https://github.com/torvalds/linux
Revision 573b3aa6940661dc50c383213d428c27df78be7c authored by Yonghong Song on 30 July 2018, 15:49:03 UTC, committed by Daniel Borkmann on 30 July 2018, 22:37:09 UTC
I hit the following problem when I tried to use bpftool
to dump a percpu array.

  $ sudo ./bpftool map show
  61: percpu_array  name stub  flags 0x0
          key 4B  value 4B  max_entries 1  memlock 4096B
  ...
  $ sudo ./bpftool map dump id 61
  bpftool: malloc.c:2406: sysmalloc: Assertion
  `(old_top == initial_top (av) && old_size == 0) || \
   ((unsigned long) (old_size) >= MINSIZE && \
   prev_inuse (old_top) && \
   ((unsigned long) old_end & (pagesize - 1)) == 0)'
  failed.
  Aborted

Further debugging revealed that this is due to
miscommunication between bpftool and kernel.
For example, for the above percpu_array with value size of 4B.
The map info returned to user space has value size of 4B.

In bpftool, the values array for lookup is allocated like:
   info->value_size * get_possible_cpus() = 4 * get_possible_cpus()
In kernel (kernel/bpf/syscall.c), the values array size is
rounded up to multiple of 8.
   round_up(map->value_size, 8) * num_possible_cpus()
   = 8 * num_possible_cpus()
So when kernel copies the values to user buffer, the kernel will
overwrite beyond user buffer boundary.

This patch fixed the issue by allocating and stepping through
percpu map value array properly in bpftool.

Fixes: 71bb428fe2c19 ("tools: bpf: add bpftool")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
1 parent 61f4b23
Raw File
Tip revision: 573b3aa6940661dc50c383213d428c27df78be7c authored by Yonghong Song on 30 July 2018, 15:49:03 UTC
tools/bpftool: fix a percpu_array map dump problem
Tip revision: 573b3aa
op-2.h
/* Software floating-point emulation.
   Basic two-word fraction declaration and manipulation.
   Copyright (C) 1997,1998,1999 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Richard Henderson (rth@cygnus.com),
		  Jakub Jelinek (jj@ultra.linux.cz),
		  David S. Miller (davem@redhat.com) and
		  Peter Maydell (pmaydell@chiark.greenend.org.uk).

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If
   not, write to the Free Software Foundation, Inc.,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#ifndef __MATH_EMU_OP_2_H__
#define __MATH_EMU_OP_2_H__

#define _FP_FRAC_DECL_2(X)	_FP_W_TYPE X##_f0 = 0, X##_f1 = 0
#define _FP_FRAC_COPY_2(D,S)	(D##_f0 = S##_f0, D##_f1 = S##_f1)
#define _FP_FRAC_SET_2(X,I)	__FP_FRAC_SET_2(X, I)
#define _FP_FRAC_HIGH_2(X)	(X##_f1)
#define _FP_FRAC_LOW_2(X)	(X##_f0)
#define _FP_FRAC_WORD_2(X,w)	(X##_f##w)

#define _FP_FRAC_SLL_2(X,N)						\
  do {									\
    if ((N) < _FP_W_TYPE_SIZE)						\
      {									\
	if (__builtin_constant_p(N) && (N) == 1) 			\
	  {								\
	    X##_f1 = X##_f1 + X##_f1 + (((_FP_WS_TYPE)(X##_f0)) < 0);	\
	    X##_f0 += X##_f0;						\
	  }								\
	else								\
	  {								\
	    X##_f1 = X##_f1 << (N) | X##_f0 >> (_FP_W_TYPE_SIZE - (N));	\
	    X##_f0 <<= (N);						\
	  }								\
      }									\
    else								\
      {									\
	X##_f1 = X##_f0 << ((N) - _FP_W_TYPE_SIZE);			\
	X##_f0 = 0;							\
      }									\
  } while (0)

#define _FP_FRAC_SRL_2(X,N)						\
  do {									\
    if ((N) < _FP_W_TYPE_SIZE)						\
      {									\
	X##_f0 = X##_f0 >> (N) | X##_f1 << (_FP_W_TYPE_SIZE - (N));	\
	X##_f1 >>= (N);							\
      }									\
    else								\
      {									\
	X##_f0 = X##_f1 >> ((N) - _FP_W_TYPE_SIZE);			\
	X##_f1 = 0;							\
      }									\
  } while (0)

/* Right shift with sticky-lsb.  */
#define _FP_FRAC_SRS_2(X,N,sz)						\
  do {									\
    if ((N) < _FP_W_TYPE_SIZE)						\
      {									\
	X##_f0 = (X##_f1 << (_FP_W_TYPE_SIZE - (N)) | X##_f0 >> (N) |	\
		  (__builtin_constant_p(N) && (N) == 1			\
		   ? X##_f0 & 1						\
		   : (X##_f0 << (_FP_W_TYPE_SIZE - (N))) != 0));	\
	X##_f1 >>= (N);							\
      }									\
    else								\
      {									\
	X##_f0 = (X##_f1 >> ((N) - _FP_W_TYPE_SIZE) |			\
		(((X##_f1 << (2*_FP_W_TYPE_SIZE - (N))) | X##_f0) != 0)); \
	X##_f1 = 0;							\
      }									\
  } while (0)

#define _FP_FRAC_ADDI_2(X,I)	\
  __FP_FRAC_ADDI_2(X##_f1, X##_f0, I)

#define _FP_FRAC_ADD_2(R,X,Y)	\
  __FP_FRAC_ADD_2(R##_f1, R##_f0, X##_f1, X##_f0, Y##_f1, Y##_f0)

#define _FP_FRAC_SUB_2(R,X,Y)	\
  __FP_FRAC_SUB_2(R##_f1, R##_f0, X##_f1, X##_f0, Y##_f1, Y##_f0)

#define _FP_FRAC_DEC_2(X,Y)	\
  __FP_FRAC_DEC_2(X##_f1, X##_f0, Y##_f1, Y##_f0)

#define _FP_FRAC_CLZ_2(R,X)	\
  do {				\
    if (X##_f1)			\
      __FP_CLZ(R,X##_f1);	\
    else 			\
    {				\
      __FP_CLZ(R,X##_f0);	\
      R += _FP_W_TYPE_SIZE;	\
    }				\
  } while(0)

/* Predicates */
#define _FP_FRAC_NEGP_2(X)	((_FP_WS_TYPE)X##_f1 < 0)
#define _FP_FRAC_ZEROP_2(X)	((X##_f1 | X##_f0) == 0)
#define _FP_FRAC_OVERP_2(fs,X)	(_FP_FRAC_HIGH_##fs(X) & _FP_OVERFLOW_##fs)
#define _FP_FRAC_CLEAR_OVERP_2(fs,X)	(_FP_FRAC_HIGH_##fs(X) &= ~_FP_OVERFLOW_##fs)
#define _FP_FRAC_EQ_2(X, Y)	(X##_f1 == Y##_f1 && X##_f0 == Y##_f0)
#define _FP_FRAC_GT_2(X, Y)	\
  (X##_f1 > Y##_f1 || (X##_f1 == Y##_f1 && X##_f0 > Y##_f0))
#define _FP_FRAC_GE_2(X, Y)	\
  (X##_f1 > Y##_f1 || (X##_f1 == Y##_f1 && X##_f0 >= Y##_f0))

#define _FP_ZEROFRAC_2		0, 0
#define _FP_MINFRAC_2		0, 1
#define _FP_MAXFRAC_2		(~(_FP_WS_TYPE)0), (~(_FP_WS_TYPE)0)

/*
 * Internals 
 */

#define __FP_FRAC_SET_2(X,I1,I0)	(X##_f0 = I0, X##_f1 = I1)

#define __FP_CLZ_2(R, xh, xl)	\
  do {				\
    if (xh)			\
      __FP_CLZ(R,xh);		\
    else 			\
    {				\
      __FP_CLZ(R,xl);		\
      R += _FP_W_TYPE_SIZE;	\
    }				\
  } while(0)

#if 0

#ifndef __FP_FRAC_ADDI_2
#define __FP_FRAC_ADDI_2(xh, xl, i)	\
  (xh += ((xl += i) < i))
#endif
#ifndef __FP_FRAC_ADD_2
#define __FP_FRAC_ADD_2(rh, rl, xh, xl, yh, yl)	\
  (rh = xh + yh + ((rl = xl + yl) < xl))
#endif
#ifndef __FP_FRAC_SUB_2
#define __FP_FRAC_SUB_2(rh, rl, xh, xl, yh, yl)	\
  (rh = xh - yh - ((rl = xl - yl) > xl))
#endif
#ifndef __FP_FRAC_DEC_2
#define __FP_FRAC_DEC_2(xh, xl, yh, yl)	\
  do {					\
    UWtype _t = xl;			\
    xh -= yh + ((xl -= yl) > _t);	\
  } while (0)
#endif

#else

#undef __FP_FRAC_ADDI_2
#define __FP_FRAC_ADDI_2(xh, xl, i)	add_ssaaaa(xh, xl, xh, xl, 0, i)
#undef __FP_FRAC_ADD_2
#define __FP_FRAC_ADD_2			add_ssaaaa
#undef __FP_FRAC_SUB_2
#define __FP_FRAC_SUB_2			sub_ddmmss
#undef __FP_FRAC_DEC_2
#define __FP_FRAC_DEC_2(xh, xl, yh, yl)	sub_ddmmss(xh, xl, xh, xl, yh, yl)

#endif

/*
 * Unpack the raw bits of a native fp value.  Do not classify or
 * normalize the data.
 */

#define _FP_UNPACK_RAW_2(fs, X, val)			\
  do {							\
    union _FP_UNION_##fs _flo; _flo.flt = (val);	\
							\
    X##_f0 = _flo.bits.frac0;				\
    X##_f1 = _flo.bits.frac1;				\
    X##_e  = _flo.bits.exp;				\
    X##_s  = _flo.bits.sign;				\
  } while (0)

#define _FP_UNPACK_RAW_2_P(fs, X, val)			\
  do {							\
    union _FP_UNION_##fs *_flo =			\
      (union _FP_UNION_##fs *)(val);			\
							\
    X##_f0 = _flo->bits.frac0;				\
    X##_f1 = _flo->bits.frac1;				\
    X##_e  = _flo->bits.exp;				\
    X##_s  = _flo->bits.sign;				\
  } while (0)


/*
 * Repack the raw bits of a native fp value.
 */

#define _FP_PACK_RAW_2(fs, val, X)			\
  do {							\
    union _FP_UNION_##fs _flo;				\
							\
    _flo.bits.frac0 = X##_f0;				\
    _flo.bits.frac1 = X##_f1;				\
    _flo.bits.exp   = X##_e;				\
    _flo.bits.sign  = X##_s;				\
							\
    (val) = _flo.flt;					\
  } while (0)

#define _FP_PACK_RAW_2_P(fs, val, X)			\
  do {							\
    union _FP_UNION_##fs *_flo =			\
      (union _FP_UNION_##fs *)(val);			\
							\
    _flo->bits.frac0 = X##_f0;				\
    _flo->bits.frac1 = X##_f1;				\
    _flo->bits.exp   = X##_e;				\
    _flo->bits.sign  = X##_s;				\
  } while (0)


/*
 * Multiplication algorithms:
 */

/* Given a 1W * 1W => 2W primitive, do the extended multiplication.  */

#define _FP_MUL_MEAT_2_wide(wfracbits, R, X, Y, doit)			\
  do {									\
    _FP_FRAC_DECL_4(_z); _FP_FRAC_DECL_2(_b); _FP_FRAC_DECL_2(_c);	\
									\
    doit(_FP_FRAC_WORD_4(_z,1), _FP_FRAC_WORD_4(_z,0), X##_f0, Y##_f0);	\
    doit(_b_f1, _b_f0, X##_f0, Y##_f1);					\
    doit(_c_f1, _c_f0, X##_f1, Y##_f0);					\
    doit(_FP_FRAC_WORD_4(_z,3), _FP_FRAC_WORD_4(_z,2), X##_f1, Y##_f1);	\
									\
    __FP_FRAC_ADD_3(_FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		    _FP_FRAC_WORD_4(_z,1), 0, _b_f1, _b_f0,		\
		    _FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		    _FP_FRAC_WORD_4(_z,1));				\
    __FP_FRAC_ADD_3(_FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		    _FP_FRAC_WORD_4(_z,1), 0, _c_f1, _c_f0,		\
		    _FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		    _FP_FRAC_WORD_4(_z,1));				\
									\
    /* Normalize since we know where the msb of the multiplicands	\
       were (bit B), we know that the msb of the of the product is	\
       at either 2B or 2B-1.  */					\
    _FP_FRAC_SRS_4(_z, wfracbits-1, 2*wfracbits);			\
    R##_f0 = _FP_FRAC_WORD_4(_z,0);					\
    R##_f1 = _FP_FRAC_WORD_4(_z,1);					\
  } while (0)

/* Given a 1W * 1W => 2W primitive, do the extended multiplication.
   Do only 3 multiplications instead of four. This one is for machines
   where multiplication is much more expensive than subtraction.  */

#define _FP_MUL_MEAT_2_wide_3mul(wfracbits, R, X, Y, doit)		\
  do {									\
    _FP_FRAC_DECL_4(_z); _FP_FRAC_DECL_2(_b); _FP_FRAC_DECL_2(_c);	\
    _FP_W_TYPE _d;							\
    int _c1, _c2;							\
									\
    _b_f0 = X##_f0 + X##_f1;						\
    _c1 = _b_f0 < X##_f0;						\
    _b_f1 = Y##_f0 + Y##_f1;						\
    _c2 = _b_f1 < Y##_f0;						\
    doit(_d, _FP_FRAC_WORD_4(_z,0), X##_f0, Y##_f0);			\
    doit(_FP_FRAC_WORD_4(_z,2), _FP_FRAC_WORD_4(_z,1), _b_f0, _b_f1);	\
    doit(_c_f1, _c_f0, X##_f1, Y##_f1);					\
									\
    _b_f0 &= -_c2;							\
    _b_f1 &= -_c1;							\
    __FP_FRAC_ADD_3(_FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		    _FP_FRAC_WORD_4(_z,1), (_c1 & _c2), 0, _d,		\
		    0, _FP_FRAC_WORD_4(_z,2), _FP_FRAC_WORD_4(_z,1));	\
    __FP_FRAC_ADDI_2(_FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		     _b_f0);						\
    __FP_FRAC_ADDI_2(_FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		     _b_f1);						\
    __FP_FRAC_DEC_3(_FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		    _FP_FRAC_WORD_4(_z,1),				\
		    0, _d, _FP_FRAC_WORD_4(_z,0));			\
    __FP_FRAC_DEC_3(_FP_FRAC_WORD_4(_z,3),_FP_FRAC_WORD_4(_z,2),	\
		    _FP_FRAC_WORD_4(_z,1), 0, _c_f1, _c_f0);		\
    __FP_FRAC_ADD_2(_FP_FRAC_WORD_4(_z,3), _FP_FRAC_WORD_4(_z,2),	\
		    _c_f1, _c_f0,					\
		    _FP_FRAC_WORD_4(_z,3), _FP_FRAC_WORD_4(_z,2));	\
									\
    /* Normalize since we know where the msb of the multiplicands	\
       were (bit B), we know that the msb of the of the product is	\
       at either 2B or 2B-1.  */					\
    _FP_FRAC_SRS_4(_z, wfracbits-1, 2*wfracbits);			\
    R##_f0 = _FP_FRAC_WORD_4(_z,0);					\
    R##_f1 = _FP_FRAC_WORD_4(_z,1);					\
  } while (0)

#define _FP_MUL_MEAT_2_gmp(wfracbits, R, X, Y)				\
  do {									\
    _FP_FRAC_DECL_4(_z);						\
    _FP_W_TYPE _x[2], _y[2];						\
    _x[0] = X##_f0; _x[1] = X##_f1;					\
    _y[0] = Y##_f0; _y[1] = Y##_f1;					\
									\
    mpn_mul_n(_z_f, _x, _y, 2);						\
									\
    /* Normalize since we know where the msb of the multiplicands	\
       were (bit B), we know that the msb of the of the product is	\
       at either 2B or 2B-1.  */					\
    _FP_FRAC_SRS_4(_z, wfracbits-1, 2*wfracbits);			\
    R##_f0 = _z_f[0];							\
    R##_f1 = _z_f[1];							\
  } while (0)

/* Do at most 120x120=240 bits multiplication using double floating
   point multiplication.  This is useful if floating point
   multiplication has much bigger throughput than integer multiply.
   It is supposed to work for _FP_W_TYPE_SIZE 64 and wfracbits
   between 106 and 120 only.  
   Caller guarantees that X and Y has (1LLL << (wfracbits - 1)) set.
   SETFETZ is a macro which will disable all FPU exceptions and set rounding
   towards zero,  RESETFE should optionally reset it back.  */

#define _FP_MUL_MEAT_2_120_240_double(wfracbits, R, X, Y, setfetz, resetfe)	\
  do {										\
    static const double _const[] = {						\
      /* 2^-24 */ 5.9604644775390625e-08,					\
      /* 2^-48 */ 3.5527136788005009e-15,					\
      /* 2^-72 */ 2.1175823681357508e-22,					\
      /* 2^-96 */ 1.2621774483536189e-29,					\
      /* 2^28 */ 2.68435456e+08,						\
      /* 2^4 */ 1.600000e+01,							\
      /* 2^-20 */ 9.5367431640625e-07,						\
      /* 2^-44 */ 5.6843418860808015e-14,					\
      /* 2^-68 */ 3.3881317890172014e-21,					\
      /* 2^-92 */ 2.0194839173657902e-28,					\
      /* 2^-116 */ 1.2037062152420224e-35};					\
    double _a240, _b240, _c240, _d240, _e240, _f240, 				\
	   _g240, _h240, _i240, _j240, _k240;					\
    union { double d; UDItype i; } _l240, _m240, _n240, _o240,			\
				   _p240, _q240, _r240, _s240;			\
    UDItype _t240, _u240, _v240, _w240, _x240, _y240 = 0;			\
										\
    if (wfracbits < 106 || wfracbits > 120)					\
      abort();									\
										\
    setfetz;									\
										\
    _e240 = (double)(long)(X##_f0 & 0xffffff);					\
    _j240 = (double)(long)(Y##_f0 & 0xffffff);					\
    _d240 = (double)(long)((X##_f0 >> 24) & 0xffffff);				\
    _i240 = (double)(long)((Y##_f0 >> 24) & 0xffffff);				\
    _c240 = (double)(long)(((X##_f1 << 16) & 0xffffff) | (X##_f0 >> 48));	\
    _h240 = (double)(long)(((Y##_f1 << 16) & 0xffffff) | (Y##_f0 >> 48));	\
    _b240 = (double)(long)((X##_f1 >> 8) & 0xffffff);				\
    _g240 = (double)(long)((Y##_f1 >> 8) & 0xffffff);				\
    _a240 = (double)(long)(X##_f1 >> 32);					\
    _f240 = (double)(long)(Y##_f1 >> 32);					\
    _e240 *= _const[3];								\
    _j240 *= _const[3];								\
    _d240 *= _const[2];								\
    _i240 *= _const[2];								\
    _c240 *= _const[1];								\
    _h240 *= _const[1];								\
    _b240 *= _const[0];								\
    _g240 *= _const[0];								\
    _s240.d =							      _e240*_j240;\
    _r240.d =						_d240*_j240 + _e240*_i240;\
    _q240.d =				  _c240*_j240 + _d240*_i240 + _e240*_h240;\
    _p240.d =		    _b240*_j240 + _c240*_i240 + _d240*_h240 + _e240*_g240;\
    _o240.d = _a240*_j240 + _b240*_i240 + _c240*_h240 + _d240*_g240 + _e240*_f240;\
    _n240.d = _a240*_i240 + _b240*_h240 + _c240*_g240 + _d240*_f240;		\
    _m240.d = _a240*_h240 + _b240*_g240 + _c240*_f240;				\
    _l240.d = _a240*_g240 + _b240*_f240;					\
    _k240 =   _a240*_f240;							\
    _r240.d += _s240.d;								\
    _q240.d += _r240.d;								\
    _p240.d += _q240.d;								\
    _o240.d += _p240.d;								\
    _n240.d += _o240.d;								\
    _m240.d += _n240.d;								\
    _l240.d += _m240.d;								\
    _k240 += _l240.d;								\
    _s240.d -= ((_const[10]+_s240.d)-_const[10]);				\
    _r240.d -= ((_const[9]+_r240.d)-_const[9]);					\
    _q240.d -= ((_const[8]+_q240.d)-_const[8]);					\
    _p240.d -= ((_const[7]+_p240.d)-_const[7]);					\
    _o240.d += _const[7];							\
    _n240.d += _const[6];							\
    _m240.d += _const[5];							\
    _l240.d += _const[4];							\
    if (_s240.d != 0.0) _y240 = 1;						\
    if (_r240.d != 0.0) _y240 = 1;						\
    if (_q240.d != 0.0) _y240 = 1;						\
    if (_p240.d != 0.0) _y240 = 1;						\
    _t240 = (DItype)_k240;							\
    _u240 = _l240.i;								\
    _v240 = _m240.i;								\
    _w240 = _n240.i;								\
    _x240 = _o240.i;								\
    R##_f1 = (_t240 << (128 - (wfracbits - 1)))					\
	     | ((_u240 & 0xffffff) >> ((wfracbits - 1) - 104));			\
    R##_f0 = ((_u240 & 0xffffff) << (168 - (wfracbits - 1)))			\
    	     | ((_v240 & 0xffffff) << (144 - (wfracbits - 1)))			\
    	     | ((_w240 & 0xffffff) << (120 - (wfracbits - 1)))			\
    	     | ((_x240 & 0xffffff) >> ((wfracbits - 1) - 96))			\
    	     | _y240;								\
    resetfe;									\
  } while (0)

/*
 * Division algorithms:
 */

#define _FP_DIV_MEAT_2_udiv(fs, R, X, Y)				\
  do {									\
    _FP_W_TYPE _n_f2, _n_f1, _n_f0, _r_f1, _r_f0, _m_f1, _m_f0;		\
    if (_FP_FRAC_GT_2(X, Y))						\
      {									\
	_n_f2 = X##_f1 >> 1;						\
	_n_f1 = X##_f1 << (_FP_W_TYPE_SIZE - 1) | X##_f0 >> 1;		\
	_n_f0 = X##_f0 << (_FP_W_TYPE_SIZE - 1);			\
      }									\
    else								\
      {									\
	R##_e--;							\
	_n_f2 = X##_f1;							\
	_n_f1 = X##_f0;							\
	_n_f0 = 0;							\
      }									\
									\
    /* Normalize, i.e. make the most significant bit of the 		\
       denominator set. */						\
    _FP_FRAC_SLL_2(Y, _FP_WFRACXBITS_##fs);				\
									\
    udiv_qrnnd(R##_f1, _r_f1, _n_f2, _n_f1, Y##_f1);			\
    umul_ppmm(_m_f1, _m_f0, R##_f1, Y##_f0);				\
    _r_f0 = _n_f0;							\
    if (_FP_FRAC_GT_2(_m, _r))						\
      {									\
	R##_f1--;							\
	_FP_FRAC_ADD_2(_r, Y, _r);					\
	if (_FP_FRAC_GE_2(_r, Y) && _FP_FRAC_GT_2(_m, _r))		\
	  {								\
	    R##_f1--;							\
	    _FP_FRAC_ADD_2(_r, Y, _r);					\
	  }								\
      }									\
    _FP_FRAC_DEC_2(_r, _m);						\
									\
    if (_r_f1 == Y##_f1)						\
      {									\
	/* This is a special case, not an optimization			\
	   (_r/Y##_f1 would not fit into UWtype).			\
	   As _r is guaranteed to be < Y,  R##_f0 can be either		\
	   (UWtype)-1 or (UWtype)-2.  But as we know what kind		\
	   of bits it is (sticky, guard, round),  we don't care.	\
	   We also don't care what the reminder is,  because the	\
	   guard bit will be set anyway.  -jj */			\
	R##_f0 = -1;							\
      }									\
    else								\
      {									\
	udiv_qrnnd(R##_f0, _r_f1, _r_f1, _r_f0, Y##_f1);		\
	umul_ppmm(_m_f1, _m_f0, R##_f0, Y##_f0);			\
	_r_f0 = 0;							\
	if (_FP_FRAC_GT_2(_m, _r))					\
	  {								\
	    R##_f0--;							\
	    _FP_FRAC_ADD_2(_r, Y, _r);					\
	    if (_FP_FRAC_GE_2(_r, Y) && _FP_FRAC_GT_2(_m, _r))		\
	      {								\
		R##_f0--;						\
		_FP_FRAC_ADD_2(_r, Y, _r);				\
	      }								\
	  }								\
	if (!_FP_FRAC_EQ_2(_r, _m))					\
	  R##_f0 |= _FP_WORK_STICKY;					\
      }									\
  } while (0)


#define _FP_DIV_MEAT_2_gmp(fs, R, X, Y)					\
  do {									\
    _FP_W_TYPE _x[4], _y[2], _z[4];					\
    _y[0] = Y##_f0; _y[1] = Y##_f1;					\
    _x[0] = _x[3] = 0;							\
    if (_FP_FRAC_GT_2(X, Y))						\
      {									\
	R##_e++;							\
	_x[1] = (X##_f0 << (_FP_WFRACBITS_##fs-1 - _FP_W_TYPE_SIZE) |	\
		 X##_f1 >> (_FP_W_TYPE_SIZE -				\
			    (_FP_WFRACBITS_##fs-1 - _FP_W_TYPE_SIZE)));	\
	_x[2] = X##_f1 << (_FP_WFRACBITS_##fs-1 - _FP_W_TYPE_SIZE);	\
      }									\
    else								\
      {									\
	_x[1] = (X##_f0 << (_FP_WFRACBITS_##fs - _FP_W_TYPE_SIZE) |	\
		 X##_f1 >> (_FP_W_TYPE_SIZE -				\
			    (_FP_WFRACBITS_##fs - _FP_W_TYPE_SIZE)));	\
	_x[2] = X##_f1 << (_FP_WFRACBITS_##fs - _FP_W_TYPE_SIZE);	\
      }									\
									\
    (void) mpn_divrem (_z, 0, _x, 4, _y, 2);				\
    R##_f1 = _z[1];							\
    R##_f0 = _z[0] | ((_x[0] | _x[1]) != 0);				\
  } while (0)


/*
 * Square root algorithms:
 * We have just one right now, maybe Newton approximation
 * should be added for those machines where division is fast.
 */
 
#define _FP_SQRT_MEAT_2(R, S, T, X, q)			\
  do {							\
    while (q)						\
      {							\
	T##_f1 = S##_f1 + q;				\
	if (T##_f1 <= X##_f1)				\
	  {						\
	    S##_f1 = T##_f1 + q;			\
	    X##_f1 -= T##_f1;				\
	    R##_f1 += q;				\
	  }						\
	_FP_FRAC_SLL_2(X, 1);				\
	q >>= 1;					\
      }							\
    q = (_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE - 1);		\
    while (q != _FP_WORK_ROUND)				\
      {							\
	T##_f0 = S##_f0 + q;				\
	T##_f1 = S##_f1;				\
	if (T##_f1 < X##_f1 || 				\
	    (T##_f1 == X##_f1 && T##_f0 <= X##_f0))	\
	  {						\
	    S##_f0 = T##_f0 + q;			\
	    S##_f1 += (T##_f0 > S##_f0);		\
	    _FP_FRAC_DEC_2(X, T);			\
	    R##_f0 += q;				\
	  }						\
	_FP_FRAC_SLL_2(X, 1);				\
	q >>= 1;					\
      }							\
    if (X##_f0 | X##_f1)				\
      {							\
	if (S##_f1 < X##_f1 || 				\
	    (S##_f1 == X##_f1 && S##_f0 < X##_f0))	\
	  R##_f0 |= _FP_WORK_ROUND;			\
	R##_f0 |= _FP_WORK_STICKY;			\
      }							\
  } while (0)


/*
 * Assembly/disassembly for converting to/from integral types.  
 * No shifting or overflow handled here.
 */

#define _FP_FRAC_ASSEMBLE_2(r, X, rsize)	\
  do {						\
    if (rsize <= _FP_W_TYPE_SIZE)		\
      r = X##_f0;				\
    else					\
      {						\
	r = X##_f1;				\
	r <<= _FP_W_TYPE_SIZE;			\
	r += X##_f0;				\
      }						\
  } while (0)

#define _FP_FRAC_DISASSEMBLE_2(X, r, rsize)				\
  do {									\
    X##_f0 = r;								\
    X##_f1 = (rsize <= _FP_W_TYPE_SIZE ? 0 : r >> _FP_W_TYPE_SIZE);	\
  } while (0)

/*
 * Convert FP values between word sizes
 */

#define _FP_FRAC_CONV_1_2(dfs, sfs, D, S)				\
  do {									\
    if (S##_c != FP_CLS_NAN)						\
      _FP_FRAC_SRS_2(S, (_FP_WFRACBITS_##sfs - _FP_WFRACBITS_##dfs),	\
		     _FP_WFRACBITS_##sfs);				\
    else								\
      _FP_FRAC_SRL_2(S, (_FP_WFRACBITS_##sfs - _FP_WFRACBITS_##dfs));	\
    D##_f = S##_f0;							\
  } while (0)

#define _FP_FRAC_CONV_2_1(dfs, sfs, D, S)				\
  do {									\
    D##_f0 = S##_f;							\
    D##_f1 = 0;								\
    _FP_FRAC_SLL_2(D, (_FP_WFRACBITS_##dfs - _FP_WFRACBITS_##sfs));	\
  } while (0)

#endif
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