I got a bunch of segfaults which are due to HAS_LLSCD cpu operating
on a semaphore which is aligned along 4-byte boundary instead of the
desired 8-byte boundary.
I traced down one such place at serial/serial_core.c:
int uart_register_driver(struct uart_driver *drv)
{
struct tty_driver *normal = NULL;
int i, retval;
BUG_ON(drv->state);
/*
* Maybe we should be using a slab cache for this, especially if
* we have a large number of ports to handle.
*/
drv->state = kmalloc(sizeof(struct uart_state) * drv->nr, GFP_KERNEL);
...
where drv->state contains a semaphore variable, but apparently kmalloc() only
give 4-byte boundary alignment.
There are many other faults, which I did not bother to trace down.
Simply removing CPU_HAS_LLSCD makes the problem go away, which probably indicates
they are all of the same nature.
I wonder why this problem only shows up now while it did not show up
earlier when we introduced the new up(). Perhaps kmalloc() always
returns 8-byte aligned blocks?
I can't think of an immediate and good fix. Hopefully someone else smarter
than me can find a solution before I come back to it on Monday. :)
Jun
