1. 12 Apr, 2023 11 commits
  2. 09 Mar, 2023 3 commits
  3. 08 Mar, 2023 3 commits
    • Linus Torvalds's avatar
      Merge tag 'fs_for_v6.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs · 6a98c9ca
      Linus Torvalds authored
      Pull udf fixes from Jan Kara:
       "Fix bugs in UDF caused by the big pile of changes that went in during
        the merge window"
      
      * tag 'fs_for_v6.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
        udf: Warn if block mapping is done for in-ICB files
        udf: Fix reading of in-ICB files
        udf: Fix lost writes in udf_adinicb_writepage()
      6a98c9ca
    • Linus Torvalds's avatar
      Merge tag 'platform-drivers-x86-v6.3-2' of... · 55ee6646
      Linus Torvalds authored
      Merge tag 'platform-drivers-x86-v6.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86
      
      Pull x86 platform driver fixes from Hans de Goede:
       "A small set of assorted bug and build/warning fixes"
      
      * tag 'platform-drivers-x86-v6.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86:
        platform: mellanox: mlx-platform: Initialize shift variable to 0
        platform/x86: int3472: Add GPIOs to Surface Go 3 Board data
        platform/x86: ISST: Fix kernel documentation warnings
        platform: x86: MLX_PLATFORM: select REGMAP instead of depending on it
        platform: mellanox: select REGMAP instead of depending on it
        platform/x86/intel/tpmi: Fix double free reported by Smatch
        platform/x86: ISST: Increase range of valid mail box commands
        platform/x86: dell-ddv: Fix temperature scaling
        platform/x86: dell-ddv: Fix cache invalidation on resume
        platform/x86/amd: pmc: remove CONFIG_SUSPEND checks
      55ee6646
    • Linus Torvalds's avatar
      x86/resctl: fix scheduler confusion with 'current' · 7fef0997
      Linus Torvalds authored
      The implementation of 'current' on x86 is very intentionally special: it
      is a very common thing to look up, and it uses 'this_cpu_read_stable()'
      to get the current thread pointer efficiently from per-cpu storage.
      
      And the keyword in there is 'stable': the current thread pointer never
      changes as far as a single thread is concerned.  Even if when a thread
      is preempted, or moved to another CPU, or even across an explicit call
      'schedule()' that thread will still have the same value for 'current'.
      
      It is, after all, the kernel base pointer to thread-local storage.
      That's why it's stable to begin with, but it's also why it's important
      enough that we have that special 'this_cpu_read_stable()' access for it.
      
      So this is all done very intentionally to allow the compiler to treat
      'current' as a value that never visibly changes, so that the compiler
      can do CSE and combine multiple different 'current' accesses into one.
      
      However, there is obviously one very special situation when the
      currently running thread does actually change: inside the scheduler
      itself.
      
      So the scheduler code paths are special, and do not have a 'current'
      thread at all.  Instead there are _two_ threads: the previous and the
      next thread - typically called 'prev' and 'next' (or prev_p/next_p)
      internally.
      
      So this is all actually quite straightforward and simple, and not all
      that complicated.
      
      Except for when you then have special code that is run in scheduler
      context, that code then has to be aware that 'current' isn't really a
      valid thing.  Did you mean 'prev'? Did you mean 'next'?
      
      In fact, even if then look at the code, and you use 'current' after the
      new value has been assigned to the percpu variable, we have explicitly
      told the compiler that 'current' is magical and always stable.  So the
      compiler is quite free to use an older (or newer) value of 'current',
      and the actual assignment to the percpu storage is not relevant even if
      it might look that way.
      
      Which is exactly what happened in the resctl code, that blithely used
      'current' in '__resctrl_sched_in()' when it really wanted the new
      process state (as implied by the name: we're scheduling 'into' that new
      resctl state).  And clang would end up just using the old thread pointer
      value at least in some configurations.
      
      This could have happened with gcc too, and purely depends on random
      compiler details.  Clang just seems to have been more aggressive about
      moving the read of the per-cpu current_task pointer around.
      
      The fix is trivial: just make the resctl code adhere to the scheduler
      rules of using the prev/next thread pointer explicitly, instead of using
      'current' in a situation where it just wasn't valid.
      
      That same code is then also used outside of the scheduler context (when
      a thread resctl state is explicitly changed), and then we will just pass
      in 'current' as that pointer, of course.  There is no ambiguity in that
      case.
      
      The fix may be trivial, but noticing and figuring out what went wrong
      was not.  The credit for that goes to Stephane Eranian.
      Reported-by: default avatarStephane Eranian <eranian@google.com>
      Link: https://lore.kernel.org/lkml/20230303231133.1486085-1-eranian@google.com/
      Link: https://lore.kernel.org/lkml/alpine.LFD.2.01.0908011214330.3304@localhost.localdomain/Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
      Tested-by: default avatarTony Luck <tony.luck@intel.com>
      Tested-by: default avatarStephane Eranian <eranian@google.com>
      Tested-by: default avatarBabu Moger <babu.moger@amd.com>
      Cc: stable@kernel.org
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7fef0997
  4. 07 Mar, 2023 11 commits
  5. 06 Mar, 2023 8 commits
  6. 05 Mar, 2023 4 commits
    • Linus Torvalds's avatar
      Linux 6.3-rc1 · fe15c26e
      Linus Torvalds authored
      fe15c26e
    • Linus Torvalds's avatar
      cpumask: re-introduce constant-sized cpumask optimizations · 596ff4a0
      Linus Torvalds authored
      Commit aa47a7c2 ("lib/cpumask: deprecate nr_cpumask_bits") resulted
      in the cpumask operations potentially becoming hugely less efficient,
      because suddenly the cpumask was always considered to be variable-sized.
      
      The optimization was then later added back in a limited form by commit
      6f9c07be ("lib/cpumask: add FORCE_NR_CPUS config option"), but that
      FORCE_NR_CPUS option is not useful in a generic kernel and more of a
      special case for embedded situations with fixed hardware.
      
      Instead, just re-introduce the optimization, with some changes.
      
      Instead of depending on CPUMASK_OFFSTACK being false, and then always
      using the full constant cpumask width, this introduces three different
      cpumask "sizes":
      
       - the exact size (nr_cpumask_bits) remains identical to nr_cpu_ids.
      
         This is used for situations where we should use the exact size.
      
       - the "small" size (small_cpumask_bits) is the NR_CPUS constant if it
         fits in a single word and the bitmap operations thus end up able
         to trigger the "small_const_nbits()" optimizations.
      
         This is used for the operations that have optimized single-word
         cases that get inlined, notably the bit find and scanning functions.
      
       - the "large" size (large_cpumask_bits) is the NR_CPUS constant if it
         is an sufficiently small constant that makes simple "copy" and
         "clear" operations more efficient.
      
         This is arbitrarily set at four words or less.
      
      As a an example of this situation, without this fixed size optimization,
      cpumask_clear() will generate code like
      
              movl    nr_cpu_ids(%rip), %edx
              addq    $63, %rdx
              shrq    $3, %rdx
              andl    $-8, %edx
              callq   memset@PLT
      
      on x86-64, because it would calculate the "exact" number of longwords
      that need to be cleared.
      
      In contrast, with this patch, using a MAX_CPU of 64 (which is quite a
      reasonable value to use), the above becomes a single
      
      	movq $0,cpumask
      
      instruction instead, because instead of caring to figure out exactly how
      many CPU's the system has, it just knows that the cpumask will be a
      single word and can just clear it all.
      
      Note that this does end up tightening the rules a bit from the original
      version in another way: operations that set bits in the cpumask are now
      limited to the actual nr_cpu_ids limit, whereas we used to do the
      nr_cpumask_bits thing almost everywhere in the cpumask code.
      
      But if you just clear bits, or scan for bits, we can use the simpler
      compile-time constants.
      
      In the process, remove 'cpumask_complement()' and 'for_each_cpu_not()'
      which were not useful, and which fundamentally have to be limited to
      'nr_cpu_ids'.  Better remove them now than have somebody introduce use
      of them later.
      
      Of course, on x86-64 with MAXSMP there is no sane small compile-time
      constant for the cpumask sizes, and we end up using the actual CPU bits,
      and will generate the above kind of horrors regardless.  Please don't
      use MAXSMP unless you really expect to have machines with thousands of
      cores.
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      596ff4a0
    • Linus Torvalds's avatar
      Merge tag 'v6.3-p2' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 · f915322f
      Linus Torvalds authored
      Pull crypto fix from Herbert Xu:
       "Fix a regression in the caam driver"
      
      * tag 'v6.3-p2' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
        crypto: caam - Fix edesc/iv ordering mixup
      f915322f
    • Linus Torvalds's avatar
      Merge tag 'x86-urgent-2023-03-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 7f9ec7d8
      Linus Torvalds authored
      Pull x86 updates from Thomas Gleixner:
       "A small set of updates for x86:
      
         - Return -EIO instead of success when the certificate buffer for SEV
           guests is not large enough
      
         - Allow STIPB to be enabled with legacy IBSR. Legacy IBRS is cleared
           on return to userspace for performance reasons, but the leaves user
           space vulnerable to cross-thread attacks which STIBP prevents.
           Update the documentation accordingly"
      
      * tag 'x86-urgent-2023-03-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        virt/sev-guest: Return -EIO if certificate buffer is not large enough
        Documentation/hw-vuln: Document the interaction between IBRS and STIBP
        x86/speculation: Allow enabling STIBP with legacy IBRS
      7f9ec7d8