From 1ec8a84cf69a53e3c02d54280ff48d22ae571abb Mon Sep 17 00:00:00 2001
From: "Pavel I. Kryukov" <kryukov@frtk.ru>
Date: Thu, 22 Mar 2018 21:57:38 +0300
Subject: [PATCH] Add CPUID leaf checks prior to SHA checks

Some old CPUs do not support CPUID to be called with eax=7
To prevent failures, call CPUID with eax=0 to get the highest possible
eax value (leaf) and compare it to 7.

GCC does this check internally with __get_cpuid_count function

Thanks to Jeffrey Walton for noticing.
---
 sshsha.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sshsha.c b/sshsha.c
index b116afc0..c3ad9574 100644
--- a/sshsha.c
+++ b/sshsha.c
@@ -501,6 +501,10 @@ const struct ssh_mac ssh_hmac_sha1_96_buggy = {
 int supports_sha_ni(void)
 {
     unsigned int CPUInfo[4];
+    __cpuid(0, CPUInfo[0], CPUInfo[1], CPUInfo[2], CPUInfo[3]);
+    if (CPUInfo[0] < 7)
+        return 0;
+
     __cpuid_count(7, 0, CPUInfo[0], CPUInfo[1], CPUInfo[2], CPUInfo[3]);
     return CPUInfo[1] & (1 << 29); /* SHA */
 }
@@ -510,6 +514,10 @@ int supports_sha_ni(void)
 int supports_sha_ni(void)
 {
     unsigned int CPUInfo[4];
+    __cpuid(CPUInfo, 0);  
+    if (CPUInfo[0] < 7)
+        return 0;
+
     __cpuidex(CPUInfo, 7, 0);
     return CPUInfo[1] & (1 << 29); /* Check SHA */
 }