1. 17 Dec, 2021 1 commit
  2. 09 Dec, 2021 1 commit
    • Jarkko Sakkinen's avatar
      x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node · 50468e43
      Jarkko Sakkinen authored
      == Problem ==
      
      The amount of SGX memory on a system is determined by the BIOS and it
      varies wildly between systems.  It can be as small as dozens of MB's
      and as large as many GB's on servers.  Just like how applications need
      to know how much regular RAM is available, enclave builders need to
      know how much SGX memory an enclave can consume.
      
      == Solution ==
      
      Introduce a new sysfs file:
      
      	/sys/devices/system/node/nodeX/x86/sgx_total_bytes
      
      to enumerate the amount of SGX memory available in each NUMA node.
      This serves the same function for SGX as /proc/meminfo or
      /sys/devices/system/node/nodeX/meminfo does for normal RAM.
      
      'sgx_total_bytes' is needed today to help drive the SGX selftests.
      SGX-specific swap code is exercised by creating overcommitted enclaves
      which are larger than the physical SGX memory on the system.  They
      currently use a CPUID-based approach which can diverge from the actual
      amount of SGX memory available.  'sgx_total_bytes' ensures that the
      selftests can work efficiently and do not attempt stupid things like
      creating a 100,000 MB enclave on a system with 128 MB of SGX memory.
      
      == Implementation Details ==
      
      Introduce CONFIG_HAVE_ARCH_NODE_DEV_GROUP opt-in flag to expose an
      arch specific attribute group, and add an attribute for the amount of
      SGX memory in bytes to each NUMA node:
      
      == ABI Design Discussion ==
      
      As opposed to the per-node ABI, a single, global ABI was considered.
      However, this would prevent enclaves from being able to size
      themselves so that they fit on a single NUMA node.  Essentially, a
      single value would rule out NUMA optimizations for enclaves.
      
      Create a new "x86/" directory inside each "nodeX/" sysfs directory.
      'sgx_total_bytes' is expected to be the first of at least a few
      sgx-specific files to be placed in the new directory.  Just scanning
      /proc/meminfo, these are the no-brainers that we have for RAM, but we
      need for SGX:
      
      	MemTotal:       xxxx kB // sgx_total_bytes (implemented here)
      	MemFree:        yyyy kB // sgx_free_bytes
      	SwapTotal:      zzzz kB // sgx_swapped_bytes
      
      So, at *least* three.  I think we will eventually end up needing
      something more along the lines of a dozen.  A new directory (as
      opposed to being in the nodeX/ "root") directory avoids cluttering the
      root with several "sgx_*" files.
      
      Place the new file in a new "nodeX/x86/" directory because SGX is
      highly x86-specific.  It is very unlikely that any other architecture
      (or even non-Intel x86 vendor) will ever implement SGX.  Using "sgx/"
      as opposed to "x86/" was also considered.  But, there is a real chance
      this can get used for other arch-specific purposes.
      
      [ dhansen: rewrite changelog ]
      Signed-off-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
      Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
      Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Acked-by: default avatarBorislav Petkov <bp@suse.de>
      Link: https://lkml.kernel.org/r/20211116162116.93081-2-jarkko@kernel.org
      50468e43
  3. 19 Nov, 2021 1 commit
  4. 17 Nov, 2021 1 commit
  5. 16 Nov, 2021 1 commit
    • Reinette Chatre's avatar
      x86/sgx: Fix free page accounting · ac5d272a
      Reinette Chatre authored
      The SGX driver maintains a single global free page counter,
      sgx_nr_free_pages, that reflects the number of free pages available
      across all NUMA nodes. Correspondingly, a list of free pages is
      associated with each NUMA node and sgx_nr_free_pages is updated
      every time a page is added or removed from any of the free page
      lists. The main usage of sgx_nr_free_pages is by the reclaimer
      that runs when it (sgx_nr_free_pages) goes below a watermark
      to ensure that there are always some free pages available to, for
      example, support efficient page faults.
      
      With sgx_nr_free_pages accessed and modified from a few places
      it is essential to ensure that these accesses are done safely but
      this is not the case. sgx_nr_free_pages is read without any
      protection and updated with inconsistent protection by any one
      of the spin locks associated with the individual NUMA nodes.
      For example:
      
            CPU_A                                 CPU_B
            -----                                 -----
       spin_lock(&nodeA->lock);              spin_lock(&nodeB->lock);
       ...                                   ...
       sgx_nr_free_pages--;  /* NOT SAFE */  sgx_nr_free_pages--;
      
       spin_unlock(&nodeA->lock);            spin_unlock(&nodeB->lock);
      
      Since sgx_nr_free_pages may be protected by different spin locks
      while being modified from different CPUs, the following scenario
      is possible:
      
            CPU_A                                CPU_B
            -----                                -----
      {sgx_nr_free_pages = 100}
       spin_lock(&nodeA->lock);              spin_lock(&nodeB->lock);
       sgx_nr_free_pages--;                  sgx_nr_free_pages--;
       /* LOAD sgx_nr_free_pages = 100 */    /* LOAD sgx_nr_free_pages = 100 */
       /* sgx_nr_free_pages--          */    /* sgx_nr_free_pages--          */
       /* STORE sgx_nr_free_pages = 99 */    /* STORE sgx_nr_free_pages = 99 */
       spin_unlock(&nodeA->lock);            spin_unlock(&nodeB->lock);
      
      In the above scenario, sgx_nr_free_pages is decremented from two CPUs
      but instead of sgx_nr_free_pages ending with a value that is two less
      than it started with, it was only decremented by one while the number
      of free pages were actually reduced by two. The consequence of
      sgx_nr_free_pages not being protected is that its value may not
      accurately reflect the actual number of free pages on the system,
      impacting the availability of free pages in support of many flows.
      
      The problematic scenario is when the reclaimer does not run because it
      believes there to be sufficient free pages while any attempt to allocate
      a page fails because there are no free pages available. In the SGX driver
      the reclaimer's watermark is only 32 pages so after encountering the
      above example scenario 32 times a user space hang is possible when there
      are no more free pages because of repeated page faults caused by no
      free pages made available.
      
      The following flow was encountered:
      asm_exc_page_fault
       ...
         sgx_vma_fault()
           sgx_encl_load_page()
             sgx_encl_eldu() // Encrypted page needs to be loaded from backing
                             // storage into newly allocated SGX memory page
               sgx_alloc_epc_page() // Allocate a page of SGX memory
                 __sgx_alloc_epc_page() // Fails, no free SGX memory
                 ...
                 if (sgx_should_reclaim(SGX_NR_LOW_PAGES)) // Wake reclaimer
                   wake_up(&ksgxd_waitq);
                 return -EBUSY; // Return -EBUSY giving reclaimer time to run
             return -EBUSY;
           return -EBUSY;
         return VM_FAULT_NOPAGE;
      
      The reclaimer is triggered in above flow with the following code:
      
      static bool sgx_should_reclaim(unsigned long watermark)
      {
              return sgx_nr_free_pages < watermark &&
                     !list_empty(&sgx_active_page_list);
      }
      
      In the problematic scenario there were no free pages available yet the
      value of sgx_nr_free_pages was above the watermark. The allocation of
      SGX memory thus always failed because of a lack of free pages while no
      free pages were made available because the reclaimer is never started
      because of sgx_nr_free_pages' incorrect value. The consequence was that
      user space kept encountering VM_FAULT_NOPAGE that caused the same
      address to be accessed repeatedly with the same result.
      
      Change the global free page counter to an atomic type that
      ensures simultaneous updates are done safely. While doing so, move
      the updating of the variable outside of the spin lock critical
      section to which it does not belong.
      
      Cc: stable@vger.kernel.org
      Fixes: 901ddbb9 ("x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page()")
      Suggested-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
      Signed-off-by: default avatarReinette Chatre <reinette.chatre@intel.com>
      Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
      Reviewed-by: default avatarTony Luck <tony.luck@intel.com>
      Acked-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
      Link: https://lkml.kernel.org/r/a95a40743bbd3f795b465f30922dde7f1ea9e0eb.1637004094.git.reinette.chatre@intel.com
      ac5d272a
  6. 15 Nov, 2021 21 commits
  7. 14 Nov, 2021 14 commits
    • Linus Torvalds's avatar
      Linux 5.16-rc1 · fa55b7dc
      Linus Torvalds authored
      fa55b7dc
    • Gustavo A. R. Silva's avatar
      kconfig: Add support for -Wimplicit-fallthrough · dee2b702
      Gustavo A. R. Silva authored
      Add Kconfig support for -Wimplicit-fallthrough for both GCC and Clang.
      
      The compiler option is under configuration CC_IMPLICIT_FALLTHROUGH,
      which is enabled by default.
      
      Special thanks to Nathan Chancellor who fixed the Clang bug[1][2]. This
      bugfix only appears in Clang 14.0.0, so older versions still contain
      the bug and -Wimplicit-fallthrough won't be enabled for them, for now.
      
      This concludes a long journey and now we are finally getting rid
      of the unintentional fallthrough bug-class in the kernel, entirely. :)
      
      Link: https://github.com/llvm/llvm-project/commit/9ed4a94d6451046a51ef393cd62f00710820a7e8 [1]
      Link: https://bugs.llvm.org/show_bug.cgi?id=51094 [2]
      Link: https://github.com/KSPP/linux/issues/115
      Link: https://github.com/ClangBuiltLinux/linux/issues/236Co-developed-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Co-developed-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
      Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
      Tested-by: default avatarNathan Chancellor <nathan@kernel.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      dee2b702
    • Linus Torvalds's avatar
      Merge tag 'xfs-5.16-merge-5' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux · ce49bfc8
      Linus Torvalds authored
      Pull xfs cleanups from Darrick Wong:
       "The most 'exciting' aspect of this branch is that the xfsprogs
        maintainer and I have worked through the last of the code
        discrepancies between kernel and userspace libxfs such that there are
        no code differences between the two except for #includes.
      
        IOWs, diff suffices to demonstrate that the userspace tools behave the
        same as the kernel, and kernel-only bits are clearly marked in the
        /kernel/ source code instead of just the userspace source.
      
        Summary:
      
         - Clean up open-coded swap() calls.
      
         - A little bit of #ifdef golf to complete the reunification of the
           kernel and userspace libxfs source code"
      
      * tag 'xfs-5.16-merge-5' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
        xfs: sync xfs_btree_split macros with userspace libxfs
        xfs: #ifdef out perag code for userspace
        xfs: use swap() to make dabtree code cleaner
      ce49bfc8
    • Linus Torvalds's avatar
      Merge tag 'for-5.16/parisc-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux · c3b68c27
      Linus Torvalds authored
      Pull more parisc fixes from Helge Deller:
       "Fix a build error in stracktrace.c, fix resolving of addresses to
        function names in backtraces, fix single-stepping in assembly code and
        flush userspace pte's when using set_pte_at()"
      
      * tag 'for-5.16/parisc-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
        parisc/entry: fix trace test in syscall exit path
        parisc: Flush kernel data mapping in set_pte_at() when installing pte for user page
        parisc: Fix implicit declaration of function '__kernel_text_address'
        parisc: Fix backtrace to always include init funtion names
      c3b68c27
    • Linus Torvalds's avatar
      Merge tag 'sh-for-5.16' of git://git.libc.org/linux-sh · 24318ae8
      Linus Torvalds authored
      Pull arch/sh updates from Rich Felker.
      
      * tag 'sh-for-5.16' of git://git.libc.org/linux-sh:
        sh: pgtable-3level: Fix cast to pointer from integer of different size
        sh: fix READ/WRITE redefinition warnings
        sh: define __BIG_ENDIAN for math-emu
        sh: math-emu: drop unused functions
        sh: fix kconfig unmet dependency warning for FRAME_POINTER
        sh: Cleanup about SPARSE_IRQ
        sh: kdump: add some attribute to function
        maple: fix wrong return value of maple_bus_init().
        sh: boot: avoid unneeded rebuilds under arch/sh/boot/compressed/
        sh: boot: add intermediate vmlinux.bin* to targets instead of extra-y
        sh: boards: Fix the cacography in irq.c
        sh: check return code of request_irq
        sh: fix trivial misannotations
      24318ae8
    • Linus Torvalds's avatar
      Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm · 6ea45c57
      Linus Torvalds authored
      Pull ARM fixes from Russell King:
      
       - Fix early_iounmap
      
       - Drop cc-option fallbacks for architecture selection
      
      * tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
        ARM: 9156/1: drop cc-option fallbacks for architecture selection
        ARM: 9155/1: fix early early_iounmap()
      6ea45c57
    • Linus Torvalds's avatar
      Merge tag 'devicetree-fixes-for-5.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux · 0d1503d8
      Linus Torvalds authored
      Pull devicetree fixes from Rob Herring:
      
       - Two fixes due to DT node name changes on Arm, Ltd. boards
      
       - Treewide rename of Ingenic CGU headers
      
       - Update ST email addresses
      
       - Remove Netlogic DT bindings
      
       - Dropping few more cases of redundant 'maxItems' in schemas
      
       - Convert toshiba,tc358767 bridge binding to schema
      
      * tag 'devicetree-fixes-for-5.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
        dt-bindings: watchdog: sunxi: fix error in schema
        bindings: media: venus: Drop redundant maxItems for power-domain-names
        dt-bindings: Remove Netlogic bindings
        clk: versatile: clk-icst: Ensure clock names are unique
        of: Support using 'mask' in making device bus id
        dt-bindings: treewide: Update @st.com email address to @foss.st.com
        dt-bindings: media: Update maintainers for st,stm32-hwspinlock.yaml
        dt-bindings: media: Update maintainers for st,stm32-cec.yaml
        dt-bindings: mfd: timers: Update maintainers for st,stm32-timers
        dt-bindings: timer: Update maintainers for st,stm32-timer
        dt-bindings: i2c: imx: hardware do not restrict clock-frequency to only 100 and 400 kHz
        dt-bindings: display: bridge: Convert toshiba,tc358767.txt to yaml
        dt-bindings: Rename Ingenic CGU headers to ingenic,*.h
      0d1503d8
    • Linus Torvalds's avatar
      Merge tag 'timers-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 622c72b6
      Linus Torvalds authored
      Pull timer fix from Thomas Gleixner:
       "A single fix for POSIX CPU timers to address a problem where POSIX CPU
        timer delivery stops working for a new child task because
        copy_process() copies state information which is only valid for the
        parent task"
      
      * tag 'timers-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        posix-cpu-timers: Clear task::posix_cputimers_work in copy_process()
      622c72b6
    • Linus Torvalds's avatar
      Merge tag 'irq-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · c36e33e2
      Linus Torvalds authored
      Pull irq fixes from Thomas Gleixner:
       "A set of fixes for the interrupt subsystem
      
        Core code:
      
         - A regression fix for the Open Firmware interrupt mapping code where
           a interrupt controller property in a node caused a map property in
           the same node to be ignored.
      
        Interrupt chip drivers:
      
         - Workaround a limitation in SiFive PLIC interrupt chip which
           silently ignores an EOI when the interrupt line is masked.
      
         - Provide the missing mask/unmask implementation for the CSKY MP
           interrupt controller.
      
        PCI/MSI:
      
         - Prevent a use after free when PCI/MSI interrupts are released by
           destroying the sysfs entries before freeing the memory which is
           accessed in the sysfs show() function.
      
         - Implement a mask quirk for the Nvidia ION AHCI chip which does not
           advertise masking capability despite implementing it. Even worse
           the chip comes out of reset with all MSI entries masked, which due
           to the missing masking capability never get unmasked.
      
         - Move the check which prevents accessing the MSI[X] masking for XEN
           back into the low level accessors. The recent consolidation missed
           that these accessors can be invoked from places which do not have
           that check which broke XEN. Move them back to he original place
           instead of sprinkling tons of these checks all over the code"
      
      * tag 'irq-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        of/irq: Don't ignore interrupt-controller when interrupt-map failed
        irqchip/sifive-plic: Fixup EOI failed when masked
        irqchip/csky-mpintc: Fixup mask/unmask implementation
        PCI/MSI: Destroy sysfs before freeing entries
        PCI: Add MSI masking quirk for Nvidia ION AHCI
        PCI/MSI: Deal with devices lying about their MSI mask capability
        PCI/MSI: Move non-mask check back into low level accessors
      c36e33e2
    • Linus Torvalds's avatar
      Merge tag 'locking-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 218cc8b8
      Linus Torvalds authored
      Pull x86 static call update from Thomas Gleixner:
       "A single fix for static calls to make the trampoline patching more
        robust by placing explicit signature bytes after the call trampoline
        to prevent patching random other jumps like the CFI jump table
        entries"
      
      * tag 'locking-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        static_call,x86: Robustify trampoline patching
      218cc8b8
    • Linus Torvalds's avatar
      Merge tag 'sched_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · fc661f2d
      Linus Torvalds authored
      Pull scheduler fixes from Borislav Petkov:
      
       - Avoid touching ~100 config files in order to be able to select the
         preemption model
      
       - clear cluster CPU masks too, on the CPU unplug path
      
       - prevent use-after-free in cfs
      
       - Prevent a race condition when updating CPU cache domains
      
       - Factor out common shared part of smp_prepare_cpus() into a common
         helper which can be called by both baremetal and Xen, in order to fix
         a booting of Xen PV guests
      
      * tag 'sched_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        preempt: Restore preemption model selection configs
        arch_topology: Fix missing clear cluster_cpumask in remove_cpu_topology()
        sched/fair: Prevent dead task groups from regaining cfs_rq's
        sched/core: Mitigate race cpus_share_cache()/update_top_cache_domain()
        x86/smp: Factor out parts of native_smp_prepare_cpus()
      fc661f2d
    • Linus Torvalds's avatar
      Merge tag 'perf_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · f7018be2
      Linus Torvalds authored
      Pull perf fixes from Borislav Petkov:
      
       - Prevent unintentional page sharing by checking whether a page
         reference to a PMU samples page has been acquired properly before
         that
      
       - Make sure the LBR_SELECT MSR is saved/restored too
      
       - Reset the LBR_SELECT MSR when resetting the LBR PMU to clear any
         residual data left
      
      * tag 'perf_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        perf/core: Avoid put_page() when GUP fails
        perf/x86/vlbr: Add c->flags to vlbr event constraints
        perf/x86/lbr: Reset LBR_SELECT during vlbr reset
      f7018be2
    • Linus Torvalds's avatar
      Merge tag 'x86_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 1654e95e
      Linus Torvalds authored
      Pull x86 fixes from Borislav Petkov:
      
       - Add the model number of a new, Raptor Lake CPU, to intel-family.h
      
       - Do not log spurious corrected MCEs on SKL too, due to an erratum
      
       - Clarify the path of paravirt ops patches upstream
      
       - Add an optimization to avoid writing out AMX components to sigframes
         when former are in init state
      
      * tag 'x86_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86/cpu: Add Raptor Lake to Intel family
        x86/mce: Add errata workaround for Skylake SKX37
        MAINTAINERS: Add some information to PARAVIRT_OPS entry
        x86/fpu: Optimize out sigframe xfeatures when in init state
      1654e95e
    • Linus Torvalds's avatar
      Merge tag 'perf-tools-for-v5.16-2021-11-13' of... · 35c8fad4
      Linus Torvalds authored
      Merge tag 'perf-tools-for-v5.16-2021-11-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux
      
      Pull more perf tools updates from Arnaldo Carvalho de Melo:
       "Hardware tracing:
      
         - ARM:
            * Print the size of the buffer size consistently in hexadecimal in
              ARM Coresight.
            * Add Coresight snapshot mode support.
            * Update --switch-events docs in 'perf record'.
            * Support hardware-based PID tracing.
            * Track task context switch for cpu-mode events.
      
         - Vendor events:
            * Add metric events JSON file for power10 platform
      
        perf test:
      
         - Get 'perf test' unit tests closer to kunit.
      
         - Topology tests improvements.
      
         - Remove bashisms from some tests.
      
        perf bench:
      
         - Fix memory leak of perf_cpu_map__new() in the futex benchmarks.
      
        libbpf:
      
         - Add some more weak libbpf functions o allow building with the
           libbpf versions, old ones, present in distros.
      
        libbeauty:
      
         - Translate [gs]setsockopt 'level' argument integer values to
           strings.
      
        tools headers UAPI:
      
         - Sync futex_waitv, arch prctl, sound, i195_drm and msr-index files
           with the kernel sources.
      
        Documentation:
      
         - Add documentation to 'struct symbol'.
      
         - Synchronize the definition of enum perf_hw_id with code in
           tools/perf/design.txt"
      
      * tag 'perf-tools-for-v5.16-2021-11-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (67 commits)
        perf tests: Remove bash constructs from stat_all_pmu.sh
        perf tests: Remove bash construct from record+zstd_comp_decomp.sh
        perf test: Remove bash construct from stat_bpf_counters.sh test
        perf bench futex: Fix memory leak of perf_cpu_map__new()
        tools arch x86: Sync the msr-index.h copy with the kernel sources
        tools headers UAPI: Sync drm/i915_drm.h with the kernel sources
        tools headers UAPI: Sync sound/asound.h with the kernel sources
        tools headers UAPI: Sync linux/prctl.h with the kernel sources
        tools headers UAPI: Sync arch prctl headers with the kernel sources
        perf tools: Add more weak libbpf functions
        perf bpf: Avoid memory leak from perf_env__insert_btf()
        perf symbols: Factor out annotation init/exit
        perf symbols: Bit pack to save a byte
        perf symbols: Add documentation to 'struct symbol'
        tools headers UAPI: Sync files changed by new futex_waitv syscall
        perf test bpf: Use ARRAY_CHECK() instead of ad-hoc equivalent, addressing array_size.cocci warning
        perf arm-spe: Support hardware-based PID tracing
        perf arm-spe: Save context ID in record
        perf arm-spe: Update --switch-events docs in 'perf record'
        perf arm-spe: Track task context switch for cpu-mode events
        ...
      35c8fad4