[linuxsh-dev] Cache bug on SH-3/4

[Paul M. <pau...@ti...>]

I've hit what looks to be another cache bug (looks like its an alias
issue), and so far it seems to hit both SH-3 and 4. (I haven't tested
SH-2 or 5 yet).

The problem pops up when doing an mmap() of /dev/zero and then reading
from it, the read is sometimes 0, but most of the time ends up getting
back garbage and promptly segfaulting.

I've attached my testcode for this as well. The fault happens right on
the read.

I've managed to fix this on SH-4 (patch attached) by doing an all out
flush_cache_all() after the activate_context() in switch_mm() .. not a
very optimal solution, but seems to do the right thing for now.

Unfortunately this same fix doesn't help SH-3 any (after implicitly
wrapping flush_cache_all() to cache_wback_all()).

Anyone seen this before?

Regards,

-- 
Paul Mundt <pau...@ti...>
TimeSys Corporation