From: Andrew Senkevich <andrew.senkevich@intel.com>
Date: Mon, 19 Dec 2016 10:20:31 +0000 (+0300)
Subject: Disable TSX on some Haswell processors.
X-Git-Tag: glibc-2.25~185
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2702856bf4;p=thirdparty%2Fglibc.git

Disable TSX on some Haswell processors.

Patch disables Intel TSX on some Haswell processors to avoid TSX
on kernels that weren't updated with the latest microcode package
(which disables broken feature by default).

    * sysdeps/x86/cpu-features.c (get_common_indeces): Add
    stepping identification.
    (init_cpu_features): Add handle of Haswell.
---

diff --git a/ChangeLog b/ChangeLog
index 8782df9c88f..6a273201137 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2016-12-19  Andrew Senkevich  <andrew.senkevich@intel.com>
+
+	* sysdeps/x86/cpu-features.c (get_common_indeces): Add
+	stepping identification.
+	(init_cpu_features): Add handle of Haswell.
+
 2016-11-25  Jim Meyering  <meyering@fb.com>
 
 	[BZ #20386]
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index e228a76c403..0ef98e68abe 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -22,7 +22,7 @@
 static void
 get_common_indeces (struct cpu_features *cpu_features,
 		    unsigned int *family, unsigned int *model,
-		    unsigned int *extended_model)
+		    unsigned int *extended_model, unsigned int *stepping)
 {
   if (family)
     {
@@ -34,6 +34,7 @@ get_common_indeces (struct cpu_features *cpu_features,
       *family = (eax >> 8) & 0x0f;
       *model = (eax >> 4) & 0x0f;
       *extended_model = (eax >> 12) & 0xf0;
+      *stepping = eax & 0x0f;
       if (*family == 0x0f)
 	{
 	  *family += (eax >> 20) & 0xff;
@@ -116,11 +117,12 @@ init_cpu_features (struct cpu_features *cpu_features)
   /* This spells out "GenuineIntel".  */
   if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
     {
-      unsigned int extended_model;
+      unsigned int extended_model, stepping;
 
       kind = arch_kind_intel;
 
-      get_common_indeces (cpu_features, &family, &model, &extended_model);
+      get_common_indeces (cpu_features, &family, &model, &extended_model,
+			  &stepping);
 
       if (family == 0x06)
 	{
@@ -201,6 +203,20 @@ init_cpu_features (struct cpu_features *cpu_features)
 		    | bit_arch_Fast_Unaligned_Copy
 		    | bit_arch_Prefer_PMINUB_for_stringop);
 	      break;
+
+	    case 0x3f:
+	      /* Xeon E7 v3 with stepping >= 4 has working TSX.  */
+	      if (stepping >= 4)
+		break;
+	    case 0x3c:
+	    case 0x45:
+	    case 0x46:
+	      /* Disable Intel TSX on Haswell processors (except Xeon E7 v3
+		 with stepping >= 4) to avoid TSX on kernels that weren't
+		 updated with the latest microcode package (which disables
+		 broken feature by default).  */
+	      cpu_features->cpuid[COMMON_CPUID_INDEX_7].ebx &= ~(bit_cpu_RTM);
+	      break;
 	    }
 	}
 
@@ -227,11 +243,12 @@ init_cpu_features (struct cpu_features *cpu_features)
   /* This spells out "AuthenticAMD".  */
   else if (ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65)
     {
-      unsigned int extended_model;
+      unsigned int extended_model, stepping;
 
       kind = arch_kind_amd;
 
-      get_common_indeces (cpu_features, &family, &model, &extended_model);
+      get_common_indeces (cpu_features, &family, &model, &extended_model,
+			  &stepping);
 
       ecx = cpu_features->cpuid[COMMON_CPUID_INDEX_1].ecx;
 
@@ -268,7 +285,7 @@ init_cpu_features (struct cpu_features *cpu_features)
   else
     {
       kind = arch_kind_other;
-      get_common_indeces (cpu_features, NULL, NULL, NULL);
+      get_common_indeces (cpu_features, NULL, NULL, NULL, NULL);
     }
 
   /* Support i586 if CX8 is available.  */