/* Software floating-point emulation. Basic eight-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) 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_8_H__ #define __MATH_EMU_OP_8_H__ /* We need just a few things from here for op-4, if we ever need some other macros, they can be added. */ #define _FP_FRAC_DECL_8(X) _FP_W_TYPE X##_f[8] #define _FP_FRAC_HIGH_8(X) (X##_f[7]) #define _FP_FRAC_LOW_8(X) (X##_f[0]) #define _FP_FRAC_WORD_8(X,w) (X##_f[w]) #define _FP_FRAC_SLL_8(X,N) \ do { \ _FP_I_TYPE _up, _down, _skip, _i; \ _skip = (N) / _FP_W_TYPE_SIZE; \ _up = (N) % _FP_W_TYPE_SIZE; \ _down = _FP_W_TYPE_SIZE - _up; \ if (!_up) \ for (_i = 7; _i >= _skip; --_i) \ X##_f[_i] = X##_f[_i-_skip]; \ else \ { \ for (_i = 7; _i > _skip; --_i) \ X##_f[_i] = X##_f[_i-_skip] << _up \ | X##_f[_i-_skip-1] >> _down; \ X##_f[_i--] = X##_f[0] << _up; \ } \ for (; _i >= 0; --_i) \ X##_f[_i] = 0; \ } while (0) #define _FP_FRAC_SRL_8(X,N) \ do { \ _FP_I_TYPE _up, _down, _skip, _i; \ _skip = (N) / _FP_W_TYPE_SIZE; \ _down = (N) % _FP_W_TYPE_SIZE; \ _up = _FP_W_TYPE_SIZE - _down; \ if (!_down) \ for (_i = 0; _i <= 7-_skip; ++_i) \ X##_f[_i] = X##_f[_i+_skip]; \ else \ { \ for (_i = 0; _i < 7-_skip; ++_i) \ X##_f[_i] = X##_f[_i+_skip] >> _down \ | X##_f[_i+_skip+1] << _up; \ X##_f[_i++] = X##_f[7] >> _down; \ } \ for (; _i < 8; ++_i) \ X##_f[_i] = 0; \ } while (0) /* Right shift with sticky-lsb. * What this actually means is that we do a standard right-shift, * but that if any of the bits that fall off the right hand side * were one then we always set the LSbit. */ #define _FP_FRAC_SRS_8(X,N,size) \ do { \ _FP_I_TYPE _up, _down, _skip, _i; \ _FP_W_TYPE _s; \ _skip = (N) / _FP_W_TYPE_SIZE; \ _down = (N) % _FP_W_TYPE_SIZE; \ _up = _FP_W_TYPE_SIZE - _down; \ for (_s = _i = 0; _i < _skip; ++_i) \ _s |= X##_f[_i]; \ _s |= X##_f[_i] << _up; \ /* s is now != 0 if we want to set the LSbit */ \ if (!_down) \ for (_i = 0; _i <= 7-_skip; ++_i) \ X##_f[_i] = X##_f[_i+_skip]; \ else \ { \ for (_i = 0; _i < 7-_skip; ++_i) \ X##_f[_i] = X##_f[_i+_skip] >> _down \ | X##_f[_i+_skip+1] << _up; \ X##_f[_i++] = X##_f[7] >> _down; \ } \ for (; _i < 8; ++_i) \ X##_f[_i] = 0; \ /* don't fix the LSB until the very end when we're sure f[0] is stable */ \ X##_f[0] |= (_s != 0); \ } while (0) #endif be passed a flow label, which it returns as is if non-0 and in some other cases, otherwise it calculates a new value. The problem is callers often pass a flowi6.flowlabel, which may also contain traffic class bits. If the traffic class is non-0 ip6_make_flowlabel() mistakes the non-0 it gets as a flow label and returns the whole thing. Thus it can return a 'flow label' longer than 20b and the low 20b of that is typically 0 resulting in packets with 0 label. Moreover, different packets of a flow may be labeled differently. For a TCP flow with ECN non-payload and payload packets get different labels as exemplified by this pair of consecutive packets: (pure ACK) Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2:: 0110 .... = Version: 6 .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT) .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0) .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0) .... .... .... 0001 1100 1110 0100 1001 = Flow Label: 0x1ce49 Payload Length: 32 Next Header: TCP (6) (payload) Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2:: 0110 .... = Version: 6 .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0)) .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0) .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2) .... .... .... 0000 0000 0000 0000 0000 = Flow Label: 0x00000 Payload Length: 688 Next Header: TCP (6) This patch allows ip6_make_flowlabel() to be passed more than just a flow label and has it extract the part it really wants. This was simpler than modifying the callers. With this patch packets like the above become Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2:: 0110 .... = Version: 6 .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT) .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0) .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0) .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e Payload Length: 32 Next Header: TCP (6) Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2:: 0110 .... = Version: 6 .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0)) .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0) .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2) .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e Payload Length: 688 Next Header: TCP (6) Signed-off-by: Dimitris Michailidis <dmichail@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>