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: Markos 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: Ralf Baechle <ralf@linux-mips.org>
Commit
Commit 1d40cfcd34
Author: Ralf Baechle <ralf@linux-mips.org>
Date: Fri Jul 15 15:23:23 2005 +0000
Avoid SMP cacheflushes. This is a minor optimization of startup but
will also avoid smp_call_function from doing stupid things when called
from a CPU that is not yet marked online.
missed an appropriate cache flush of TLB refill handler because that time it was
at fixed location CAC_BASE. After years the refill handler in EBASE vector
is not at that location and can be allocated in some another memory and needs
I-cache sync as other TLB exception vectors.
Besides that, the new function - local_flash_icache_range() was introduced
to avoid SMP cacheflushes.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: paul.gortmaker@windriver.com
Cc: jchandra@broadcom.com
Cc: linux-kernel@vger.kernel.org
Cc: david.daney@cavium.com
Patchwork: https://patchwork.linux-mips.org/patch/7312/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Code in a switch statement in probe_pcache checks the CPU type twice
unnecessarily for processor implementations that have the alias removal
feature reported by the CP0 Config7.AR and Config7.IAR bits. This change
rewrites the affected fragment avoiding the extraneous check and improving
readability.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7221/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull MIPS updates from Ralf Baechle:
- three fixes for 3.15 that didn't make it in time
- limited Octeon 3 support.
- paravirtualization support
- improvment to platform support for Netlogix SOCs.
- add support for powering down the Malta eval board in software
- add many instructions to the in-kernel microassembler.
- add support for the BPF JIT.
- minor cleanups of the BCM47xx code.
- large cleanup of math emu code resulting in significant code size
reduction, better readability of the code and more accurate
emulation.
- improvments to the MIPS CPS code.
- support C3 power status for the R4k count/compare clock device.
- improvments to the GIO support for older SGI workstations.
- increase number of supported CPUs to 256; this can be reached on
certain embedded multithreaded ccNUMA configurations.
- various small cleanups, updates and fixes
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (173 commits)
MIPS: IP22/IP28: Improve GIO support
MIPS: Octeon: Add twsi interrupt initialization for OCTEON 3XXX, 5XXX, 63XX
DEC: Document the R4k MB ASIC mini interrupt controller
DEC: Add self as the maintainer
MIPS: Add microMIPS MSA support.
MIPS: Replace calls to obsolete strict_strto call with kstrto* equivalents.
MIPS: Replace obsolete strict_strto call with kstrto
MIPS: BFP: Simplify code slightly.
MIPS: Call find_vma with the mmap_sem held
MIPS: Fix 'write_msa_##' inline macro.
MIPS: Fix MSA toolchain support detection.
mips: Update the email address of Geert Uytterhoeven
MIPS: Add minimal defconfig for mips_paravirt
MIPS: Enable build for new system 'paravirt'
MIPS: paravirt: Add pci controller for virtio
MIPS: Add code for new system 'paravirt'
MIPS: Add functions for hypervisor call
MIPS: OCTEON: Add OCTEON3 to __get_cpu_type
MIPS: Add function get_ebase_cpunum
MIPS: Add minimal support for OCTEON3 to c-r4k.c
...
Currently hugepage migration is available for all archs which support
pmd-level hugepage, but testing is done only for x86_64 and there're
bugs for other archs. So to avoid breaking such archs, this patch
limits the availability strictly to x86_64 until developers of other
archs get interested in enabling this feature.
Simply disabling hugepage migration on non-x86_64 archs is not enough to
fix the reported problem where sys_move_pages() hits the BUG_ON() in
follow_page(FOLL_GET), so let's fix this by checking if hugepage
migration is supported in vma_migratable().
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: <stable@vger.kernel.org> [3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull KVM updates from Paolo Bonzini:
"At over 200 commits, covering almost all supported architectures, this
was a pretty active cycle for KVM. Changes include:
- a lot of s390 changes: optimizations, support for migration, GDB
support and more
- ARM changes are pretty small: support for the PSCI 0.2 hypercall
interface on both the guest and the host (the latter acked by
Catalin)
- initial POWER8 and little-endian host support
- support for running u-boot on embedded POWER targets
- pretty large changes to MIPS too, completing the userspace
interface and improving the handling of virtualized timer hardware
- for x86, a larger set of changes is scheduled for 3.17. Still, we
have a few emulator bugfixes and support for running nested
fully-virtualized Xen guests (para-virtualized Xen guests have
always worked). And some optimizations too.
The only missing architecture here is ia64. It's not a coincidence
that support for KVM on ia64 is scheduled for removal in 3.17"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (203 commits)
KVM: add missing cleanup_srcu_struct
KVM: PPC: Book3S PR: Rework SLB switching code
KVM: PPC: Book3S PR: Use SLB entry 0
KVM: PPC: Book3S HV: Fix machine check delivery to guest
KVM: PPC: Book3S HV: Work around POWER8 performance monitor bugs
KVM: PPC: Book3S HV: Make sure we don't miss dirty pages
KVM: PPC: Book3S HV: Fix dirty map for hugepages
KVM: PPC: Book3S HV: Put huge-page HPTEs in rmap chain for base address
KVM: PPC: Book3S HV: Fix check for running inside guest in global_invalidates()
KVM: PPC: Book3S: Move KVM_REG_PPC_WORT to an unused register number
KVM: PPC: Book3S: Add ONE_REG register names that were missed
KVM: PPC: Add CAP to indicate hcall fixes
KVM: PPC: MPIC: Reset IRQ source private members
KVM: PPC: Graciously fail broken LE hypercalls
PPC: ePAPR: Fix hypercall on LE guest
KVM: PPC: BOOK3S: Remove open coded make_dsisr in alignment handler
KVM: PPC: BOOK3S: Always use the saved DAR value
PPC: KVM: Make NX bit available with magic page
KVM: PPC: Disable NX for old magic page using guests
KVM: PPC: BOOK3S: HV: Add mixed page-size support for guest
...
It will be used later on by bpf-jit
[ralf@linux-mips.org: Resolved conflict.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/6736/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It will be used later on by bpf-jit
[ralf@linux-mips.org: Resolved conflict.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/6733/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It will be used later on by bpf-jit
[ralf@linux-mips.org: Resolved conflict.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/6732/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It will be used later on by bpf-jit
[ralf@linux-mips.org: Resolved conflict.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/6731/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It will be used later on by bpf-jit
[ralf@linux-mips.org: Resolved conflict.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/6730/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It will be used later on by bpf-jit
[ralf@linux-mips.org: Resolved conflict.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/6729/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It will be used later on by bpf-jit
[ralf@linux-mips.org: Resolved conflict.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: http://patchwork.linux-mips.org/patch/6728/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It will be used later on by bpf-jit
[ralf@linux-mips.org: Resolved conflict.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/6727/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It will be used later on by bpf-jit
[ralf@linux-mips.org: Fixed conflict due to other preceeding conflicts.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/6726/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This patch allows use of the MT ASE yield instruction from uasm. It will
be used by a subsequent patch.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This patch allows for use of the beq instruction with labels from uasm,
much as bne & others already do. It will be used by a subsequent patch.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This is identical to kmap_coherent apart from the cache coherency
attribute used for the TLB entry, so kmap_coherent is abstracted to
kmap_prot which is then called for both kmap_coherent &
kmap_noncoherent. This will be used by a subsequent patch.
Suggested-by: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Nobody is maintaining SMTC anymore and there also seems to be no userbase.
Which is a pity - the SMTC technology primarily developed by Kevin D.
Kissell <kevink@paralogos.com> is an ingenious demonstration for the MT
ASE's power and elegance.
Based on Markos Chandras <Markos.Chandras@imgtec.com> patch
https://patchwork.linux-mips.org/patch/6719/ which while very similar did
no longer apply cleanly when I tried to merge it plus some additional
post-SMTC cleanup - SMTC was a feature as tricky to remove as it was to
merge once upon a time.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
R4600_HIT_CACHEOP_WAR_IMPL is only needed on R4600 v1.6 and the R4600 has
data cache lines that are always 32 bytes so the call is pointless in
r4k_blast_dcache_page_dc64.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Add a CPU power management callback for the r4k TLB which reconfigures
it after the CPU leaves a powered down state.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Implement a CPU power management callback for the r4k cache, to set up
coherency again after leaving a powered down state.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
The lkdtm module performs tests against executable memory ranges, so it
needs to flush the icache for proper behaviors. Other architectures
already export this, so do the same for MIPS.
[akpm@linux-foundation.org: relocate export sites]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Sanjay Lal <sanjayl@kymasys.com>
Cc: John Crispin <blogic@openwrt.org>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
