Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935323AbXLQXy3 (ORCPT ); Mon, 17 Dec 2007 18:54:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964839AbXLQXxk (ORCPT ); Mon, 17 Dec 2007 18:53:40 -0500 Received: from terminus.zytor.com ([198.137.202.10]:59517 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935518AbXLQXxa (ORCPT ); Mon, 17 Dec 2007 18:53:30 -0500 Date: Mon, 17 Dec 2007 15:45:42 -0800 Message-Id: <200712172345.lBHNjgGq021212@tazenda.hos.anvin.org> From: "H. Peter Anvin" Subject: [PATCH] Avoid overflows in kernel/time.c (version 4) To: Andrew Morton Cc: Linux Kernel Mailing List , Linux Arch Mailing List , Ralf Baechle , Sam Ravnborg , Paul Mundt , Richard Henderson , Michael Starvik , David Howells , Yoshinori Sato , Hirokazu Takata , Geert Uytterhoeven , Roman Zippel , "William L. Irwin" , Chris Zankel , "H. Peter Anvin" , Jan Engelhardt Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 28069 Lines: 968 When the conversion factor between jiffies and milli- or microseconds is not a single multiply or divide, as for the case of HZ == 300, we currently do a multiply followed by a divide. The intervening result, however, is subject to overflows, especially since the fraction is not simplified (for HZ == 300, we multiply by 300 and divide by 1000). This is exposed to the user when passing a large timeout to poll(), for example. This patch replaces the multiply-divide with a reciprocal multiplication on 32-bit platforms. When the input is an unsigned long, there is no portable way to do this on 64-bit platforms there is no portable way to do this since it requires a 128-bit intermediate result (which gcc does support on 64-bit platforms but may generate libgcc calls, e.g. on 64-bit s390), but since the output is a 32-bit integer in the cases affected, just simplify the multiply-divide (*3/10 instead of *300/1000). The reciprocal multiply used can have off-by-one errors in the upper half of the valid output range. This could be avoided at the expense of having to deal with a potential 65-bit intermediate result. Since the intent is to avoid overflow problems and most of the other time conversions are only semiexact, the off-by-one errors were considered an acceptable tradeoff. At Ralf Baechle's suggestion, this version uses a Perl script to compute the necessary constants. We already have dependencies on Perl for kernel compiles. This does, however, require the Perl module Math::BigInt, which is included in the standard Perl distribution starting with version 5.8.0. In order to support older versions of Perl, include a table of canned constants in the script itself, and structure the script so that Math::BigInt isn't required if pulling values from said table. Running the script requires that the HZ value is available from the Makefile. Thus, this patch also adds the Kconfig variable CONFIG_HZ to the architectures which didn't already have it (alpha, cris, frv, h8300, m32r, m68k, m68knommu, sh64, sparc, v850, and xtensa.) It does *not* resolve a weird case in the sh architecture, where HZ != CONFIG_HZ if CONFIG_SH_WDT is set. Paul Mundt has been contacted about that, and has agreed to fix it up. Signed-off-by: H. Peter Anvin --- Delta from previous version: indentation fixed in timeconst.pl arch/alpha/Kconfig | 5 + arch/cris/Kconfig | 4 + arch/frv/Kconfig | 4 + arch/h8300/Kconfig | 4 + arch/m32r/Kconfig | 4 + arch/m68k/Kconfig | 4 + arch/m68knommu/Kconfig | 5 + arch/sh64/Kconfig | 6 + arch/sparc/Kconfig | 4 + arch/v850/Kconfig | 7 + arch/xtensa/Kconfig | 4 + include/asm-alpha/param.h | 10 +- include/asm-cris/param.h | 2 +- include/asm-frv/param.h | 2 +- include/asm-h8300/param.h | 2 +- include/asm-m32r/param.h | 2 +- include/asm-m68k/param.h | 2 +- include/asm-m68knommu/param.h | 8 +- include/asm-sh64/param.h | 6 +- include/asm-sparc/param.h | 2 +- include/asm-v850/anna.h | 6 - include/asm-v850/as85ep1.h | 6 - include/asm-v850/fpga85e2c.h | 6 - include/asm-v850/param.h | 3 +- include/asm-v850/rte_cb.h | 6 - include/asm-v850/sim.h | 5 - include/asm-v850/sim85e2.h | 6 - include/asm-xtensa/param.h | 2 +- kernel/Makefile | 8 + kernel/time.c | 29 +++- kernel/timeconst.pl | 340 +++++++++++++++++++++++++++++++++++++++++ 31 files changed, 431 insertions(+), 73 deletions(-) create mode 100644 kernel/timeconst.pl diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 4c002ba..442e4e7 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -616,6 +616,11 @@ config VERBOSE_MCHECK_ON Take the default (1) unless you want more control or more info. +config HZ + int + default 1200 if ALPHA_RAWHIDE + default 1024 + source "drivers/pci/Kconfig" source "drivers/eisa/Kconfig" diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig index 222da15..fcc6a9e 100644 --- a/arch/cris/Kconfig +++ b/arch/cris/Kconfig @@ -55,6 +55,10 @@ config CRIS bool default y +config HZ + int + default 100 + source "init/Kconfig" menu "General setup" diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig index 43153e7..57bdf2d 100644 --- a/arch/frv/Kconfig +++ b/arch/frv/Kconfig @@ -57,6 +57,10 @@ config ARCH_HAS_ILOG2_U64 bool default y +config HZ + int + default 1000 + mainmenu "Fujitsu FR-V Kernel Configuration" source "init/Kconfig" diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig index ff6a871..8a40a6f 100644 --- a/arch/h8300/Kconfig +++ b/arch/h8300/Kconfig @@ -79,6 +79,10 @@ config PCI bool default n +config HZ + int + default 100 + source "init/Kconfig" source "arch/h8300/Kconfig.cpu" diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig index ab9a264..1547d81 100644 --- a/arch/m32r/Kconfig +++ b/arch/m32r/Kconfig @@ -34,6 +34,10 @@ config NO_IOPORT config NO_DMA def_bool y +config HZ + int + default 100 + source "init/Kconfig" diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index 01dee84..06ccc89 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -52,6 +52,10 @@ config NO_IOPORT config NO_DMA def_bool SUN3 +config HZ + int + default 100 + mainmenu "Linux/68k Kernel Configuration" source "init/Kconfig" diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig index f4b582c..da393c4 100644 --- a/arch/m68knommu/Kconfig +++ b/arch/m68knommu/Kconfig @@ -518,6 +518,11 @@ config 4KSTACKS running more threads on a system and also reduces the pressure on the VM subsystem for higher order allocations. +config HZ + int + default 1000 if CLEOPATRA + default 100 + comment "RAM configuration" config RAMBASE diff --git a/arch/sh64/Kconfig b/arch/sh64/Kconfig index 6884d5a..95b76aa 100644 --- a/arch/sh64/Kconfig +++ b/arch/sh64/Kconfig @@ -293,3 +293,9 @@ source "security/Kconfig" source "crypto/Kconfig" source "lib/Kconfig" + +# Higher frequency needed for high-res WOVF +config HZ + int + default 1000 if SH_WDT + default 100 diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index 527adc8..e2991f9 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -27,6 +27,10 @@ config ARCH_NO_VIRT_TO_BUS config OF def_bool y +config HZ + int + default 100 + source "init/Kconfig" menu "General machine setup" diff --git a/arch/v850/Kconfig b/arch/v850/Kconfig index b6a50b8..b9c8b54 100644 --- a/arch/v850/Kconfig +++ b/arch/v850/Kconfig @@ -212,6 +212,13 @@ menu "Processor type and features" bool default !V850E_CACHE && !V850E2_CACHE + # HZ depends on the platform + config HZ + int + default 24 if V850E_SIM || V850E2_SIM85E2 + default 122 if V850E2_FPGA85E2C + default 100 + #### Misc config config ROM_KERNEL diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index d3cb3d6..2a2aff1 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -49,6 +49,10 @@ config ARCH_HAS_ILOG2_U64 config NO_IOPORT def_bool y +config HZ + int + default 100 + source "init/Kconfig" menu "Processor type and features" diff --git a/include/asm-alpha/param.h b/include/asm-alpha/param.h index 214e799..0982f1d 100644 --- a/include/asm-alpha/param.h +++ b/include/asm-alpha/param.h @@ -5,15 +5,7 @@ hardware ignores reprogramming. We also need userland buy-in to the change in HZ, since this is visible in the wait4 resources etc. */ - -#ifndef HZ -# ifndef CONFIG_ALPHA_RAWHIDE -# define HZ 1024 -# else -# define HZ 1200 -# endif -#endif - +#define HZ CONFIG_HZ #define USER_HZ HZ #define EXEC_PAGESIZE 8192 diff --git a/include/asm-cris/param.h b/include/asm-cris/param.h index b249726..0e47994 100644 --- a/include/asm-cris/param.h +++ b/include/asm-cris/param.h @@ -3,7 +3,7 @@ /* Currently we assume that HZ=100 is good for CRIS. */ #ifdef __KERNEL__ -# define HZ 100 /* Internal kernel timer frequency */ +# define HZ CONFIG_HZ /* Internal kernel timer frequency */ # define USER_HZ 100 /* .. some user interfaces are in "ticks" */ # define CLOCKS_PER_SEC (USER_HZ) /* like times() */ #endif diff --git a/include/asm-frv/param.h b/include/asm-frv/param.h index 365653b..6859dd5 100644 --- a/include/asm-frv/param.h +++ b/include/asm-frv/param.h @@ -2,7 +2,7 @@ #define _ASM_PARAM_H #ifdef __KERNEL__ -#define HZ 1000 /* Internal kernel timer frequency */ +#define HZ CONFIG_HZ /* Internal kernel timer frequency */ #define USER_HZ 100 /* .. some user interfaces are in "ticks" */ #define CLOCKS_PER_SEC (USER_HZ) /* like times() */ #endif diff --git a/include/asm-h8300/param.h b/include/asm-h8300/param.h index c25806e..04f64f1 100644 --- a/include/asm-h8300/param.h +++ b/include/asm-h8300/param.h @@ -3,7 +3,7 @@ #ifndef HZ -#define HZ 100 +#define HZ CONFIG_HZ #endif #ifdef __KERNEL__ diff --git a/include/asm-m32r/param.h b/include/asm-m32r/param.h index 3e14026..94c7701 100644 --- a/include/asm-m32r/param.h +++ b/include/asm-m32r/param.h @@ -2,7 +2,7 @@ #define _ASM_M32R_PARAM_H #ifdef __KERNEL__ -# define HZ 100 /* Internal kernel timer frequency */ +# define HZ CONFIG_HZ /* Internal kernel timer frequency */ # define USER_HZ 100 /* .. some user interfaces are in "ticks" */ # define CLOCKS_PER_SEC (USER_HZ) /* like times() */ #endif diff --git a/include/asm-m68k/param.h b/include/asm-m68k/param.h index 60f409d..536a278 100644 --- a/include/asm-m68k/param.h +++ b/include/asm-m68k/param.h @@ -2,7 +2,7 @@ #define _M68K_PARAM_H #ifdef __KERNEL__ -# define HZ 100 /* Internal kernel timer frequency */ +# define HZ CONFIG_HZ /* Internal kernel timer frequency */ # define USER_HZ 100 /* .. some user interfaces are in "ticks" */ # define CLOCKS_PER_SEC (USER_HZ) /* like times() */ #endif diff --git a/include/asm-m68knommu/param.h b/include/asm-m68knommu/param.h index 4c9904d..96c4510 100644 --- a/include/asm-m68knommu/param.h +++ b/include/asm-m68knommu/param.h @@ -1,13 +1,7 @@ #ifndef _M68KNOMMU_PARAM_H #define _M68KNOMMU_PARAM_H - -#if defined(CONFIG_CLEOPATRA) -#define HZ 1000 -#endif -#ifndef HZ -#define HZ 100 -#endif +#define HZ CONFIG_HZ #ifdef __KERNEL__ #define USER_HZ HZ diff --git a/include/asm-sh64/param.h b/include/asm-sh64/param.h index f409adb..4665154 100644 --- a/include/asm-sh64/param.h +++ b/include/asm-sh64/param.h @@ -14,11 +14,7 @@ #ifdef __KERNEL__ -# ifdef CONFIG_SH_WDT -# define HZ 1000 /* Needed for high-res WOVF */ -# else -# define HZ 100 -# endif +# define HZ CONFIG_HZ # define USER_HZ 100 /* User interfaces are in "ticks" */ # define CLOCKS_PER_SEC (USER_HZ) /* frequency at which times() counts */ #endif diff --git a/include/asm-sparc/param.h b/include/asm-sparc/param.h index beaf02d..86ba59a 100644 --- a/include/asm-sparc/param.h +++ b/include/asm-sparc/param.h @@ -3,7 +3,7 @@ #define _ASMSPARC_PARAM_H #ifdef __KERNEL__ -# define HZ 100 /* Internal kernel timer frequency */ +# define HZ CONFIG_HZ /* Internal kernel timer frequency */ # define USER_HZ 100 /* .. some user interfaces are in "ticks" */ # define CLOCKS_PER_SEC (USER_HZ) #endif diff --git a/include/asm-v850/anna.h b/include/asm-v850/anna.h index 3be77d5..cd5eaee 100644 --- a/include/asm-v850/anna.h +++ b/include/asm-v850/anna.h @@ -134,10 +134,4 @@ extern void anna_uart_pre_configure (unsigned chan, #define V850E_TIMER_D_TMCD_CS_MIN 1 /* min 2^1 divider */ -/* For */ -#ifndef HZ -#define HZ 100 -#endif - - #endif /* __V850_ANNA_H__ */ diff --git a/include/asm-v850/as85ep1.h b/include/asm-v850/as85ep1.h index 659bc91..5a5ca90 100644 --- a/include/asm-v850/as85ep1.h +++ b/include/asm-v850/as85ep1.h @@ -149,10 +149,4 @@ extern void as85ep1_uart_pre_configure (unsigned chan, #define V850E_TIMER_D_TMCD_CS_MIN 2 /* min 2^2 divider */ -/* For */ -#ifndef HZ -#define HZ 100 -#endif - - #endif /* __V850_AS85EP1_H__ */ diff --git a/include/asm-v850/fpga85e2c.h b/include/asm-v850/fpga85e2c.h index d32f045..23aae66 100644 --- a/include/asm-v850/fpga85e2c.h +++ b/include/asm-v850/fpga85e2c.h @@ -79,10 +79,4 @@ extern char _r0_ram; #endif -/* For */ -#ifndef HZ -#define HZ 122 /* actually, 8.192ms ticks =~ 122.07 */ -#endif - - #endif /* __V850_FPGA85E2C_H__ */ diff --git a/include/asm-v850/param.h b/include/asm-v850/param.h index 3c65bd5..2818326 100644 --- a/include/asm-v850/param.h +++ b/include/asm-v850/param.h @@ -23,8 +23,7 @@ #define MAXHOSTNAMELEN 64 /* max length of hostname */ #ifdef __KERNEL__ -#include /* For HZ */ - +# define HZ CONFIG_HZ # define USER_HZ 100 # define CLOCKS_PER_SEC USER_HZ #endif diff --git a/include/asm-v850/rte_cb.h b/include/asm-v850/rte_cb.h index e85d261..db9879f 100644 --- a/include/asm-v850/rte_cb.h +++ b/include/asm-v850/rte_cb.h @@ -69,12 +69,6 @@ #endif /* CONFIG_RTE_MB_A_PCI */ -/* For */ -#ifndef HZ -#define HZ 100 -#endif - - #ifndef __ASSEMBLY__ extern void rte_cb_early_init (void); extern void rte_cb_init_irqs (void); diff --git a/include/asm-v850/sim.h b/include/asm-v850/sim.h index 10236ab..026932d 100644 --- a/include/asm-v850/sim.h +++ b/include/asm-v850/sim.h @@ -40,11 +40,6 @@ #define R0_RAM_ADDR 0xFFFFF000 -/* For */ -#ifndef HZ -#define HZ 24 /* Minimum supported frequency. */ -#endif - /* For */ #define NUM_CPU_IRQS 6 diff --git a/include/asm-v850/sim85e2.h b/include/asm-v850/sim85e2.h index 17dd4fa..8b4d697 100644 --- a/include/asm-v850/sim85e2.h +++ b/include/asm-v850/sim85e2.h @@ -66,10 +66,4 @@ #define R0_RAM_ADDR 0xFFFFE000 -/* For */ -#ifndef HZ -#define HZ 24 /* Minimum supported frequency. */ -#endif - - #endif /* __V850_SIM85E2_H__ */ diff --git a/include/asm-xtensa/param.h b/include/asm-xtensa/param.h index ce3a336..82ad34d 100644 --- a/include/asm-xtensa/param.h +++ b/include/asm-xtensa/param.h @@ -12,7 +12,7 @@ #define _XTENSA_PARAM_H #ifdef __KERNEL__ -# define HZ 100 /* internal timer frequency */ +# define HZ CONFIG_HZ /* internal timer frequency */ # define USER_HZ 100 /* for user interfaces in "ticks" */ # define CLOCKS_PER_SEC (USER_HZ) /* frequnzy at which times() counts */ #endif diff --git a/kernel/Makefile b/kernel/Makefile index dfa9695..749825a 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -80,3 +80,11 @@ quiet_cmd_ikconfiggz = IKCFG $@ targets += config_data.h $(obj)/config_data.h: $(obj)/config_data.gz FORCE $(call if_changed,ikconfiggz) + +$(obj)/time.o: $(obj)/timeconst.h + +quiet_cmd_timeconst = TIMEC $@ + cmd_timeconst = $(PERL) $< $(CONFIG_HZ) > $@ +targets += timeconst.h +$(obj)/timeconst.h: $(src)/timeconst.pl $(wildcard include/config/hz.h) FORCE + $(call if_changed,timeconst) diff --git a/kernel/time.c b/kernel/time.c index 09d3c45..8e790b5 100644 --- a/kernel/time.c +++ b/kernel/time.c @@ -39,6 +39,8 @@ #include #include +#include "timeconst.h" + /* * The timezone where the local system is located. Used as a default by some * programs who obtain this value by using gettimeofday. @@ -93,7 +95,8 @@ asmlinkage long sys_stime(time_t __user *tptr) #endif /* __ARCH_WANT_SYS_TIME */ -asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz) +asmlinkage long sys_gettimeofday(struct timeval __user *tv, + struct timezone __user *tz) { if (likely(tv != NULL)) { struct timeval ktv; @@ -118,7 +121,7 @@ asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __us * hard to make the program warp the clock precisely n hours) or * compile in the timezone information into the kernel. Bad, bad.... * - * - TYT, 1992-01-01 + * - TYT, 1992-01-01 * * The best thing to do is to keep the CMOS clock in universal time (UTC) * as real UNIX machines always do it. This avoids all headaches about @@ -239,7 +242,11 @@ unsigned int inline jiffies_to_msecs(const unsigned long j) #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); #else - return (j * MSEC_PER_SEC) / HZ; +# if BITS_PER_LONG == 32 + return ((u64)HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32; +# else + return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN; +# endif #endif } EXPORT_SYMBOL(jiffies_to_msecs); @@ -251,7 +258,11 @@ unsigned int inline jiffies_to_usecs(const unsigned long j) #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC); #else - return (j * USEC_PER_SEC) / HZ; +# if BITS_PER_LONG == 32 + return ((u64)HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32; +# else + return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN; +# endif #endif } EXPORT_SYMBOL(jiffies_to_usecs); @@ -351,7 +362,7 @@ EXPORT_SYMBOL(mktime); * normalize to the timespec storage format * * Note: The tv_nsec part is always in the range of - * 0 <= tv_nsec < NSEC_PER_SEC + * 0 <= tv_nsec < NSEC_PER_SEC * For negative values only the tv_sec field is negative ! */ void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec) @@ -452,12 +463,13 @@ unsigned long msecs_to_jiffies(const unsigned int m) /* * Generic case - multiply, round and divide. But first * check that if we are doing a net multiplication, that - * we wouldnt overflow: + * we wouldn't overflow: */ if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) return MAX_JIFFY_OFFSET; - return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC; + return ((u64)MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) + >> MSEC_TO_HZ_SHR32; #endif } EXPORT_SYMBOL(msecs_to_jiffies); @@ -471,7 +483,8 @@ unsigned long usecs_to_jiffies(const unsigned int u) #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) return u * (HZ / USEC_PER_SEC); #else - return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC; + return ((u64)USEC_TO_HZ_MUL32 * m + USEC_TO_HZ_ADJ32) + >> USEC_TO_HZ_SHR32; #endif } EXPORT_SYMBOL(usecs_to_jiffies); diff --git a/kernel/timeconst.pl b/kernel/timeconst.pl new file mode 100644 index 0000000..42572e3 --- /dev/null +++ b/kernel/timeconst.pl @@ -0,0 +1,340 @@ +#!/usr/bin/perl +# ----------------------------------------------------------------------- +# +# Copyright 2007 rPath, Inc. - All Rights Reserved +# +# This file is part of the Linux kernel, and is made available under +# the terms of the GNU General Public License version 2 or (at your +# option) any later version; incorporated herein by reference. +# +# ----------------------------------------------------------------------- +# + +# +# Usage: timeconst.pl HZ > timeconst.h +# + +# Precomputed values for systems without Math::BigInt +# Generated by: +# timeconst.pl --can 24 32 48 64 100 122 128 200 250 256 300 512 \ +# 1000 1024 1200 +%canned_values = ( + 24 => [ + '0xa6aaaaab','0x2aaaaaa',26, + '0xa6aaaaaaaaaaaaab','0x2aaaaaaaaaaaaaa',58, + '0xc49ba5e4','0x1fbe76c8b4',37, + '0xc49ba5e353f7ceda','0x1fbe76c8b439581062',69, + '0xa2c2aaab','0xaaaa',16, + '0xa2c2aaaaaaaaaaab','0xaaaaaaaaaaaa',48, + '0xc9539b89','0x7fffbce4217d',47, + '0xc9539b8887229e91','0x7fffbce4217d2849cb25',79, + ], 32 => [ + '0xfa000000','0x6000000',27, + '0xfa00000000000000','0x600000000000000',59, + '0x83126e98','0xfdf3b645a',36, + '0x83126e978d4fdf3c','0xfdf3b645a1cac0831',68, + '0xf4240000','0x0',17, + '0xf424000000000000','0x0',49, + '0x8637bd06','0x3fff79c842fa',46, + '0x8637bd05af6c69b6','0x3fff79c842fa5093964a',78, + ], 48 => [ + '0xa6aaaaab','0x6aaaaaa',27, + '0xa6aaaaaaaaaaaaab','0x6aaaaaaaaaaaaaa',59, + '0xc49ba5e4','0xfdf3b645a',36, + '0xc49ba5e353f7ceda','0xfdf3b645a1cac0831',68, + '0xa2c2aaab','0x15555',17, + '0xa2c2aaaaaaaaaaab','0x1555555555555',49, + '0xc9539b89','0x3fffbce4217d',46, + '0xc9539b8887229e91','0x3fffbce4217d2849cb25',78, + ], 64 => [ + '0xfa000000','0xe000000',28, + '0xfa00000000000000','0xe00000000000000',60, + '0x83126e98','0x7ef9db22d',35, + '0x83126e978d4fdf3c','0x7ef9db22d0e560418',67, + '0xf4240000','0x0',18, + '0xf424000000000000','0x0',50, + '0x8637bd06','0x1fff79c842fa',45, + '0x8637bd05af6c69b6','0x1fff79c842fa5093964a',77, + ], 100 => [ + '0xa0000000','0x0',28, + '0xa000000000000000','0x0',60, + '0xcccccccd','0x733333333',35, + '0xcccccccccccccccd','0x73333333333333333',67, + '0x9c400000','0x0',18, + '0x9c40000000000000','0x0',50, + '0xd1b71759','0x1fff2e48e8a7',45, + '0xd1b71758e219652c','0x1fff2e48e8a71de69ad4',77, + ], 122 => [ + '0x8325c53f','0xfbcda3a',28, + '0x8325c53ef368eb05','0xfbcda3ac10c9714',60, + '0xf9db22d1','0x7fbe76c8b',35, + '0xf9db22d0e560418a','0x7fbe76c8b43958106',67, + '0x8012e2a0','0x3ef36',18, + '0x8012e29f79b47583','0x3ef368eb04325',50, + '0xffda4053','0x1ffffbce4217',45, + '0xffda4052d666a983','0x1ffffbce4217d2849cb2',77, + ], 128 => [ + '0xfa000000','0x1e000000',29, + '0xfa00000000000000','0x1e00000000000000',61, + '0x83126e98','0x3f7ced916',34, + '0x83126e978d4fdf3c','0x3f7ced916872b020c',66, + '0xf4240000','0x40000',19, + '0xf424000000000000','0x4000000000000',51, + '0x8637bd06','0xfffbce4217d',44, + '0x8637bd05af6c69b6','0xfffbce4217d2849cb25',76, + ], 200 => [ + '0xa0000000','0x0',29, + '0xa000000000000000','0x0',61, + '0xcccccccd','0x333333333',34, + '0xcccccccccccccccd','0x33333333333333333',66, + '0x9c400000','0x0',19, + '0x9c40000000000000','0x0',51, + '0xd1b71759','0xfff2e48e8a7',44, + '0xd1b71758e219652c','0xfff2e48e8a71de69ad4',76, + ], 250 => [ + '0x80000000','0x0',29, + '0x8000000000000000','0x0',61, + '0x80000000','0x180000000',33, + '0x8000000000000000','0x18000000000000000',65, + '0xfa000000','0x0',20, + '0xfa00000000000000','0x0',52, + '0x83126e98','0x7ff7ced9168',43, + '0x83126e978d4fdf3c','0x7ff7ced916872b020c4',75, + ], 256 => [ + '0xfa000000','0x3e000000',30, + '0xfa00000000000000','0x3e00000000000000',62, + '0x83126e98','0x1fbe76c8b',33, + '0x83126e978d4fdf3c','0x1fbe76c8b43958106',65, + '0xf4240000','0xc0000',20, + '0xf424000000000000','0xc000000000000',52, + '0x8637bd06','0x7ffde7210be',43, + '0x8637bd05af6c69b6','0x7ffde7210be9424e592',75, + ], 300 => [ + '0xd5555556','0x2aaaaaaa',30, + '0xd555555555555556','0x2aaaaaaaaaaaaaaa',62, + '0x9999999a','0x1cccccccc',33, + '0x999999999999999a','0x1cccccccccccccccc',65, + '0xd0555556','0xaaaaa',20, + '0xd055555555555556','0xaaaaaaaaaaaaa',52, + '0x9d495183','0x7ffcb923a29',43, + '0x9d495182a9930be1','0x7ffcb923a29c779a6b5',75, + ], 512 => [ + '0xfa000000','0x7e000000',31, + '0xfa00000000000000','0x7e00000000000000',63, + '0x83126e98','0xfdf3b645',32, + '0x83126e978d4fdf3c','0xfdf3b645a1cac083',64, + '0xf4240000','0x1c0000',21, + '0xf424000000000000','0x1c000000000000',53, + '0x8637bd06','0x3ffef39085f',42, + '0x8637bd05af6c69b6','0x3ffef39085f4a1272c9',74, + ], 1000 => [ + '0x80000000','0x0',31, + '0x8000000000000000','0x0',63, + '0x80000000','0x0',31, + '0x8000000000000000','0x0',63, + '0xfa000000','0x0',22, + '0xfa00000000000000','0x0',54, + '0x83126e98','0x1ff7ced9168',41, + '0x83126e978d4fdf3c','0x1ff7ced916872b020c4',73, + ], 1024 => [ + '0xfa000000','0xfe000000',32, + '0xfa00000000000000','0xfe00000000000000',64, + '0x83126e98','0x7ef9db22',31, + '0x83126e978d4fdf3c','0x7ef9db22d0e56041',63, + '0xf4240000','0x3c0000',22, + '0xf424000000000000','0x3c000000000000',54, + '0x8637bd06','0x1fff79c842f',41, + '0x8637bd05af6c69b6','0x1fff79c842fa5093964',73, + ], 1200 => [ + '0xd5555556','0xd5555555',32, + '0xd555555555555556','0xd555555555555555',64, + '0x9999999a','0x66666666',31, + '0x999999999999999a','0x6666666666666666',63, + '0xd0555556','0x2aaaaa',22, + '0xd055555555555556','0x2aaaaaaaaaaaaa',54, + '0x9d495183','0x1ffcb923a29',41, + '0x9d495182a9930be1','0x1ffcb923a29c779a6b5',73, + ] +); + +$has_bigint = eval 'use Math::BigInt qw(bgcd); 1;'; + +sub bint($) +{ + my($x) = @_; + return Math::BigInt->new($x); +} + +# +# Constants for division by reciprocal multiplication. +# (bits, numerator, denominator) +# +sub fmul($$$) +{ + my ($b,$n,$d) = @_; + + $n = bint($n); + $d = bint($d); + + return scalar (($n << $b)+$d-bint(1))/$d; +} + +sub fadj($$$) +{ + my($b,$n,$d) = @_; + + $n = bint($n); + $d = bint($d); + + $d = $d/bgcd($n, $d); + return scalar (($d-bint(1)) << $b)/$d; +} + +sub fmuls($$$) { + my($b,$n,$d) = @_; + my($s,$m); + my($thres) = bint(1) << ($b-1); + + $n = bint($n); + $d = bint($d); + + for ($s = 0; 1; $s++) { + $m = fmul($s,$n,$d); + return $s if ($m >= $thres); + } + return 0; +} + +sub compute_values($) { + my($hz) = @_; + my @val = (); + my $s, $m, $a; + + if (!$has_bigint) { + die "$0: HZ == $hz not canned and ". + "Math::BigInt not available\n"; + } + + # HZ_TO_MSEC_*32 + $s = fmuls(32, 1000, $hz); + $m = fmul($s, 1000, $hz); + $a = fadj($s, 1000, $hz); + push(@val, $m->as_hex(), $a->as_hex(), $s); + + # HZ_TO_MSEC_*64 + $s = fmuls(64, 1000, $hz); + $m = fmul($s, 1000, $hz); + $a = fadj($s, 1000, $hz); + push(@val, $m->as_hex(), $a->as_hex(), $s); + + # MSEC_TO_HZ_*32 + $s = fmuls(32, $hz, 1000); + $m = fmul($s, $hz, 1000); + $a = fadj($s, $hz, 1000); + push(@val, $m->as_hex(), $a->as_hex(), $s); + + # MSEC_TO_HZ_*64 + $s = fmuls(64, $hz, 1000); + $m = fmul($s, $hz, 1000); + $a = fadj($s, $hz, 1000); + push(@val, $m->as_hex(), $a->as_hex(), $s); + + # HZ_TO_USEC_*32 + $s = fmuls(32, 1000000, $hz); + $m = fmul($s, 1000000, $hz); + $a = fadj($s, 1000000, $hz); + push(@val, $m->as_hex(), $a->as_hex(), $s); + + # HZ_TO_USEC_*64 + $s = fmuls(64, 1000000, $hz); + $m = fmul($s, 1000000, $hz); + $a = fadj($s, 1000000, $hz); + push(@val, $m->as_hex(), $a->as_hex(), $s); + + # USEC_TO_HZ_*32 + $s = fmuls(32, $hz, 1000000); + $m = fmul($s, $hz, 1000000); + $a = fadj($s, $hz, 1000000); + push(@val, $m->as_hex(), $a->as_hex(), $s); + + # USEC_TO_HZ_*64 + $s = fmuls(64, $hz, 1000000); + $m = fmul($s, $hz, 1000000); + $a = fadj($s, $hz, 1000000); + push(@val, $m->as_hex(), $a->as_hex(), $s); + + return @val; +} + +sub output($@) +{ + my($hz, @val) = @_; + my $pfx, $bit, $suf, $s, $m, $a; + + print "/* Automatically generated by kernel/timeconst.pl */\n"; + print "/* Conversion constants for HZ == $hz */\n"; + print "\n"; + print "#ifndef KERNEL_TIMECONST_H\n"; + print "#define KERNEL_TIMECONST_H\n"; + print "\n"; + + print "#include \n"; + + print "\n"; + print "#if HZ != $hz\n"; + print "#error \"kernel/timeconst.h has the wrong HZ value!\"\n"; + print "#endif\n"; + print "\n"; + + foreach $pfx ('HZ_TO_MSEC','MSEC_TO_HZ', + 'USEC_TO_HZ','HZ_TO_USEC') { + foreach $bit (32, 64) { + foreach $suf ('MUL', 'ADJ', 'SHR') { + printf "#define %-23s %s\n", + "${pfx}_$suf$bit", shift(@val); + } + } + } + + print "\n"; + print "#endif /* KERNEL_TIMECONST_H */\n"; +} + +($hz) = @ARGV; + +# Use this to generate the %canned_values structure +if ($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 $m = shift(@values); + my $a = shift(@values); + my $s = shift(@values); + print "\t\t\'",$m,"\',\'",$a,"\',",$s,",\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; -- 1.5.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/