Remove cpu.has_avx_hardware()

Update NSS to remove work around cpu detection bug in nss 3.15

BUG=chromium:320524

Review URL: https://codereview.chromium.org/1381603004

Cr-Commit-Position: refs/heads/master@{#352633}

3 files changed, 1 insertions, 29 deletions

diff --git a/base/cpu.cc b/base/cpu.cc
index edba2c2..ecffb86 100644
--- a/base/cpu.cc
+++ b/base/cpu.cc
@@ -43,7 +43,6 @@ CPU::CPU()
     has_sse41_(false),
     has_sse42_(false),
     has_avx_(false),
-    has_avx_hardware_(false),
     has_avx2_(false),
     has_aesni_(false),
     has_non_stop_time_stamp_counter_(false),
@@ -232,8 +231,6 @@ void CPU::Initialize() {
     has_ssse3_ = (cpu_info[2] & 0x00000200) != 0;
     has_sse41_ = (cpu_info[2] & 0x00080000) != 0;
     has_sse42_ = (cpu_info[2] & 0x00100000) != 0;
-    has_avx_hardware_ =
-                 (cpu_info[2] & 0x10000000) != 0;
     // AVX instructions will generate an illegal instruction exception unless
     //   a) they are supported by the CPU,
     //   b) XSAVE is supported by the CPU and
@@ -245,7 +242,7 @@ void CPU::Initialize() {
     // Because of that, we also test the XSAVE bit because its description in
     // the CPUID documentation suggests that it signals xgetbv support.
     has_avx_ =
-        has_avx_hardware_ &&
+        (cpu_info[2] & 0x10000000) != 0 &&
         (cpu_info[2] & 0x04000000) != 0 /* XSAVE */ &&
         (cpu_info[2] & 0x08000000) != 0 /* OSXSAVE */ &&
         (_xgetbv(0) & 6) == 6 /* XSAVE enabled by kernel */;
diff --git a/base/cpu.h b/base/cpu.h
index b396078..8c3c06c 100644
--- a/base/cpu.h
+++ b/base/cpu.h
@@ -48,12 +48,6 @@ class BASE_EXPORT CPU {
   bool has_sse42() const { return has_sse42_; }
   bool has_avx() const { return has_avx_; }
   bool has_avx2() const { return has_avx2_; }
-  // has_avx_hardware returns true when AVX is present in the CPU. This might
-  // differ from the value of |has_avx()| because |has_avx()| also tests for
-  // operating system support needed to actually call AVX instuctions.
-  // Note: you should never need to call this function. It was added in order
-  // to workaround a bug in NSS but |has_avx()| is what you want.
-  bool has_avx_hardware() const { return has_avx_hardware_; }
   bool has_aesni() const { return has_aesni_; }
   bool has_non_stop_time_stamp_counter() const {
     return has_non_stop_time_stamp_counter_;
@@ -85,7 +79,6 @@ class BASE_EXPORT CPU {
   bool has_sse41_;
   bool has_sse42_;
   bool has_avx_;
-  bool has_avx_hardware_;
   bool has_avx2_;
   bool has_aesni_;
   bool has_non_stop_time_stamp_counter_;
diff --git a/crypto/nss_util.cc b/crypto/nss_util.cc
index d13170c..8e378f4 100644
--- a/crypto/nss_util.cc
+++ b/crypto/nss_util.cc
@@ -682,8 +682,6 @@ class NSSInitSingleton {
     // other threads from accessing until the constructor is done.
     thread_checker_.DetachFromThread();
 
-    DisableAESNIIfNeeded();
-
     EnsureNSPRInit();
 
     // We *must* have NSS >= 3.14.3.
@@ -845,22 +843,6 @@ class NSSInitSingleton {
   }
 #endif
 
-  static void DisableAESNIIfNeeded() {
-    if (NSS_VersionCheck("3.15") && !NSS_VersionCheck("3.15.4")) {
-      // Some versions of NSS have a bug that causes AVX instructions to be
-      // used without testing whether XSAVE is enabled by the operating system.
-      // In order to work around this, we disable AES-NI in NSS when we find
-      // that |has_avx()| is false (which includes the XSAVE test). See
-      // https://bugzilla.mozilla.org/show_bug.cgi?id=940794
-      base::CPU cpu;
-
-      if (cpu.has_avx_hardware() && !cpu.has_avx()) {
-        scoped_ptr<base::Environment> env(base::Environment::Create());
-        env->SetVar("NSS_DISABLE_HW_AES", "1");
-      }
-    }
-  }
-
   bool tpm_token_enabled_for_nss_;
   bool initializing_tpm_token_;
   typedef std::vector<base::Closure> TPMReadyCallbackList;