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gdt::get_main_iopb does not prevent creation of multiple mut ref. #98

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todo bot opened this issue Dec 22, 2018 · 0 comments
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gdt::get_main_iopb does not prevent creation of multiple mut ref. #98

todo bot opened this issue Dec 22, 2018 · 0 comments
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@roblabla @Orycterope
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project-kernel Related to the kernel safety Something is unsound, could be unsafe todo 🗒️ Created by the todo bot type-bug Something isn't working

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todo bot commented Dec 22, 2018

There's currently no guarantee that we don't create multiple &mut pointer to the IOPB region, which would cause undefined behavior. In practice, it should only be used by `i386::process_switch`, and as such, there is never actually two main_iopb active at the same time. Still, it'd be nicer to have safe functions to access the IOPB.

https://github.com/roblabla42/KFS/blob/adee47274ba5c0dc0ef112ce8933becd63d3da77/kernel/src/i386/gdt.rs#L189-L199

This issue was generated by todo based on a TODO comment in adee472 when #90 was merged. cc @roblabla.
@todo todo bot assigned roblabla Dec 22, 2018
@todo todo bot added the todo 🗒️ Created by the todo bot label Dec 22, 2018
@roblabla roblabla added type-bug Something isn't working project-kernel Related to the kernel safety Something is unsound, could be unsafe labels Dec 23, 2018
@Orycterope Orycterope self-assigned this Jul 9, 2019
Orycterope referenced this issue in Orycterope/SunriseOS Jul 10, 2019
@Orycterope
kernel: MAIN_TSS safety
46bc1dc 
Changing the way we allocate and initialize the MAIN_TSS and DOUBLE_FAULT_TSS.

They used to be lazily allocated, and the both the DOUBLE_FAULT_TSS stack and TSS were allocated by the IDT, and pushed to the GDT late.

Now the MAIN_TSS, DOUBLE_FAULT_TSS, and DOUBLE_FAULT_STACK all live in the .bss, and are fully initialized on GDT init.

The IDT only takes a segment selector pointing to the already initialized TSS for task gates.

The MAIN_TSS and its IOPB are now behind a lock. This fixes #98.

Following c6641998, the GDT is now an open fixed-sized array, addressable from other modules. We use this property to modify some segments base addresses in the process-switch.
roblabla pushed a commit to roblabla/KFS that referenced this issue Jul 20, 2019
@Orycterope @roblabla
kernel: MAIN_TSS safety
4e6135e 
Changing the way we allocate and initialize the MAIN_TSS and DOUBLE_FAULT_TSS.

They used to be lazily allocated, and the both the DOUBLE_FAULT_TSS stack and TSS were allocated by the IDT, and pushed to the GDT late.

Now the MAIN_TSS, DOUBLE_FAULT_TSS, and DOUBLE_FAULT_STACK all live in the .bss, and are fully initialized on GDT init.

The IDT only takes a segment selector pointing to the already initialized TSS for task gates.

The MAIN_TSS and its IOPB are now behind a lock. This fixes sunriseos#98.

Following c6641998, the GDT is now an open fixed-sized array, addressable from other modules. We use this property to modify some segments base addresses in the process-switch.
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@Orycterope Orycterope

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project-kernel Related to the kernel safety Something is unsound, could be unsafe todo 🗒️ Created by the todo bot type-bug Something isn't working
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