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libitm: Disable TSX on processors on which it may be broken.

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libitm/ChangeLog

	* config/x86/target.h (htm_available): Add check for some processors
	on which TSX is broken.

From-SVN: r244594
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Torvald Riegel 2017-01-18 20:22:02 +00:00 committed by Torvald Riegel
parent b7d3a6a6b2
commit f8a94453ad
2 changed files with 27 additions and 0 deletions
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libitm/ChangeLog
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@ -1,3 +1,8 @@
2017-01-18 Torvald Riegel <triegel@redhat.com>
* config/x86/target.h (htm_available): Add check for some processors
on which TSX is broken.
2017-01-17 Jakub Jelinek <jakub@redhat.com>
PR other/79046

22
libitm/config/x86/target.h
View File

@ -78,6 +78,28 @@ htm_available ()
if (__get_cpuid_max (0, NULL) >= 7)
{
unsigned a, b, c, d;
/* TSX is broken on some processors. This can be fixed by microcode,
but we cannot reliably detect whether the microcode has been
updated. Therefore, do not report availability of TSX on these
processors. We use the same approach here as in glibc (see
https://sourceware.org/ml/libc-alpha/2016-12/msg00470.html). */
__cpuid (0, a, b, c, d);
if (b == 0x756e6547 && c == 0x6c65746e && d == 0x49656e69)
{
__cpuid (1, a, b, c, d);
if (((a >> 8) & 0x0f) == 0x06) // Family.
{
unsigned model = ((a >> 4) & 0x0f) // Model.
+ ((a >> 12) & 0xf0); // Extended model.
unsigned stepping = a & 0x0f;
if ((model == 0x3c)
|| (model == 0x45)
|| (model == 0x46)
/* Xeon E7 v3 has correct TSX if stepping >= 4. */
|| ((model == 0x3f) && (stepping < 4)))
return false;
}
}
__cpuid_count (7, 0, a, b, c, d);
if (b & cpuid_rtm)
return true;