From: "Jason A. Donenfeld" Jason@zx2c4.com
stable inclusion from stable-v5.10.119 commit 0b93f40cbe9712563bb15329768bd73c9c19ac03 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6BB
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit c04e72700f2293013dab40208e809369378f224c upstream.
In the event that random_get_entropy() can't access a cycle counter or similar, falling back to returning 0 is really not the best we can do. Instead, at least calling random_get_entropy_fallback() would be preferable, because that always needs to return _something_, even falling back to jiffies eventually. It's not as though random_get_entropy_fallback() is super high precision or guaranteed to be entropic, but basically anything that's not zero all the time is better than returning zero all the time.
Cc: Thomas Gleixner tglx@linutronix.de Cc: Arnd Bergmann arnd@arndb.de Acked-by: Dinh Nguyen dinguyen@kernel.org Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- arch/nios2/include/asm/timex.h | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/nios2/include/asm/timex.h b/arch/nios2/include/asm/timex.h index a769f871b28d..40a1adc9bd03 100644 --- a/arch/nios2/include/asm/timex.h +++ b/arch/nios2/include/asm/timex.h @@ -8,5 +8,8 @@ typedef unsigned long cycles_t;
extern cycles_t get_cycles(void); +#define get_cycles get_cycles + +#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())
#endif