MdePkg/Library/BaseLib/X64/RdRand.nasm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
   4 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   5 ;
   6 ; Module Name:
   7 ;
   8 ;   RdRand.nasm
   9 ;
  10 ; Abstract:
  11 ;
  12 ;   Generates random number through CPU RdRand instruction under 64-bit platform.
  13 ;
  14 ; Notes:
  15 ;
  16 ;------------------------------------------------------------------------------
  17
  18     DEFAULT REL
  19     SECTION .text
  20
  21 ;------------------------------------------------------------------------------
  22 ;  Generates a 16 bit random number through RDRAND instruction.
  23 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  24 ;
  25 ;  BOOLEAN EFIAPI InternalX86RdRand16 (UINT16 *Rand);
  26 ;------------------------------------------------------------------------------
  27 global ASM_PFX(InternalX86RdRand16)
  28 ASM_PFX(InternalX86RdRand16):
  29     ; rdrand   ax                  ; generate a 16 bit RN into eax,
  30                                    ; CF=1 if RN generated ok, otherwise CF=0
  31     db     0xf, 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    [rcx], ax
  37     mov    rax,  1
  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 InternalX86RdRand32 (UINT32 *Rand);
  45 ;------------------------------------------------------------------------------
  46 global ASM_PFX(InternalX86RdRand32)
  47 ASM_PFX(InternalX86RdRand32):
  48     ; rdrand   eax                 ; generate a 32 bit RN into eax,
  49                                    ; CF=1 if RN generated ok, otherwise CF=0
  50     db     0xf, 0xc7, 0xf0         ; rdrand r32: "0f c7 /6  ModRM:r/m(w)"
  51     jc     rn32_ok                 ; jmp if CF=1
  52     xor    rax, rax                ; reg=0 if CF=0
  53     ret                            ; return with failure status
  54 rn32_ok:
  55     mov    [rcx], eax
  56     mov    rax,  1
  57     ret
  58
  59 ;------------------------------------------------------------------------------
  60 ;  Generates a 64 bit random number through one RDRAND instruction.
  61 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  62 ;
  63 ;  BOOLEAN EFIAPI InternalX86RdRand64 (UINT64 *Random);
  64 ;------------------------------------------------------------------------------
  65 global ASM_PFX(InternalX86RdRand64)
  66 ASM_PFX(InternalX86RdRand64):
  67     ; rdrand   rax                 ; generate a 64 bit RN into rax,
  68                                    ; CF=1 if RN generated ok, otherwise CF=0
  69     db     0x48, 0xf, 0xc7, 0xf0   ; rdrand r64: "REX.W + 0f c7 /6 ModRM:r/m(w)"
  70     jc     rn64_ok                 ; jmp if CF=1
  71     xor    rax, rax                ; reg=0 if CF=0
  72     ret                            ; return with failure status
  73 rn64_ok:
  74     mov    [rcx], rax
  75     mov    rax, 1
  76     ret
  77