MdePkg/Library/BaseLib/X64/RdRand.S

   1 #------------------------------------------------------------------------------ ;
   2 # Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>
   3 # This program and the accompanying materials
   4 # are licensed and made available under the terms and conditions of the BSD License
   5 # which accompanies this distribution.  The full text of the license may be found at
   6 # http://opensource.org/licenses/bsd-license.php.
   7 #
   8 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
   9 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  10 #
  11 # Module Name:
  12 #
  13 #   RdRand.S
  14 #
  15 # Abstract:
  16 #
  17 #   Generates random number through CPU RdRand instruction under 64-bit platform.
  18 #
  19 # Notes:
  20 #
  21 #------------------------------------------------------------------------------
  22
  23 //------------------------------------------------------------------------------
  24 //  Generates a 16 bit random number through RDRAND instruction.
  25 //  Return TRUE if Rand generated successfully, or FALSE if not.
  26 //
  27 //  BOOLEAN EFIAPI AsmRdRand16 (UINT16 *Rand);
  28 //------------------------------------------------------------------------------
  29 ASM_GLOBAL ASM_PFX(AsmRdRand16)
  30 ASM_PFX(AsmRdRand16):
  31     .byte  0x0f, 0xc7, 0xf0        // rdrand r16: "0f c7 /6  ModRM:r/m(w)"
  32     jc     rn16_ok                 // jmp if CF=1
  33     xor    %rax, %rax              // reg=0 if CF=0
  34     ret                            // return with failure status
  35 rn16_ok:
  36     mov    %ax, (%rcx)
  37     mov    $0x1, %rax
  38     ret
  39
  40 //------------------------------------------------------------------------------
  41 //  Generates a 32 bit random number through RDRAND instruction.
  42 //  Return TRUE if Rand generated successfully, or FALSE if not.
  43 //
  44 //  BOOLEAN EFIAPI AsmRdRand32 (UINT32 *Rand);
  45 //------------------------------------------------------------------------------
  46 ASM_GLOBAL ASM_PFX(AsmRdRand32)
  47 ASM_PFX(AsmRdRand32):
  48     .byte  0x0f, 0xc7, 0xf0        // rdrand r32: "0f c7 /6  ModRM:r/m(w)"
  49     jc     rn32_ok                 // jmp if CF=1
  50     xor    %rax, %rax              // reg=0 if CF=0
  51     ret                            // return with failure status
  52 rn32_ok:
  53     mov    %eax, (%rcx)
  54     mov    $0x1, %rax
  55     ret
  56
  57 //------------------------------------------------------------------------------
  58 //  Generates a 64 bit random number through RDRAND instruction.
  59 //  Return TRUE if Rand generated successfully, or FALSE if not.
  60 //
  61 //  BOOLEAN EFIAPI AsmRdRand64 (UINT64 *Rand);
  62 //------------------------------------------------------------------------------
  63 ASM_GLOBAL ASM_PFX(AsmRdRand64)
  64 ASM_PFX(AsmRdRand64):
  65     .byte  0x48, 0x0f, 0xc7, 0xf0  // rdrand r64: "REX.W + 0f c7 /6 ModRM:r/m(w)"
  66     jc     rn64_ok                 // jmp if CF=1
  67     xor    %rax, %rax              // reg=0 if CF=0
  68     ret                            // return with failure status
  69 rn64_ok:
  70     mov    %rax, (%rcx)
  71     mov    $0x1, %rax
  72     ret