PTWRITE - Write Data to a Processor Trace Packet

Opcode/

Op/

64/32 bit

CPUID

Description

Instruction En Mode Support Feature Flag
F3 REX.W 0F AE /4 PTWRITE r64/m64 RM V/N.E Reads the data from r64/m64 to encode into a PTW packet if dependencies are met (see details below).
F3 0F AE /4 PTWRITE r32/m32 RM V/V Reads the data from r32/m32 to encode into a PTW packet if dependencies are met (see details below).

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RM ModRM:rm (r) NA NA NA

Description

This instruction reads data in the source operand and sends it to the Intel Processor Trace hardware to be encoded in a PTW packet if TriggerEn, ContextEn, FilterEn, and PTWEn are all set to 1. For more details on these values, see Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3C, Section 31.2.2, “Software Trace Instrumentation with PTWRITE”. The size of data is 64-bit if using REX.W in 64-bit mode, otherwise 32-bits of data are copied from the source operand.

Note: The instruction will #UD if prefix 66H is used.

Operation

IF (IA32_RTIT_STATUS.TriggerEn & IA32_RTIT_STATUS.ContextEn & IA32_RTIT_STATUS.FilterEn & IA32_RTIT_CTL.PTWEn) = 1
    PTW.PayloadBytes := Encoded payload size;
    PTW.IP := IA32_RTIT_CTL.FUPonPTW
    IF IA32_RTIT_CTL.FUPonPTW = 1
         Insert FUP packet with IP of PTWRITE;
    FI;
FI;

Flags Affected

None.

Other Exceptions

#GP(0) If a memory operand effective address is outside the CS, DS, ES, FS or GS segments.
#SS(0) If a memory operand effective address is outside the SS segment limit.
#PF (fault-code) For a page fault.
#AC(0) If an unaligned memory reference is made while the current privilege level is 3 and alignment checking is enabled.
#UD

If CPUID.(EAX=14H, ECX=0):EBX.PTWRITE [Bit 4] = 0.

If LOCK prefix is used.

If 66H prefix is used.

Real-Address Mode Exceptions

#GP(0) If any part of the operand lies outside of the effective address space from 0 to 0FFFFH.
#SS(0) If a memory operand effective address is outside the SS segment limit.
#UD

If CPUID.(EAX=14H, ECX=0):EBX.PTWRITE [Bit 4] = 0.

If LOCK prefix is used.

If 66H prefix is used.

Virtual 8086 Mode Exceptions

#GP(0) If any part of the operand lies outside of the effective address space from 0 to 0FFFFH.
#SS(0) If a memory operand effective address is outside the SS segment limit.
#PF (fault-code) For a page fault.
#AC(0) If an unaligned memory reference is made while alignment checking is enabled.
#UD

If CPUID.(EAX=14H, ECX=0):EBX.PTWRITE [Bit 4] = 0.

If LOCK prefix is used.

If 66H prefix is used.

Compatibility Mode Exceptions

Same exceptions as in Protected Mode.

64-Bit Mode Exceptions

#GP(0) If the memory address is in a non-canonical form.
#SS(0) If a memory address referencing the SS segment is in a non-canonical form.
#PF (fault-code) For a page fault.
#AC(0) If alignment checking is enabled and an unaligned memory reference is made while the current privilege level is 3.
#UD

If CPUID.(EAX=14H, ECX=0):EBX.PTWRITE [Bit 4] = 0.

If LOCK prefix is used.

If 66H prefix is used.