1. 22 Apr, 2014 37 commits
  2. 16 Apr, 2014 3 commits
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux · 0f689a33
      Linus Torvalds authored
      Pull s390 patches from Martin Schwidefsky:
       "An update to the oops output with additional information about the
        crash.  The renameat2 system call is enabled.  Two patches in regard
        to the PTR_ERR_OR_ZERO cleanup.  And a bunch of bug fixes"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
        s390/sclp_cmd: replace PTR_RET with PTR_ERR_OR_ZERO
        s390/sclp: replace PTR_RET with PTR_ERR_OR_ZERO
        s390/sclp_vt220: Fix kernel panic due to early terminal input
        s390/compat: fix typo
        s390/uaccess: fix possible register corruption in strnlen_user_srst()
        s390: add 31 bit warning message
        s390: wire up sys_renameat2
        s390: show_registers() should not map user space addresses to kernel symbols
        s390/mm: print control registers and page table walk on crash
        s390/smp: fix smp_stop_cpu() for !CONFIG_SMP
        s390: fix control register update
      0f689a33
    • Linus Torvalds's avatar
      Merge tag 'please-pull-ia64-erratum' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux · 7d38cc02
      Linus Torvalds authored
      Pull itanium erratum fix from Tony Luck:
       "Small workaround for a rare, but annoying, erratum #237"
      
      * tag 'please-pull-ia64-erratum' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
        [IA64] Change default PSR.ac from '1' to '0' (Fix erratum #237)
      7d38cc02
    • Tony Luck's avatar
      [IA64] Change default PSR.ac from '1' to '0' (Fix erratum #237) · c0b5a64d
      Tony Luck authored
      April 2014 Itanium processor specification update:
      
      http://www.intel.com/content/www/us/en/processors/itanium/itanium-specification-update.html
      
      describes this erratum:
      
      =========================================================================
      237. Under a complex set of conditions, store to load forwarding for a
      sub 8-byte load may complete incorrectly
      
      Problem: A load instruction may complete incorrectly when a code sequence
      using 4-byte or smaller load and store operations to the same address
      is executed in combination with specific timing of all the following
      concurrent conditions: store to load forwarding, alignment checking
      enabled, a mis-predicted branch, and complex cache utilization activity.
      
      Implication: The affected sub 8-byte instruction may complete
      incorrectly resulting in unpredictable system behavior. There is an
      extremely low probability of exposure due to the significant number of
      complex microarchitectural concurrent conditions required to encounter
      the erratum.
      
      Workaround: Set PSR.ac = 0 to completely avoid the erratum. Disabling
      Hyper-Threading will significantly reduce exposure to the conditions
      that contribute to encountering the erratum.
      
      Status: See the Summary Table of Changes for the affected steppings.
      =========================================================================
      
      [Table of changes essentially lists all models from McKinley to Tukwila]
      
      The PSR.ac bit controls whether the processor will always generate
      an unaligned reference trap (0x5a00) for a misaligned data access
      (when PSR.ac=1) or if it will let the access succeed when running
      on a cpu that implements logic to handle some unaligned accesses.
      
      Way back in 2008 in commit b704882e
        [IA64] Rationalize kernel mode alignment checking
      we made the decision to always enable strict checking. We were
      already doing so in trap/interrupt context because the common
      preamble code set this bit - but the rest of supervisor code
      (and by inheritance user code) ran with PSR.ac=0.
      
      We now reverse that decision and set PSR.ac=0 everywhere in the
      kernel (also inherited by user processes). This will avoid the
      erratum using the method described in the Itanium specification
      update.  Net effect for users is that the processor will handle
      unaligned access when it can (typically with a tiny performance
      bubble in the pipeline ... but much less invasive than taking a
      trap and having the OS perform the access).
      Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
      c0b5a64d