Re: Handling page faults in syscalls

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From: Stefan =?UTF-8?B?RMO2c2luZ2Vy?= <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: Handling page faults in syscalls
Date: Tue, 23 Dec 2025 10:18:59 +0300
Message-ID: <5464877.31r3eYUQgx@strix>
In-Reply-To: <[email protected]>
References: <[email protected]>
MIME-Version: 1.0

Am Dienstag, 23. Dezember 2025, 02:12:57 Ostafrikanische Zeit schrieb 
tblodt--- via Wine-devel:

> My guess is these are caught instead of killing the process because that's
> the expected behavior of an NT syscall when you pass a bad pointer to it -
> that a bad dereference of a userspace pointer would be handled and turned
> into returning an fault error code.

Some of the unexpected syscall faults I debugged happened because of 
incorrectly set up host libraries - libGL segfaulting when trying to create a 
context, gnutls or kerberos crashing when trying to load them. Those are not 
necessary for the base functionality of Wine, so we don't want to crash and 
burn due to it.

I don't know if that's the real reason for the silent swallowing of SIGSEGVs. 
It is something to keep in mind though when changing the behavior. I ran into 
cases myself where I wish I had gotten more obvious notifications. The Vulkan 
code has assert(!status) after most calls after basic initialization, which 
will make a syscall sigsegv fatal.

On the other hand, a Windows-side STATUS_ACCESS_VIOLATION also won't print 
anything by default, there are many applications that generate a ton of them 
in their normal operation.

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