[Bug 48989] Riot Vanguard (Riot Games) 'vgk.sys' crashes on unimplemented function ntoskrnl.exe.KeIpiGenericCall

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=48989

--- Comment #1 from Anastasius Focht <focht at gmx.net> ---
Hello folks,

small addendum...

I propose to keep it as stub for now, that is not calling the supplied
'BroadcastFunction'.

--- snip ---
001b:fixme:ntoskrnl:KeIpiGenericCall stub: 0000000000D61D74 0000000000000000
--- snip ---

It's used as one of many anti-debugging measures:

--- snip ---
0000000000D61D74 | 48:83EC 28       | sub rsp,28       |
0000000000D61D78 | 33C9             | xor ecx,ecx      |
0000000000D61D7A | E9 2A3A2E00      | jmp vgk.10457A9  |
...
00000000010457A9 | 90               | nop              |
00000000010457AA | E9 00000000      | jmp vgk.10457AF  |
00000000010457AF | FA               | cli              |
00000000010457B0 | 41:81F8 934FCB45 | cmp r8d,45CB4F93 |
00000000010457B7 | 6644:3BD9        | cmp r11w,cx      |
00000000010457BB | F9               | stc              |
00000000010457BC | 33C0             | xor eax,eax      |
00000000010457BE | E9 00000000      | jmp vgk.10457C3  |
00000000010457C3 | 0F23F8           | mov dr7,rax      | zap debug control
00000000010457C6 | E9 00000000      | jmp vgk.10457CB  |
00000000010457CB | FB               | sti              |
00000000010457CC | F5               | cmc              |
00000000010457CD | F8               | clc              |
00000000010457CE | 48:83C4 28       | add rsp,28       |
00000000010457D2 | E9 00000000      | jmp vgk.10457D7  |
00000000010457D7 | C3               | ret              |
--- snip ---

It zeros out dr7 (debug control) in attempt to prevent hw breakpoints.

Although such measures can be defeated why not avoiding the trouble in first
place.

Regards

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