Bug 1361687 - make improved x86 feature detection available to all of freebl, r=mt

Differential Revision: https://nss-review.dev.mozaws.net/D290

1 files changed, 115 insertions, 0 deletions

diff --git a/lib/freebl/blinit.c b/lib/freebl/blinit.c
new file mode 100644
index 000000000..2f167efd2
--- /dev/null
+++ b/lib/freebl/blinit.c
@@ -0,0 +1,115 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifdef FREEBL_NO_DEPEND
+#include "stubs.h"
+#endif
+
+#include "blapii.h"
+#include "mpi.h"
+#include "secerr.h"
+#include "prtypes.h"
+#include "prinit.h"
+#include "prenv.h"
+
+#if defined(_MSC_VER) && !defined(_M_IX86)
+#include <intrin.h> /* for _xgetbv() */
+#endif
+
+static PRCallOnceType coFreeblInit;
+
+/* State variables. */
+static PRBool aesni_support_ = PR_FALSE;
+static PRBool clmul_support_ = PR_FALSE;
+static PRBool avx_support_ = PR_FALSE;
+
+#ifdef NSS_X86_OR_X64
+/*
+ * Adapted from the example code in "How to detect New Instruction support in
+ * the 4th generation Intel Core processor family" by Max Locktyukhin.
+ *
+ * XGETBV:
+ *   Reads an extended control register (XCR) specified by ECX into EDX:EAX.
+ */
+static PRBool
+check_xcr0_ymm()
+{
+    PRUint32 xcr0;
+#if defined(_MSC_VER)
+#if defined(_M_IX86)
+    __asm {
+        mov ecx, 0
+        xgetbv
+        mov xcr0, eax
+    }
+#else
+    xcr0 = (PRUint32)_xgetbv(0); /* Requires VS2010 SP1 or later. */
+#endif /* _M_IX86 */
+#else  /* _MSC_VER */
+    __asm__("xgetbv"
+            : "=a"(xcr0)
+            : "c"(0)
+            : "%edx");
+#endif /* _MSC_VER */
+    /* Check if xmm and ymm state are enabled in XCR0. */
+    return (xcr0 & 6) == 6;
+}
+
+#define ECX_AESNI (1 << 25)
+#define ECX_CLMUL (1 << 1)
+#define ECX_XSAVE (1 << 26)
+#define ECX_OSXSAVE (1 << 27)
+#define ECX_AVX (1 << 28)
+#define AVX_BITS (ECX_XSAVE | ECX_OSXSAVE | ECX_AVX)
+
+void
+CheckX86CPUSupport()
+{
+    unsigned long eax, ebx, ecx, edx;
+    char *disable_hw_aes = PR_GetEnvSecure("NSS_DISABLE_HW_AES");
+    freebl_cpuid(1, &eax, &ebx, &ecx, &edx);
+    aesni_support_ = (PRBool)((ecx & ECX_AESNI) != 0 && disable_hw_aes == NULL);
+    clmul_support_ = (PRBool)((ecx & ECX_CLMUL) != 0);
+    /* For AVX we check AVX, OSXSAVE, and XSAVE
+     * as well as XMM and YMM state. */
+    avx_support_ = (PRBool)((ecx & AVX_BITS) == AVX_BITS) && check_xcr0_ymm();
+}
+#endif /* NSS_X86_OR_X64 */
+
+PRBool
+aesni_support()
+{
+    return aesni_support_;
+}
+PRBool
+clmul_support()
+{
+    return clmul_support_;
+}
+PRBool
+avx_support()
+{
+    return avx_support_;
+}
+
+static PRStatus
+FreeblInit(void)
+{
+#ifdef NSS_X86_OR_X64
+    CheckX86CPUSupport();
+#endif
+    return PR_SUCCESS;
+}
+
+SECStatus
+BL_Init()
+{
+    if (PR_CallOnce(&coFreeblInit, FreeblInit) != PR_SUCCESS) {
+        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
+        return SECFailure;
+    }
+    RSA_Init();
+
+    return SECSuccess;
+}