Module Name: src
Committed By: maxv
Date: Mon Jul 9 18:43:05 UTC 2018
Modified Files:
src/sys/arch/amd64/amd64: locore.S
Log Message:
Small optimization: don't execute the Meltdown/SpectreV2 cswitch code if
we're leaving a softint. We were executing the softint with the LWP's
context, so no need to switch the SVS/IBRS contexts, we already are in
the desired contexts.
To generate a diff of this commit:
cvs rdiff -u -r1.167 -r1.168 src/sys/arch/amd64/amd64/locore.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/amd64/amd64/locore.S
diff -u src/sys/arch/amd64/amd64/locore.S:1.167 src/sys/arch/amd64/amd64/locore.S:1.168
--- src/sys/arch/amd64/amd64/locore.S:1.167 Fri Jun 29 19:21:43 2018
+++ src/sys/arch/amd64/amd64/locore.S Mon Jul 9 18:43:05 2018
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.S,v 1.167 2018/06/29 19:21:43 maxv Exp $ */
+/* $NetBSD: locore.S,v 1.168 2018/07/09 18:43:05 maxv Exp $ */
/*
* Copyright-o-rama!
@@ -1088,26 +1088,6 @@ ENTRY(cpu_switchto)
movq %rbp,PCB_RBP(%rax)
.Lskip_save:
-#ifdef SVS
- pushq %rdx
- movb _C_LABEL(svs_enabled),%dl
- testb %dl,%dl
- jz .Lskip_svs
- callq _C_LABEL(svs_lwp_switch)
-.Lskip_svs:
- popq %rdx
-
- /* RDI/RSI got clobbered. */
- movq %r13,%rdi
- movq %r12,%rsi
-#endif
-
-#ifndef XEN
- pushq %rdx
- callq _C_LABEL(speculation_barrier)
- popq %rdx
-#endif
-
/* Switch to newlwp's stack. */
movq L_PCB(%r12),%r14
movq PCB_RSP(%r14),%rsp
@@ -1124,6 +1104,24 @@ ENTRY(cpu_switchto)
testb %dl,%dl /* returning = true ? */
jnz .Lswitch_return
+#ifdef SVS
+ pushq %rdx
+ movb _C_LABEL(svs_enabled),%dl
+ testb %dl,%dl
+ jz .Lskip_svs
+ callq _C_LABEL(svs_lwp_switch)
+.Lskip_svs:
+ popq %rdx
+#endif
+
+#ifndef XEN
+ pushq %rdx
+ movq %r13,%rdi
+ movq %r12,%rsi
+ callq _C_LABEL(speculation_barrier)
+ popq %rdx
+#endif
+
/* Switch ring0 stack */
#ifdef SVS
movb _C_LABEL(svs_enabled),%al
