1. Oct 08, 2019
    • Vladimir Oltean's avatar
      spi: Add a PTP system timestamp to the transfer structure · b42faeee
      Vladimir Oltean authored
      
      
      SPI is one of the interfaces used to access devices which have a POSIX
      clock driver (real time clocks, 1588 timers etc). The fact that the SPI
      bus is slow is not what the main problem is, but rather the fact that
      drivers don't take a constant amount of time in transferring data over
      SPI. When there is a high delay in the readout of time, there will be
      uncertainty in the value that has been read out of the peripheral.
      When that delay is constant, the uncertainty can at least be
      approximated with a certain accuracy which is fine more often than not.
      
      Timing jitter occurs all over in the kernel code, and is mainly caused
      by having to let go of the CPU for various reasons such as preemption,
      servicing interrupts, going to sleep, etc. Another major reason is CPU
      dynamic frequency scaling.
      
      It turns out that the problem of retrieving time from a SPI peripheral
      with high accuracy can be solved by the use of "PTP system
      timestamping" - a mechanism to correlate the time when the device has
      snapshotted its internal time counter with the Linux system time at that
      same moment. This is sufficient for having a precise time measurement -
      it is not necessary for the whole SPI transfer to be transmitted "as
      fast as possible", or "as low-jitter as possible". The system has to be
      low-jitter for a very short amount of time to be effective.
      
      This patch introduces a PTP system timestamping mechanism in struct
      spi_transfer. This is to be used by SPI device drivers when they need to
      know the exact time at which the underlying device's time was
      snapshotted. More often than not, SPI peripherals have a very exact
      timing for when their SPI-to-interconnect bridge issues a transaction
      for snapshotting and reading the time register, and that will be
      dependent on when the SPI-to-interconnect bridge figures out that this
      is what it should do, aka as soon as it sees byte N of the SPI transfer.
      Since spi_device drivers are the ones who'd know best how the peripheral
      behaves in this regard, expose a mechanism in spi_transfer which allows
      them to specify which word (or word range) from the transfer should be
      timestamped.
      
      Add a default implementation of the PTP system timestamping in the SPI
      core. This is not going to be satisfactory performance-wise, but should
      at least increase the likelihood that SPI device drivers will use PTP
      system timestamping in the future.
      There are 3 entry points from the core towards the SPI controller
      drivers:
      
      - transfer_one: The driver is passed individual spi_transfers to
        execute. This is the easiest to timestamp.
      
      - transfer_one_message: The core passes the driver an entire spi_message
        (a potential batch of spi_transfers). The core puts the same pre and
        post timestamp to all transfers within a message. This is not ideal,
        but nothing better can be done by default anyway, since the core has
        no insight into how the driver batches the transfers.
      
      - transfer: Like transfer_one_message, but for unqueued drivers (i.e.
        the driver implements its own queue scheduling).
      
      Signed-off-by: default avatarVladimir Oltean <olteanv@gmail.com>
      Link: https://lore.kernel.org/r/20190905010114.26718-3-olteanv@gmail.com
      
      
      Signed-off-by: default avatarMark Brown <broonie@kernel.org>
      b42faeee
  2. Oct 07, 2019
  3. Oct 02, 2019
  4. Oct 01, 2019
  5. Sep 30, 2019
    • Krzysztof Wilczynski's avatar
      csky: Move static keyword to the front of declaration · 9af032a3
      Krzysztof Wilczynski authored
      
      
      Move the static keyword to the front of declaration of
      csky_pmu_of_device_ids, and resolve the following compiler
      warning that can be seen when building with warnings
      enabled (W=1):
      
      arch/csky/kernel/perf_event.c:1340:1: warning:
        ‘static’ is not at beginning of declaration [-Wold-style-declaration]
      
      Signed-off-by: default avatarKrzysztof Wilczynski <kw@linux.com>
      Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
      9af032a3
    • Valentin Schneider's avatar
      csky: entry: Remove unneeded need_resched() loop · a2139d3b
      Valentin Schneider authored
      
      
      Since the enabling and disabling of IRQs within preempt_schedule_irq()
      is contained in a need_resched() loop, we don't need the outer arch
      code loop.
      
      Signed-off-by: default avatarValentin Schneider <valentin.schneider@arm.com>
      Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
      a2139d3b
    • Linus Torvalds's avatar
      Merge tag 'char-misc-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc · 97f9a3c4
      Linus Torvalds authored
      Pull Documentation/process update from Greg KH:
       "Here are two small Documentation/process/embargoed-hardware-issues.rst
        file updates that missed my previous char/misc pull request.
      
        The first one adds an Intel representative for the process, and the
        second one cleans up the text a bit more when it comes to how the
        disclosure rules work, as it was a bit confusing to some companies"
      
      * tag 'char-misc-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
        Documentation/process: Clarify disclosure rules
        Documentation/process: Volunteer as the ambassador for Intel
      97f9a3c4
    • Linus Torvalds's avatar
      Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · 1eb80d6f
      Linus Torvalds authored
      Pull more vfs updates from Al Viro:
       "A couple of misc patches"
      
      * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
        afs dynroot: switch to simple_dir_operations
        fs/handle.c - fix up kerneldoc
      1eb80d6f
    • Linus Torvalds's avatar
      Merge tag '5.4-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6 · 7edee522
      Linus Torvalds authored
      Pull more cifs updates from Steve French:
       "Fixes from the recent SMB3 Test events and Storage Developer
        Conference (held the last two weeks).
      
        Here are nine smb3 patches including an important patch for debugging
        traces with wireshark, with three patches marked for stable.
      
        Additional fixes from last week to better handle some newly discovered
        reparse points, and a fix the create/mkdir path for setting the mode
        more atomically (in SMB3 Create security descriptor context), and one
        for path name processing are still being tested so are not included
        here"
      
      * tag '5.4-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
        CIFS: Fix oplock handling for SMB 2.1+ protocols
        smb3: missing ACL related flags
        smb3: pass mode bits into create calls
        smb3: Add missing reparse tags
        CIFS: fix max ea value size
        fs/cifs/sess.c: Remove set but not used variable 'capabilities'
        fs/cifs/smb2pdu.c: Make SMB2_notify_init static
        smb3: fix leak in "open on server" perf counter
        smb3: allow decryption keys to be dumped by admin for debugging
      7edee522
    • Mao Han's avatar
      csky: Fixup csky_pmu.max_period assignment · 3a09d8e2
      Mao Han authored
      
      
      The csky_pmu.max_period has type u64, and BIT() can only return
      32 bits unsigned long on C-SKY. The initialization for max_period
      will be incorrect when count_width is bigger than 32.
      
      Use BIT_ULL()
      
      Signed-off-by: default avatarMao Han <han_mao@c-sky.com>
      Signed-off-by: default avatarGuo Ren <ren_guo@c-sky.com>
      3a09d8e2
    • Guo Ren's avatar
      csky: Fixup add zero_fp fixup perf backtrace panic · 48ede51f
      Guo Ren authored
      
      
      We need set fp zero to let backtrace know the end. The patch fixup perf
      callchain panic problem, because backtrace didn't know what is the end
      of fp.
      
      Signed-off-by: default avatarGuo Ren <ren_guo@c-sky.com>
      Reported-by: default avatarMao Han <han_mao@c-sky.com>
      48ede51f
    • Mike Rapoport's avatar
      csky: Use generic free_initrd_mem() · fdbdcddc
      Mike Rapoport authored
      
      
      The csky implementation of free_initrd_mem() is an open-coded version of
      free_reserved_area() without poisoning.
      
      Remove it and make csky use the generic version of free_initrd_mem().
      
      Signed-off-by: default avatarMike Rapoport <rppt@linux.ibm.com>
      Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
      fdbdcddc
    • Linus Torvalds's avatar
      Merge branch 'entropy' · 3f2dc279
      Linus Torvalds authored
      Merge active entropy generation updates.
      
      This is admittedly partly "for discussion".  We need to have a way
      forward for the boot time deadlocks where user space ends up waiting for
      more entropy, but no entropy is forthcoming because the system is
      entirely idle just waiting for something to happen.
      
      While this was triggered by what is arguably a user space bug with
      GDM/gnome-session asking for secure randomness during early boot, when
      they didn't even need any such truly secure thing, the issue ends up
      being that our "getrandom()" interface is prone to that kind of
      confusion, because people don't think very hard about whether they want
      to block for sufficient amounts of entropy.
      
      The approach here-in is to decide to not just passively wait for entropy
      to happen, but to start actively collecting it if it is missing.  This
      is not necessarily always possible, but if the architecture has a CPU
      cycle counter, there is a fair amount of noise in the exact timings of
      reasonably complex loads.
      
      We may end up tweaking the load and the entropy estimates, but this
      should be at least a reasonable starting point.
      
      As part of this, we also revert the revert of the ext4 IO pattern
      improvement that ended up triggering the reported lack of external
      entropy.
      
      * getrandom() active entropy waiting:
        Revert "Revert "ext4: make __ext4_get_inode_loc plug""
        random: try to actively add entropy rather than passively wait for it
      3f2dc279
    • Linus Torvalds's avatar
      Revert "Revert "ext4: make __ext4_get_inode_loc plug"" · 02f03c42
      Linus Torvalds authored
      This reverts commit 72dbcf72
      
      .
      
      Instead of waiting forever for entropy that may just not happen, we now
      try to actively generate entropy when required, and are thus hopefully
      avoiding the problem that caused the nice ext4 IO pattern fix to be
      reverted.
      
      So revert the revert.
      
      Cc: Ahmed S. Darwish <darwish.07@gmail.com>
      Cc: Ted Ts'o <tytso@mit.edu>
      Cc: Willy Tarreau <w@1wt.eu>
      Cc: Alexander E. Patrakov <patrakov@gmail.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      02f03c42
    • Linus Torvalds's avatar
      random: try to actively add entropy rather than passively wait for it · 50ee7529
      Linus Torvalds authored
      For 5.3 we had to revert a nice ext4 IO pattern improvement, because it
      caused a bootup regression due to lack of entropy at bootup together
      with arguably broken user space that was asking for secure random
      numbers when it really didn't need to.
      
      See commit 72dbcf72
      
       (Revert "ext4: make __ext4_get_inode_loc plug").
      
      This aims to solve the issue by actively generating entropy noise using
      the CPU cycle counter when waiting for the random number generator to
      initialize.  This only works when you have a high-frequency time stamp
      counter available, but that's the case on all modern x86 CPU's, and on
      most other modern CPU's too.
      
      What we do is to generate jitter entropy from the CPU cycle counter
      under a somewhat complex load: calling the scheduler while also
      guaranteeing a certain amount of timing noise by also triggering a
      timer.
      
      I'm sure we can tweak this, and that people will want to look at other
      alternatives, but there's been a number of papers written on jitter
      entropy, and this should really be fairly conservative by crediting one
      bit of entropy for every timer-induced jump in the cycle counter.  Not
      because the timer itself would be all that unpredictable, but because
      the interaction between the timer and the loop is going to be.
      
      Even if (and perhaps particularly if) the timer actually happens on
      another CPU, the cacheline interaction between the loop that reads the
      cycle counter and the timer itself firing is going to add perturbations
      to the cycle counter values that get mixed into the entropy pool.
      
      As Thomas pointed out, with a modern out-of-order CPU, even quite simple
      loops show a fair amount of hard-to-predict timing variability even in
      the absense of external interrupts.  But this tries to take that further
      by actually having a fairly complex interaction.
      
      This is not going to solve the entropy issue for architectures that have
      no CPU cycle counter, but it's not clear how (and if) that is solvable,
      and the hardware in question is largely starting to be irrelevant.  And
      by doing this we can at least avoid some of the even more contentious
      approaches (like making the entropy waiting time out in order to avoid
      the possibly unbounded waiting).
      
      Cc: Ahmed Darwish <darwish.07@gmail.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: Nicholas Mc Guire <hofrat@opentech.at>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Willy Tarreau <w@1wt.eu>
      Cc: Alexander E. Patrakov <patrakov@gmail.com>
      Cc: Lennart Poettering <mzxreary@0pointer.de>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      50ee7529
    • Olof Johansson's avatar
      Merge tag 'fixes-5.4-merge-window' of... · 9bfd7319
      Olof Johansson authored
      Merge tag 'fixes-5.4-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into arm/fixes
      
      Fixes for omap variants
      
      Few fixes for ti-sysc interconnect target module driver for no-idle
      quirks that caused nfsroot to fail on some dra7 boards.
      
      And let's fixes to get LCD working again for logicpd board that got
      broken a while back with removal of panel-dpi driver. We need to now
      use generic CONFIG_DRM_PANEL_SIMPLE instead.
      
      * tag 'fixes-5.4-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
        bus: ti-sysc: Remove unpaired sysc_clkdm_deny_idle()
        ARM: dts: logicpd-som-lv: Fix i2c2 and i2c3 Pin mux
        ARM: dts: am3517-evm: Fix missing video
        ARM: dts: logicpd-torpedo-baseboard: Fix missing video
        ARM: omap2plus_defconfig: Fix missing video
        bus: ti-sysc: Fix handling of invalid clocks
        bus: ti-sysc: Fix clock handling for no-idle quirks
      
      Link: https://lore.kernel.org/r/pull-1568819401-72461@atomide.com
      
      
      Signed-off-by: default avatarOlof Johansson <olof@lixom.net>
      9bfd7319
    • Olof Johansson's avatar
      Merge tag 'scmi-fixes-5.4' of... · a4207a1c
      Olof Johansson authored
      Merge tag 'scmi-fixes-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into arm/fixes
      
      ARM SCMI fixes for v5.4
      
      Couple of fixes: one in scmi reset driver initialising missed scmi handle
      and an other in scmi reset API implementation fixing the assignment of
      reset state
      
      * tag 'scmi-fixes-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
        reset: reset-scmi: add missing handle initialisation
        firmware: arm_scmi: reset: fix reset_state assignment in scmi_domain_reset
      
      Link: https://lore.kernel.org/r/20190918142139.GA4370@bogus
      
      
      Signed-off-by: default avatarOlof Johansson <olof@lixom.net>
      a4207a1c
    • Linus Torvalds's avatar
      Merge tag 'libnvdimm-fixes-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm · a3c0e7b1
      Linus Torvalds authored
      More libnvdimm updates from Dan Williams:
      
       - Complete the reworks to interoperate with powerpc dynamic huge page
         sizes
      
       - Fix a crash due to missed accounting for the powerpc 'struct
         page'-memmap mapping granularity
      
       - Fix badblock initialization for volatile (DRAM emulated) pmem ranges
      
       - Stop triggering request_key() notifications to userspace when
         NVDIMM-security is disabled / not present
      
       - Miscellaneous small fixups
      
      * tag 'libnvdimm-fixes-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
        libnvdimm/region: Enable MAP_SYNC for volatile regions
        libnvdimm: prevent nvdimm from requesting key when security is disabled
        libnvdimm/region: Initialize bad block for volatile namespaces
        libnvdimm/nfit_test: Fix acpi_handle redefinition
        libnvdimm/altmap: Track namespace boundaries in altmap
        libnvdimm: Fix endian conversion issues 
        libnvdimm/dax: Pick the right alignment default when creating dax devices
        powerpc/book3s64: Export has_transparent_hugepage() related functions.
      a3c0e7b1
    • Linus Torvalds's avatar
      Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal · 939ca9f1
      Linus Torvalds authored
      Pull thermal SoC updates from Eduardo Valentin:
       "This is a really small pull in the midst of a lot of pending patches.
      
        We are in the middle of restructuring how we are maintaining the
        thermal subsystem, as per discussion in our last LPC. For now, I am
        sending just some changes that were pending in my tree. Looking
        forward to get a more streamlined process in the next merge window"
      
      * 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal:
        thermal: db8500: Rewrite to be a pure OF sensor
        thermal: db8500: Use dev helper variable
        thermal: db8500: Finalize device tree conversion
        thermal: thermal_mmio: remove some dead code
      939ca9f1