Let's assume the counter value is 0xf0000000, the pistachio clocksource
read cycles function should return ~0x0fffffff but actually it returns
0xffffffff0fffffff.
That occurs because:
~(cycle_t)value is different from (cycle_t)~value.
unsigned long val = ~(unsigned long)0xf0000000;
40049a: 48 b8 ff ff ff 0f ff movabs $0xffffffff0fffffff,%rax
unsigned long val = (unsigned long)~0xf0000000;
40049a: 48 c7 45 f8 ff ff ff movq $0xfffffff,-0x8(%rbp)
We fix this issue by calculating bitwise-not counter, then cast to
cycle_t.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Currently pistachio can be used as a scheduler clock. We properly marked
pistachio_read_sched_clock() as notrace but we then call another function
pistachio_clocksource_read_cycles() that _wasn't_ notrace.
Having a traceable function in the sched_clock() path leads to a recursion
within ftrace and a kernel crash.
Fix this by adding notrace attribute to the pistachio_clocksource_read_cycles()
function.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
