The R4000 and R4400 have an errata where if the cp0 count register is read
in the exact moment when it matches the compare register no interrupt will
be generated.
This bug may be triggered if the cp0 count register is being used as
clocksource and the compare interrupt as clockevent. So a simple
workaround is to avoid using the compare for both facilities on the
affected CPUs.
This is different from the workaround suggested in the old errata documents;
at some opportunity probably the official version should be implemented
and tested. Another thing to find out is which processor versions
exactly are affected. I only have errata documents upto R4400 V3.0
available so for the moment the code treats all R4000 and R4400 as broken.
This is potencially a problem for some machines that have no other decent
clocksource available; this workaround will cause them to fall back to
another clocksource, worst case the "jiffies" source.
The LL / SC loops in __futex_atomic_op() have the usual fixups necessary
for memory acccesses to userspace from kernel space installed:
__asm__ __volatile__(
" .set push \n"
" .set noat \n"
" .set mips3 \n"
"1: ll %1, %4 # __futex_atomic_op \n"
" .set mips0 \n"
" " insn " \n"
" .set mips3 \n"
"2: sc $1, %2 \n"
" beqz $1, 1b \n"
__WEAK_LLSC_MB
"3: \n"
" .set pop \n"
" .set mips0 \n"
" .section .fixup,\"ax\" \n"
"4: li %0, %6 \n"
" j 2b \n" <-----
" .previous \n"
" .section __ex_table,\"a\" \n"
" "__UA_ADDR "\t1b, 4b \n"
" "__UA_ADDR "\t2b, 4b \n"
" .previous \n"
: "=r" (ret), "=&r" (oldval), "=R" (*uaddr)
: "0" (0), "R" (*uaddr), "Jr" (oparg), "i" (-EFAULT)
: "memory");
The branch at the end of the fixup code, it goes back to the SC
instruction, no matter if the fault was first taken by the LL or SC
instruction resulting in an endless loop which will only terminate if
the address become valid again due to another thread setting up an
accessible mapping and the CPU happens to execute the SC instruction
successfully which due to the preceeding ERET instruction of the fault
handler would only happen if UNPREDICTABLE instruction behaviour of the
SC instruction without a preceeding LL happens to favor that outcome.
But normally processes are nice, pass valid arguments and we were just
getting away with this.
Thanks to Kaz Kylheku <kaz@zeugmasystems.com> for providing the original
report and a test case.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
A new born thread starts execution not in schedule but rather in
ret_from_fork which results in it bypassing the part of the code to
load a new context written in C which are the DSP context and the
userlocal register which Linux uses for the TLS pointer. Frequently
we were just getting away with this bug for a number of reasons:
o Real world application scenarios are very unlikely to use clone or fork
in blocks of DSP code.
o Linux by default runs the child process right after the fork, so the
child by luck will find all the right context in the DSP and userlocal
registers.
o So far the rdhwr instruction was emulated on all hardware so userlocal
wasn't getting referenced at all and the emulation wasn't suffering
from the issue since it gets it's value straight from the thread's
thread_info.
Fixed by moving the code to load the context from switch_to() to
finish_arch_switch which will be called by newborn and old threads.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86:
x86: simplify "make ARCH=x86" and fix kconfig all.config
x86: reboot fixup for wrap2c board
x86: check boundary in count setup resource
x86: fix reboot with no keyboard attached
x86: add hpet sanity checks
x86: on x86_64, correct reading of PC RTC when update in progress in time_64.c
x86: fix freeze in x86_64 RTC update code in time_64.c
ntp: fix typo that makes sync_cmos_clock erratic
Remove x86 merge artifact from top Makefile
x86: fixup cpu_info array conversion
x86: show cpuinfo only for online CPUs
x86: fix cpu-hotplug regression
x86: ignore the sys_getcpu() tcache parameter
x86: voyager use correct header file name
x86: fix smp init sections
x86: fix voyager_cat_init section
x86: fix bogus memcpy in es7000_check_dsdt()
Simplify "make ARCH=x86" and fix kconfig so we again can set 64BIT in
all.config.
For a fix the diffstat is nice:
6 files changed, 3 insertions(+), 36 deletions(-)
The patch reverts these commits:
- 0f855aa64b ("kconfig: add helper to set
config symbol from environment variable")
- 2a113281f5 ("kconfig: use $K64BIT to
set 64BIT with all*config targets")
Roman Zippel pointed out that kconfig supported string compares so
the additional complexity introduced by the above two patches were
not needed.
With this patch we have following behaviour:
# make {allno,allyes,allmod,rand}config [ARCH=...]
option \ host arch | 32bit | 64bit
=====================================================
./. | 32bit | 64bit
ARCH=x86 | 32bit | 32bit
ARCH=i386 | 32bit | 32bit
ARCH=x86_64 | 64bit | 64bit
The general rule are that ARCH= and native architecture takes
precedence over the configuration.
So make ARCH=i386 [whatever] will always build a 32-bit kernel
no matter what the configuration says. The configuration will
be updated to 32-bit if it was configured to 64-bit and the
other way around.
This behaviour is consistent with previous behaviour so no
suprises here.
make ARCH=x86 will per default result in a 32-bit kernel but as
the only ARCH= value x86 allow the user to select between 32-bit
and 64-bit using menuconfig.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andreas Herrmann <aherrman@arcor.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Simplify "make ARCH=x86" and fix kconfig so we again
can set 64BIT in all.config.
For a fix the diffstat is nice:
6 files changed, 3 insertions(+), 36 deletions(-)
The patch reverts these commits:
0f855aa64b
-> kconfig: add helper to set config symbol from environment variable
2a113281f5
-> kconfig: use $K64BIT to set 64BIT with all*config targets
Roman Zippel pointed out that kconfig supported string
compares so the additional complexity introduced by the
above two patches were not needed.
With this patch we have following behaviour:
# make {allno,allyes,allmod,rand}config [ARCH=...]
option \ host arch | 32bit | 64bit
=====================================================
./. | 32bit | 64bit
ARCH=x86 | 32bit | 32bit
ARCH=i386 | 32bit | 32bit
ARCH=x86_64 | 64bit | 64bit
The general rule are that ARCH= and native architecture
takes precedence over the configuration.
So make ARCH=i386 [whatever] will always build a 32-bit
kernel no matter what the configuration says.
The configuration will be updated to 32-bit if it was
configured to 64-bit and the other way around.
This behaviour is consistent with previous behaviour so
no suprises here.
make ARCH=x86 will per default result in a 32-bit kernel
but as the only ARCH= value x86 allow the user to select
between 32-bit and 64-bit using menuconfig.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andreas Herrmann <aherrman@arcor.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Some BIOSes advertise HPET at 0x0. We really do no want to
allocate a resource there. Check for it and leave early.
Other BIOSes tell us the HPET is at 0xfed0000000000000
instead of 0xfed00000. Add a check and fix it up with a warning
on user request.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Correct potentially unstable PC RTC time register reading in time_64.c
Stop the use of an incorrect technique for reading the standard PC RTC
timer, which is documented to "disconnect" time registers from the bus
while updates are in progress. The use of UIP flag while interrupts
are disabled to protect a 244 microsecond window is one of the
Motorola spec sheet's documented ways to read the RTC time registers
reliably.
tglx: removed locking changes from original patch, as they gain nothing
(read_persistent_clock is only called during boot, suspend, resume - so
no hot path affected) and conflict with the paravirt locking scheme
(see 32bit code), which we do not want to complicate for no benefit.
Signed-off-by: David P. Reed <dpreed@reed.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix hard freeze on x86_64 when the ntpd service calls
update_persistent_clock()
A repeatable but randomly timed freeze has been happening in Fedora 6
and 7 for the last year, whenever I run the ntpd service on my AMD64x2
HP Pavilion dv9000z laptop. This freeze is due to the use of
spin_lock(&rtc_lock) under the assumption (per a bad comment) that
set_rtc_mmss is called only with interrupts disabled. The call from
ntp.c to update_persistent_clock is made with interrupts enabled.
Signed-off-by: David P. Reed <dpreed@reed.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix a typo in ntp.c that has caused updating of the persistent (RTC)
clock when synced to NTP to behave erratically.
When debugging a freeze that arises on my AMD64 machines when I
run the ntpd service, I added a number of printk's to monitor the
sync_cmos_clock procedure. I discovered that it was not syncing to
cmos RTC every 11 minutes as documented, but instead would keep trying
every second for hours at a time. The reason turned out to be a typo
in sync_cmos_clock, where it attempts to ensure that
update_persistent_clock is called very close to 500 msec. after a 1
second boundary (required by the PC RTC's spec). That typo referred to
"xtime" in one spot, rather than "now", which is derived from "xtime"
but not equal to it. This makes the test erratic, creating a
"coin-flip" that decides when update_persistent_clock is called - when
it is called, which is rarely, it may be at any time during the one
second period, rather than close to 500 msec, so the value written is
needlessly incorrect, too.
Signed-off-by: David P. Reed
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The x86 merge modified the tags target to handle the two separate
source directories. Remove it now that i386/x86_64 are gone completely.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
92cb7612ae sets cpu_info->cpu_index to zero
for no reason. Referencing cpu_info->cpu_index now points always to CPU#0,
which is apparently not what we want.
Remove it.
Spotted-by: Zou Nan hai <nanhai.zou@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix regressions introduced with 92cb7612ae.
It can happen that cpuinfo is displayed for CPUs that are not online or
even worse for CPUs not present at all. As an example, following was
shown for a "second" CPU of a single core K8 variant:
processor : 0
vendor_id : unknown
cpu family : 0
model : 0
model name : unknown
stepping : 0
cache size : 0 KB
fpu : yes
fpu_exception : yes
cpuid level : 0
wp : yes
flags :
bogomips : 0.00
clflush size : 0
cache_alignment : 0
address sizes : 0 bits physical, 0 bits virtual
power management:
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Commit d435d862ba
("cpu hotplug: mce: fix cpu hotplug error handling")
changed the error handling in mce_cpu_callback.
In cases where not all CPUs are brought up during
boot (e.g. using maxcpus and additional_cpus parameters)
mce_cpu_callback now returns NOTFIY_BAD because
for such CPUs cpu_data is not completely filled when
the notifier is called. Thus mce_create_device fails right
at its beginning:
if (!mce_available(&cpu_data[cpu]))
return -EIO;
As a quick fix I suggest to check boot_cpu_data for MCE.
To reproduce this regression:
(1) boot with maxcpus=2 addtional_cpus=2 on a 4 CPU x86-64 system
(2) # echo 1 >/sys/devices/system/cpu/cpu2/online
-bash: echo: write error: Invalid argument
dmesg shows:
_cpu_up: attempt to bring up CPU 2 failed
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
dont use the vgetcpu tcache - it's causing problems with tasks
migrating, they'll see the old cache up to a jiffy after the
migration, further increasing the costs of the migration.
In the worst case they see a complete bogus information from
the tcache, when a sys_getcpu() call "invalidated" the cache
info by incrementing the jiffies _and_ the cpuid info in the
cache and the following vdso_getcpu() call happens after
vdso_jiffies have been incremented.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix header file name for Voyager build.
In file included from arch/x86/kernel/setup_32.c:61:
include/asm-x86/mach-voyager/setup_arch.h:2:26: error: asm/setup_32.h: No such file or directory
make[1]: *** [arch/x86/kernel/setup_32.o] Error 1
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix Voyager section mismatch due to using __devinit instead of __cpuinit.
WARNING: vmlinux.o(.text+0xd943): Section mismatch: reference to .init.text:init_gdt (between 'voyager_smp_prepare_boot_cpu' and 'smp_vic_cmn_interrupt')
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
