1. 23 May, 2018 1 commit
  2. 18 Jan, 2018 1 commit
    • Dimitris Papastamos's avatar
      sp_min: Implement workaround for CVE-2017-5715 · 7343505d
      Dimitris Papastamos authored
      
      
      This patch introduces two workarounds for ARMv7 systems.  The
      workarounds need to be applied prior to any `branch` instruction in
      secure world.  This is achieved using a custom vector table where each
      entry is an `add sp, sp, #1` instruction.
      
      On entry to monitor mode, once the sequence of `ADD` instructions is
      executed, the branch target buffer (BTB) is invalidated.  The bottom
      bits of `SP` are then used to decode the exception entry type.
      
      A side effect of this change is that the exception vectors are
      installed before the CPU specific reset function.  This is now
      consistent with how it is done on AArch64.
      
      Note, on AArch32 systems, the exception vectors are typically tightly
      integrated with the secure payload (e.g. the Trusted OS).  This
      workaround will need porting to each secure payload that requires it.
      
      The patch to modify the AArch32 per-cpu vbar to the corresponding
      workaround vector table according to the CPU type will be done in a
      later patch.
      
      Change-Id: I5786872497d359e496ebe0757e8017fa98f753fa
      Signed-off-by: default avatarDimitris Papastamos <dimitris.papastamos@arm.com>
      7343505d