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amd64 pmap: simplify vtopte() and vtopde()

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Pre-calculate masks and page table/page directory bases, for LA48 and
LA57 cases, trading a conditional for the memory accesses.

This shaves 672 bytes of .text, by the cost of 32 .data bytes.  Note
that eliminated code contained one conditional, and several costly
movabs instructions, which are traded by two memory fetches per
vtop{t,d}e() inlines.

Reviewed by:	markj
Discussed with:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D33776
This commit is contained in:
Konstantin Belousov 2022-01-05 02:26:12 +02:00
parent aaaa4fb54e
commit 720a892ac6
1 changed files with 17 additions and 22 deletions
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39
sys/amd64/amd64/pmap.c
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@ -1516,40 +1516,28 @@ pmap_pt_page_count_adj(pmap_t pmap, int count)
}
}
pt_entry_t vtoptem __read_mostly = (1ul << (NPTEPGSHIFT + NPDEPGSHIFT +
NPDPEPGSHIFT + NPML4EPGSHIFT)) - 1;
pt_entry_t *PTmap __read_mostly = P4Tmap;
PMAP_INLINE pt_entry_t *
vtopte(vm_offset_t va)
{
u_int64_t mask;
KASSERT(va >= VM_MAXUSER_ADDRESS, ("vtopte on a uva/gpa 0x%0lx", va));
if (la57) {
mask = ((1ul << (NPTEPGSHIFT + NPDEPGSHIFT + NPDPEPGSHIFT +
NPML4EPGSHIFT + NPML5EPGSHIFT)) - 1);
return (P5Tmap + ((va >> PAGE_SHIFT) & mask));
} else {
mask = ((1ul << (NPTEPGSHIFT + NPDEPGSHIFT + NPDPEPGSHIFT +
NPML4EPGSHIFT)) - 1);
return (P4Tmap + ((va >> PAGE_SHIFT) & mask));
}
return (PTmap + ((va >> PAGE_SHIFT) & vtoptem));
}
pd_entry_t vtopdem __read_mostly = (1ul << (NPDEPGSHIFT + NPDPEPGSHIFT +
NPML4EPGSHIFT)) - 1;
pd_entry_t *PDmap __read_mostly = P4Dmap;
static __inline pd_entry_t *
vtopde(vm_offset_t va)
{
u_int64_t mask;
KASSERT(va >= VM_MAXUSER_ADDRESS, ("vtopde on a uva/gpa 0x%0lx", va));
if (la57) {
mask = ((1ul << (NPDEPGSHIFT + NPDPEPGSHIFT +
NPML4EPGSHIFT + NPML5EPGSHIFT)) - 1);
return (P5Dmap + ((va >> PDRSHIFT) & mask));
} else {
mask = ((1ul << (NPDEPGSHIFT + NPDPEPGSHIFT +
NPML4EPGSHIFT)) - 1);
return (P4Dmap + ((va >> PDRSHIFT) & mask));
}
return (PDmap + ((va >> PDRSHIFT) & vtopdem));
}
static u_int64_t
@ -2241,6 +2229,13 @@ pmap_bootstrap_la57(void *arg __unused)
*/
v_pml5[PML5PML5I] = KPML5phys | X86_PG_RW | X86_PG_V | pg_nx;
vtoptem = (1ul << (NPTEPGSHIFT + NPDEPGSHIFT + NPDPEPGSHIFT +
NPML4EPGSHIFT + NPML5EPGSHIFT)) - 1;
PTmap = P5Tmap;
vtopdem = (1ul << (NPDEPGSHIFT + NPDPEPGSHIFT +
NPML4EPGSHIFT + NPML5EPGSHIFT)) - 1;
PDmap = P5Dmap;
kernel_pmap->pm_cr3 = KPML5phys;
kernel_pmap->pm_pmltop = v_pml5;
pmap_pt_page_count_adj(kernel_pmap, 1);