UefiCpuPkg/Library/CpuCommonFeaturesLib/ExecuteDisable.c

   1 /** @file
   2   Execute Disable feature.
   3
   4   Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
   5   This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include "CpuCommonFeatures.h"
  16
  17 /**
  18   Detects if Execute Disable feature supported on current processor.
  19
  20   @param[in]  ProcessorNumber  The index of the CPU executing this function.
  21   @param[in]  CpuInfo          A pointer to the REGISTER_CPU_FEATURE_INFORMATION
  22                                structure for the CPU executing this function.
  23   @param[in]  ConfigData       A pointer to the configuration buffer returned
  24                                by CPU_FEATURE_GET_CONFIG_DATA.  NULL if
  25                                CPU_FEATURE_GET_CONFIG_DATA was not provided in
  26                                RegisterCpuFeature().
  27
  28   @retval TRUE     Execute Disable feature is supported.
  29   @retval FALSE    Execute Disable feature is not supported.
  30
  31   @note This service could be called by BSP/APs.
  32 **/
  33 BOOLEAN
  34 EFIAPI
  35 ExecuteDisableSupport (
  36   IN UINTN                             ProcessorNumber,
  37   IN REGISTER_CPU_FEATURE_INFORMATION  *CpuInfo,
  38   IN VOID                              *ConfigData  OPTIONAL
  39   )
  40 {
  41   UINT32                         Eax;
  42   CPUID_EXTENDED_CPU_SIG_EDX     Edx;
  43
  44   AsmCpuid (CPUID_EXTENDED_FUNCTION, &Eax, NULL, NULL, NULL);
  45   if (Eax <= CPUID_EXTENDED_FUNCTION) {
  46     //
  47     // Extended CPUID functions are not supported on this processor.
  48     //
  49     return FALSE;
  50   }
  51
  52   AsmCpuid (CPUID_EXTENDED_CPU_SIG, NULL, NULL, NULL, &Edx.Uint32);
  53   return (Edx.Bits.NX != 0);
  54 }
  55
  56 /**
  57   Initializes Execute Disable feature to specific state.
  58
  59   @param[in]  ProcessorNumber  The index of the CPU executing this function.
  60   @param[in]  CpuInfo          A pointer to the REGISTER_CPU_FEATURE_INFORMATION
  61                                structure for the CPU executing this function.
  62   @param[in]  ConfigData       A pointer to the configuration buffer returned
  63                                by CPU_FEATURE_GET_CONFIG_DATA.  NULL if
  64                                CPU_FEATURE_GET_CONFIG_DATA was not provided in
  65                                RegisterCpuFeature().
  66   @param[in]  State            If TRUE, then the Execute Disable feature must be enabled.
  67                                If FALSE, then the Execute Disable feature must be disabled.
  68
  69   @retval RETURN_SUCCESS       Execute Disable feature is initialized.
  70
  71   @note This service could be called by BSP only.
  72 **/
  73 RETURN_STATUS
  74 EFIAPI
  75 ExecuteDisableInitialize (
  76   IN UINTN                             ProcessorNumber,
  77   IN REGISTER_CPU_FEATURE_INFORMATION  *CpuInfo,
  78   IN VOID                              *ConfigData,  OPTIONAL
  79   IN BOOLEAN                           State
  80   )
  81 {
  82   //
  83   // The scope of the MSR_IA32_EFER is core for below processor type, only program
  84   // MSR_IA32_EFER for thread 0 in each core.
  85   //
  86   if (IS_SILVERMONT_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel)) {
  87     if (CpuInfo->ProcessorInfo.Location.Thread != 0) {
  88       return RETURN_SUCCESS;
  89     }
  90   }
  91
  92   CPU_REGISTER_TABLE_WRITE_FIELD (
  93     ProcessorNumber,
  94     Msr,
  95     MSR_IA32_EFER,
  96     MSR_IA32_EFER_REGISTER,
  97     Bits.NXE,
  98     (State) ? 1 : 0
  99     );
 100   return RETURN_SUCCESS;
 101 }