Add GCRYCTL_DISABLE_HWF

This option is useful to disable detected hardware features. It has
been implemented in benchmark, so that it is now possible to run

  tests/benchmark --disable-hwf intel-aesni  cipher aes aes192 aes256

to compare the use of AES-NI insns to the pure C code.

5 files changed, 55 insertions, 18 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index b150b40c..4f3a4e33 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,14 @@
+2011-02-16  Werner Koch  <wk@g10code.com>
+
+	* gcrypt.h.in (GCRYCTL_DISABLE_HWF): New.
+	* global.c (_gcry_vcontrol): Support new control code.
+	(print_config): Factor list of hwfeatures out to ...
+	(hwflist): new.
+	(disabled_hw_features): New.
+	(global_init): Pass new variable to _gcry_detect_hw_features.
+	* hwfeatures.c (_gcry_detect_hw_features): Add arg
+	DISABLED_FEATURES and disable detected features.
+
 2011-02-11  Werner Koch  <wk@g10code.com>
 
 	* g10lib.h (HWF_INTEL_AES): Rename to HWF_INTEL_AESNI.
diff --git a/src/g10lib.h b/src/g10lib.h
index 28c5e936..8d98ae38 100644
--- a/src/g10lib.h
+++ b/src/g10lib.h
@@ -152,7 +152,7 @@ int _gcry_log_verbosity( int level );
 
 
 unsigned int _gcry_get_hw_features (void);
-void _gcry_detect_hw_features (void);
+void _gcry_detect_hw_features (unsigned int);
 
 
 /*-- mpi/mpiutil.c --*/
diff --git a/src/gcrypt.h.in b/src/gcrypt.h.in
index f8daeb35..54fa9f37 100644
--- a/src/gcrypt.h.in
+++ b/src/gcrypt.h.in
@@ -414,8 +414,9 @@ enum gcry_ctl_cmds
     GCRYCTL_OPERATIONAL_P = 54,
     GCRYCTL_FIPS_MODE_P = 55,
     GCRYCTL_FORCE_FIPS_MODE = 56,
-    GCRYCTL_SELFTEST = 57
+    GCRYCTL_SELFTEST = 57,
     /* Note: 58 .. 62 are used internally.  */
+    GCRYCTL_DISABLE_HWF = 63
   };
 
 /* Perform various operations defined by CMD. */
diff --git a/src/global.c b/src/global.c
index 35a2ca14..6336fea2 100644
--- a/src/global.c
+++ b/src/global.c
@@ -1,6 +1,6 @@
 /* global.c  -	global control functions
  * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
- *               2004, 2005, 2006, 2008  Free Software Foundation, Inc.
+ *               2004, 2005, 2006, 2008, 2011  Free Software Foundation, Inc.
  *
  * This file is part of Libgcrypt.
  *
@@ -53,6 +53,24 @@ static int force_fips_mode;
 /* Controlled by global_init().  */
 static int any_init_done;
 
+/* A table to map hardware features to a string.  */
+static struct
+{
+  unsigned int flag;
+  const char *desc;
+} hwflist[] =
+  {
+    { HWF_PADLOCK_RNG, "padlock-rng" },
+    { HWF_PADLOCK_AES, "padlock-aes" },
+    { HWF_PADLOCK_SHA, "padlock-sha" },
+    { HWF_PADLOCK_MMUL,"padlock-mmul"},
+    { HWF_INTEL_AESNI, "intel-aesni" },
+    { 0, NULL}
+  };
+
+/* A bit vector with the hardware features which shall not be used.
+   This variable must be set prior to any initialization.  */
+static unsigned int disabled_hw_features;
 
 
 /* Memory management. */
@@ -94,7 +112,7 @@ global_init (void)
 
   /* Before we do any other initialization we need to test available
      hardware features.  */
-  _gcry_detect_hw_features ();
+  _gcry_detect_hw_features (disabled_hw_features);
 
   err = _gcry_cipher_init ();
   if (err)
@@ -258,16 +276,6 @@ static void
 print_config ( int (*fnc)(FILE *fp, const char *format, ...), FILE *fp)
 {
   unsigned int hwf;
-  struct {
-    unsigned int flag;
-    const char *desc;
-  } hwflist[] = {
-    { HWF_PADLOCK_RNG, "padlock-rng" },
-    { HWF_PADLOCK_AES, "padlock-aes" },
-    { HWF_PADLOCK_SHA, "padlock-sha" },
-    { HWF_INTEL_AESNI, "intel-aesni" },
-    { 0, NULL}
-  };
   int i;
 
   fnc (fp, "version:%s:\n", VERSION);
@@ -292,8 +300,8 @@ print_config ( int (*fnc)(FILE *fp, const char *format, ...), FILE *fp)
   hwf = _gcry_get_hw_features ();
   fnc (fp, "hwflist:");
   for (i=0; hwflist[i].desc; i++)
-  if ( (hwf & hwflist[i].flag) )
-    fnc (fp, "%s:", hwflist[i].desc);
+    if ( (hwf & hwflist[i].flag) )
+      fnc (fp, "%s:", hwflist[i].desc);
   fnc (fp, "\n");
   /* We use y/n instead of 1/0 for the simple reason that Emacsen's
      compile error parser would accidently flag that line when printed
@@ -565,6 +573,21 @@ _gcry_vcontrol (enum gcry_ctl_cmds cmd, va_list arg_ptr)
       }
       break;
 
+    case GCRYCTL_DISABLE_HWF:
+      {
+        const char *name = va_arg (arg_ptr, const char *);
+        int i;
+
+        for (i=0; hwflist[i].desc; i++)
+          if (!strcmp (hwflist[i].desc, name))
+            {
+              disabled_hw_features |= hwflist[i].flag;
+              break;
+            }
+        if (!hwflist[i].desc)
+          err = GPG_ERR_INV_NAME;
+      }
+      break;
 
     default:
       /* A call to make sure that the dummy code is linked in.  */
diff --git a/src/hwfeatures.c b/src/hwfeatures.c
index 5a0a8055..2b3bb2cb 100644
--- a/src/hwfeatures.c
+++ b/src/hwfeatures.c
@@ -1,5 +1,5 @@
 /* hwfeatures.c - Detect hardware features.
- * Copyright (C) 2007  Free Software Foundation, Inc.
+ * Copyright (C) 2007, 2011  Free Software Foundation, Inc.
  *
  * This file is part of Libgcrypt.
  *
@@ -172,7 +172,7 @@ detect_ia32_gnuc (void)
    once right at startup and we assume that no other threads are
    running.  */
 void
-_gcry_detect_hw_features (void)
+_gcry_detect_hw_features (unsigned int disabled_features)
 {
   hw_features = 0;
 
@@ -187,4 +187,6 @@ _gcry_detect_hw_features (void)
 #ifdef __GNUC__
 #endif
 #endif
+
+  hw_features &= ~disabled_features;
 }