In light of the commit 16f77de8 (Revert "MIPS: Save/restore MSA
context around signals") the MSA support in the kernel is incomplete.
Until the replacement for the former sigcontext changes is agreed upon
and in tree, mark MSA experimental & disable it by default.

MSA is only implemented by one CPU supported by the kernel, the P5600.
The P5600 is a 32 bit core, and thus MSA can only be used when the
experimental CONFIG_MIPS_O32_FP64_SUPPORT option is enabled. Therefore
MSA is only being used in experimental settings anyway and this change
doesn't actually make any difference beyond clarifying the state of
MSA support.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7311/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

MSA requires that Status.FR == 1, so for MIPS32 tasks MSA can only be
used if CONFIG_MIPS_O32_FP64_SUPPORT is enabled. If it is not & the
kernel is 32bit, there's no point including support for MSA.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7310/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The TIF_MSA_CTX_LIVE flag (indicating that a task has MSA context which
needs to be preserved) was being cleared in start_thread, but the
TIF_USEDMSA flag (indicating that a task has used MSA in this timeslice)
was not. In copy_thread neither flag was cleared, but both need to be.
Without clearing these flags the kernel will proceed to attempt to save
MSA context when the task is context switched out, and if the task had
not used MSA in the meantime then it will fail because MSA or the FPU
are disabled. The end result is typically:

  do_cpu invoked from kernel context![#1]:
  CPU: 0 PID: 99 Comm: sh Not tainted 3.16.0-rc4-00025-g6dc9476-dirty #88
  task: 8f23dc60 ti: 8f1d8000 task.ti: 8f1d8000
  ...
  Call Trace:
  [<8010edbc>] resume+0x5c/0x280
  [<80481e0c>] __schedule+0x370/0x800
  [<80104838>] work_resched+0x8/0x2c

Fix by consistently clearing both flags in both functions.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7309/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The MSA specification upon first read appears to suggest that it is safe
to perform vector loads & stores with arbitrary alignment. However it
leaves provision for "address-dependent exceptions"... Align the vector
context to a 16 byte boundary to ensure that the kernel cannot cause any
such exceptions.

Note that the fpu field of struct thread_struct was already at a 16 byte
boundary within the struct, the introduction of FPU_ALIGN simply makes
the requirement explicit. The only part of this impacting the generated
kernel binary is ARCH_MIN_TASKALIGN.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7308/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Preemption must be disabled throughout the process of enabling the FPU,
enabling MSA & initialising the vector registers. Without doing so it
is possible to lose the FPU or MSA whilst initialising them causing
that initialisation to fail.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7307/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The kernel relies upon MSA being disabled when a task begins running,
so that it can initialise or restore context in response to the
resulting MSA disabled exception. Previously the state of MSA following
boot was left as it was before the kernel ran, where MSA could
potentially have been enabled. Explicitly disable it during boot to
prevent any problems.

As a nice side effect the code reads a little better too.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7306/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Commit d96cc3d1 "MIPS: Add microMIPS MSA support." attempted to use
the value of a macro within an inline asm statement but instead emitted
a comment leading to the cfcmsa & ctcmsa instructions being omitted. Fix
that by passing CFC_MSA_INSN & CTC_MSA_INSN as arguments to the asm
statements.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7305/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

If a task does not execute scalar FP instructions prior to using MSA
then the flags indicating that the task has live MSA context were not
being set. The upper 64b of each vector register would then be lost
upon the tasks first context switch after using MSA.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7500/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

When a task first makes use of MSA we need to ensure that the upper
64b of the vector registers are set to some value such that no
information can be leaked to it from the previous task to use MSA
context on the CPU. The architecture formerly specified that these
bits would be cleared to 0 when a scalar FP instructions wrote to the
aliased FP registers, which would have implicitly handled this as the
kernel restored scalar FP context. However more recent versions of the
specification now state that the value of the bits in such cases is
unpredictable. Initialise them explictly to be sure, and set all the
bits to 1 rather than 0 for consistency with the least significant
64b.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7497/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The kernel depends upon MSA never being enabled when the FPU is not, a
condition which is currently violated in a few places (whilst saving
sigcontext, following mips_cpu_save). Catch all the problem cases by
disabling MSA in lose_fpu, after saving context if necessary.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7302/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Switching the vector context implicitly saves & restores the state of
the aliased scalar FP data registers, however the scalar FP control
& status register is distinct from the MSA control & status register.
In order to allow scalar FP to function correctly in programs using
MSA, the scalar CSR needs to be saved & restored along with the MSA
vector context.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7301/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

I added a field for the MSACSR register in struct mips_fpu_struct, but
never actually made use of it... This is a clear bug. Save and restore
the MSACSR register along with the vector registers.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7300/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Just #ifdef away the C functions when included from an assembly file,
as will be done in a following commit.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7299/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Add interface & port definitions for D-Link DSR-1000N.
Signed-off-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: David Daney <ddaney.cavm@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/7219/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Add USB clock type for D-Link DSR-1000N.
Signed-off-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: David Daney <ddaney.cavm@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/7218/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Add a definition for D-Link DSR-1000N router. The bootloader on this board
supplies 20006 in the bootinfo; the enum CVMX_BOARD_TYPE_CUST_DSR1000N
comes from the GPL sources of the board.
Signed-off-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: David Daney <ddaney.cavm@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/7217/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Disable HOTPLUG_CPU functionality if the bootloader version is incorrect.
Signed-off-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Cc: David Daney <ddaney.cavm@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/7200/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

If nosmp kernel option given, we can assume HOTPLUG_CPU is disabled.
Signed-off-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: NDavid Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7202/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

If CONFIG_HOTPLUG_CPU is set, the driver thinks bootloader entry
address is configured and we should jump there. However, this is
not necessarily true if the kernel is booted on a system
with older/incompatible bootloader.

Add dynamic checks for the bootloader entry address.
Signed-off-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: David Daney <ddaney.cavm@gmail.com>
Cc: linux-watchdog@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7201/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The same check is already done earlier in octeon_smp_hotplug_setup().
Signed-off-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: NDavid Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Patchwork: https://patchwork.linux-mips.org/patch/7199/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Commit 35133692 ("[MIPS] Allow setting
of the cache attribute at run time") introduced the 'cca=' kernel
command-line parameter which allows overriding the kernel pages
cacheable attributes, document that parameter.

[ralf@linux-mips.org: replace @mips.com email addresses with it's imgtec.com
equivalent in this commit message.  Rephrase slightly for a bit more
pedantic correctness.]
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: blogic@openwrt.org
Cc: anemo@mba.ocn.ne.jp
Cc: chris.dearman@imgtec.com
Patchwork: https://patchwork.linux-mips.org/patch/7182/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The GICBIS macro could update the GIC registers incorrectly, depending
on the data value passed in:

* Bits were only OR'd into the register data, so register fields could
  not be cleared.

* Bits were OR'd into the register data without masking the data to the
  correct field width, corrupting adjacent bits.
Signed-off-by: NJeffrey Deans <jeffrey.deans@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7378/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The Malta malta_ipi_irqdispatch() routine now checks only IPI interrupts
when handling IPIs. It could previously call do_IRQ() for non-IPIs, and
also call do_IRQ() with an invalid IRQ number if there were no pending
GIC interrupts when gic_get_int() was called.
Signed-off-by: NJeffrey Deans <jeffrey.deans@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7377/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Move most of the functionality of gic_get_int() into a new function
gic_get_int_mask() which takes a bitmask of interrupts in which the
caller is interested, and returns the subset which are pending for the
current CPU.

This allows CP0 IRQ dispatch routines to check only the GIC interrupts
which are routed to a particular CPU interrupt input.

gic_get_int() is reimplemented using gic_get_int_mask() and is retained
for use by any platforms for which gic_get_int() is sufficient.
Signed-off-by: NJeffrey Deans <jeffrey.deans@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7376/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

A GIC interrupt which is declared as having a GIC_MAP_TO_NMI_MSK
mapping causes the cpu parameter to gic_setup_intr() to be increased
to 32, causing memory corruption when pcpu_masks[] is written to again
later in the function.
Signed-off-by: NJeffrey Deans <jeffrey.deans@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: stable@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7375/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

irq-gic.c:gic_get_int() masks out interrupts from the pending set which
aren’t in the pcpu_mask. Only interrupts marked with GIC_FLAG_IPI were
set in pcpu_mask, meaning that peripheral interrupts also had to be
marked as IPIs. Remove the use of GIC_FLAG_IPI and allow the flags
member of struct gic_intr_map to be zero.
Signed-off-by: NJeffrey Deans <jeffrey.deans@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7374/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The value of GIC_NUM_INTRS is platform-specific. Using a default value
from gic.h will result in incorrect behaviour on some systems, so
require a suitable definition to be present in the platform's irq.h.
Signed-off-by: NJeffrey Deans <jeffrey.deans@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7373/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Several bitmaps are declared in arch/mips/include/asm/gic.h, but the
scope of their use is limited to arch/mips/kernel/irq-gic.c. Move the
declarations from the header file to the C file.
Signed-off-by: NJeffrey Deans <jeffrey.deans@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7372/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Detect if the core supports unique exception codes for the
Read-Inhibit and Execute-Inhibit exceptions and set the
option accordingly. The RI/XI exception support is detected
by setting the 27th bit (IEC) of the PageGrain C0 register
and reading back the value of that register to verify the
bit is enabled.
Signed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7340/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Use the regular tlb_do_page_fault_0 (no write) handler to handle
the RI and XI exceptions. Also skip the RI/XI validation check
on TLB load handler since it's redundant when the CPU has
unique RI/XI exceptions.
Singed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7339/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

MIPSr5 added support for unique exception codes for the Read-Inhibit
and Execute-Inhibit exceptions.
Signed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7338/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The Hardware Page Table Walker aims to speed up TLB refill exceptions
by handling them in the hardware level instead of having a software
TLB refill handler. However, a TLB refill exception can still be
thrown in certain cases such as, synchronus exceptions, or address
translation or memory errors during the HTW operation. As a result of
which, HTW must not be considered a complete replacement for the TLB
refill software handler, but rather a fast-path for it.
For HTW to work, the PWBase register must contain the task's page
global directory address so the HTW will kick in on TLB refill
exceptions.

Due to HTW being a separate engine embedded deep in the CPU pipeline,
we need to restart the HTW everytime a PTE changes to avoid HTW
fetching a old entry from the page tables. It's also necessary to
restart the HTW on context switches to prevent it from fetching a
page from the previous process. Finally, since HTW is using the
entryhi register to write the translations to the TLB, it's necessary
to stop the HTW whenever the entryhi changes (eg for tlb probe
perations) and enable it back afterwards.

== Performance ==

The following trivial test was used to measure the performance of the
HTW. Using the same root filesystem, the following command was used
to measure the number of tlb refill handler executions with and
without (using 'nohtw' kernel parameter) HTW support.  The kernel was
modified to use a scratch register as a counter for the TLB refill
exceptions.

find /usr -type f -exec ls -lh {} \;

HTW Enabled:
TLB refill exceptions: 12306

HTW Disabled:
TLB refill exceptions: 17805
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/7336/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Detect if the core implements the HTW and set the option accordingly.
Also, add a new kernel parameter called 'nohtw' allowing
the user to disable the htw support and fallback to the software
refill handler.
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7335/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7326/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Moreover, report hardware page table walker support as 'htw' in the ASE
list of /proc/cpuinfo, if the core implements this feature.
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7334/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Long integers which are 4 bytes in MIPS32 can't hold new CPU
options anymore, so the type of the 'options' variable is changed
to unsigned long long which allows 32 more cpu options to be defined
for MIPS32

Also, re-arrange the 'options' struct member to avoid potential 4-byte
alignment gap in the middle of the struct.
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7324/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Add cases in perf_event_mipsxx.c for CPU_P5600. All the event numbers
listed for proAptiv also apply to P5600, so we use mipsxxcore_event_map2
and mipsxxcore_cache_map2 too, but the P5600 has 8-bit event numbers so
bit 8 (256) of the user ABI config is used for the parity bit (to
specify odd/even counter events).
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7242/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

In mipsxx_pmu_map_raw_event(), set event_id to base_id after the cpu
type conditional code to allow that code to override the base_id to use
more bits from the config and a higher bit for parity.

This will allow cores with up to 512 events between all even/odd
counters (an 8-bit event id) such as P5600 to use bit 8 for parity.
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7243/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

This header defines an exported interface (the register layout used in
core dumps and the GP regset accessible with PTRACE_{GET,SET}REGSET),
therefore belongs in uapi.
Signed-off-by: NAlex Smith <alex@alex-smith.me.uk>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7458/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The struct user definition in this file is not used anywhere (the ELF
core dumper does not use that format). Therefore, remove the header and
instead enable the asm-generic user.h which is an empty header to
satisfy a few generic headers which still try to include user.h.
Signed-off-by: NAlex Smith <alex@alex-smith.me.uk>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7459/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>