fix(guest-bin): align user memory allocations #753
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andreiltd
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The guest allocation wrapper aligned only the total memory block but did not guarantee that the pointer returned to the user was itself properly aligned. This patch attempts to fix that. It also adds alloc_aligned function which would be tricky to implement outside the guest but will make implementing other posix like allocation API much easier. Signed-off-by: Tomasz Andrzejak <[email protected]>
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Signed-off-by: Tomasz Andrzejak <[email protected]>
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| /// # Safety | ||
| /// The returned pointer must be freed with `memory::free` when it is no longer needed, otherwise memory will leak. | ||
| unsafe fn alloc_helper(size: usize, zero: bool) -> *mut c_void { | ||
| unsafe fn alloc_helper(size: usize, alignment: usize, zero: bool) -> *mut c_void { |
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Are there any tests we should be adding to verify this new behavior?
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Yeah, this is tricky. This crate default target is baremetal and cargo doesn't allow different default targets for build and test: rust-lang/cargo#6784 so cargo test won't work.
It really only make sense to write the tests within this module so we have an access to internal memory layout with header and whatnot. So we should probably either use custom test harness or unstable test_runner features?
https://doc.rust-lang.org/beta/unstable-book/language-features/custom-test-frameworks.html
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The guest allocation wrapper aligned only the total memory block but did not guarantee that the pointer returned to the user was itself properly aligned. This patch attempts to fix that.
It also adds alloc_aligned function which would be tricky to implement outside the guest but will make implementing other posix like allocation API much easier.