On Tue, Oct 15, 2013 at 02:16:28PM -0400, Carlos O'Donell wrote:
> There is no effective security difference between accessing the randomized
> stack guard value from a global variable or a value stored in the dynamic
> thread vector.
>
> It is only a performance optimization. The choice of a global variable vs.
> DTV offset has only to do with the speed of access of the stack guard.
DTV access is of course going to be expensive, after all, that is a function
call, the question was about reserving a word at fixed constant offset from
the TLS base and how expensive that is vs. global variable access.
For soft FP I guess global variable access must win, for -mtp=cp15
]it depends on how fast the mrc instruction is.
Jakub
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