On Sun, 8 Sep 2013 12:04:27 -0700 Dave Taht <[email protected]> wrote:
> In light of the whole nsa hoo-ra (stuff like this) > > https://plus.google.com/u/0/117091380454742934025/posts/SDcoemc9V3J > > Ted Tso has pointed out to me that apparently mips' does not have a working > generic get_cycles() call, but instead returns 0 in all cases. > > e.g: In arch/mips/include/asm/timex.h: > > typedef unsigned int cycles_t; > > static inline cycles_t get_cycles(void) > { > return 0; > } > > Um..... > > get_cycles() is used in innumerable places in random.c. > > This is double plus ungood... I am REALLY hoping I'm merely misreading > the code... > > An example: > > (see drivers/char/random.c for how often it is used) > > /* > * Add device- or boot-specific data to the input and nonblocking > * pools to help initialize them to unique values. > * > * None of this adds any entropy, it is meant to avoid the > * problem of the nonblocking pool having similar initial state > * across largely identical devices. > */ > > void add_device_randomness(const void *buf, unsigned int size) > { > unsigned long time = get_cycles() ^ jiffies; > > ... > > So, what blocks having a working get_cycles in common mips architectures? In order to implement get_cycles() a high resolution hardware counter with quick access is necessary. _______________________________________________ Cerowrt-devel mailing list [email protected] https://lists.bufferbloat.net/listinfo/cerowrt-devel
