1. Jul 04, 2014
    • Tejun Heo's avatar
      ptrace,x86: force IRET path after a ptrace_stop() · b9cd18de
      Tejun Heo authored
      
      
      The 'sysret' fastpath does not correctly restore even all regular
      registers, much less any segment registers or reflags values.  That is
      very much part of why it's faster than 'iret'.
      
      Normally that isn't a problem, because the normal ptrace() interface
      catches the process using the signal handler infrastructure, which
      always returns with an iret.
      
      However, some paths can get caught using ptrace_event() instead of the
      signal path, and for those we need to make sure that we aren't going to
      return to user space using 'sysret'.  Otherwise the modifications that
      may have been done to the register set by the tracer wouldn't
      necessarily take effect.
      
      Fix it by forcing IRET path by setting TIF_NOTIFY_RESUME from
      arch_ptrace_stop_needed() which is invoked from ptrace_stop().
      
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Reported-by: default avatarAndy Lutomirski <luto@amacapital.net>
      Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
      Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b9cd18de
  2. Jun 30, 2014
  3. Jun 25, 2014
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  5. Jun 21, 2014
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  13. Jun 09, 2014
  14. Jun 08, 2014
    • Matt Fleming's avatar
      x86/boot: EFI_MIXED should not prohibit loading above 4G · 745c5167
      Matt Fleming authored
      commit 7d453eee ("x86/efi: Wire up CONFIG_EFI_MIXED") introduced a
      regression for the functionality to load kernels above 4G. The relevant
      (incorrect) reasoning behind this change can be seen in the commit
      message,
      
        "The xloadflags field in the bzImage header is also updated to reflect
        that the kernel supports both entry points by setting both of
        XLF_EFI_HANDOVER_32 and XLF_EFI_HANDOVER_64 when CONFIG_EFI_MIXED=y.
        XLF_CAN_BE_LOADED_ABOVE_4G is disabled so that the kernel text is
        guaranteed to be addressable with 32-bits."
      
      This is obviously bogus since 32-bit EFI loaders will never place the
      kernel above the 4G mark. So this restriction is entirely unnecessary.
      
      But things are worse than that - since we want to encourage people to
      always compile with CONFIG_EFI_MIXED=y so that their kernels work out of
      the box for both 32-bit and 64-bit firmware, commit 7d453eee
      
      
      effectively disables XLF_CAN_BE_LOADED_ABOVE_4G completely.
      
      Remove the overzealous and superfluous restriction and restore the
      XLF_CAN_BE_LOADED_ABOVE_4G functionality.
      
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Dave Young <dyoung@redhat.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
      Link: http://lkml.kernel.org/r/1402140380-15377-1-git-send-email-matt@console-pimps.org
      
      
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
      745c5167
  15. Jun 07, 2014
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