MdePkg/Library/BaseLib/X64/RdRand.asm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
   4 ; This program and the accompanying materials
   5 ; are licensed and made available under the terms and conditions of the BSD License
   6 ; which accompanies this distribution.  The full text of the license may be found at
   7 ; http://opensource.org/licenses/bsd-license.php.
   8 ;
   9 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 ;
  12 ; Module Name:
  13 ;
  14 ;   RdRand.asm
  15 ;
  16 ; Abstract:
  17 ;
  18 ;   Generates random number through CPU RdRand instruction under 64-bit platform.
  19 ;
  20 ; Notes:
  21 ;
  22 ;------------------------------------------------------------------------------
  23
  24     .code
  25
  26 ;------------------------------------------------------------------------------
  27 ;  Generates a 16 bit random number through RDRAND instruction.
  28 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  29 ;
  30 ;  BOOLEAN EFIAPI InternalX86RdRand16 (UINT16 *Rand);
  31 ;------------------------------------------------------------------------------
  32 InternalX86RdRand16  PROC
  33     ; rdrand   ax                  ; generate a 16 bit RN into eax,
  34                                    ; CF=1 if RN generated ok, otherwise CF=0
  35     db     0fh, 0c7h, 0f0h         ; rdrand r16: "0f c7 /6  ModRM:r/m(w)"
  36     jc     rn16_ok                 ; jmp if CF=1
  37     xor    rax, rax                ; reg=0 if CF=0
  38     ret                            ; return with failure status
  39 rn16_ok:
  40     mov    [rcx], ax
  41     mov    rax,  1
  42     ret
  43 InternalX86RdRand16 ENDP
  44
  45 ;------------------------------------------------------------------------------
  46 ;  Generates a 32 bit random number through RDRAND instruction.
  47 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  48 ;
  49 ;  BOOLEAN EFIAPI InternalX86RdRand32 (UINT32 *Rand);
  50 ;------------------------------------------------------------------------------
  51 InternalX86RdRand32  PROC
  52     ; rdrand   eax                 ; generate a 32 bit RN into eax,
  53                                    ; CF=1 if RN generated ok, otherwise CF=0
  54     db     0fh, 0c7h, 0f0h         ; rdrand r32: "0f c7 /6  ModRM:r/m(w)"
  55     jc     rn32_ok                 ; jmp if CF=1
  56     xor    rax, rax                ; reg=0 if CF=0
  57     ret                            ; return with failure status
  58 rn32_ok:
  59     mov    [rcx], eax
  60     mov    rax,  1
  61     ret
  62 InternalX86RdRand32 ENDP
  63
  64 ;------------------------------------------------------------------------------
  65 ;  Generates a 64 bit random number through one RDRAND instruction.
  66 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  67 ;
  68 ;  BOOLEAN EFIAPI InternalX86RdRand64 (UINT64 *Random);
  69 ;------------------------------------------------------------------------------
  70 InternalX86RdRand64  PROC
  71     ; rdrand   rax                 ; generate a 64 bit RN into rax,
  72                                    ; CF=1 if RN generated ok, otherwise CF=0
  73     db     048h, 0fh, 0c7h, 0f0h   ; rdrand r64: "REX.W + 0f c7 /6 ModRM:r/m(w)"
  74     jc     rn64_ok                 ; jmp if CF=1
  75     xor    rax, rax                ; reg=0 if CF=0
  76     ret                            ; return with failure status
  77 rn64_ok:
  78     mov    [rcx], rax
  79     mov    rax, 1
  80     ret
  81 InternalX86RdRand64 ENDP
  82
  83     END