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add Mapper::clear to clear any page table entry regardless of present flag #484

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merged 3 commits into from
May 24, 2024
Merged

add Mapper::clear to clear any page table entry regardless of present flag #484

merged 3 commits into from
May 24, 2024

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Wasabi375
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Add a way to clear page table entries that don't have the present flag set.

See #481 for an explanation

fixes: #481

Freax13
Freax13 requested changes May 19, 2024
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Thank you for your contribution!

src/structures/paging/mapper/mod.rs Outdated Show resolved Hide resolved
src/structures/paging/mapper/mapped_page_table.rs Outdated Show resolved Hide resolved
src/structures/paging/mapper/mod.rs Outdated Show resolved Hide resolved
src/structures/paging/mapper/mod.rs Outdated Show resolved Hide resolved
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@Wasabi375 Wasabi375 changed the base branch from master to next May 20, 2024 09:14
@Wasabi375 Wasabi375 changed the base branch from next to master May 20, 2024 09:14
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Looks like cargo doc is still failing. I should have a fix for that shortly

@Wasabi375 Wasabi375 changed the title add Mapper::unmap_ignore_present add Mapper::clear to clear any page table entry regardless of present flag May 20, 2024
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I merged my commits and also added a changelog entry. Let me know if there is anything else I should do.

I noticed that unmap and now clear are both safe functions. Shouldn't they be marked as unsafe? After all using unmap or clear can invalidate any existing reference and rust safety guarantees require all references to be valid?
In any case that should probably be a second PR/issue

@Wasabi375 Wasabi375 requested a review from Freax13 May 20, 2024 10:07
@Wasabi375 Wasabi375 changed the base branch from master to next May 20, 2024 10:08
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Freax13 commented May 22, 2024

I noticed that unmap and now clear are both safe functions. Shouldn't they be marked as unsafe? After all using unmap or clear can invalidate any existing reference and rust safety guarantees require all references to be valid? In any case that should probably be a second PR/issue

We don't consider page faults to be UB so unmapping memory by itself isn't unsafe.

Freax13
Freax13 reviewed May 22, 2024
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I noticed that unmap and now clear are both safe functions. Shouldn't they be marked as unsafe? After all using unmap or clear can invalidate any existing reference and rust safety guarantees require all references to be valid? In any case that should probably be a second PR/issue

We don't consider page faults to be UB so unmapping memory by itself isn't unsafe.

I'm not sure i agree with that, but it doesn't matter for this pr anyways

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Freax13 commented May 22, 2024

I noticed that unmap and now clear are both safe functions. Shouldn't they be marked as unsafe? After all using unmap or clear can invalidate any existing reference and rust safety guarantees require all references to be valid? In any case that should probably be a second PR/issue

We don't consider page faults to be UB so unmapping memory by itself isn't unsafe.

I'm not sure i agree with that, but it doesn't matter for this pr anyways

Feel free to open an issue, if you want to discuss this more!

@Wasabi375 Wasabi375 mentioned this pull request May 22, 2024
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Freax13
Freax13 reviewed May 23, 2024
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Wasabi375 added 2 commits May 24, 2024 11:43
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add Mapper::unmap_ignore_present
ca63fa9 
Add a way to clear page table entries that don't have the present flag
set.

fixes: rust-osdev#481
@Wasabi375
Mapper::unmap now also returns the flags of the page
49802d1
Freax13
Freax13 approved these changes May 24, 2024
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Looks good to me, thank you again for your contribution!

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Freax13 commented May 24, 2024

Recently, the clippy CI job got broken again by new lints in nightly, so I'll temporarily disable the merge requirement for that job to merge this PR.

@Freax13 Freax13 merged commit 8468914 into rust-osdev:next May 24, 2024
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@Freax13 Freax13 mentioned this pull request May 24, 2024
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PageTable: Handling of pages without the present flag set
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@Wasabi375 @Freax13 @phil-opp