER_MPI_LIMB - +					   normalization_steps); + +				/* Possible optimization: +				 * if (r == 0 +				 * && divisor_limb > ((n1 << normalization_steps) +				 *                 | (dividend_ptr[dividend_size - 2] >> ...))) +				 * ...one division less... +				 */ +				for (i = dividend_size - 2; i >= 0; i--) { +					n0 = dividend_ptr[i]; +					udiv_qrnnd(dummy, r, r, +						   ((n1 << normalization_steps) +						    | (n0 >> +						       (BITS_PER_MPI_LIMB - +							normalization_steps))), +						   divisor_limb); +					n1 = n0; +				} +				udiv_qrnnd(dummy, r, r, +					   n1 << normalization_steps, +					   divisor_limb); +				return r >> normalization_steps; +			} +		} +		/* No normalization needed, either because udiv_qrnnd doesn't require +		 * it, or because DIVISOR_LIMB is already normalized.  */ +		i = dividend_size - 1; +		r = dividend_ptr[i]; + +		if (r >= divisor_limb) +			r = 0; +		else +			i--; + +		for (; i >= 0; i--) { +			n0 = dividend_ptr[i]; +			udiv_qrnnd(dummy, r, r, n0, divisor_limb); +		} +		return r; +	} +} + +/* Divide num (NP/NSIZE) by den (DP/DSIZE) and write + * the NSIZE-DSIZE least significant quotient limbs at QP + * and the DSIZE long remainder at NP.	If QEXTRA_LIMBS is + * non-zero, generate that many fraction bits and append them after the + * other quotient limbs. + * Return the most significant limb of the quotient, this is always 0 or 1. + * + * Preconditions: + * 0. NSIZE >= DSIZE. + * 1. The most significant bit of the divisor must be set. + * 2. QP must either not overlap with the input operands at all, or + *    QP + DSIZE >= NP must hold true.	(This means that it's + *    possible to put the quotient in the high part of NUM, right after the + *    remainder in NUM. + * 3. NSIZE >= DSIZE, even if QEXTRA_LIMBS is non-zero. + */ + +mpi_limb_t +mpihelp_divrem(mpi_ptr_t qp, mpi_size_t qextra_limbs, +	       mpi_ptr_t np, mpi_size_t nsize, mpi_ptr_t dp, mpi_size_t dsize) +{ +	mpi_limb_t most_significant_q_limb = 0; + +	switch (dsize) { +	case 0: +		/* We are asked to divide by zero, so go ahead and do it!  (To make +		   the compiler not remove this statement, return the value.)  */ +		return 1 / dsize; + +	case 1: +		{ +			mpi_size_t i; +			mpi_limb_t n1; +			mpi_limb_t d; + +			d = dp[0]; +			n1 = np[nsize - 1]; + +			if (n1 >= d) { +				n1 -= d; +				most_significant_q_limb = 1; +			} + +			qp += qextra_limbs; +			for (i = nsize - 2; i >= 0; i--) +				udiv_qrnnd(qp[i], n1, n1, np[i], d); +			qp -= qextra_limbs; + +			for (i = qextra_limbs - 1; i >= 0; i--) +				udiv_qrnnd(qp[i], n1, n1, 0, d); + +			np[0] = n1; +		} +		break; + +	case 2: +		{ +			mpi_size_t i; +			mpi_limb_t n1, n0, n2; +			mpi_limb_t d1, d0; + +			np += nsize - 2; +			d1 = dp[1]; +			d0 = dp[0]; +			n1 = np[1]; +			n0 = np[0]; + +			if (n1 >= d1 && (n1 > d1 || n0 >= d0)) { +				sub_ddmmss(n1, n0, n1, n0, d1, d0); +				most_significant_q_limb = 1; +			} + +			for (i = qextra_limbs + nsize - 2 - 1; i >= 0; i--) { +				mpi_limb_t q; +				mpi_limb_t r; + +				if (i >= qextra_limbs) +					np--; +				else +					np[0] = 0; + +				if (n1 == d1) { +					/* Q should be either 111..111 or 111..110.  Need special +					 * treatment of this rare case as normal division would +					 * give overflow.  */ +					q = ~(mpi_limb_t) 0; + +					r = n0 + d1; +					if (r < d1) {	/* Carry in the addition? */ +						add_ssaaaa(n1, n0, r - d0, +							   np[0], 0, d0); +						qp[i] = q; +						continue; +					} +					n1 = d0 - (d0 != 0 ? 1 : 0); +					n0 = -d0; +				} else { +					udiv_qrnnd(q, r, n1, n0, d1); +					umul_ppmm(n1, n0, d0, q); +				} + +				n2 = np[0]; +q_test: +				if (n1 > r || (n1 == r && n0 > n2)) { +					/* The estimated Q was too large.  */ +					q--; +					sub_ddmmss(n1, n0, n1, n0, 0, d0); +					r += d1; +					if (r >= d1)	/* If not carry, test Q again.  */ +						goto q_test; +				} + +				qp[i] = q; +				sub_ddmmss(n1, n0, r, n2, n1, n0); +			} +			np[1] = n1; +			np[0] = n0; +		} +		break; + +	default: +		{ +			mpi_size_t i; +			mpi_limb_t dX, d1, n0; + +			np += nsize - dsize; +			dX = dp[dsize - 1]; +			d1 = dp[dsize - 2]; +			n0 = np[dsize - 1]; + +			if (n0 >= dX) { +				if (n0 > dX +				    || mpihelp_cmp(np, dp, dsize - 1) >= 0) { +					mpihelp_sub_n(np, np, dp, dsize); +					n0 = np[dsize - 1]; +					most_significant_q_limb = 1; +				} +			} + +			for (i = qextra_limbs + nsize - dsize - 1; i >= 0; i--) { +				mpi_limb_t q; +				mpi_limb_t n1, n2; +				mpi_limb_t cy_limb; + +				if (i >= qextra_limbs) { +					np--; +					n2 = np[dsize]; +				} else { +					n2 = np[dsize - 1]; +					MPN_COPY_DECR(np + 1, np, dsize - 1); +					np[0] = 0; +				} + +				if (n0 == dX) { +					/* This might over-estimate q, but it's probably not worth +					 * the extra code here to find out.  */ +					q = ~(mpi_limb_t) 0; +				} else { +					mpi_limb_t r; + +					udiv_qrnnd(q, r, n0, np[dsize - 1], dX); +					umul_ppmm(n1, n0, d1, q); + +					while (n1 > r +					       || (n1 == r +						   && n0 > np[dsize - 2])) { +						q--; +						r += dX; +						if (r < dX)	/* I.e. "carry in previous addition?" */ +							break; +						n1 -= n0 < d1; +						n0 -= d1; +					} +				} + +				/* Possible optimization: We already have (q * n0) and (1 * n1) +				 * after the calculation of q.  Taking advantage of that, we +				 * could make this loop make two iterations less.  */ +				cy_limb = mpihelp_submul_1(np, dp, dsize, q); + +				if (n2 != cy_limb) { +					mpihelp_add_n(np, np, dp, dsize); +					q--; +				} + +				qp[i] = q; +				n0 = np[dsize - 1]; +			} +		} +	} + +	return most_significant_q_limb; +} + +/**************** + * Divide (DIVIDEND_PTR,,DIVIDEND_SIZE) by DIVISOR_LIMB. + * Write DIVIDEND_SIZE limbs of quotient at QUOT_PTR. + * Return the single-limb remainder. + * There are no constraints on the value of the divisor. + * + * QUOT_PTR and DIVIDEND_PTR might point to the same limb. + */ + +mpi_limb_t +mpihelp_divmod_1(mpi_ptr_t quot_ptr, +		 mpi_ptr_t dividend_ptr, mpi_size_t dividend_size, +		 mpi_limb_t divisor_limb) +{ +	mpi_size_t i; +	mpi_limb_t n1, n0, r; +	int dummy; + +	if (!dividend_size) +		return 0; + +	/* If multiplication is much faster than division, and the +	 * dividend is large, pre-invert the divisor, and use +	 * only multiplications in the inner loop. +	 * +	 * This test should be read: +	 * Does it ever help to use udiv_qrnnd_preinv? +	 * && Does what we save compensate for the inversion overhead? +	 */ +	if (UDIV_TIME > (2 * UMUL_TIME + 6) +	    && (UDIV_TIME - (2 * UMUL_TIME + 6)) * dividend_size > UDIV_TIME) { +		int normalization_steps; + +		count_leading_zeros(normalization_steps, divisor_limb); +		if (normalization_steps) { +			mpi_limb_t divisor_limb_inverted; + +			divisor_limb <<= normalization_steps; + +			/* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB.  The +			 * result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the +			 * most significant bit (with weight 2**N) implicit. +			 */ +			/* Special case for DIVISOR_LIMB == 100...000.  */ +			if (!(divisor_limb << 1)) +				divisor_limb_inverted = ~(mpi_limb_t) 0; +			else +				udiv_qrnnd(divisor_limb_inverted, dummy, +					   -divisor_limb, 0, divisor_limb); + +			n1 = dividend_ptr[dividend_size - 1]; +			r = n1 >> (BITS_PER_MPI_LIMB - normalization_steps); + +			/* Possible optimization: +			 * if (r == 0 +			 * && divisor_limb > ((n1 << normalization_steps) +			 *                 | (dividend_ptr[dividend_size - 2] >> ...))) +			 * ...one division less... +			 */ +			for (i = dividend_size - 2; i >= 0; i--) { +				n0 = dividend_ptr[i]; +				UDIV_QRNND_PREINV(quot_ptr[i + 1], r, r, +						  ((n1 << normalization_steps) +						   | (n0 >> +						      (BITS_PER_MPI_LIMB - +						       normalization_steps))), +						  divisor_limb, +						  divisor_limb_inverted); +				n1 = n0; +			} +			UDIV_QRNND_PREINV(quot_ptr[0], r, r, +					  n1 << normalization_steps, +					  divisor_limb, divisor_limb_inverted); +			return r >> normalization_steps; +		} else { +			mpi_limb_t divisor_limb_inverted; + +			/* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB.  The +			 * result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the +			 * most significant bit (with weight 2**N) implicit. +			 */ +			/* Special case for DIVISOR_LIMB == 100...000.  */ +			if (!(divisor_limb << 1)) +				divisor_limb_inverted = ~(mpi_limb_t) 0; +			else +				udiv_qrnnd(divisor_limb_inverted, dummy, +					   -divisor_limb, 0, divisor_limb); + +			i = dividend_size - 1; +			r = dividend_ptr[i]; + +			if (r >= divisor_limb) +				r = 0; +			else +				quot_ptr[i--] = 0; + +			for (; i >= 0; i--) { +				n0 = dividend_ptr[i]; +				UDIV_QRNND_PREINV(quot_ptr[i], r, r, +						  n0, divisor_limb, +						  divisor_limb_inverted); +			} +			return r; +		} +	} else { +		if (UDIV_NEEDS_NORMALIZATION) { +			int normalization_steps; + +			count_leading_zeros(normalization_steps, divisor_limb); +			if (normalization_steps) { +				divisor_limb <<= normalization_steps; + +				n1 = dividend_ptr[dividend_size - 1]; +				r = n1 >> (BITS_PER_MPI_LIMB - +					   normalization_steps); + +				/* Possible optimization: +				 * if (r == 0 +				 * && divisor_limb > ((n1 << normalization_steps) +				 *                 | (dividend_ptr[dividend_size - 2] >> ...))) +				 * ...one division less... +				 */ +				for (i = dividend_size - 2; i >= 0; i--) { +					n0 = dividend_ptr[i]; +					udiv_qrnnd(quot_ptr[i + 1], r, r, +						   ((n1 << normalization_steps) +						    | (n0 >> +						       (BITS_PER_MPI_LIMB - +							normalization_steps))), +						   divisor_limb); +					n1 = n0; +				} +				udiv_qrnnd(quot_ptr[0], r, r, +					   n1 << normalization_steps, +					   divisor_limb); +				return r >> normalization_steps; +			} +		} +		/* No normalization needed, either because udiv_qrnnd doesn't require +		 * it, or because DIVISOR_LIMB is already normalized.  */ +		i = dividend_size - 1; +		r = dividend_ptr[i]; + +		if (r >= divisor_limb) +			r = 0; +		else +			quot_ptr[i--] = 0; + +		for (; i >= 0; i--) { +			n0 = dividend_ptr[i]; +			udiv_qrnnd(quot_ptr[i], r, r, n0, divisor_limb); +		} +		return r; +	} +}  | 
