21 May
2019
21 May
'19
1:54 a.m.
On Mon, May 20, 2019 at 01:53:29PM -0600, Mathieu Poirier wrote:
[...]
+static bool cs_etm_buffer_has_wrapped(unsigned char *buffer,
size_t buffer_size, u64 head)+{
u64 i, watermark;u64 *buf = (u64 *)buffer;size_t buf_size = buffer_size;/** We want to look the very last 512 byte (chosen arbitrarily) in* the ring buffer.*/watermark = buf_size - 512;/** @head is continuously increasing - if its value is equal or greater* than the size of the ring buffer, it has wrapped around.*/if (head >= buffer_size)return true;/** The value of @head is somewhere within the size of the ring buffer.* This can be that there hasn't been enough data to fill the ring* buffer yet or the trace time was so long that @head has numerically* wrapped around. To find we need to check if we have data at the very* end of the ring buffer. We can reliably do this because mmap'ed* pages are zeroed out and there is a fresh mapping with every new* session.*//* @head is less than 512 byte from the end of the ring buffer */if (head > watermark)watermark = head;/** Speed things up by using 64 bit transactions (see "u64 *buf" above)*/watermark >>= 3;buf_size >>= 3;/** If we find trace data at the end of the ring buffer, @head has* been there and has numerically wrapped around at least once.*/for (i = watermark; i < buf_size; i++)if (buf[i])I think here should be: if (buf[i << 3])
It would be if buf[] was a char *, but it is a u64 *.
You are right, I missed that. Sorry for noise.
Thanks, Leo Yan