MdePkg/Library/BaseLib/X64/RdRand.nasm

   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.nasm
  15 ;
  16 ; Abstract:
  17 ;
  18 ;   Generates random number through CPU RdRand instruction under 64-bit platform.
  19 ;
  20 ; Notes:
  21 ;
  22 ;------------------------------------------------------------------------------
  23
  24     DEFAULT REL
  25     SECTION .text
  26
  27 ;------------------------------------------------------------------------------
  28 ;  Generates a 16 bit random number through RDRAND instruction.
  29 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  30 ;
  31 ;  BOOLEAN EFIAPI InternalX86RdRand16 (UINT16 *Rand);
  32 ;------------------------------------------------------------------------------
  33 global ASM_PFX(InternalX86RdRand16)
  34 ASM_PFX(InternalX86RdRand16):
  35     ; rdrand   ax                  ; generate a 16 bit RN into eax,
  36                                    ; CF=1 if RN generated ok, otherwise CF=0
  37     db     0xf, 0xc7, 0xf0         ; rdrand r16: "0f c7 /6  ModRM:r/m(w)"
  38     jc     rn16_ok                 ; jmp if CF=1
  39     xor    rax, rax                ; reg=0 if CF=0
  40     ret                            ; return with failure status
  41 rn16_ok:
  42     mov    [rcx], ax
  43     mov    rax,  1
  44     ret
  45
  46 ;------------------------------------------------------------------------------
  47 ;  Generates a 32 bit random number through RDRAND instruction.
  48 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  49 ;
  50 ;  BOOLEAN EFIAPI InternalX86RdRand32 (UINT32 *Rand);
  51 ;------------------------------------------------------------------------------
  52 global ASM_PFX(InternalX86RdRand32)
  53 ASM_PFX(InternalX86RdRand32):
  54     ; rdrand   eax                 ; generate a 32 bit RN into eax,
  55                                    ; CF=1 if RN generated ok, otherwise CF=0
  56     db     0xf, 0xc7, 0xf0         ; rdrand r32: "0f c7 /6  ModRM:r/m(w)"
  57     jc     rn32_ok                 ; jmp if CF=1
  58     xor    rax, rax                ; reg=0 if CF=0
  59     ret                            ; return with failure status
  60 rn32_ok:
  61     mov    [rcx], eax
  62     mov    rax,  1
  63     ret
  64
  65 ;------------------------------------------------------------------------------
  66 ;  Generates a 64 bit random number through one RDRAND instruction.
  67 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  68 ;
  69 ;  BOOLEAN EFIAPI InternalX86RdRand64 (UINT64 *Random);
  70 ;------------------------------------------------------------------------------
  71 global ASM_PFX(InternalX86RdRand64)
  72 ASM_PFX(InternalX86RdRand64):
  73     ; rdrand   rax                 ; generate a 64 bit RN into rax,
  74                                    ; CF=1 if RN generated ok, otherwise CF=0
  75     db     0x48, 0xf, 0xc7, 0xf0   ; rdrand r64: "REX.W + 0f c7 /6 ModRM:r/m(w)"
  76     jc     rn64_ok                 ; jmp if CF=1
  77     xor    rax, rax                ; reg=0 if CF=0
  78     ret                            ; return with failure status
  79 rn64_ok:
  80     mov    [rcx], rax
  81     mov    rax, 1
  82     ret
  83