SYSENTER hook

[Mkz]

evaluator,

On an AMD this is what I get (XP SP1):

7FFE0300   8BD4             MOV EDX,ESP
7FFE0302   0F34             SYSENTER
7FFE0304   C3               RETN ; ring0 returns to this line

This is the rest of the code, but it isn't called:

7FFE0305   9C               PUSHFD
7FFE0306   810C24 00010000  OR DWORD PTR SS:[ESP],100
7FFE030D   9D               POPFD
7FFE030E   C3               RETN
7FFE030F   8BD4             MOV EDX,ESP
7FFE0311   0F05             SYSCALL
7FFE0313   C3               RETN
7FFE0314   9C               PUSHFD
7FFE0315   810C24 00010000  OR DWORD PTR SS:[ESP],100
7FFE031C   9D               POPFD
7FFE031D   C3               RETN
7FFE031E   C2 0800          RETN 8

And here's a sample call

77D6E285   B8 41110000      MOV EAX,1141
77D6E28A   BA 0003FE7F      MOV EDX,7FFE0300
77D6E28F   FFD2             CALL EDX
77D6E291   C2 1000          RETN 10

Seems that the same instruction is used as in Intel, not the 0F05 variant...

Here's the cpu info before you say it's a pentium

[ WCPUID Version 3.0g  (c) 1996-2002  By H.Oda! ]

  Processor #1 : AMD Athlon (Model 4) / ...
      Platform : Socket A (Socket 462)
 Vendor String : AuthenticAMD
      CPU Type : Original OEM Processor (0)
        Family : 6  (7)
         Model : 4  (4)
   Stepping ID : 4  (4)
         Brand : ----
          APIC : ----
   Name String : AMD Athlon(tm) Processor

Internal Clock : 1399.32 MHz
    System Bus :  266.54 MHz DDR
  System Clock :  133.27 MHz
    Multiplier :   10.5  

    L1 I-Cache :   64K Byte
    L1 D-Cache :   64K Byte
    L1 T-Cache :  ----
    L1  Cache  :  ----
    L2  Cache  :  256K Byte
    L2  Speed  : 1399.32 MHz (Full)

    MMX   Unit : Supported
    SSE   Unit : Not Supported
   SSE2   Unit : Not Supported
   MMX2   Unit : Supported
  3DNow!  Unit : Supported
  3DNow!+ Unit : Supported