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Add the following CET instructions to the opcode map:

  INCSSP:
      Increment Shadow Stack pointer (SSP).

  RDSSP:
      Read SSP into a GPR.

  SAVEPREVSSP:
      Use "previous ssp" token at top of current Shadow Stack (SHSTK) to
      create a "restore token" on the previous (outgoing) SHSTK.

  RSTORSSP:
      Restore from a "restore token" to SSP.

  WRSS:
      Write to kernel-mode SHSTK (kernel-mode instruction).

  WRUSS:
      Write to user-mode SHSTK (kernel-mode instruction).

  SETSSBSY:
      Verify the "supervisor token" pointed by MSR_IA32_PL0_SSP, set the
      token busy, and set then Shadow Stack pointer(SSP) to the value of
      MSR_IA32_PL0_SSP.

  CLRSSBSY:
      Verify the "supervisor token" and clear its busy bit.

  ENDBR64/ENDBR32:
      Mark a valid 64/32 bit control transfer endpoint.

Detailed information of CET instructions can be found in Intel Software
Developer's Manual.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi v. Shankar <ravi.v.shankar@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: http://lore.kernel.org/lkml/20200204171425.28073-2-yu-cheng.yu@intel.com

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>