diff options
| author |   guenther <guenther@openbsd.org> | 2018-09-12 06:12:59 +0000 |
|---|---|---|
| committer | guenther <guenther@openbsd.org> | 2018-09-12 06:12:59 +0000 |
| commit | 00ac7aa268cae987065973acd010273c2a84e88c (patch) | |
| tree | 4bd02d24f5e4c7640f9934ac48767fa7d9a9f737 | |
| parent | When shooting pages in the KVA range, all pmaps have the page mapped, (diff) | |
| download | wireguard-openbsd-00ac7aa268cae987065973acd010273c2a84e88c.tar.xz wireguard-openbsd-00ac7aa268cae987065973acd010273c2a84e88c.zip | |
Now that the pmap is more paranoid about some shootdowns (pmap.c rev 1.119),
avoid some TLB flushes by not reloading %cr3 when the value isn't changing.
original diff by and ok mlarkin@
| -rw-r--r-- | sys/arch/amd64/amd64/locore.S | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/sys/arch/amd64/amd64/locore.S b/sys/arch/amd64/amd64/locore.S index ecc9eedc05d..a205e681012 100644 --- a/sys/arch/amd64/amd64/locore.S +++ b/sys/arch/amd64/amd64/locore.S @@ -1,4 +1,4 @@ -/* $OpenBSD: locore.S,v 1.108 2018/09/09 22:09:36 guenther Exp $ */ +/* $OpenBSD: locore.S,v 1.109 2018/09/12 06:12:59 guenther Exp $ */ /* $NetBSD: locore.S,v 1.13 2004/03/25 18:33:17 drochner Exp $ */ /* @@ -445,9 +445,15 @@ restore_saved: /* Stack pivot done, setup RETGUARD */ RETGUARD_SETUP_OFF(cpu_switchto, r11, 6*8) - movq PCB_CR3(%r13),%rax + /* don't switch cr3 to the same thing it already was */ + movq %cr3,%rax + cmpq PCB_CR3(%r13),%rax + movq PCB_CR3(%r13),%rax /* flags from cmpq unchanged */ + jz .Lsame_cr3 + movq %rax,%cr3 /* %rax used below too */ +.Lsame_cr3: /* * If we switched from a userland thread with a shallow call stack * (e.g interrupt->ast->mi_ast->prempt->mi_switch->cpu_switchto) |