From: Andy Polyakov <appro@openssl.org>
Date: Sat, 23 Jul 2011 12:10:26 +0000 (+0000)
Subject: cryptlib.c: OPENSSL_ia32cap environment variable to interpret ~ as cpuid mask.
X-Git-Tag: OpenSSL-fips-2_0-rc1~240
X-Git-Url: https://git.openssl.org/?p=openssl.git;a=commitdiff_plain;h=2667162d33ab21b6477f224040106c1d460e9249

cryptlib.c: OPENSSL_ia32cap environment variable to interpret ~ as cpuid mask.
---

diff --git a/crypto/cryptlib.c b/crypto/cryptlib.c
index d4b236284e..8a8fac3d13 100644
--- a/crypto/cryptlib.c
+++ b/crypto/cryptlib.c
@@ -144,12 +144,15 @@ void OPENSSL_cpuid_setup(void)
     if (trigger)	return;
 
     trigger=1;
-    if ((env=getenv("OPENSSL_ia32cap")))
+    if ((env=getenv("OPENSSL_ia32cap"))) {
+	int off = (env[0]=='~')?1:0;
 #if defined(_WIN32)
-    {	if (!sscanf(env,"%I64i",&vec)) vec = strtoul(env,NULL,0);   }
+    	if (!sscanf(env+off,"%I64i",&vec)) vec = strtoul(env+off,NULL,0);
 #else
-	vec = strtoull(env,NULL,0);
+	vec = strtoull(env+off,NULL,0);
 #endif
+	if (off) vec = OPENSSL_ia32_cpuid()&~vec;
+    }
     else
 	vec = OPENSSL_ia32_cpuid();
 
diff --git a/doc/crypto/OPENSSL_ia32cap.pod b/doc/crypto/OPENSSL_ia32cap.pod
index 17189ed843..16f500fc76 100644
--- a/doc/crypto/OPENSSL_ia32cap.pod
+++ b/doc/crypto/OPENSSL_ia32cap.pod
@@ -61,10 +61,10 @@ capable CPU, but under control of OS that does not enable XMM
 registers. Even though you can manipulate the value programmatically,
 you most likely will find it more appropriate to set up an environment
 variable with the same name prior starting target application, e.g. on
-Intel P4 processor 'env OPENSSL_ia32cap=0x16980010 apps/openssl', to
-achieve same effect without modifying the application source code.
-Alternatively you can reconfigure the toolkit with no-sse2 option and
-recompile.
+Intel P4 processor 'env OPENSSL_ia32cap=0x16980010 apps/openssl', or
+better yet 'env OPENSSL_ia32cap=~0x1000000 apps/openssl' to achieve same
+effect without modifying the application source code. Alternatively you
+can reconfigure the toolkit with no-sse2 option and recompile.
 
 Less intuituve is clearing bit #28. The truth is that it's not copied
 from CPUID output verbatim, but is adjusted to reflect whether or not