In f761622e59 we changed
early_setup_secondary so it's called using the proper kernel stack
rather than the emergency one.
Unfortunately, this stack pointer can't be used when translation is off
on PHYP as this stack pointer might be outside the RMO. This results in
the following on all non zero cpus:
cpu 0x1: Vector: 300 (Data Access) at [c00000001639fd10]
pc: 000000000001c50c
lr: 000000000000821c
sp: c00000001639ff90
msr: 8000000000001000
dar: c00000001639ffa0
dsisr: 42000000
current = 0xc000000016393540
paca = 0xc000000006e00200
pid = 0, comm = swapper
The original patch was only tested on bare metal system, so it never
caught this problem.
This changes __secondary_start so that we calculate the new stack
pointer but only start using it after we've called early_setup_secondary.
With this patch, the above problem goes away.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Commit 0fe1ac48 ("powerpc/perf_event: Fix oops due to
perf_event_do_pending call") moved the call to perf_event_do_pending
in timer_interrupt() down so that it was after the irq_enter() call.
Unfortunately this moved it after the code that checks whether it
is time for the next decrementer clock event. The result is that
the call to perf_event_do_pending() won't happen until the next
decrementer clock event is due. This was pointed out by Milton
Miller.
This fixes it by moving the check for whether it's time for the
next decrementer clock event down to the point where we're about
to call the event handler, after we've called perf_event_do_pending.
This has the side effect that on old pre-Core99 Powermacs where we
use the ppc_n_lost_interrupts mechanism to replay interrupts, a
replayed interrupt will incur a little more latency since it will
now do the code from the irq_enter down to the irq_exit, that it
used to skip. However, these machines are now old and rare enough
that this doesn't matter. To make it clear that ppc_n_lost_interrupts
is only used on Powermacs, and to speed up the code slightly on
non-Powermac ppc32 machines, the code that tests ppc_n_lost_interrupts
is now conditional on CONFIG_PMAC as well as CONFIG_PPC32.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: stable@kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Call kexec purgatory code correctly. We were getting lucky before.
If you examine the powerpc 32bit kexec "purgatory" code you will
see it expects the following:
>From kexec-tools: purgatory/arch/ppc/v2wrap_32.S
-> calling convention:
-> r3 = physical number of this cpu (all cpus)
-> r4 = address of this chunk (master only)
As such, we need to set r3 to the current core, r4 happens to be
unused by purgatory at the moment but we go ahead and set it
here as well
Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
pci_device_to_OF_node() can return null, and list_for_each_entry will
never enter the loop when dev is NULL, so it looks like this test is
a typo.
Reported-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
As early setup calls down to slb_initialize(), we must have kstack
initialised before checking "should we add a bolted SLB entry for our kstack?"
Failing to do so means stack access requires an SLB miss exception to refill
an entry dynamically, if the stack isn't accessible via SLB(0) (kernel text
& static data). It's not always allowable to take such a miss, and
intermittent crashes will result.
Primary CPUs don't have this issue; an SLB entry is not bolted for their
stack anyway (as that lives within SLB(0)). This patch therefore only
affects the init of secondaries.
Signed-off-by: Matt Evans <matt@ozlabs.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
When looking at some issues with the virtual ethernet driver I noticed
that TCE allocation was following a very strange pattern:
address 00e9000 length 2048
address 0409000 length 2048 <-----
address 0429000 length 2048
address 0449000 length 2048
address 0469000 length 2048
address 0489000 length 2048
address 04a9000 length 2048
address 04c9000 length 2048
address 04e9000 length 2048
address 4009000 length 2048 <-----
address 4029000 length 2048
Huge unexplained gaps in what should be an empty TCE table. It turns out
it_blocksize, the amount we want to align the next allocation to, was
c0000000fe903b20. Completely bogus.
Initialise it to something reasonable in the VIO IOMMU code, and use kzalloc
everywhere to protect against this when we next add a non compulsary
field to iommu code and forget to initialise it.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
I'm sick of seeing ppc64_runlatch_off in our profiles, so inline it
into the callers. To avoid a mess of circular includes I didn't add
it as an inline function.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The 'smt_enabled=X' boot option does not handle values of X > 2.
For Power 7 processors with smt modes of 0,1,2,3, and 4 this does
not work. This patch allows the smt_enabled option to be set to
any value limited to a max equal to the number of threads per
core.
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
During CPU offline/online tests __cpu_up would flood the logs with
the following message:
Processor 0 found.
This provides no useful information to the user as there is no context
provided, and since the operation was a success (to this point) it is expected
that the CPU will come back online, providing all the feedback necessary.
Change the "Processor found" message to DBG() similar to other such messages in
the same function. Also, add an appropriate log level for the "Processor is
stuck" message.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Acked-by: Will Schmidt <will_schmidt@vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nathan Fontenot <nfont@austin.ibm.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
start_secondary() is called shortly after _start and also via
cpu_idle()->cpu_die()->pseries_mach_cpu_die()
start_secondary() expects a preempt_count() of 0. pseries_mach_cpu_die() is
called via the cpu_idle() routine with preemption disabled, resulting in the
following repeating message during rapid cpu offline/online tests
with CONFIG_PREEMPT=y:
BUG: scheduling while atomic: swapper/0/0x00000002
Modules linked in: autofs4 binfmt_misc dm_mirror dm_region_hash dm_log [last unloaded: scsi_wait_scan]
Call Trace:
[c00000010e7079c0] [c0000000000133ec] .show_stack+0xd8/0x218 (unreliable)
[c00000010e707aa0] [c0000000006a47f0] .dump_stack+0x28/0x3c
[c00000010e707b20] [c00000000006e7a4] .__schedule_bug+0x7c/0x9c
[c00000010e707bb0] [c000000000699d9c] .schedule+0x104/0x800
[c00000010e707cd0] [c000000000015b24] .cpu_idle+0x1c4/0x1d8
[c00000010e707d70] [c0000000006aa1b4] .start_secondary+0x398/0x3d4
[c00000010e707e30] [c000000000008278] .start_secondary_resume+0x10/0x14
Move the cpu_die() call inside the existing preemption enabled block of
cpu_idle(). This is safe as the idle task is affined to a single CPU so the
debug_smp_processor_id() tests (from cpu_should_die()) won't trigger as we are
in a "migration disabled" region.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Acked-by: Will Schmidt <will_schmidt@vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nathan Fontenot <nfont@austin.ibm.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
list_for_each_entry binds its first argument to a non-null value, and thus
any null test on the value of that argument is superfluous.
The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@@
iterator I;
expression x,E,E1,E2;
statement S,S1,S2;
@@
I(x,...) { <...
- if (x != NULL || ...)
S
...> }
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
During kdump we run the crash handlers first then stop all other CPUs.
We really want to stop all CPUs as close to the fail as possible and also
have a very controlled environment for running the crash handlers, so it
makes sense to reverse the order.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Use is_32bit_task() helper to test 32 bit binary.
Signed-off-by: Denis Kirjanov <dkirjanov@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The interrupt stacks need to be indexed by the physical cpu since the
critical, debug and machine check handlers use the contents of SPRN_PIR to
index the critirq_ctx, dbgirq_ctx, and mcheckirq_ctx arrays.
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
There are two entries for .cpu_user_features in
arch/powerpc/kernel/cputable.c. Remove the one that doesn't belong
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Clear the machine check syndrom register before enabling machine check
interrupts. The initial state of the tlb can lead to parity errors being
flagged early after a cold boot.
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Make do_execve() take a const filename pointer so that kernel_execve() compiles
correctly on ARM:
arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type
This also requires the argv and envp arguments to be consted twice, once for
the pointer array and once for the strings the array points to. This is
because do_execve() passes a pointer to the filename (now const) to
copy_strings_kernel(). A simpler alternative would be to cast the filename
pointer in do_execve() when it's passed to copy_strings_kernel().
do_execve() may not change any of the strings it is passed as part of the argv
or envp lists as they are some of them in .rodata, so marking these strings as
const should be fine.
Further kernel_execve() and sys_execve() need to be changed to match.
This has been test built on x86_64, frv, arm and mips.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mark arguments to certain system calls as being const where they should be but
aren't. The list includes:
(*) The filename arguments of various stat syscalls, execve(), various utimes
syscalls and some mount syscalls.
(*) The filename arguments of some syscall helpers relating to the above.
(*) The buffer argument of various write syscalls.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'timers-timekeeping-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
um: Fix read_persistent_clock fallout
kgdb: Do not access xtime directly
powerpc: Clean up obsolete code relating to decrementer and timebase
powerpc: Rework VDSO gettimeofday to prevent time going backwards
clocksource: Add __clocksource_updatefreq_hz/khz methods
x86: Convert common clocksources to use clocksource_register_hz/khz
timekeeping: Make xtime and wall_to_monotonic static
hrtimer: Cleanup direct access to wall_to_monotonic
um: Convert to use read_persistent_clock
timkeeping: Fix update_vsyscall to provide wall_to_monotonic offset
powerpc: Cleanup xtime usage
powerpc: Simplify update_vsyscall
time: Kill off CONFIG_GENERIC_TIME
time: Implement timespec_add
x86: Fix vtime/file timestamp inconsistencies
Trivial conflicts in Documentation/feature-removal-schedule.txt
Much less trivial conflicts in arch/powerpc/kernel/time.c resolved as
per Thomas' earlier merge commit 47916be4e2 ("Merge branch
'powerpc.cherry-picks' into timers/clocksource")
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (27 commits)
sched: Use correct macro to display sched_child_runs_first in /proc/sched_debug
sched: No need for bootmem special cases
sched: Revert nohz_ratelimit() for now
sched: Reduce update_group_power() calls
sched: Update rq->clock for nohz balanced cpus
sched: Fix spelling of sibling
sched, cpuset: Drop __cpuexit from cpu hotplug callbacks
sched: Fix the racy usage of thread_group_cputimer() in fastpath_timer_check()
sched: run_posix_cpu_timers: Don't check ->exit_state, use lock_task_sighand()
sched: thread_group_cputime: Simplify, document the "alive" check
sched: Remove the obsolete exit_state/signal hacks
sched: task_tick_rt: Remove the obsolete ->signal != NULL check
sched: __sched_setscheduler: Read the RLIMIT_RTPRIO value lockless
sched: Fix comments to make them DocBook happy
sched: Fix fix_small_capacity
powerpc: Exclude arch_sd_sibiling_asym_packing() on UP
powerpc: Enable asymmetric SMT scheduling on POWER7
sched: Add asymmetric group packing option for sibling domain
sched: Fix capacity calculations for SMT4
sched: Change nohz idle load balancing logic to push model
...
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (162 commits)
tracing/kprobes: unregister_trace_probe needs to be called under mutex
perf: expose event__process function
perf events: Fix mmap offset determination
perf, powerpc: fsl_emb: Restore setting perf_sample_data.period
perf, powerpc: Convert the FSL driver to use local64_t
perf tools: Don't keep unreferenced maps when unmaps are detected
perf session: Invalidate last_match when removing threads from rb_tree
perf session: Free the ref_reloc_sym memory at the right place
x86,mmiotrace: Add support for tracing STOS instruction
perf, sched migration: Librarize task states and event headers helpers
perf, sched migration: Librarize the GUI class
perf, sched migration: Make the GUI class client agnostic
perf, sched migration: Make it vertically scrollable
perf, sched migration: Parameterize cpu height and spacing
perf, sched migration: Fix key bindings
perf, sched migration: Ignore unhandled task states
perf, sched migration: Handle ignored migrate out events
perf: New migration tool overview
tracing: Drop cpparg() macro
perf: Use tracepoint_synchronize_unregister() to flush any pending tracepoint call
...
Fix up trivial conflicts in Makefile and drivers/cpufreq/cpufreq.c
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
debug_core,kdb: fix crash when arch does not have single step
kgdb,x86: use macro HBP_NUM to replace magic number 4
kgdb,mips: remove unused kgdb_cpu_doing_single_step operations
mm,kdb,kgdb: Add a debug reference for the kdb kmap usage
KGDB: Remove set but unused newPC
ftrace,kdb: Allow dumping a specific cpu's buffer with ftdump
ftrace,kdb: Extend kdb to be able to dump the ftrace buffer
kgdb,powerpc: Replace hardcoded offset by BREAK_INSTR_SIZE
arm,kgdb: Add ability to trap into debugger on notify_die
gdbstub: do not directly use dbg_reg_def[] in gdb_cmd_reg_set()
gdbstub: Implement gdbserial 'p' and 'P' packets
kgdb,arm: Individual register get/set for arm
kgdb,mips: Individual register get/set for mips
kgdb,x86: Individual register get/set for x86
kgdb,kdb: individual register set and and get API
gdbstub: Optimize kgdb's "thread:" response for the gdb serial protocol
kgdb: remove custom hex_to_bin()implementation
* 'next-devicetree' of git://git.secretlab.ca/git/linux-2.6: (63 commits)
of/platform: Register of_platform_drivers with an "of:" prefix
of/address: Clean up function declarations
of/spi: call of_register_spi_devices() from spi core code
of: Provide default of_node_to_nid() implementation.
of/device: Make of_device_make_bus_id() usable by other code.
of/irq: Fix endian issues in parsing interrupt specifiers
of: Fix phandle endian issues
of/flattree: fix of_flat_dt_is_compatible() to match the full compatible string
of: remove of_default_bus_ids
of: make of_find_device_by_node generic
microblaze: remove references to of_device and to_of_device
sparc: remove references to of_device and to_of_device
powerpc: remove references to of_device and to_of_device
of/device: Replace of_device with platform_device in includes and core code
of/device: Protect against binding of_platform_drivers to non-OF devices
of: remove asm/of_device.h
of: remove asm/of_platform.h
of/platform: remove all of_bus_type and of_platform_bus_type references
of: Merge of_platform_bus_type with platform_bus_type
drivercore/of: Add OF style matching to platform bus
...
Fix up trivial conflicts in arch/microblaze/kernel/Makefile due to just
some obj-y removals by the devicetree branch, while the microblaze
updates added a new file.
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (79 commits)
powerpc/8xx: Add support for the MPC8xx based boards from TQC
powerpc/85xx: Introduce support for the Freescale P1022DS reference board
powerpc/85xx: Adding DTS for the STx GP3-SSA MPC8555 board
powerpc/85xx: Change deprecated binding for 85xx-based boards
powerpc/tqm85xx: add a quirk for ti1520 PCMCIA bridge
powerpc/tqm85xx: update PCI interrupt-map attribute
powerpc/mpc8308rdb: support for MPC8308RDB board from Freescale
powerpc/fsl_pci: add quirk for mpc8308 pcie bridge
powerpc/85xx: Cleanup QE initialization for MPC85xxMDS boards
powerpc/85xx: Fix booting for P1021MDS boards
powerpc/85xx: Fix SWIOTLB initalization for MPC85xxMDS boards
powerpc/85xx: kexec for SMP 85xx BookE systems
powerpc/5200/i2c: improve i2c bus error recovery
of/xilinxfb: update tft compatible versions
powerpc/fsl-diu-fb: Support setting display mode using EDID
powerpc/5121: doc/dts-bindings: update doc of FSL DIU bindings
powerpc/5121: shared DIU framebuffer support
powerpc/5121: move fsl-diu-fb.h to include/linux
powerpc/5121: fsl-diu-fb: fix issue with re-enabling DIU area descriptor
powerpc/512x: add clock structure for Video-IN (VIU) unit
...
kgdb_handle_breakpoint checks the first arch_kgdb_breakpoint
which is not known by gdb that's why is necessary jump over
it. The jump lenght is equal to BREAK_INSTR_SIZE that's
why is cleaner to use defined macro instead of hardcoded
non-described offset.
Signed-off-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Commit 6b95ed345b changed from
a struct initializer to perf_sample_data_init(), but the setting
of the .period member was left out.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Cc: stable@kernel.org
Signed-off-by: Paul Mackerras <paulus@samba.org>
For some reason the FSL driver got left out when we converted perf
to use local64_t instead of atomic64_t.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This patch moves the declaration of of_get_address(), of_get_pci_address(),
and of_pci_address_to_resource() out of arch code and into the common
linux/of_address header file.
This patch also fixes some of the asm/prom.h ordering issues. It still
includes some header files that it ideally shouldn't be, but at least the
ordering is consistent now so that of_* overrides work.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Instead of instantiating a whole thread_struct on the stack use only the
required parts of it.
Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Tested-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
When CPU hotplug is used, some CPUs may be offline at the time a kexec is
performed. The subsequent kernel may expect these CPUs to be already running,
and will declare them stuck. On pseries, there's also a soft-offline (cede)
state that CPUs may be in; this can also cause problems as the kexeced kernel
may ask RTAS if they're online -- and RTAS would say they are. The CPU will
either appear stuck, or will cause a crash as we replace its cede loop beneath
it.
This patch kicks each present offline CPU awake before the kexec, so that
none are forever lost to these assumptions in the subsequent kernel.
Now, the behaviour is that all available CPUs that were offlined are now
online & usable after the kexec. This mimics the behaviour of a full reboot
(on which all CPUs will be restarted).
Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tidies some typos, KERN_INFO-ise an info msg, and add a debug msg showing
when the final sequence starts.
Also adds a comment to kexec_prepare_cpus_wait() to make note of a possible
problem; the need for kexec to deal with CPUs that failed to originally start
up.
Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently we look pretty stupid when printing out a bunch of things in
prom_init.c. eg.
Max number of cores passed to firmware: 0x0000000000000080
So I've change this to print in decimal:
Max number of cores passed to firmware: 128 (NR_CPUS = 256)
This required adding a prom_print_dec() function and changing some
prom_printk() calls from %x to %lu.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We already defined start_cpu_decrementer() to invoke decrementer for AP as
the following path:
start_secondary() -> secondary_cpu_time_init() -> start_cpu_decrementer()
So remove these incorrect codes introduced from commit:
e7f75ad0 powerpc/47x: Base ppc476 support
And actually we really should not enable decrementer before calling set_dec().
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Fix sizes of variables so correct values are exported via /proc.
Cast variable in comparison to avoid compiler error.
Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
With dynamic PACAs, the kexecing CPU's PACA won't lie within the kernel
static data and there is a chance that something may stomp it when preparing
to kexec. This patch switches this final CPU to a static PACA just before
we pull the switch.
Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Conflicts:
arch/powerpc/kernel/time.c
Reason: The powerpc next tree contains two commits which conflict with
the timekeeping changes:
8fd63a9e powerpc: Rework VDSO gettimeofday to prevent time going backwards
c1aa687d powerpc: Clean up obsolete code relating to decrementer and timebase
John Stultz identified them and provided the conflict resolution.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since the decrementer and timekeeping code was moved over to using
the generic clockevents and timekeeping infrastructure, several
variables and functions have been obsolete and effectively unused.
This deletes them.
In particular, wakeup_decrementer() is no longer needed since the
generic code reprograms the decrementer as part of the process of
resuming the timekeeping code, which happens during sysdev resume.
Thus the wakeup_decrementer calls in the suspend_enter methods for
52xx platforms have been removed. The call in the powermac cpu
frequency change code has been replaced by set_dec(1), which will
cause a timer interrupt as soon as interrupts are enabled, and the
generic code will then reprogram the decrementer with the correct
value.
This also simplifies the generic_suspend_en/disable_irqs functions
and makes them static since they are not referenced outside time.c.
The preempt_enable/disable calls are removed because the generic
code has disabled all but the boot cpu at the point where these
functions are called, so we can't be moved to another cpu.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently it is possible for userspace to see the result of
gettimeofday() going backwards by 1 microsecond, assuming that
userspace is using the gettimeofday() in the VDSO. The VDSO
gettimeofday() algorithm computes the time in "xsecs", which are
units of 2^-20 seconds, or approximately 0.954 microseconds,
using the algorithm
now = (timebase - tb_orig_stamp) * tb_to_xs + stamp_xsec
and then converts the time in xsecs to seconds and microseconds.
The kernel updates the tb_orig_stamp and stamp_xsec values every
tick in update_vsyscall(). If the length of the tick is not an
integer number of xsecs, then some precision is lost in converting
the current time to xsecs. For example, with CONFIG_HZ=1000, the
tick is 1ms long, which is 1048.576 xsecs. That means that
stamp_xsec will advance by either 1048 or 1049 on each tick.
With the right conditions, it is possible for userspace to get
(timebase - tb_orig_stamp) * tb_to_xs being 1049 if the kernel is
slightly late in updating the vdso_datapage, and then for stamp_xsec
to advance by 1048 when the kernel does update it, and for userspace
to then see (timebase - tb_orig_stamp) * tb_to_xs being zero due to
integer truncation. The result is that time appears to go backwards
by 1 microsecond.
To fix this we change the VDSO gettimeofday to use a new field in the
VDSO datapage which stores the nanoseconds part of the time as a
fractional number of seconds in a 0.32 binary fraction format.
(Or put another way, as a 32-bit number in units of 0.23283 ns.)
This is convenient because we can use the mulhwu instruction to
convert it to either microseconds or nanoseconds.
Since it turns out that computing the time of day using this new field
is simpler than either using stamp_xsec (as gettimeofday does) or
stamp_xtime.tv_nsec (as clock_gettime does), this converts both
gettimeofday and clock_gettime to use the new field. The existing
__do_get_tspec function is converted to use the new field and take
a parameter in r7 that indicates the desired resolution, 1,000,000
for microseconds or 1,000,000,000 for nanoseconds. The __do_get_xsec
function is then unused and is deleted.
The new algorithm is
now = ((timebase - tb_orig_stamp) << 12) * tb_to_xs
+ (stamp_xtime_seconds << 32) + stamp_sec_fraction
with 'now' in units of 2^-32 seconds. That is then converted to
seconds and either microseconds or nanoseconds with
seconds = now >> 32
partseconds = ((now & 0xffffffff) * resolution) >> 32
The 32-bit VDSO code also makes a further simplification: it ignores
the bottom 32 bits of the tb_to_xs value, which is a 0.64 format binary
fraction. Doing so gets rid of 4 multiply instructions. Assuming
a timebase frequency of 1GHz or less and an update interval of no
more than 10ms, the upper 32 bits of tb_to_xs will be at least
4503599, so the error from ignoring the low 32 bits will be at most
2.2ns, which is more than an order of magnitude less than the time
taken to do gettimeofday or clock_gettime on our fastest processors,
so there is no possibility of seeing inconsistent values due to this.
This also moves update_gtod() down next to its only caller, and makes
update_vsyscall use the time passed in via the wall_time argument rather
than accessing xtime directly. At present, wall_time always points to
xtime, but that could change in future.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We should use perf_sample_data_init() to initialize struct
perf_sample_data. As explained in the description of commit dc1d628a
("perf: Provide generic perf_sample_data initialization"), it is
possible for userspace to get the kernel to dereference data.raw,
so if it is not initialized, that means that unprivileged userspace
can possibly oops the kernel. Using perf_sample_data_init makes sure
it gets initialized to NULL.
This conversion should have been included in commit dc1d628a, but it
got missed.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
update_vsyscall() did not provide the wall_to_monotoinc offset,
so arch specific implementations tend to reference wall_to_monotonic
directly. This limits future cleanups in the timekeeping core, so
this patch fixes the update_vsyscall interface to provide
wall_to_monotonic, allowing wall_to_monotonic to be made static
as planned in Documentation/feature-removal-schedule.txt
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Tony Luck <tony.luck@intel.com>
LKML-Reference: <1279068988-21864-7-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This removes powerpc's direct xtime usage, allowing for further
generic timeekeping cleanups
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Anton Blanchard <anton@samba.org>
LKML-Reference: <1279068988-21864-6-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
