1. 10 Nov, 2015 1 commit
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  3. 06 Nov, 2015 3 commits
  4. 05 Nov, 2015 1 commit
    • Lorenzo Pieralisi's avatar
      arm64: cmpxchg_dbl: fix return value type · 57a65667
      Lorenzo Pieralisi authored
      The current arm64 __cmpxchg_double{_mb} implementations carry out the
      compare exchange by first comparing the old values passed in to the
      values read from the pointer provided and by stashing the cumulative
      bitwise difference in a 64-bit register.
      
      By comparing the register content against 0, it is possible to detect if
      the values read differ from the old values passed in, so that the compare
      exchange detects whether it has to bail out or carry on completing the
      operation with the exchange.
      
      Given the current implementation, to detect the cmpxchg operation
      status, the __cmpxchg_double{_mb} functions should return the 64-bit
      stashed bitwise difference so that the caller can detect cmpxchg failure
      by comparing the return value content against 0. The current implementation
      declares the return value as an int, which means that the 64-bit
      value stashing the bitwise difference is truncated before being
      returned to the __cmpxchg_double{_mb} callers, which means that
      any bitwise difference present in the top 32 bits goes undetected,
      triggering false positives and subsequent kernel failures.
      
      This patch fixes the issue by declaring the arm64 __cmpxchg_double{_mb}
      return values as a long, so that the bitwise difference is
      properly propagated on failure, restoring the expected behaviour.
      
      Fixes: e9a4b795 ("arm64: cmpxchg_dbl: patch in lse instructions when supported by the CPU")
      Cc: <stable@vger.kernel.org> # 4.3+
      Cc: Marc Zyngier <marc.zyngier@arm.com>
      Acked-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
      Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      57a65667
  5. 02 Nov, 2015 1 commit
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