MIPS: dec: prom: Address -Warray-bounds warning

Zero-length arrays are deprecated, and we are replacing them with flexible
array members instead. So, replace zero-length array with flexible-array
member in struct memmap.

Address the following warning found after building (with GCC-13) mips64
with decstation_64_defconfig:
In function 'rex_setup_memory_region',
inlined from 'prom_meminit' at arch/mips/dec/prom/memory.c:91:3:
arch/mips/dec/prom/memory.c:72:31: error: array subscript i is outside array bounds of 'unsigned char[0]' [-Werror=array-bounds=]
72 | if (bm->bitmap[i] == 0xff)
| ~~~~~~~~~~^~~
In file included from arch/mips/dec/prom/memory.c:16:
./arch/mips/include/asm/dec/prom.h: In function 'prom_meminit':
./arch/mips/include/asm/dec/prom.h:73:23: note: while referencing 'bitmap'
73 | unsigned char bitmap[0];

This helps with the ongoing efforts to globally enable -Warray-bounds.

This results in no differences in binary output.

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/323
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

DEC: Limit PMAX memory probing to R3k systems

Recent tightening of the opcode table in binutils so as to consistently
disallow the assembly or disassembly of CP0 instructions not supported
by the processor architecture chosen has caused a regression like below:

arch/mips/dec/prom/locore.S: Assembler messages:
arch/mips/dec/prom/locore.S:29: Error: opcode not supported on this processor: r4600 (mips3) `rfe'

in a piece of code used to probe for memory with PMAX DECstation models,
which have non-REX firmware. Those computers always have an R2000 CPU
and consequently the exception handler used in memory probing uses the
RFE instruction, which those processors use.

While adding 64-bit support this code was correctly excluded for 64-bit
configurations, however it should have also been excluded for irrelevant
32-bit configurations. Do this now then, and only enable PMAX memory
probing for R3k systems.

Reported-by: Jan-Benedict Glaw <jbglaw@lug-owl.de>
Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org # v2.6.12+
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MIPS: DEC/SNI: O32 wrapper stack switching fixes

Commit 231a35d37293ab88d325a9cb94e5474c156282c0 [[MIPS] RM: Collected
changes] broke DECstation support by introducing an incompatible copy of
arch/mips/dec/prom/call_o32.S in arch/mips/fw/lib/, built unconditionally.
The copy happens to land earlier of the two among the modules used in the
link and is therefore chosen for the DECstation rather than the intended
original. As a result random kernel data is corrupted because a pointer
to the "%s" formatted output template is used as a temporary stack pointer
rather than being passed down to prom_printf. This also explains why
prom_printf still works, up to a point -- the next argument is the actual
string to output so it works just fine as the output template until enough
kernel data has been corrupted to cause a crash.

This change adjusts the modified wrapper in arch/mips/fw/lib/call_o32.S to
let callers request no stack switching by passing a null temporary stack
pointer in $a1, reworks the DECstation callers to work with the updated
interface and removes the old copy from arch/mips/dec/prom/call_o32.S. A
few minor readability adjustments are included as well, most importantly
O32_SZREG is now used throughout where applicable rather than hardcoded
multiplies of 4 and $fp is used to access the argument save area as a more
usual register to operate the stack with rather than $s0.

Finally an update is made to the temporary stack space used by the SNI
platform to guarantee 8-byte alignment as per o32 requirements.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6668/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

DEC: Whitespace cleanup

Commit 7034228792cc561e79ff8600f02884bd4c80e287 [MIPS: Whitespace
cleanup.] did a lot of good and a little damage. Revert the damage.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5875/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Whitespace cleanup.

Having received another series of whitespace patches I decided to do this
once and for all rather than dealing with this kind of patches trickling
in forever.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

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

MIPS: Move headfiles to new location below arch/mips/include

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>