The current LWS cas only works correctly for 32bit. The new LWS allows
for CAS operations of variable size.

Signed-off-by: Guy Martin <gmsoft@tuxicoman.be>
Cc: <stable@vger.kernel.org> # 3.13+
Signed-off-by: Helge Deller <deller@gmx.de>

The attached change significantly improves the performance of the LWS-CAS code
in syscall.S.
This allows a number of packages to build (e.g., zeromq3, gtest and libxs)
that previously failed because slow LWS-CAS performance under contention. In
particular, interrupts taken while the lock was taken degraded performance
significantly.

The change does the following:

1) Disables interrupts around the CAS operation, and
2) Changes the loads and stores to use the ordered completer, "o", on
PA 2.0. "o" and "ma" with a zero offset are equivalent. The latter is
accepted on both PA 1.X and 2.0.

The use of ordered loads and stores probably makes no difference on all
existing hardware, but it seemed pedantically correct. In particular, the CAS
operation must complete before LDCW lock is released. As written before, a
processor could reorder the operations.

I don't believe the period interrupts are disabled is long enough to
significantly increase interrupt latency. For example, the TLB insert code is
longer. Worst case is a memory fault in the CAS operation.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # 3.13+
Signed-off-by: Helge Deller <deller@gmx.de>

Provide a macro ASM_EXCEPTIONTABLE_ENTRY() to create exception table
entries and convert all open-coded places to use that macro.

This patch is a first step toward creating a exception table which only
holds 32bit pointers even on a 64bit kernel. That way in my own kernel
I was able to reduce the in-kernel exception table from 44kB to 22kB.

Signed-off-by: Helge Deller <deller@gmx.de>

Include some documentation about how the parisc gateway page technically
works and how it is used from userspace.

James Bottomley is the original author of this description and it was
copied here out of an email thread from Apr 12 2013 titled:
man2 : syscall.2 : document syscall calling conventions

CC: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Helge Deller <deller@gmx.de>

This patch fixes partly PAGE_SIZEs of 16K or 64K by adjusting the
assembler PTE lookup code and the assembler TEMPALIAS code.  Furthermore
some data alignments for PAGE_SIZE have been limited to 4K (or less) to
not waste too much memory with greater page sizes. As a side note, the
palo loader can (currently) only handle up to 10 ELF segments which is
fixed with tighter aligning as well.

My testings indicated that the ldci command in the sba iommu coding
needed adjustment by the PAGE_SHIFT value and that the I/O PDIR Page
size was only set to 4K for my machine (C3000).

All this fixes partly the boot, but there are still quite some caching
problems left.  Examples are e.g. the symbios logic driver which is
failing:

sym0: <896> rev 0x7 at pci 0000:00:0f.0 irq 69
sym0: PA-RISC Firmware, ID 7, Fast-40, SE, parity checking
CACHE TEST FAILED: DMA error (dstat=0x81).sym0: CACHE INCORRECTLY CONFIGURED.

and the tulip network driver which doesn't seem to work correctly
either:

Sending BOOTP requests .net eth0: Setting full-duplex based on MII#1
link partner capability of 05e1
..... timed out!

Beside those kernel fixes glibc will need fixes too to be able to handle
>4K page sizes.

Signed-off-by: Helge Deller <deller@gmx.de>

1) PTRACE_SYSCALL doesn't work for 64bit process on parisc64.
Compat syscall table is used instead of 64bit one.  IMO we should either
refuse to allow PTRACE_SYSCALL for 64bit processes or duplicate the
logics choosing the right syscall table into .Ltracesys.

	2) if you have let the tracee run with PTRACE_SYSCALL and
it had stopped, you can use PTRACE_POKEUSR to modify syscall number
(r20) and arguments 1--4 (r26--r23).  Modifications will have effect.
However, modifying arguments 5 and 6 (r22 and r21 resp.) works only
when process (32bit one) runs on 64bit host - on 32bit one it has no
effect.  AFAICS, the diff below should fix that one.

Signed-off-by: Al Viro <viro@ZenIV.linux.org.uk>
Tested-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Don't bother restoring r28 on syscall restarts; it's clobbered by
syscall anyway.  Reuse (now unused) ->orig_r28 as "no restarts allowed"
flag.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

1) Gate immediately and save a branch.
2) Fix off by one error in checking entry number.
3) Use sr7 instead of sr3 in error return path as sr3 might not
   contain correct value.
4) Enable locking on UP systems to prevent incorrect operation of
   the cas_action critical region on page faults.

Tested on several systems, including UP c3750 with 2.6.33.2 kernel.

Signed-off-by: John David Anglin <dave.anglin@nrc-cnrc.gc.ca>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>