MdePkg/Library/BaseLib/Ia32/ReadMsr64.c

   1 /** @file
   2   AsmReadMsr64 function
   3
   4   Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9
  10
  11
  12 /**
  13   Returns a 64-bit Machine Specific Register(MSR).
  14
  15   Reads and returns the 64-bit MSR specified by Index. No parameter checking is
  16   performed on Index, and some Index values may cause CPU exceptions. The
  17   caller must either guarantee that Index is valid, or the caller must set up
  18   exception handlers to catch the exceptions. This function is only available
  19   on IA-32 and x64.
  20
  21   @param  Index The 32-bit MSR index to read.
  22
  23   @return The value of the MSR identified by Index.
  24
  25 **/
  26 UINT64
  27 EFIAPI
  28 AsmReadMsr64 (
  29   IN UINT32  Index
  30   )
  31 {
  32   _asm {
  33     mov     ecx, Index
  34     rdmsr
  35   }
  36 }
  37