We currently use an atomic_swap to atomically store and load a PTE, but
this is excessive. Use regular loads and stores instead when possible.
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Event Timeline
| sys/riscv/riscv/pmap.c | ||
|---|---|---|
| 1901 ↗ | (On Diff #52485) | Could this be expressed by in-place and-ing instead of load/and/store ? |
| sys/riscv/riscv/pmap.c | ||
|---|---|---|
| 1901 ↗ | (On Diff #52485) | I think it's more consistent with the current code. However, if we wanted to drop pmap_load/pmap_store entirely and just use regular assignments for simple loads and stores, then replacing this with 'entry &= ~PTE_W' probably would make sense. amd64 uses regular assignments ('*pte = newpte;', etc.) It's not clear to me that the wrappers are useful if you don't really need them. |
| sys/riscv/riscv/pmap.c | ||
|---|---|---|
| 1901 ↗ | (On Diff #52485) | (Note that this code is changed in D18719.) I somewhat prefer to use the wrappers since they guard accesses of memory that may be updated concurrently by hardware. In practice they probably aren't necessary; it's hard to see any cases in the amd64 pmap where a compiler optimization might introduce an unexpected side effect, but I don't see why it isn't possible. |