Russell Currey [Fri, 27 Nov 2015 06:23:07 +0000 (17:23 +1100)]
powerpc/powernv: Add a kmsg_dumper that flushes console output on panic
On BMC machines, console output is controlled by the OPAL firmware and is
only flushed when its pollers are called. When the kernel is in a panic
state, it no longer calls these pollers and thus console output does not
completely flush, causing some output from the panic to be lost.
Output is only actually lost when the kernel is configured to not power off
or reboot after panic (i.e. CONFIG_PANIC_TIMEOUT is set to 0) since OPAL
flushes the console buffer as part of its power down routines. Before this
patch, however, only partial output would be printed during the timeout wait.
This patch adds a new kmsg_dumper which gets called at panic time to ensure
panic output is not lost. It accomplishes this by calling OPAL_CONSOLE_FLUSH
in the OPAL API, and if that is not available, the pollers are called enough
times to (hopefully) completely flush the buffer.
The flushing mechanism will only affect output printed at and before the
kmsg_dump call in kernel/panic.c:panic(). As such, the "end Kernel panic"
message may still be truncated as follows:
This functionality is implemented as a kmsg_dumper as it seems to be the
most sensible way to introduce platform-specific functionality to the
panic function.
Signed-off-by: Russell Currey <ruscur@russell.cc> Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Neuling [Thu, 10 Dec 2015 22:34:42 +0000 (09:34 +1100)]
powerpc: Copy only required pieces of the mm_context_t to the paca
Currently we copy the whole mm_context_t to the paca but only access a
few bits of it. This is wasteful of space paca and also takes quite
some time in the hot path of context switching.
This patch pulls in only the required bits from the mm_context_t to
the paca and on context switch, copies only those.
Benchmarking this (On top of Anton's recent MSR context switching
changes [1]) using processes and yield shows an improvement of almost
3% on POWER8:
Signed-off-by: Michael Neuling <mikey@neuling.org>
[mpe: Rename paca fields to be mm_ctx_foo rather than context_foo] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Nathan Fontenot [Wed, 16 Dec 2015 20:55:07 +0000 (14:55 -0600)]
powerpc/pseries: Add CPU dlpar add functionality
Add the ability to hotplug add cpus via rtas hotplug events by either
specifying the drc index of the CPU to add, or providing a count of the
number of CPUs to add.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Nathan Fontenot [Wed, 16 Dec 2015 20:54:05 +0000 (14:54 -0600)]
powerpc/pseries: Add CPU dlpar remove functionality
Add the ability to dlpar remove CPUs via hotplug rtas events, either by
specifying the drc-index of the CPU to remove or providing a count of cpus
to remove.
To remove multiple cpus in a single request we create a list of possible
DR (Dynamic Reconfiguration) cpus and their drc indexes that can be
removed. We can then traverse the list remove each cpu and easily clean
up in any cases of failure.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Nathan Fontenot [Wed, 16 Dec 2015 20:51:26 +0000 (14:51 -0600)]
powerpc/pseries: Factor out common cpu hotplug code
Re-factor the cpu hotplug code to support doing cpu hotplug completely in
the kernel and using the existing sysfs probe/release interfaces. This
patch pulls out pieces of existing cpu hotplug code into common routines,
dlpar_cpu_add() and dlpar_cpu_remove(), to be used by both interfaces.
There are no functional changes introduced.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Nathan Fontenot [Wed, 16 Dec 2015 20:50:21 +0000 (14:50 -0600)]
powerpc/pseries: Consolidate CPU hotplug code to hotplug-cpu.c
No functional changes, this patch is simply a move of the cpu hotplug
code from pseries/dlpar.c to pseries/hotplug-cpu.c. This is in an effort
to consolidate all of the cpu hotplug code in a common place.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Nathan Fontenot [Fri, 23 Oct 2015 17:45:57 +0000 (12:45 -0500)]
powerpc/pseries: Verify CPU doesn't exist before adding
When DLPAR adding a CPU we should verify that the CPU does not already
exist. Failure to do so can generate a kernel oops;
[ 9.465585] kernel BUG at arch/powerpc/platforms/pseries/dlpar.c:382!
[ 9.465796] Oops: Exception in kernel mode, sig: 5 [#1]
This oops can be generated by causing a probe to be performed on a cpu
by writing to the sysfs cpu probe file (/sys/devices/system/cpu/probe).
This patch adds a check for the existence of cpu prior to probing the cpu
so userspace doing the wrong thing won't trigger a BUG_ON().
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Alistair Popple [Mon, 14 Dec 2015 03:31:24 +0000 (14:31 +1100)]
powerpc/476fpe: Add support for kexec
PPC476FPE has a different PVR from previous PPC476 processors. The
kexec code checks the PVR in order to correctly setup the MMU. When
the initial support for 476FPE processors was added the corresponding
change in the kexec code was missed. This patch simply adds the check
and solves the following bug on kexec:
kexec: Starting new kernel
Bye!
Unable to handle kernel paging request for instruction fetch
Faulting instruction address: 0xee9a50f8
cpu 0x0: Vector: 400 (Instruction Access) at [ee9d7d20]
pc: ee9a50f8
lr: ee9a50e4
sp: ee9d7dd0
msr: 21020
current = 0xee40f000
pid = 960, comm = kexec
enter ? for help
[link register ] ee9a50e4
[ee9d7dd0] c0013748 default_machine_kexec+0x58/0x70 (unreliable)
[ee9d7df0] c0012f04 machine_kexec+0x34/0x40
[ee9d7e00] c00aa1ec kernel_kexec+0x9c/0xb0
[ee9d7e20] c005d704 SyS_reboot+0x1f4/0x220
[ee9d7f40] c000db68 ret_from_syscall+0x0/0x3c
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Alistair Popple [Thu, 17 Dec 2015 02:43:13 +0000 (13:43 +1100)]
powerpc/powernv: Add support for Nvlink NPUs
NVLink is a high speed interconnect that is used in conjunction with a
PCI-E connection to create an interface between CPU and GPU that
provides very high data bandwidth. A PCI-E connection to a GPU is used
as the control path to initiate and report status of large data
transfers sent via the NVLink.
On IBM Power systems the NVLink processing unit (NPU) is similar to
the existing PHB3. This patch adds support for a new NPU PHB type. DMA
operations on the NPU are not supported as this patch sets the TCE
translation tables to be the same as the related GPU PCIe device for
each NVLink. Therefore all DMA operations are setup and controlled via
the PCIe device.
EEH is not presently supported for the NPU devices, although it may be
added in future.
This commit removed the pcidev field from struct pci_dn as it was no
longer in use by the kernel. However to support finding the
association of Nvlink devices to GPU devices from the device-tree this
field is required.
This reverts commit 250c7b277c65 ("powerpc/pci: Remove unused struct
pci_dn.pcidev field").
Signed-off-by: Alistair Popple <alistair@popple.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Gavin Shan [Thu, 22 Oct 2015 01:03:08 +0000 (12:03 +1100)]
powerpc/powernv: Fix M64 resource name in /proc/iomem
The name of PCI root bus's M64 resource isn't initialized properly.
When dumping "/proc/iomem", "<BAD>" is seen for those M64 resources
on PCI root buses.
This fixes the issue by setting the name of PCI root bus's M64
resource to that of PHB's device node full name. With the patch,
no "<BAD>" is seen from "/proc/iomem".
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Laurent Dufour [Thu, 3 Dec 2015 10:29:19 +0000 (11:29 +0100)]
powerpc/mm: Add page soft dirty tracking
User space checkpoint and restart tool (CRIU) needs the page's change
to be soft tracked. This allows to do a pre checkpoint and then dump
only touched pages.
This is done by using a newly assigned PTE bit (_PAGE_SOFT_DIRTY) when
the page is backed in memory, and a new _PAGE_SWP_SOFT_DIRTY bit when
the page is swapped out.
To introduce a new PTE _PAGE_SOFT_DIRTY bit value common to hash 4k
and hash 64k pte, the bits already defined in hash-*4k.h should be
shifted left by one.
The _PAGE_SWP_SOFT_DIRTY bit is dynamically put after the swap type in
the swap pte. A check is added to ensure that the bit is not
overwritten by _PAGE_HPTEFLAGS.
Michael Ellerman [Wed, 16 Dec 2015 10:10:22 +0000 (21:10 +1100)]
powerpc/kernel: Combine vec/loc for STD_EXCEPTION_PSERIES
The STD_EXCEPTION_PSERIES macro takes both a vector number, and a
location (memory address). However both are always identical, so combine
them to save repeating ourselves.
This does mean an exception handler must always exist at the location in
memory that matches its vector number. But that's OK because this is the
"STD" macro (standard), which does exactly that. We have other macros
for the other cases, eg. STD_EXCEPTION_PSERIES_OOL (out of line).
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Ellerman [Wed, 25 Nov 2015 03:25:16 +0000 (14:25 +1100)]
powerpc/kernel: Drop HMT_MEDIUM_PPR_DISCARD
HMT_MEDIUM_PPR_DISCARD is a macro which is present at the start of most
of our first level exception handlers. It conditionally executes a
HMT_MEDIUM instruction, which sets the processor priority to medium.
On on modern systems, ie. Power7 and later, it is nop'ed out at boot.
All it does is make the exception vectors more cramped, and consume 4
bytes of icache.
On old systems it has the effect of boosting the processor priority at
the start of exception processing. If we were previously in the idle
loop for example, we may be at low or very low priority. This is
desirable as we want to process the exception as fast as possible.
However looking closely at the generated code, we see that in all cases
we execute another HMT_MEDIUM just four instructions later. With code
patching applied, the final code on an old (Power6) system will look
like, eg:
So I suggest that the added code complexity of HMT_MEDIUM_PPR_DISCARD is
not justified by the benefit of boosting the processor priority for the
duration of four instructions, and therefore we drop it.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Ellerman [Tue, 24 Nov 2015 11:26:12 +0000 (22:26 +1100)]
powerpc/rtas: Make enter_rtas() private
There are no longer any users of enter_rtas() outside of rtas.c, so make
it "private", by moving the declaration inside rtas.c. Hopefully this
will encourage people to use one of the wrappers which takes the sharp
edges off the RTAS calling sequence.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Ellerman [Tue, 24 Nov 2015 11:26:11 +0000 (22:26 +1100)]
powerpc/rtas: Use rtas_call_unlocked() in call_rtas_display_status()
Although call_rtas_display_status() does actually want to use the
regular RTAS locking, it doesn't want the extra logic that is in
rtas_call(), so currently it open codes the logic.
Instead we can use rtas_call_unlocked(), after taking the RTAS lock.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Ellerman [Wed, 16 Dec 2015 10:01:42 +0000 (21:01 +1100)]
powerpc/rtas: Add rtas_call_unlocked()
Most users of RTAS (Run-Time Abstraction Services) use rtas_call(),
which deals with locking as well as endian handling.
However we have two users outside of rtas.c that can't use rtas_call()
because they have different locking requirements.
The hotplug CPU code can't take the RTAS lock because the CPU would go
offline with the lock held and no other CPUs would be able to call RTAS
until the CPU came back online.
The xmon code doesn't want to take the lock because it would risk dead
locking when we are trying to recover from a crash.
Both sites required multiple patches when we added little endian
support, proving that programmers can't do endian right.
Although that ship has sailed, we can still clean the code up by
providing an unlocked version of rtas_call() which avoids the need to
open code the logic elsewhere.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Stewart Smith [Wed, 9 Dec 2015 06:18:20 +0000 (17:18 +1100)]
powerpc/powernv: remove FW_FEATURE_OPALv3 and just use FW_FEATURE_OPAL
Long ago, only in the lab, there was OPALv1 and OPALv2. Now there is
just OPALv3, with nobody ever expecting anything on pre-OPALv3 to
be cared about or supported by mainline kernels.
So, let's remove FW_FEATURE_OPALv3 and instead use FW_FEATURE_OPAL
exclusively.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Stewart Smith [Wed, 9 Dec 2015 06:18:19 +0000 (17:18 +1100)]
powerpc/powernv: Remove OPALv2 firmware define and references
OPALv2 only ever existed in the lab and didn't escape to the world.
All OPAL systems in the wild are OPALv3.
The probability of there being an OPALv2 system still powered on
anywhere inside IBM is approximately zero, let alone anyone
expecting to run mainline kernels.
So, start to remove references to OPALv2.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Stewart Smith [Wed, 9 Dec 2015 06:18:18 +0000 (17:18 +1100)]
powerpc/powernv: panic() on OPAL < V3
The OpenPower Abstraction Layer firmware went through a couple
of iterations in the lab before being released. What we now know
as OPAL advertises itself as OPALv3.
OPALv2 and OPALv1 never made it outside the lab, and the possibility
of anyone at all ever building a mainline kernel today and expecting
it to boot on such hardware is zero.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Daniel Axtens [Sun, 6 Dec 2015 23:50:51 +0000 (10:50 +1100)]
selftests/powerpc: Add script to test HMI functionality
HMIs (Hypervisor Management|Maintenance Interrupts) are a class of interrupt
on POWER systems.
HMI support has traditionally been exceptionally difficult to test, however
Skiboot ships a tool that, with the correct magic numbers, will inject them.
This, therefore, is a first pass at a script to inject HMIs and monitor
Linux's response. It injects an HMI on each core on every chip in turn
It then watches dmesg to see if it's acknowledged by Linux.
On a Tuletta, I observed that we see 8 (or sometimes 9 or more) events per
injection, regardless of SMT setting, so we wait for 8 before progressing.
It sits in a new scripts/ directory in selftests/powerpc, because it's not
designed to be run as part of the regular make selftests process. In
particular, it is quite possibly going to end up garding lots of your CPUs,
so it should only be run if you know how to undo that.
CC: Mahesh J Salgaonkar <mahesh.salgaonkar@in.ibm.com> Signed-off-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Daniel Axtens [Tue, 15 Dec 2015 07:09:14 +0000 (18:09 +1100)]
powerpc: Remove broken GregorianDay()
GregorianDay() is supposed to calculate the day of the week
(tm->tm_wday) for a given day/month/year. In that calcuation it
indexed into an array called MonthOffset using tm->tm_mon-1. However
tm_mon is zero-based, not one-based, so this is off-by-one. It also
means that every January, GregoiranDay() will access element -1 of
the MonthOffset array.
It also doesn't appear to be a correct algorithm either: see in
contrast kernel/time/timeconv.c's time_to_tm function.
It's been broken forever, which suggests no-one in userland uses
this. It looks like no-one in the kernel uses tm->tm_wday either
(see e.g. drivers/rtc/rtc-ds1305.c:319).
tm->tm_wday is conventionally set to -1 when not available in
hardware so we can simply set it to -1 and drop the function.
(There are over a dozen other drivers in drivers/rtc that do
this.)
Found using UBSAN.
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrew Morton <akpm@linux-foundation.org> # as an example of what UBSan finds. Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com> Cc: rtc-linux@googlegroups.com Signed-off-by: Daniel Axtens <dja@axtens.net> Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Rashmica Gupta [Thu, 10 Dec 2015 09:49:33 +0000 (20:49 +1100)]
selftests/powerpc: Add test to check if VSRs are corrupted
When a transaction is aborted, VSR values should rollback to the
checkpointed values before the transaction began. VSRs used elsewhere in
the kernel during a transaction, or while the transaction is suspended
should not affect the checkpointed values.
Prior to the bug fix in commit d31626f70b61 ("powerpc: Don't corrupt
transactional state when using FP/VMX in kernel") when VMX was requested
by the kernel the .vr_state (which held the checkpointed state of VSRs
before the transaction) was overwritten with the current state from
outside the transation. Thus if the transaction did not complete, the
VSR values would be "rolled back" to potentially incorrect values.
Signed-off-by: Rashmica Gupta <rashmicy@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Rashmica Gupta [Wed, 25 Nov 2015 02:46:25 +0000 (13:46 +1100)]
powerpc/xmon: Append linux_banner to exception information in xmon.
Currently if you are in xmon without an oops etc. to view the kernel
version you have to type "d $linux_banner" - not necessarily obvious. As
this is useful information, append to the output of "e" command.
Kernel prints respective warnings about various EPOW events for
user information/action after parsing EPOW interrupts. At times
below EPOW reset event warning is seen to be flooding kernel log
over a period of time.
May 25 03:46:34 alp kernel: Non critical power or cooling issue cleared
May 25 03:46:52 alp kernel: Non critical power or cooling issue cleared
May 25 03:53:48 alp kernel: Non critical power or cooling issue cleared
May 25 03:55:46 alp kernel: Non critical power or cooling issue cleared
May 25 03:56:34 alp kernel: Non critical power or cooling issue cleared
May 25 03:59:04 alp kernel: Non critical power or cooling issue cleared
May 25 04:02:01 alp kernel: Non critical power or cooling issue cleared
These EPOW reset events are spurious in nature and are triggered by
firmware without an actual EPOW event being reset. This patch avoids these
multiple EPOW reset warnings by using a counter variable. This variable
is incremented every time an EPOW event is reported. Upon receiving a EPOW
reset event the same variable is checked to filter out spurious events and
decremented accordingly.
This patch also improves log messages to better describe EPOW event being
reported. Merged adjacent log messages into single one to reduce number of
lines printed per event.
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Vipin K Parashar <vipin@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Neuling [Fri, 20 Nov 2015 04:15:34 +0000 (15:15 +1100)]
selftests/powerpc: Add TM signal with invalid stack test
Test the kernels signal generation code to ensure it can handle an
invalid stack pointer when transactional.
Signed-off-by: Michael Neuling <mikey@neuling.org> Tested-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
[mpe: Skip if we don't have TM] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Neuling [Fri, 20 Nov 2015 04:15:33 +0000 (15:15 +1100)]
selftests/powerpc: Add TM signal return test
Test the kernel's signal return code to ensure that it doesn't crash
when both the transactional and suspend MSR bits are set in the signal
context.
Signed-off-by: Michael Neuling <mikey@neuling.org> Tested-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
[mpe: Skip if we don't have TM] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
You get the TM[] only if at least one TM MSR bit is set. Inside the
TM[], E means Enabled (bit 32), S means Suspended (bit 33), and T
means Transactional (bit 34)
If no bits are set, you get no TM[] output.
Include rework of printbits() to handle this case.
Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Boqun Feng [Mon, 2 Nov 2015 01:30:32 +0000 (09:30 +0800)]
powerpc: Make {cmp}xchg* and their atomic_ versions fully ordered
According to memory-barriers.txt, xchg*, cmpxchg* and their atomic_
versions all need to be fully ordered, however they are now just
RELEASE+ACQUIRE, which are not fully ordered.
So also replace PPC_RELEASE_BARRIER and PPC_ACQUIRE_BARRIER with
PPC_ATOMIC_ENTRY_BARRIER and PPC_ATOMIC_EXIT_BARRIER in
__{cmp,}xchg_{u32,u64} respectively to guarantee fully ordered semantics
of atomic{,64}_{cmp,}xchg() and {cmp,}xchg(), as a complement of commit b97021f85517 ("powerpc: Fix atomic_xxx_return barrier semantics")
This patch depends on patch "powerpc: Make value-returning atomics fully
ordered" for PPC_ATOMIC_ENTRY_BARRIER definition.
Cc: stable@vger.kernel.org # 3.2+ Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Boqun Feng [Mon, 2 Nov 2015 01:30:31 +0000 (09:30 +0800)]
powerpc: Make value-returning atomics fully ordered
According to memory-barriers.txt:
> Any atomic operation that modifies some state in memory and returns
> information about the state (old or new) implies an SMP-conditional
> general memory barrier (smp_mb()) on each side of the actual
> operation ...
Which mean these operations should be fully ordered. However on PPC,
PPC_ATOMIC_ENTRY_BARRIER is the barrier before the actual operation,
which is currently "lwsync" if SMP=y. The leading "lwsync" can not
guarantee fully ordered atomics, according to Paul Mckenney:
https://lkml.org/lkml/2015/10/14/970
To fix this, we define PPC_ATOMIC_ENTRY_BARRIER as "sync" to guarantee
the fully-ordered semantics.
This also makes futex atomics fully ordered, which can avoid possible
memory ordering problems if userspace code relies on futex system call
for fully ordered semantics.
Fixes: b97021f85517 ("powerpc: Fix atomic_xxx_return barrier semantics") Cc: stable@vger.kernel.org # 3.2+ Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The slot information of base page size hash pte is stored in the
pgtable_t w.r.t transparent hugepage. We need to make sure we don't
index beyond pgtable_t size.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
pte and pmd table size are dependent on config items. Don't
hard code the same. This make sure we use the right value
when masking pmd entries and also while checking pmd_bad
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
For a pte entry we will have _PAGE_PTE set. Our pte page
address have a minimum alignment requirement of HUGEPD_SHIFT_MASK + 1.
We use the lower 7 bits to indicate hugepd. ie.
For pmd and pgd we can find:
1) _PAGE_PTE set pte -> indicate PTE
2) bits [2..6] non zero -> indicate hugepd.
They also encode the size. We skip bit 1 (_PAGE_PRESENT).
3) othewise pointer to next table.
Acked-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
W.r.t hugetlb, we support two format for pmd. With book3s_64 and
64K linux page size, we can have pte at the pmd level. Hence we
don't need to support hugepd there. For everything else hugepd
is supported and pmd_huge is (0).
Acked-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
powerpc/mm: Add helper for converting pte bit to hpte bits
Instead of open coding it in multiple code paths, export the helper
and add more documentation. Also make sure we don't make assumption
regarding pte bit position
Acked-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
powerpc/mm: Don't track subpage valid bit in pte_t
This free up 11 bits in pte_t. In the later patch we also change
the pte_t format so that we can start supporting migration pte
at pmd level. We now track 4k subpage valid bit as below
If we have _PAGE_COMBO set, we override the _PAGE_F_GIX_SHIFT
and _PAGE_F_SECOND. Together we have 4 bits, each of them
used to indicate whether any of the 4 4k subpage in that group
is valid. ie,
[ group 1 bit ] [ group 2 bit ] ..... [ group 4 ]
[ subpage 1 - 4] [ subpage 5- 8] ..... [ subpage 13 - 16]
We still track each 4k subpage slot number and secondary hash
information in the second half of pgtable_t. Removing the subpage
tracking have some significant overhead on aim9 and ebizzy benchmark and
to support THP with 4K subpage, we do need a pgtable_t of 4096 bytes.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We copy only needed PTE bits define from pte-common.h to respective
hash related header. This should greatly simply later patches in which
we are going to change the pte format for hash config
Acked-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
powerpc/mm: Don't have generic headers introduce functions touching pte bits
We are going to drop pte_common.h in the later patch. The idea is to
enable hash code not require to define all PTE bits. Having PTE bits
defined in pte_common.h made the code unnecessarily complex.
Acked-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
powerpc/mm: Fix infinite loop in hash fault with 4K page size
This is the same bug we fixed as part of 09567e7fd44291bfc08accfdd67ad8f467842332
("powerpc/mm: Check paca psize is up to date for huge mappings"). Please
check that for details. The difference here is that faults were
happening on a 4K page at an address previously mapped by hugetlb.
Anton Blanchard [Wed, 9 Dec 2015 09:11:47 +0000 (20:11 +1100)]
powerpc: Fix DSCR inheritance over fork()
Two DSCR tests have a hack in them:
/*
* XXX: Force a context switch out so that DSCR
* current value is copied into the thread struct
* which is required for the child to inherit the
* changed value.
*/
sleep(1);
We should not be working around this in the testcase, it is a kernel bug.
Fix it by copying the current DSCR to the child, instead of what we
had in the thread struct at last context switch.
Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Anton Blanchard [Thu, 10 Dec 2015 09:44:39 +0000 (20:44 +1100)]
powerpc: Call restore_sprs() before _switch()
commit 152d523e6307 ("powerpc: Create context switch helpers save_sprs()
and restore_sprs()") moved the restore of SPRs after the call to _switch().
There is an issue with this approach - new tasks do not return through
_switch(), they are set up by copy_thread() to directly return through
ret_from_fork() or ret_from_kernel_thread(). This means restore_sprs() is
not getting called for new tasks.
Fix this by moving restore_sprs() before _switch().
Fixes: 152d523e6307 ("powerpc: Create context switch helpers save_sprs() and restore_sprs()") Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Anton Blanchard [Thu, 10 Dec 2015 09:04:05 +0000 (20:04 +1100)]
powerpc: Call check_if_tm_restore_required() in enable_kernel_*()
Commit a0e72cf12b1a ("powerpc: Create msr_check_and_{set,clear}()")
removed a call to check_if_tm_restore_required() in the
enable_kernel_*() functions. Add them back in.
Fixes: a0e72cf12b1a ("powerpc: Create msr_check_and_{set,clear}()") Reported-by: Rashmica Gupta <rashmicy@gmail.com> Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The enable_kernel_*() functions leave the relevant MSR bits enabled
until we exit the kernel sometime later. Create disable versions
that wrap the kernel use of FP, Altivec VSX or SPE.
While we don't want to disable it normally for performance reasons
(MSR writes are slow), it will be used for a debug boot option that
does this and catches bad uses in other areas of the kernel.
Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Anton Blanchard [Thu, 29 Oct 2015 00:44:04 +0000 (11:44 +1100)]
powerpc: Create msr_check_and_{set,clear}()
Create helper functions to set and clear MSR bits after first
checking if they are already set. Grouping them will make it
easy to avoid the MSR writes in a subsequent optimisation.
Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Anton Blanchard [Thu, 29 Oct 2015 00:44:02 +0000 (11:44 +1100)]
powerpc: Move part of giveup_vsx into c
Move the MSR modification into c. Removing it from the assembly
function will allow us to avoid costly MSR writes by batching them
up.
Check the FP and VMX bits before calling the relevant giveup_*()
function. This makes giveup_vsx() and flush_vsx_to_thread() perform
more like their sister functions, and allows us to use
flush_vsx_to_thread() in the signal code.
Move the check_if_tm_restore_required() check in.
Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Anton Blanchard [Thu, 29 Oct 2015 00:44:00 +0000 (11:44 +1100)]
powerpc: Remove NULL task struct pointer checks in FP and vector code
We used to allow giveup_*() to be called with a NULL task struct
pointer. Now those cases are handled in the caller we can remove
the checks. We can also remove giveup_altivec_notask() which is also
unused.
Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Anton Blanchard [Thu, 29 Oct 2015 00:43:58 +0000 (11:43 +1100)]
powerpc: Simplify TM restore checks
Instead of having multiple giveup_*_maybe_transactional() functions,
separate out the TM check into a new function called
check_if_tm_restore_required().
This will make it easier to optimise the giveup_*() functions in a
subsequent patch.
Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Anton Blanchard [Thu, 29 Oct 2015 00:43:57 +0000 (11:43 +1100)]
powerpc: Remove UP only lazy floating point and vector optimisations
The UP only lazy floating point and vector optimisations were written
back when SMP was not common, and neither glibc nor gcc used vector
instructions. Now SMP is very common, glibc aggressively uses vector
instructions and gcc autovectorises.
We want to add new optimisations that apply to both UP and SMP, but
in preparation for that remove these UP only optimisations.
Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Anton Blanchard [Thu, 29 Oct 2015 00:43:55 +0000 (11:43 +1100)]
powerpc: Create context switch helpers save_sprs() and restore_sprs()
Move all our context switch SPR save and restore code into two
helpers. We do a few optimisations:
- Group all mfsprs and all mtsprs. In many cases an mtspr sets a
scoreboarding bit that an mfspr waits on, so the current practise of
mfspr A; mtspr A; mfpsr B; mtspr B is the worst scheduling we can
do.
- SPR writes are slow, so check that the value is changing before
writing it.
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