Re: [ros-dev] [ros-diffs] [sginsberg] 56333: - Even while I love having the trap/fpu/context code in C, the bugs this switch introduced continue to amaze me. This time, fix a bug from 45156 when KiFlushNPXState was rewritte...

[Aleksey Bragin]

That was a nice catch!

07.04.2012 0:13, sginsberg(a)svn.reactos.org пишет:
>   Author: sginsberg
>  Date: Fri Apr  6 20:13:33 2012
>  New Revision: 56333
>
>  URL: http://svn.reactos.org/svn/reactos?rev=56333&view=rev
>  Log:
>  - Even while I love having the trap/fpu/context code in C, the bugs this switch
> introduced continue to amaze me. This time, fix a bug from 45156 when KiFlushNPXState was
> rewritten in C. The C version could miss to restore the interrupt state, which would lead
> to interrupts being disabled when it was not expected. This "interrupt leak" was
> seen in the page fault handler if a page fault occurred after interrupts had been disabled
> (which had sometimes been observed to occur on the test server during exception handling
> and thread creation when KiFlushNPXState had been called). This didn't completely hang
> the system because during thread creation (and other system calls where this may have
> happened) interrupts would be re-enabled when returning to user mode when restoring
> eflags, and the exception handling would result in a system call which would enable
> interrupts again (it appears exception handler would have run with interrupts disabled,
> though!). This is now fixed, as well as any other issues this might have caused. The hack
> in the page fault handler remains until another issue has been fixed.
>
>  Modified:
>       trunk/reactos/ntoskrnl/ke/i386/cpu.c
>
>  Modified: trunk/reactos/ntoskrnl/ke/i386/cpu.c
>  URL:
> http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/ke/i386/cpu.c?rev…
>  ==============================================================================
>  --- trunk/reactos/ntoskrnl/ke/i386/cpu.c [iso-8859-1] (original)
>  +++ trunk/reactos/ntoskrnl/ke/i386/cpu.c [iso-8859-1] Fri Apr  6 20:13:33 2012
>  @@ -1323,7 +1323,12 @@
>        if (Thread->NpxState != NPX_STATE_LOADED)
>        {
>            /* If there's nothing to load, quit */
>  -        if (!SaveArea) return;
>  +        if (!SaveArea)
>  +        {
>  +            /* Restore interrupt state and return */
>  +            __writeeflags(EFlags);
>  +            return;
>  +        }
>
>            /* Need FXSR support for this */
>            ASSERT(KeI386FxsrPresent == TRUE);
>
>