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commit c3d8dc45c9df199b8334599a6cbd98c9950dba62
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Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Date: Thu Oct 11 15:18:40 2018 -0300
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x86: Fix Haswell strong flags (BZ#23709)
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Th commit 'Disable TSX on some Haswell processors.' (2702856bf4) changed the
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default flags for Haswell models. Previously, new models were handled by the
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default switch path, which assumed a Core i3/i5/i7 if AVX is available. After
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the patch, Haswell models (0x3f, 0x3c, 0x45, 0x46) do not set the flags
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Fast_Rep_String, Fast_Unaligned_Load, Fast_Unaligned_Copy, and
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Prefer_PMINUB_for_stringop (only the TSX one).
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This patch fixes it by disentangle the TSX flag handling from the memory
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optimization ones. The strstr case cited on patch now selects the
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__strstr_sse2_unaligned as expected for the Haswell cpu.
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Checked on x86_64-linux-gnu.
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[BZ #23709]
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* sysdeps/x86/cpu-features.c (init_cpu_features): Set TSX bits
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independently of other flags.
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diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
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index 0667e486959a8a91..d134ef3a92cbc83d 100644
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--- a/sysdeps/x86/cpu-features.c
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+++ b/sysdeps/x86/cpu-features.c
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@@ -133,7 +133,13 @@ init_cpu_features (struct cpu_features *cpu_features)
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| bit_Fast_Unaligned_Load
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| bit_Prefer_PMINUB_for_stringop);
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break;
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+ }
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+ /* Disable TSX on some Haswell processors to avoid TSX on kernels that
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+ weren't updated with the latest microcode package (which disables
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+ broken feature by default). */
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+ switch (model)
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+ {
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case 0x3f:
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/* Xeon E7 v3 with stepping >= 4 has working TSX. */
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if (stepping >= 4)
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