From 889f8689d9ee280ad230ec9c6b9a47154cc80dda Mon Sep 17 00:00:00 2001
From: mmokhi <mmokhi@FreeBSD.org>
Date: Fri, 23 Jun 2017 10:36:27 +0000
Subject: [PATCH] Fix caveat in new implementation of linprocfs_docpuinfo():
 Prevent kernel panic in case that extended-cpuid isn't supported by CPU

Reviewed by:	kib, ngie, trasz
Approved by:	trasz
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D11294
---
 sys/compat/linprocfs/linprocfs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
index 57853e6385c1..b707a18d3e87 100644
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -245,7 +245,10 @@ linprocfs_docpuinfo(PFS_FILL_ARGS)
 		break;
 	}
 #endif
-	do_cpuid(0x80000006, cache_size);
+	if (cpu_exthigh >= 0x80000006)
+		do_cpuid(0x80000006, cache_size);
+	else
+		memset(cache_size, 0, sizeof(cache_size));
 	for (i = 0; i < mp_ncpus; ++i) {
 		fqmhz = 0;
 		fqkhz = 0;
-- 
2.41.0