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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2018-10-11 15:18:40 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2018-10-23 14:57:02 -0300
commitc3d8dc45c9df199b8334599a6cbd98c9950dba62 (patch)
tree723bf34e95345abb6fe13f4afa6f4821a317b92e /sysdeps/x86
parentf1034472e21d77b978464b73adbb0f9f1f032c91 (diff)
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x86: Fix Haswell strong flags (BZ#23709)
Th commit 'Disable TSX on some Haswell processors.' (2702856bf4) changed the
default flags for Haswell models.  Previously, new models were handled by the
default switch path, which assumed a Core i3/i5/i7 if AVX is available. After
the patch, Haswell models (0x3f, 0x3c, 0x45, 0x46) do not set the flags
Fast_Rep_String, Fast_Unaligned_Load, Fast_Unaligned_Copy, and
Prefer_PMINUB_for_stringop (only the TSX one).

This patch fixes it by disentangle the TSX flag handling from the memory
optimization ones.  The strstr case cited on patch now selects the
__strstr_sse2_unaligned as expected for the Haswell cpu.

Checked on x86_64-linux-gnu.

	[BZ #23709]
	* sysdeps/x86/cpu-features.c (init_cpu_features): Set TSX bits
	independently of other flags.
Diffstat (limited to 'sysdeps/x86')
-rw-r--r--sysdeps/x86/cpu-features.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index f4e0f5a2ed..80b3054cf8 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -316,7 +316,13 @@ init_cpu_features (struct cpu_features *cpu_features)
 		    | bit_arch_Fast_Unaligned_Copy
 		    | bit_arch_Prefer_PMINUB_for_stringop);
 	      break;
+	    }
 
+	 /* Disable 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).  */
+	 switch (model)
+	    {
 	    case 0x3f:
 	      /* Xeon E7 v3 with stepping >= 4 has working TSX.  */
 	      if (stepping >= 4)