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Source code

AESDECWIDE256KL

Perform 14 Rounds of AES Decryption Flow With Key Locker on 8 Blocks

stableVMJITAOTinstruction

Encodings

OpcodeInstructionOp/En64-bitCompat/LegacyDescription
F3 0F 38 D8 !(11):011:bbbAESDECWIDE256KL m512, <XMM0-7>AValidValidDecrypt XMM0-7 using 256-bit AES key indicated by handle at m512 and store each resultant block back to its corresponding register.

Operand encoding

Each mode is a value of the Op/En column above. It says which field of the encoded instruction carries each operand, in the order they are written, and whether the instruction reads it, writes it or both.

A

  1. modrm.rm lecturaModRM byte, r/m field (bits 2-0); with the SIB byte and the displacement when the mod field asks for them
  2. XMM0-7 lectura y escritura

Measured cost

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Flags named

Description

The AESDECWIDE256KL1 instruction performs 14 rounds of AES to decrypt each of the eight blocks in XMM0-7 using the 256-bit key indicated by the handle from the second operand. It replaces each input block in XMM0-7 with its corresponding decrypted block if the operation succeeds (e.g., does not run into a handle violation failure).

Operation

AESDECWIDE256KL
Handle := UnalignedLoad of 512 bit (SRC); // Load is not guaranteed to be atomic.
Illegal Handle = (HandleReservedBitSet (Handle) ||

                      (Handle[0] AND (CPL > 0)) ||
                      Handle [2] ||
                      HandleKeyType (Handle) != HANDLE_KEY_TYPE_AES256);
IF (Illegal Handle) {
    THEN RFLAGS.ZF := 1;
    ELSE
          (UnwrappedKey, Authentic) := UnwrapKeyAndAuthenticate512 (Handle[511:0], IWKey);
          IF (Authentic == 0)
                THEN RFLAGS.ZF := 1;
                ELSE
                      XMM0 := AES256Decrypt (XMM0, UnwrappedKey) ;
                      XMM1 := AES256Decrypt (XMM1, UnwrappedKey) ;
                      XMM2 := AES256Decrypt (XMM2, UnwrappedKey) ;
                      XMM3 := AES256Decrypt (XMM3, UnwrappedKey) ;
                      XMM4 := AES256Decrypt (XMM4, UnwrappedKey) ;
                      XMM5 := AES256Decrypt (XMM5, UnwrappedKey) ;
                      XMM6 := AES256Decrypt (XMM6, UnwrappedKey) ;
                      XMM7 := AES256Decrypt (XMM7, UnwrappedKey) ;
                      RFLAGS.ZF := 0;
          FI;
FI;
RFLAGS.OF, SF, AF, PF, CF := 0;

Flags affected

ZF is set to 0 if the operation succeeded and set to 1 if the operation failed due to a handle violation. The other arithmetic flags (OF, SF, AF, PF, CF) are cleared to 0.

  1. Further details on Key Locker and usage of this instruction can be found here: https://software.intel.com/content/www/us/en/develop/download/intel-key-locker-specification.html.

Intel C/C++ compiler intrinsics

AESDECWIDE256KLunsigned char _mm_aesdecwide256kl_u8(__m128i odata[8], const __m128i idata[8], const void* h);

Exceptions

Real address mode
#UDIf the LOCK prefix is used. If CPUID.07H.00H:ECX.KEY_LOCKER[23] = 0. If CR4.KL = 0. If CPUID.19H:EBX.AESKLE[0] = 0. If CR0.EM = 1. If CR4.OSFXSR = 0. If CPUID.19H:EBX.AES_WIDE[2] = 0.
#NMIf CR0.TS = 1.
#PFIf a page fault occurs.
#GP(0)If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register is used to access memory and it contains a NULL segment selector. If the memory address is in a non-canonical form.
#SS(0)If a memory operand effective address is outside the SS segment limit. If a memory address referencing the SS segment is in a non-canonical form.
Protected mode
#UDIf the LOCK prefix is used. If CPUID.07H.00H:ECX.KEY_LOCKER[23] = 0. If CR4.KL = 0. If CPUID.19H:EBX.AESKLE[0] = 0. If CR0.EM = 1. If CR4.OSFXSR = 0. If CPUID.19H:EBX.AES_WIDE[2] = 0.
#NMIf CR0.TS = 1.
#PFIf a page fault occurs.
#GP(0)If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register is used to access memory and it contains a NULL segment selector. If the memory address is in a non-canonical form.
#SS(0)If a memory operand effective address is outside the SS segment limit. If a memory address referencing the SS segment is in a non-canonical form.
Virtual-8086 mode
#UDIf the LOCK prefix is used. If CPUID.07H.00H:ECX.KEY_LOCKER[23] = 0. If CR4.KL = 0. If CPUID.19H:EBX.AESKLE[0] = 0. If CR0.EM = 1. If CR4.OSFXSR = 0. If CPUID.19H:EBX.AES_WIDE[2] = 0.
#NMIf CR0.TS = 1.
#PFIf a page fault occurs.
#GP(0)If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register is used to access memory and it contains a NULL segment selector. If the memory address is in a non-canonical form.
#SS(0)If a memory operand effective address is outside the SS segment limit. If a memory address referencing the SS segment is in a non-canonical form.
Compatibility mode
#UDIf the LOCK prefix is used. If CPUID.07H.00H:ECX.KEY_LOCKER[23] = 0. If CR4.KL = 0. If CPUID.19H:EBX.AESKLE[0] = 0. If CR0.EM = 1. If CR4.OSFXSR = 0. If CPUID.19H:EBX.AES_WIDE[2] = 0.
#NMIf CR0.TS = 1.
#PFIf a page fault occurs.
#GP(0)If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register is used to access memory and it contains a NULL segment selector. If the memory address is in a non-canonical form.
#SS(0)If a memory operand effective address is outside the SS segment limit. If a memory address referencing the SS segment is in a non-canonical form.
64-bit mode
#UDIf the LOCK prefix is used. If CPUID.07H.00H:ECX.KEY_LOCKER[23] = 0. If CR4.KL = 0. If CPUID.19H:EBX.AESKLE[0] = 0. If CR0.EM = 1. If CR4.OSFXSR = 0. If CPUID.19H:EBX.AES_WIDE[2] = 0.
#NMIf CR0.TS = 1.
#PFIf a page fault occurs.
#GP(0)If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register is used to access memory and it contains a NULL segment selector. If the memory address is in a non-canonical form.
#SS(0)If a memory operand effective address is outside the SS segment limit. If a memory address referencing the SS segment is in a non-canonical form.

Sources