Fix the alloc_slabmgmt panic
Hopefully this should also fix a lot of other intermittent kernel bugs.
The problem has been around since 2.6.9-rc2-pa6 when we allowed
floating point registers to be used in kernel code. The essence of
the problem is that gcc prefers to use floating point for integer
divides and multiples. Further, it can rely on the values in the no
clobber fp regs being correct across a function call. Unfortunately,
our task switch function only saves the integer no clobber registers,
not the fp ones, so if gcc makes a function call to any function in
the kernel which could sleep, the values it is relying on in any no
clobber floating point register may be lost. In the case of
alloc_slabmgmt, the value of the page offset is being stored in %fr12
across a call to kmem_getpages(), which sleeps if no pages are
available. Thus, the offset can be trashed and the slab code can end
up with a completely bogus address leading to corruption.
Kudos to Randolph who came up with the program to trip this problem at
will and thus allowed it to be tracked and fixed.
Signed-off-by: James Bottomley <jejb@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2.6.12-rc4-pa3 : first pass at making sure use of RFI conforms to
PA 2.0 arch pages F-4 and F-5, PA 1.1 Arch page 3-19 and 3-20.
The discussion revolves around all the rules for clearing PSW Q-bit.
The hard part is meeting all the rules for "relied upon translation".
.align directive is used to guarantee the critical sequence ends more than
8 instructions (32 bytes) from the end of page.
Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
