H. Peter Anvin
bdc807871d
avoid overflows in kernel/time.c
...
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, sparc, v850, and xtensa.) It does *not* touch the sh or
sh64 architectures, since Paul Mundt has dealt with those separately in the
sh tree.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Ralf Baechle <ralf@linux-mips.org>,
Cc: Sam Ravnborg <sam@ravnborg.org>,
Cc: Paul Mundt <lethal@linux-sh.org>,
Cc: Richard Henderson <rth@twiddle.net>,
Cc: Michael Starvik <starvik@axis.com>,
Cc: David Howells <dhowells@redhat.com>,
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>,
Cc: Hirokazu Takata <takata@linux-m32r.org>,
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
Cc: Roman Zippel <zippel@linux-m68k.org>,
Cc: William L. Irwin <sparclinux@vger.kernel.org>,
Cc: Chris Zankel <chris@zankel.net>,
Cc: H. Peter Anvin <hpa@zytor.com>,
Cc: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:39 -08:00
..
a.out-core.h
aout: suppress A.OUT library support if !CONFIG_ARCH_SUPPORTS_AOUT
2008-02-08 09:22:30 -08:00
a.out.h
aout: move STACK_TOP[_MAX] to asm/processor.h
2008-02-08 09:22:29 -08:00
apc.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
asi.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
asmmacro.h
Don't include linux/config.h from anywhere else in include/
2006-04-26 12:56:16 +01:00
atomic.h
Add cmpxchg_local to sparc, move __cmpxchg to system.h
2008-02-07 08:42:32 -08:00
auxio.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
auxvec.h
[PATCH] auxiliary vector cleanups
2005-09-07 16:57:21 -07:00
bitext.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
bitops.h
forbid asm/bitops.h direct inclusion
2007-10-19 11:53:41 -07:00
bpp.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
bsderrno.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
btfixup.h
[PATCH] fix the breakage in sparc headers
2005-10-05 07:33:42 -07:00
bug.h
[PATCH] remove all kernel BUGs
2005-05-01 08:59:01 -07:00
bugs.h
Don't include linux/config.h from anywhere else in include/
2006-04-26 12:56:16 +01:00
byteorder.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
cache.h
[PATCH] Kill L1_CACHE_SHIFT_MAX
2006-01-08 20:13:39 -08:00
cacheflush.h
[PATCH] Optimize D-cache alias handling on fork
2006-12-13 09:27:08 -08:00
checksum.h
[SPARC32]: Fix over-optimization by GCC near ip_fast_csum.
2007-02-01 20:24:35 -08:00
clock.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
contregs.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
cpudata.h
[SPARC]: Try to start getting SMP back into shape.
2006-03-23 22:36:19 -08:00
cputime.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
current.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
cypress.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
delay.h
Don't include linux/config.h from anywhere else in include/
2006-04-26 12:56:16 +01:00
device.h
[SPARC64]: Fix conflicts in SBUS/PCI/EBUS/ISA DMA handling.
2007-07-30 00:27:34 -07:00
div64.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
dma-mapping.h
[PATCH] sparc: have dma-mapping.h include generic/dma-mapping-broken in non-PCI case
2007-03-14 15:27:49 -07:00
dma.h
[SPARC32]: __inline__ --> inline
2007-10-27 00:17:01 -07:00
ebus.h
[SPARC]: Port of_device layer and make ebus use it.
2006-06-23 23:15:47 -07:00
ecc.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
eeprom.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
elf.h
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
2008-02-07 10:21:26 -08:00
emergency-restart.h
[PATCH] Add emergency_restart()
2005-07-26 14:35:41 -07:00
errno.h
[PATCH] add EOWNERDEAD and ENOTRECOVERABLE version 2
2005-05-01 08:59:06 -07:00
fb.h
[SPARC]: Implement fb_is_primary_device().
2007-07-20 17:15:09 -07:00
fbio.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
fcntl.h
[SPARC32]: Fix build.
2007-08-04 21:17:18 -07:00
fixmap.h
Don't include linux/config.h from anywhere else in include/
2006-04-26 12:56:16 +01:00
floppy.h
[SPARC32]: __inline__ --> inline
2007-10-27 00:17:01 -07:00
futex.h
[PATCH] consolidate asm/futex.h
2006-01-08 20:13:39 -08:00
hardirq.h
Don't include linux/config.h from anywhere else in include/
2006-04-26 12:56:16 +01:00
head.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
highmem.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
hw_irq.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
ide.h
[SPARC32]: __inline__ --> inline
2007-10-27 00:17:01 -07:00
idprom.h
[SPARC]: Clean up idprom header files.
2006-03-20 01:12:08 -08:00
io-unit.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
io.h
Remove dma_cache_(wback|inv|wback_inv) functions
2007-10-17 08:42:57 -07:00
ioctl.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
ioctls.h
[SPARC]: Support for new termios.
2007-10-17 19:38:10 -07:00
iommu.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
ipcbuf.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
irq.h
[SPARC32]: Fix modular build of floppy driver.
2007-08-03 14:08:42 -07:00
irq_regs.h
[PATCH] sparc32 pt_regs fixes
2006-10-08 12:32:35 -07:00
irqflags.h
[SPARC32]: Add irqflags.h to sparc32 and use it from generic code.
2007-10-13 21:53:11 -07:00
jsflash.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
Kbuild
Fix exported headers for SPARC, SPARC64
2006-09-21 08:48:27 +01:00
kdebug.h
[SPARC32]: Fix sparc32 kdebug changes.
2007-05-14 03:22:08 -07:00
kgdb.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
kmap_types.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
linkage.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
local.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
machines.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
mbus.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
mc146818rtc.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
memreg.h
[PATCH] sun4c_memerr_reg __iomem annotations
2005-12-15 10:01:29 -08:00
mman.h
[PATCH] IA64,sparc: local DoS with corrupted ELFs
2006-09-08 08:40:46 -07:00
mmu.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
mmu_context.h
[PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction
2007-05-02 19:27:14 +02:00
module.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
mostek.h
[SPARC]: sparc64 gcc-4.2.0 20070317 -Werror failure
2007-03-27 01:13:55 -07:00
mpmbox.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
msgbuf.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
msi.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
mutex.h
[PATCH] mutex subsystem, add default include/asm-*/mutex.h files
2006-01-09 15:59:19 -08:00
mxcc.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
namei.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
obio.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
of_device.h
Create linux/of_platorm.h
2007-07-20 14:25:22 +10:00
of_platform.h
[SPARC/64]: Consolidate of_register_driver
2007-10-17 21:17:42 -07:00
openprom.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
openpromio.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
oplib.h
[SPARC]: Fix serial console device detection.
2007-07-20 16:59:26 -07:00
page.h
Cleanup asm/{elf,page,user}.h: #ifdef __KERNEL__ is no longer needed
2008-02-07 08:42:30 -08:00
param.h
avoid overflows in kernel/time.c
2008-02-08 09:22:39 -08:00
pbm.h
[SPARC]: Port sparc64 in-kernel device tree code to sparc32.
2006-06-23 23:15:45 -07:00
pci.h
PCI: remove pci_dac_dma_... APIs
2007-07-11 16:02:11 -07:00
pcic.h
[PATCH] fix iomem annotations in sparc32 pcic code
2005-12-15 10:01:28 -08:00
pconf.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
percpu.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
perfctr.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
pgalloc.h
add mm argument to pte/pmd/pud/pgd_free
2008-02-05 09:44:18 -08:00
pgtable.h
[SPARC32]: Make PAGE_SHARED a read-mostly variable.
2007-07-21 19:20:34 -07:00
pgtsrmmu.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
pgtsun4.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
pgtsun4c.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
poll.h
Consolidate asm/poll.h
2007-05-11 08:29:34 -07:00
posix_types.h
asm-*/posix_types.h: scrub __GLIBC__
2008-02-08 09:22:34 -08:00
processor.h
aout: move STACK_TOP[_MAX] to asm/processor.h
2008-02-08 09:22:29 -08:00
prom.h
[SPARC]: Centralize find_in_proplist() instead of duplicating N times.
2007-08-07 18:46:36 -07:00
psr.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
ptrace.h
[SPARC]: Move over to arch_ptrace().
2008-02-07 03:00:17 -08:00
reg.h
fix file specification in comments
2006-10-03 23:01:26 +02:00
resource.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
ross.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
rtc.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
sbi.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
sbus.h
[SPARC32]: Remove iommu from struct sbus_bus and use archdata like sparc64.
2007-08-10 15:52:06 -07:00
scatterlist.h
Add CONFIG_DEBUG_SG sg validation
2007-10-22 21:20:03 +02:00
sections.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
semaphore.h
kill DECLARE_MUTEX_LOCKED
2007-10-17 08:42:47 -07:00
sembuf.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
setup.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
sfp-machine.h
[MATH-EMU]: Fix underflow exception reporting.
2007-08-16 22:59:49 -07:00
shmbuf.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
shmparam.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
sigcontext.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
siginfo.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
signal.h
[SPARC]: Fix SA_STATIC_ALLOC value.
2006-07-24 22:34:00 -07:00
smp.h
Remove hardcoding of hard_smp_processor_id on UP systems
2007-05-09 12:30:48 -07:00
smpprim.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
socket.h
[NET]: Introducing socket mark socket option.
2008-01-31 19:27:19 -08:00
sockios.h
[NET]: Introduce SIOCGSTAMPNS ioctl to get timestamps with nanosec resolution
2007-04-25 22:24:04 -07:00
solerrno.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
spinlock.h
[PATCH] sparc32 rwlock fix
2006-10-08 12:32:35 -07:00
spinlock_types.h
[PATCH] spinlock consolidation
2005-09-10 10:06:21 -07:00
stat.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
statfs.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
string.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
sun4paddr.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
sun4prom.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
sunbpp.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
svr4.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
swift.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
sysen.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
system.h
Add cmpxchg_local to sparc, move __cmpxchg to system.h
2008-02-07 08:42:32 -08:00
termbits.h
[SPARC]: Support for new termios.
2007-10-17 19:38:10 -07:00
termios.h
[SPARC]: Support for new termios.
2007-10-17 19:38:10 -07:00
thread_info.h
[SPARC]: Add support for *at(), ppoll, and pselect syscalls.
2006-01-19 02:42:49 -08:00
timer.h
Don't include linux/config.h from anywhere else in include/
2006-04-26 12:56:16 +01:00
timex.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
tlb.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
tlbflush.h
remove unused flush_tlb_pgtables
2007-10-19 11:53:34 -07:00
topology.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
traps.h
[SPARC]: "extern inline" doesn't make much sense.
2005-10-03 17:37:02 -07:00
tsunami.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
turbosparc.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
types.h
[PATCH] sab: consolidate kmem_bufctl_t
2005-09-05 00:05:48 -07:00
uaccess.h
aout: remove unnecessary inclusions of {asm, linux}/a.out.h
2008-02-08 09:22:30 -08:00
unaligned.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
unistd.h
[SPARC]: Add new timerfd syscall entries.
2008-02-06 04:12:23 -08:00
user.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
vac-ops.h
Don't include linux/config.h from anywhere else in include/
2006-04-26 12:56:16 +01:00
vaddrs.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
vfc_ioctls.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
vga.h
[PATCH] sparc32 vga support
2006-04-11 06:18:54 -07:00
viking.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
winmacro.h
Don't include linux/config.h from anywhere else in include/
2006-04-26 12:56:16 +01:00
xor.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00