[src/trunk]: src/sys/arch/amd64/amd64 Deal with KMSAN fussiness. Pointed out...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/03c06f636b76
branches:  trunk
changeset: 933171:03c06f636b76
user:      ad <ad%NetBSD.org@localhost>
date:      Wed May 20 18:39:25 2020 +0000

description:
Deal with KMSAN fussiness.  Pointed out by msaitoh@.

diffstat:

 sys/arch/amd64/amd64/cpufunc.S |  27 ++++++++++++++++++++-------
 1 files changed, 20 insertions(+), 7 deletions(-)

diffs (51 lines):

diff -r 863c0f97454b -r 03c06f636b76 sys/arch/amd64/amd64/cpufunc.S
--- a/sys/arch/amd64/amd64/cpufunc.S    Wed May 20 18:37:50 2020 +0000
+++ b/sys/arch/amd64/amd64/cpufunc.S    Wed May 20 18:39:25 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cpufunc.S,v 1.54 2020/05/19 21:54:10 ad Exp $  */
+/*     $NetBSD: cpufunc.S,v 1.55 2020/05/20 18:39:25 ad Exp $  */
 
 /*
  * Copyright (c) 1998, 2007, 2008, 2020 The NetBSD Foundation, Inc.
@@ -206,7 +206,23 @@
 END(x86_hotpatch)
 #endif /* !XENPV */
 
-ENTRY(tsc_get_timecount)
+/* Could be exact same as cpu_counter but for KASAN fussiness. */
+ENTRY(cpu_counter32)
+       movq    CPUVAR(CURLWP), %rcx
+1:
+       movq    L_NCSW(%rcx), %rdi
+       rdtsc
+       addl    CPUVAR(CC_SKEW), %eax
+       cmpq    %rdi, L_NCSW(%rcx)
+       jne     2f
+       KMSAN_INIT_RET(4)
+       ret
+2:
+       jmp     1b
+END(cpu_counter32)
+STRONG_ALIAS(tsc_get_timecount, cpu_counter32)
+
+ENTRY(cpu_counter)
        movq    CPUVAR(CURLWP), %rcx
 1:
        movq    L_NCSW(%rcx), %rdi
@@ -216,14 +232,11 @@
        addq    CPUVAR(CC_SKEW), %rax
        cmpq    %rdi, L_NCSW(%rcx)
        jne     2f
-       KMSAN_INIT_RET(4)
+       KMSAN_INIT_RET(8)
        ret
 2:
        jmp     1b
-END(tsc_get_timecount)
-
-STRONG_ALIAS(cpu_counter, tsc_get_timecount)
-STRONG_ALIAS(cpu_counter32, tsc_get_timecount)
+END(cpu_counter)
 
 ENTRY(rdmsr_safe)
        movq    CPUVAR(CURLWP), %r8