riscv pmap: only need to re-read l3 when crossing the page boundary #1589
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markjdb
reviewed
Feb 7, 2025
sys/riscv/riscv/pmap.c
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| l3 = pmap_l3(kernel_pmap, va); | ||
| while (true) { | ||
| KASSERT(l3 != NULL, ("%s: Invalid page table, va: 0x%lx", | ||
| __func__, va)); |
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I think a better pattern is something like
for (l3 = NULL; size > 0; size -= PAGE_SIZE) {
if (l3 == NULL || __is_aligned((uintptr_t)l3, PAGE_SIZE))
l3 = pmap_l3(kernel_pmap, va);
...
va += PAGE_SIZE;
l3++;
}
This way, we don't need the extra size == 0 check, and there's only one use of pmap_l3().
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This will miss the KASSERT check for (l3 != NULL).
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Well, it can be added after the pmap_l3() call of course. But I'm not sure such an assertion is very useful at all - we will crash regardless if l3 == NULL.
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The new code is uploaded.
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