Names, updates, and an overflow fix#68
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dancrossnyc merged 3 commits intomainfrom Apr 18, 2026
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It is possible to map a loadable ELF segment at the very top of virtual memory, and if we do so, then the end address of the resulting region will overflow and wrap around to 0. This is expected. The virtual memory code correctly handles this, but the loader uses `end - begin` to calculate the lengths of segments, and that can wrap when `end` is rounded "up" to 0. To make explicit that this is permissible (and to avoid panics in debug builds), we should use `.wrapping_sub` instead of bare subtraction. I should stress that, while this behavior is supported, it does not happen in practice, as no binary that we load with `phbl` maps anything in that region of the virtual address space; in that sense, this change is a no-op. But as a code hygiene issue, the program should be correct in all regards, and hence should handle this case explicitly. Signed-off-by: Dan Cross <cross@oxidecomputer.com>
ELF "sections" are not exactly the same thing as loadable "segments", and we should be clear with nomenclature. The ELF standard uses the term "segment" for what is described by the program headers, which are the things that we load, so we should, too. Signed-off-by: Dan Cross <cross@oxidecomputer.com>
Trivial update to a newer Rust version and updating dependencies via `cargo update`. Signed-off-by: Dan Cross <cross@oxidecomputer.com>
citrus-it
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Apr 17, 2026
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Tested on sn6.