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lylcheat Cheater Reputation: 0
Joined: 14 Feb 2009 Posts: 27 Location: Planet 3 Solar System Orion Arm Spiral Galaxy Milky Way
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Posted: Thu May 23, 2019 3:36 am Post subject: Memory With WriteCombine Protection |
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I'm using systinternal's VMMap to list the memory map of a game client.
I notice that some memory regions have the protection attribute WriteCombine.
The msdn page https://docs.microsoft.com/en-us/windows/desktop/Memory/memory-protection-constants has some vague description and i guess that these writecombine pages should be some kind of shared video memory since I am using on-board display chip to play my game.
My question
1) what exactly are these pages with Writecombine protection flag?
2) how do we skip all these Writecombine pages when scanning, just like skipping non-writable pages[/url]
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Dark Byte Site Admin Reputation: 458
Joined: 09 May 2003 Posts: 25295 Location: The netherlands
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Posted: Thu May 23, 2019 4:17 am Post subject: |
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write combine is a paging technique where some caching happens but writes get sent to the hardware immediately
Normally those memoryregions are marked as mem_mapped, and by default CE will skip that
check with memoryview-view-memory regions
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lylcheat Cheater Reputation: 0
Joined: 14 Feb 2009 Posts: 27 Location: Planet 3 Solar System Orion Arm Spiral Galaxy Milky Way
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Posted: Thu May 23, 2019 4:49 am Post subject: |
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Dark Byte wrote: | write combine is a paging technique where some caching happens but writes get sent to the hardware immediately
Normally those memoryregions are marked as mem_mapped, and by default CE will skip that
check with memoryview-view-memory regions |
Look at my printscreen, clearly both private memory MEM_PRIVATE (those in yellow) and sharable MEM_MAPPED (those in white, i.e. mem_mapped memory which are backed by paging file) can be Writecombine (it is a memory protection attribute not memory type). So skipping MEM_MAPPED seems not specific enough.
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Dark Byte Site Admin Reputation: 458
Joined: 09 May 2003 Posts: 25295 Location: The netherlands
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Posted: Thu May 23, 2019 4:56 am Post subject: |
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post a screenshot of CE's memory regions window
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lylcheat Cheater Reputation: 0
Joined: 14 Feb 2009 Posts: 27 Location: Planet 3 Solar System Orion Arm Spiral Galaxy Milky Way
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Posted: Fri May 24, 2019 3:18 am Post subject: |
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Here is a screen shot using mame64 as the client (without anti-cheat issue).
CE doesn't seem to support WriteCombine flag at all. 0x16891000 is the mem page with WriteCombine flag as seen in VMMap, but it it not shown by CE. When scanning this memory page is treated as ordinary committed private page.
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cheat engine memory region print screen |
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