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

[Jakub Jelinek]

On Wed, Jan 18, 2017 at 10:48:28PM +0100, Uros Bizjak wrote:
> Hello!
> 
> > This fix follows the same approach that glibc uses to disable TSX on
> > processors on which it is broken.  TSX can also be disabled through a
> > microcode update on these processors, but glibc consensus is that it
> > cannot be detected reliably whether the microcode update has been
> > applied.  Thus, we just look for affected models/steppings.
> >
> > Tested on x86_64-linux (but I don't have a machine with broken TSX
> > available).
> >
> >        libitm/ChangeLog
> >
> >        * config/x86/target.h (htm_available): Add check for some processors
> >        on which TSX is broken.
> 
> +      __cpuid (0, a, b, c, d);
> +      if (b == 0x756e6547 && c == 0x6c65746e && d == 0x49656e69)
> 
> You can use:
> 
> #define signature_INTEL_ebx    0x756e6547
> #define signature_INTEL_ecx    0x6c65746e
> #define signature_INTEL_edx    0x49656e69
> 
> defines from cpuid.h here.

Also, can you please remove the unneeded 5 pairs of parens in:
+             if ((model == 0x3c)                                                                                                                  
+                 || (model == 0x45)                                                                                                               
+                 || (model == 0x46)                                                                                                               
+                 /* Xeon E7 v3 has correct TSX if stepping >= 4.  */                                                                              
+                 || ((model == 0x3f) && (stepping < 4)))                                                                                          
?

	Jakub