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| author | Mark Johnston <markj@FreeBSD.org> | 2021-10-20 00:29:18 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2021-10-20 01:22:57 +0000 |
| commit | 34fac29e98313fb0bfba0503e2e19e352b452516 (patch) | |
| tree | b85213abad7f5e62051107136bf11dc638f1f723 /sys/amd64/amd64 | |
| parent | ff93447d8ed61081adfe00a23a1e4c7bee479e53 (diff) | |
| download | src-34fac29e98313fb0bfba0503e2e19e352b452516.tar.gz src-34fac29e98313fb0bfba0503e2e19e352b452516.zip | |
amd64: Add comments to pmap_pinit_type()
... explaining why we don't pass the pmap pointer to
pmap_alloc_pt_page().
Reported by: alc
Reviewed by: alc, kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D32528
Diffstat (limited to 'sys/amd64/amd64')
| -rw-r--r-- | sys/amd64/amd64/pmap.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c index 8d6379ab170c..66d7ac6669da 100644 --- a/sys/amd64/amd64/pmap.c +++ b/sys/amd64/amd64/pmap.c @@ -4345,7 +4345,9 @@ pmap_pinit_type(pmap_t pmap, enum pmap_type pm_type, int flags) int i; /* - * allocate the page directory page + * Allocate the page directory page. Pass NULL instead of a pointer to + * the pmap here to avoid recording this page in the resident count, as + * optimizations in pmap_remove() depend on this. */ pmltop_pg = pmap_alloc_pt_page(NULL, 0, VM_ALLOC_WIRED | VM_ALLOC_ZERO | VM_ALLOC_WAITOK); @@ -4377,6 +4379,10 @@ pmap_pinit_type(pmap_t pmap, enum pmap_type pm_type, int flags) else pmap_pinit_pml4(pmltop_pg); if ((curproc->p_md.md_flags & P_MD_KPTI) != 0) { + /* + * As with pmltop_pg, pass NULL instead of a pointer to + * the pmap to ensure that the PTI page isn't counted. + */ pmltop_pgu = pmap_alloc_pt_page(NULL, 0, VM_ALLOC_WIRED | VM_ALLOC_WAITOK); pmap->pm_pmltopu = (pml4_entry_t *)PHYS_TO_DMAP( |