[Cerowrt-devel] getting more randomness by improving MIPS get_cycles()
dave.taht at bufferbloat.net
Sun Sep 8 15:04:27 EDT 2013
In light of the whole nsa hoo-ra (stuff like this)
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)
get_cycles() is used in innumerable places in random.c.
This is double plus ungood... I am REALLY hoping I'm merely misreading
(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?
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