m68k: Leave stack mangling to asm wrapper of sigreturn()

sigreturn has to deal with an unpleasant problem - exception stack frames
have different sizes, depending upon the exception (and processor model, as
well) and variable-sized part of exception frame may contain information
needed for instruction restart. So when signal handler terminates and calls
sigreturn to resume the execution at the place where we'd been when we caught
the signal, it has to rearrange the frame at the bottom of kernel stack.
Worse, it might need to open a gap in the kernel stack, shifting pt_regs
towards lower addresses.

Doing that from C is insane - we'd need to shift stack frames (return addresses,
local variables, etc.) of C call chain, right under the nose of compiler and
hope it won't fall apart horribly. What had been actually done is only slightly
less insane - an inline asm in mangle_kernel_stack() moved the stuff around,
then reset stack pointer and jumped to label in asm glue.

However, we can avoid all that mess if the asm wrapper we have to use anyway
would reserve some space on the stack between switch_stack and the C stack
frame of do_{rt_,}sigreturn(). Then C part can simply memmove() pt_regs +
switch_stack, memcpy() the variable part of exception frame into the opened
gap - all of that without inline asm, buggering C call chain, magical jumps
to asm labels, etc.

Asm wrapper would need to know where the moved switch_stack has ended up -
it might have been shifted into the gap we'd reserved before do_rt_sigreturn()
call. That's where it needs to set the stack pointer to. So let the C part
return just that and be done with that.

While we are at it, the call of berr_040cleanup() we need to do when
returning via 68040 bus error exception frame can be moved into C part
as well.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>
Tested-by: Finn Thain <fthain@linux-m68k.org>
Link: https://lore.kernel.org/r/YP2dTQPm1wGPWFgD@zeniv-ca.linux.org.uk
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

m68k: print memory layout info in boot log

Output a table of the kernel memory regions at boot time.
This is taken directly from the ARM architecture code that does this.
The table looks like this:

Virtual kernel memory layout:
vector : 0x00000000 - 0x00000400 ( 0 KiB)
kmap : 0xd0000000 - 0xe0000000 ( 256 MiB)
vmalloc : 0xc0000000 - 0xcfffffff ( 255 MiB)
lowmem : 0x00000000 - 0x02000000 ( 32 MiB)
.init : 0x00128000 - 0x00134000 ( 48 KiB)
.text : 0x00020000 - 0x00118d54 ( 996 KiB)
.data : 0x00118d60 - 0x00126000 ( 53 KiB)
.bss : 0x00134000 - 0x001413e0 ( 53 KiB)

This has been very useful while debugging the ColdFire virtual memory
support code. But in general I think it is nice to know extacly where
the kernel has layed everything out on boot.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>

m68knommu: correctly use trap_init

Currently trap_init() is an empty function for m68knommu. Instead
the vectors are being setup as part of the IRQ initialization.
This is inconsistent with m68k and other architectures.

Change the local init_vectors() to be trap_init(), and init the
vectors at the correct time during startup. This will help merge of
m68k and m68knommu trap code in the furture.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>

m68k/m68knommu: merge the MMU and non-MMU traps.h

The MMU and non-MMU versions of traps.h are virtually identical,
merge them into a single file.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

m68k,m68knommu: merge header files

Merge header files for m68k and m68knommu to the single location:

arch/m68k/include/asm

The majority of this patch was the result of the
script that is included in the changelog below.

The script was originally written by Arnd Bergman and
exten by me to cover a few more files.

When the header files differed the script uses the following:

The original m68k file is named <file>_mm.h [mm for memory manager]
The m68knommu file is named <file>_no.h [no for no memory manager]

The files uses the following include guard:

This include gaurd works as the m68knommu toolchain set
the __uClinux__ symbol - so this should work in userspace too.

Merging the header files for m68k and m68knommu exposes the
(unexpected?) ABI differences thus it is easier to actually
identify these and thus to fix them.

The commit has been build tested with both a m68k and
a m68knommu toolchain - with success.

The commit has also been tested with "make headers_check"
and this patch fixes make headers_check for m68knommu.

The script used:
TARGET=arch/m68k/include/asm
SOURCE=arch/m68knommu/include/asm

INCLUDE="cachectl.h errno.h fcntl.h hwtest.h ioctls.h ipcbuf.h \
linkage.h math-emu.h md.h mman.h movs.h msgbuf.h openprom.h \
oplib.h poll.h posix_types.h resource.h rtc.h sembuf.h shmbuf.h \
shm.h shmparam.h socket.h sockios.h spinlock.h statfs.h stat.h \
termbits.h termios.h tlb.h types.h user.h"

EQUAL="auxvec.h cputime.h device.h emergency-restart.h futex.h \
ioctl.h irq_regs.h kdebug.h local.h mutex.h percpu.h \
sections.h topology.h"

NOMUUFILES="anchor.h bootstd.h coldfire.h commproc.h dbg.h \
elia.h flat.h m5206sim.h m520xsim.h m523xsim.h m5249sim.h \
m5272sim.h m527xsim.h m528xsim.h m5307sim.h m532xsim.h \
m5407sim.h m68360_enet.h m68360.h m68360_pram.h m68360_quicc.h \
m68360_regs.h MC68328.h MC68332.h MC68EZ328.h MC68VZ328.h \
mcfcache.h mcfdma.h mcfmbus.h mcfne.h mcfpci.h mcfpit.h \
mcfsim.h mcfsmc.h mcftimer.h mcfuart.h mcfwdebug.h \
nettel.h quicc_simple.h smp.h"

FILES="atomic.h bitops.h bootinfo.h bug.h bugs.h byteorder.h cache.h \
cacheflush.h checksum.h current.h delay.h div64.h \
dma-mapping.h dma.h elf.h entry.h fb.h fpu.h hardirq.h hw_irq.h io.h \
irq.h kmap_types.h machdep.h mc146818rtc.h mmu.h mmu_context.h \
module.h page.h page_offset.h param.h pci.h pgalloc.h \
pgtable.h processor.h ptrace.h scatterlist.h segment.h \
setup.h sigcontext.h siginfo.h signal.h string.h system.h swab.h \
thread_info.h timex.h tlbflush.h traps.h uaccess.h ucontext.h \
unaligned.h unistd.h"

mergefile() {
BASE=${1%.h}
git mv ${SOURCE}/$1 ${TARGET}/${BASE}_no.h
git mv ${TARGET}/$1 ${TARGET}/${BASE}_mm.h

cat << EOF > ${TARGET}/$1
EOF

git add ${TARGET}/$1
}

set -e

mkdir -p ${TARGET}

git mv include/asm-m68k/* ${TARGET}
rmdir include/asm-m68k

git rm ${SOURCE}/Kbuild
for F in $INCLUDE $EQUAL; do
git rm ${SOURCE}/$F
done

for F in $NOMUUFILES; do
git mv ${SOURCE}/$F ${TARGET}/$F
done

for F in $FILES ; do
mergefile $F
done

rmdir arch/m68knommu/include/asm
rmdir arch/m68knommu/include

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>