kernel: Replace timeconst.pl with a bc script
bc is the standard tool for multi-precision arithmetic. We switched to Perl because akpm reported a hard-to-reproduce build hang, which was very odd because affected and unaffected machines were all running the same version of GNU bc. Unfortunately switching to Perl required a really ugly "canning" mechanism to support Perl < 5.8 installations lacking the Math::BigInt module. It was recently pointed out to me that some very old versions of GNU make had problems with pipes in subshells, which was indeed the construct used in the Makefile rules in that version of the patch; Perl didn't need it so switching to Perl fixed the problem for unrelated reasons. With the problem (hopefully) root-caused, we can switch back to bc and do the arbitrary-precision arithmetic naturally. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Andrew Morton <akpm@linux-foundation.org> Acked-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Michal Marek <mmarek@suse.cz>
This commit is contained in:
H. Peter Anvin
Michal Marek
parent
6543becf26
commit
70730bca13
3 changed files with 120 additions and 382 deletions
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@ -127,11 +127,19 @@ $(obj)/config_data.h: $(obj)/config_data.gz FORCE
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$(obj)/time.o: $(obj)/timeconst.h
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quiet_cmd_timeconst = TIMEC $@
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cmd_timeconst = $(PERL) $< $(CONFIG_HZ) > $@
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quiet_cmd_hzfile = HZFILE $@
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cmd_hzfile = echo "hz=$(CONFIG_HZ)" > $@
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targets += hz.bc
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$(obj)/hz.bc: $(objtree)/include/config/hz.h FORCE
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$(call if_changed,hzfile)
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quiet_cmd_bc = BC $@
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cmd_bc = bc -q $(filter-out FORCE,$^) > $@
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targets += timeconst.h
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$(obj)/timeconst.h: $(src)/timeconst.pl FORCE
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$(call if_changed,timeconst)
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$(obj)/timeconst.h: $(obj)/hz.bc $(src)/timeconst.bc FORCE
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$(call if_changed,bc)
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ifeq ($(CONFIG_MODULE_SIG),y)
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#
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108
kernel/timeconst.bc
Normal file
108
kernel/timeconst.bc
Normal file
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@ -0,0 +1,108 @@
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scale=0
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define gcd(a,b) {
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auto t;
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while (b) {
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t = b;
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b = a % b;
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a = t;
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}
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return a;
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}
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/* Division by reciprocal multiplication. */
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define fmul(b,n,d) {
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return (2^b*n+d-1)/d;
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}
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/* Adjustment factor when a ceiling value is used. Use as:
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(imul * n) + (fmulxx * n + fadjxx) >> xx) */
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define fadj(b,n,d) {
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auto v;
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d = d/gcd(n,d);
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v = 2^b*(d-1)/d;
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return v;
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}
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/* Compute the appropriate mul/adj values as well as a shift count,
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which brings the mul value into the range 2^b-1 <= x < 2^b. Such
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a shift value will be correct in the signed integer range and off
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by at most one in the upper half of the unsigned range. */
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define fmuls(b,n,d) {
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auto s, m;
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for (s = 0; 1; s++) {
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m = fmul(s,n,d);
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if (m >= 2^(b-1))
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return s;
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}
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return 0;
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}
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define timeconst(hz) {
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print "/* Automatically generated by kernel/timeconst.bc */\n"
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print "/* Time conversion constants for HZ == ", hz, " */\n"
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print "\n"
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print "#ifndef KERNEL_TIMECONST_H\n"
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print "#define KERNEL_TIMECONST_H\n\n"
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print "#include <linux/param.h>\n"
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print "#include <linux/types.h>\n\n"
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print "#if HZ != ", hz, "\n"
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print "#error \qkernel/timeconst.h has the wrong HZ value!\q\n"
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print "#endif\n\n"
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if (hz < 2) {
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print "#error Totally bogus HZ value!\n"
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} else {
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s=fmuls(32,1000,hz)
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obase=16
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print "#define HZ_TO_MSEC_MUL32\tU64_C(0x", fmul(s,1000,hz), ")\n"
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print "#define HZ_TO_MSEC_ADJ32\tU64_C(0x", fadj(s,1000,hz), ")\n"
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obase=10
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print "#define HZ_TO_MSEC_SHR32\t", s, "\n"
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s=fmuls(32,hz,1000)
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obase=16
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print "#define MSEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000), ")\n"
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print "#define MSEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000), ")\n"
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obase=10
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print "#define MSEC_TO_HZ_SHR32\t", s, "\n"
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obase=10
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cd=gcd(hz,1000)
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print "#define HZ_TO_MSEC_NUM\t\t", 1000/cd, "\n"
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print "#define HZ_TO_MSEC_DEN\t\t", hz/cd, "\n"
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print "#define MSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
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print "#define MSEC_TO_HZ_DEN\t\t", 1000/cd, "\n"
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print "\n"
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s=fmuls(32,1000000,hz)
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obase=16
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print "#define HZ_TO_USEC_MUL32\tU64_C(0x", fmul(s,1000000,hz), ")\n"
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print "#define HZ_TO_USEC_ADJ32\tU64_C(0x", fadj(s,1000000,hz), ")\n"
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obase=10
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print "#define HZ_TO_USEC_SHR32\t", s, "\n"
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s=fmuls(32,hz,1000000)
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obase=16
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print "#define USEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000000), ")\n"
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print "#define USEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000000), ")\n"
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obase=10
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print "#define USEC_TO_HZ_SHR32\t", s, "\n"
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obase=10
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cd=gcd(hz,1000000)
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print "#define HZ_TO_USEC_NUM\t\t", 1000000/cd, "\n"
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print "#define HZ_TO_USEC_DEN\t\t", hz/cd, "\n"
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print "#define USEC_TO_HZ_NUM\t\t", hz/cd, "\n"
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print "#define USEC_TO_HZ_DEN\t\t", 1000000/cd, "\n"
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print "\n"
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print "#endif /* KERNEL_TIMECONST_H */\n"
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}
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halt
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}
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timeconst(hz)
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@ -1,378 +0,0 @@
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#!/usr/bin/perl
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# -----------------------------------------------------------------------
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#
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# Copyright 2007-2008 rPath, Inc. - All Rights Reserved
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#
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# This file is part of the Linux kernel, and is made available under
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# the terms of the GNU General Public License version 2 or (at your
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# option) any later version; incorporated herein by reference.
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#
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# -----------------------------------------------------------------------
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#
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#
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# Usage: timeconst.pl HZ > timeconst.h
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#
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# Precomputed values for systems without Math::BigInt
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# Generated by:
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# timeconst.pl --can 24 32 48 64 100 122 128 200 250 256 300 512 1000 1024 1200
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%canned_values = (
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24 => [
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'0xa6aaaaab','0x2aaaaaa',26,
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125,3,
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'0xc49ba5e4','0x1fbe76c8b4',37,
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3,125,
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'0xa2c2aaab','0xaaaa',16,
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125000,3,
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'0xc9539b89','0x7fffbce4217d',47,
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3,125000,
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], 32 => [
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'0xfa000000','0x6000000',27,
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125,4,
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'0x83126e98','0xfdf3b645a',36,
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4,125,
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'0xf4240000','0x0',17,
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31250,1,
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'0x8637bd06','0x3fff79c842fa',46,
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1,31250,
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], 48 => [
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'0xa6aaaaab','0x6aaaaaa',27,
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125,6,
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'0xc49ba5e4','0xfdf3b645a',36,
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6,125,
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'0xa2c2aaab','0x15555',17,
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62500,3,
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'0xc9539b89','0x3fffbce4217d',46,
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3,62500,
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], 64 => [
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'0xfa000000','0xe000000',28,
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125,8,
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'0x83126e98','0x7ef9db22d',35,
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8,125,
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'0xf4240000','0x0',18,
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15625,1,
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'0x8637bd06','0x1fff79c842fa',45,
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1,15625,
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], 100 => [
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'0xa0000000','0x0',28,
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10,1,
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'0xcccccccd','0x733333333',35,
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1,10,
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'0x9c400000','0x0',18,
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10000,1,
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'0xd1b71759','0x1fff2e48e8a7',45,
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1,10000,
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], 122 => [
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'0x8325c53f','0xfbcda3a',28,
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500,61,
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'0xf9db22d1','0x7fbe76c8b',35,
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61,500,
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'0x8012e2a0','0x3ef36',18,
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500000,61,
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'0xffda4053','0x1ffffbce4217',45,
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61,500000,
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], 128 => [
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'0xfa000000','0x1e000000',29,
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125,16,
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'0x83126e98','0x3f7ced916',34,
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16,125,
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'0xf4240000','0x40000',19,
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15625,2,
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'0x8637bd06','0xfffbce4217d',44,
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2,15625,
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], 200 => [
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'0xa0000000','0x0',29,
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5,1,
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'0xcccccccd','0x333333333',34,
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1,5,
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'0x9c400000','0x0',19,
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5000,1,
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'0xd1b71759','0xfff2e48e8a7',44,
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1,5000,
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], 250 => [
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'0x80000000','0x0',29,
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4,1,
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'0x80000000','0x180000000',33,
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1,4,
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'0xfa000000','0x0',20,
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4000,1,
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'0x83126e98','0x7ff7ced9168',43,
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1,4000,
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], 256 => [
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'0xfa000000','0x3e000000',30,
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125,32,
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'0x83126e98','0x1fbe76c8b',33,
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32,125,
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'0xf4240000','0xc0000',20,
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15625,4,
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'0x8637bd06','0x7ffde7210be',43,
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4,15625,
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], 300 => [
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'0xd5555556','0x2aaaaaaa',30,
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10,3,
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'0x9999999a','0x1cccccccc',33,
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3,10,
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'0xd0555556','0xaaaaa',20,
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10000,3,
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'0x9d495183','0x7ffcb923a29',43,
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3,10000,
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], 512 => [
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'0xfa000000','0x7e000000',31,
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125,64,
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'0x83126e98','0xfdf3b645',32,
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64,125,
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'0xf4240000','0x1c0000',21,
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15625,8,
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'0x8637bd06','0x3ffef39085f',42,
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8,15625,
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], 1000 => [
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'0x80000000','0x0',31,
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1,1,
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'0x80000000','0x0',31,
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1,1,
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'0xfa000000','0x0',22,
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1000,1,
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'0x83126e98','0x1ff7ced9168',41,
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1,1000,
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], 1024 => [
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'0xfa000000','0xfe000000',32,
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125,128,
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'0x83126e98','0x7ef9db22',31,
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128,125,
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'0xf4240000','0x3c0000',22,
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15625,16,
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'0x8637bd06','0x1fff79c842f',41,
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16,15625,
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], 1200 => [
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'0xd5555556','0xd5555555',32,
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5,6,
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'0x9999999a','0x66666666',31,
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6,5,
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'0xd0555556','0x2aaaaa',22,
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2500,3,
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'0x9d495183','0x1ffcb923a29',41,
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3,2500,
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]
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);
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$has_bigint = eval 'use Math::BigInt qw(bgcd); 1;';
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sub bint($)
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{
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my($x) = @_;
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return Math::BigInt->new($x);
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}
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#
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# Constants for division by reciprocal multiplication.
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# (bits, numerator, denominator)
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#
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sub fmul($$$)
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{
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my ($b,$n,$d) = @_;
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$n = bint($n);
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$d = bint($d);
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return scalar (($n << $b)+$d-bint(1))/$d;
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}
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sub fadj($$$)
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{
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my($b,$n,$d) = @_;
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$n = bint($n);
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$d = bint($d);
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$d = $d/bgcd($n, $d);
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return scalar (($d-bint(1)) << $b)/$d;
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}
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sub fmuls($$$) {
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my($b,$n,$d) = @_;
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my($s,$m);
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my($thres) = bint(1) << ($b-1);
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$n = bint($n);
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$d = bint($d);
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for ($s = 0; 1; $s++) {
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$m = fmul($s,$n,$d);
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return $s if ($m >= $thres);
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}
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return 0;
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}
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# Generate a hex value if the result fits in 64 bits;
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# otherwise skip.
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sub bignum_hex($) {
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my($x) = @_;
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my $s = $x->as_hex();
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return (length($s) > 18) ? undef : $s;
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}
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# Provides mul, adj, and shr factors for a specific
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# (bit, time, hz) combination
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sub muladj($$$) {
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my($b, $t, $hz) = @_;
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my $s = fmuls($b, $t, $hz);
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my $m = fmul($s, $t, $hz);
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my $a = fadj($s, $t, $hz);
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return (bignum_hex($m), bignum_hex($a), $s);
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}
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# Provides numerator, denominator values
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sub numden($$) {
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my($n, $d) = @_;
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my $g = bgcd($n, $d);
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return ($n/$g, $d/$g);
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}
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# All values for a specific (time, hz) combo
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sub conversions($$) {
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my ($t, $hz) = @_;
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my @val = ();
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# HZ_TO_xx
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push(@val, muladj(32, $t, $hz));
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push(@val, numden($t, $hz));
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# xx_TO_HZ
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push(@val, muladj(32, $hz, $t));
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push(@val, numden($hz, $t));
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return @val;
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}
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sub compute_values($) {
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my($hz) = @_;
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my @val = ();
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my $s, $m, $a, $g;
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if (!$has_bigint) {
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die "$0: HZ == $hz not canned and ".
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"Math::BigInt not available\n";
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}
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# MSEC conversions
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push(@val, conversions(1000, $hz));
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# USEC conversions
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push(@val, conversions(1000000, $hz));
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return @val;
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}
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sub outputval($$)
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{
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my($name, $val) = @_;
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my $csuf;
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if (defined($val)) {
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if ($name !~ /SHR/) {
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$val = "U64_C($val)";
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}
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printf "#define %-23s %s\n", $name.$csuf, $val.$csuf;
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}
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}
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sub output($@)
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{
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my($hz, @val) = @_;
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my $pfx, $bit, $suf, $s, $m, $a;
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print "/* Automatically generated by kernel/timeconst.pl */\n";
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print "/* Conversion constants for HZ == $hz */\n";
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print "\n";
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print "#ifndef KERNEL_TIMECONST_H\n";
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print "#define KERNEL_TIMECONST_H\n";
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print "\n";
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print "#include <linux/param.h>\n";
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print "#include <linux/types.h>\n";
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print "\n";
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print "#if HZ != $hz\n";
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print "#error \"kernel/timeconst.h has the wrong HZ value!\"\n";
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print "#endif\n";
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print "\n";
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foreach $pfx ('HZ_TO_MSEC','MSEC_TO_HZ',
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'HZ_TO_USEC','USEC_TO_HZ') {
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foreach $bit (32) {
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foreach $suf ('MUL', 'ADJ', 'SHR') {
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outputval("${pfx}_$suf$bit", shift(@val));
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}
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}
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foreach $suf ('NUM', 'DEN') {
|
||||
outputval("${pfx}_$suf", shift(@val));
|
||||
}
|
||||
}
|
||||
|
||||
print "\n";
|
||||
print "#endif /* KERNEL_TIMECONST_H */\n";
|
||||
}
|
||||
|
||||
# Pretty-print Perl values
|
||||
sub perlvals(@) {
|
||||
my $v;
|
||||
my @l = ();
|
||||
|
||||
foreach $v (@_) {
|
||||
if (!defined($v)) {
|
||||
push(@l, 'undef');
|
||||
} elsif ($v =~ /^0x/) {
|
||||
push(@l, "\'".$v."\'");
|
||||
} else {
|
||||
push(@l, $v.'');
|
||||
}
|
||||
}
|
||||
return join(',', @l);
|
||||
}
|
||||
|
||||
($hz) = @ARGV;
|
||||
|
||||
# Use this to generate the %canned_values structure
|
||||
if ($hz eq '--can') {
|
||||
shift(@ARGV);
|
||||
@hzlist = sort {$a <=> $b} (@ARGV);
|
||||
|
||||
print "# Precomputed values for systems without Math::BigInt\n";
|
||||
print "# Generated by:\n";
|
||||
print "# timeconst.pl --can ", join(' ', @hzlist), "\n";
|
||||
print "\%canned_values = (\n";
|
||||
my $pf = "\t";
|
||||
foreach $hz (@hzlist) {
|
||||
my @values = compute_values($hz);
|
||||
print "$pf$hz => [\n";
|
||||
while (scalar(@values)) {
|
||||
my $bit;
|
||||
foreach $bit (32) {
|
||||
my $m = shift(@values);
|
||||
my $a = shift(@values);
|
||||
my $s = shift(@values);
|
||||
print "\t\t", perlvals($m,$a,$s), ",\n";
|
||||
}
|
||||
my $n = shift(@values);
|
||||
my $d = shift(@values);
|
||||
print "\t\t", perlvals($n,$d), ",\n";
|
||||
}
|
||||
print "\t]";
|
||||
$pf = ', ';
|
||||
}
|
||||
print "\n);\n";
|
||||
} else {
|
||||
$hz += 0; # Force to number
|
||||
if ($hz < 1) {
|
||||
die "Usage: $0 HZ\n";
|
||||
}
|
||||
|
||||
@val = @{$canned_values{$hz}};
|
||||
if (!defined(@val)) {
|
||||
@val = compute_values($hz);
|
||||
}
|
||||
output($hz, @val);
|
||||
}
|
||||
exit 0;
|
||||
Loading…
Reference in a new issue