s390/boot: enable .bss section for compressed kernel

- Support static uninitialized variables in compressed kernel.
- Remove chkbss script
- Get rid of workarounds for not having .bss section

Signe

s390/boot: enable .bss section for compressed kernel

- Support static uninitialized variables in compressed kernel.
- Remove chkbss script
- Get rid of workarounds for not having .bss section

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390: fix __EMIT_BUG() macro

Setting a kprobe on getname_flags() failed:

$ echo 'p:tmr1 getname_flags +0(%r2):ustring' > kprobe_events
-bash: echo: write error: Invalid argument

Debugging the kpro

s390: fix __EMIT_BUG() macro

Setting a kprobe on getname_flags() failed:

$ echo 'p:tmr1 getname_flags +0(%r2):ustring' > kprobe_events
-bash: echo: write error: Invalid argument

Debugging the kprobes code showed that the address of
getname_flags() is contained in the __bug_table. Kprobes
doesn't allow to set probes at BUG() locations.

$ objdump -j __bug_table -x build/fs/namei.o
[..]
0000000000000108 R_390_PC32 .text+0x00000000000075a8
000000000000010c R_390_PC32 .L223+0x0000000000000004

I was expecting getname_flags() to start with a BUG(), but:

7598: e3 20 10 00 00 04 lg %r2,0(%r1)
759e: c0 f4 00 00 00 00 jg 759e <putname+0x7e>
75a0: R_390_PLT32DBL kmem_cache_free+0x2
75a4: a7 f4 00 01 j 75a6 <putname+0x86>

00000000000075a8 <getname_flags>:
75a8: c0 04 00 00 00 00 brcl 0,75a8 <getname_flags>
75ae: eb 6f f0 48 00 24 stmg %r6,%r15,72(%r15)
75b4: b9 04 00 ef lgr %r14,%r15
75b8: e3 f0 ff a8 ff 71 lay %r15,-88(%r15)

So the BUG() is actually the last opcode of the previous function.
Fix this by switching to using the MONITOR CALL (MC) instruction,
and set the entry in __bug_table to the beginning of that MC.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/startup: add pgm check info printing

Try to print out startup pgm check info including exact linux kernel
version, pgm interruption code and ilc, psw and general registers. Like
the following:

s390/startup: add pgm check info printing

Try to print out startup pgm check info including exact linux kernel
version, pgm interruption code and ilc, psw and general registers. Like
the following:

Linux version 5.3.0-rc7-07282-ge7b4d41d61bd-dirty (gor@tuxmaker) #3 SMP PREEMPT Thu Sep 5 16:07:34 CEST 2019
Kernel fault: interruption code 0005 ilc:2
PSW : 0000000180000000 0000000000012e52
R:0 T:0 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:0 CC:0 PM:0 RI:0 EA:3
GPRS: 0000000000000000 00ffffffffffffff 0000000000000000 0000000000019a58
000000000000bf68 0000000000000000 0000000000000000 0000000000000000
0000000000000000 0000000000000000 000000000001a041 0000000000000000
0000000004c9c000 0000000000010070 0000000000012e42 000000000000beb0

This info makes it apparent that kernel startup failed and might help
to understand what went wrong without actual standalone dump.

Printing code runs on its own stack of 1 page (at unused 0x5000), which
should be sufficient for sclp_early_printk usage (typical stack usage
observed has been around 512 bytes).

The code has pgm check recursion prevention, despite pgm check info
printing failure (follow on pgm check) or success it restores original
faulty psw and gprs and does disabled wait.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

show more ...

s390/startup: add initial pgm check handler

The startup code is getting more complicated with features like kaslr and
secure boot in place. In a potential unexpected startup code crash case
the syst

s390/startup: add initial pgm check handler

The startup code is getting more complicated with features like kaslr and
secure boot in place. In a potential unexpected startup code crash case
the system would end up in a pgm check loop at address 0, overwriting
pgm check old psw value and just making debugging more complicated. To
avoid that introduce startup program check handler which is active
immediately after kernel start and until early_pgm_check_handler is set
in kernel/early.c. So it covers kernel relocation phase and transition
to it. This pgm check handler simply saves general/control registers and
psw in the save area which should guarantee that we still have something
to look at when standalone dumper is called without saving registers. And
it does disabled wait with a faulty address in the end.

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390: enable detection of kernel version from bzImage

Extend "parmarea" to include an offset of the version string, which is
stored as 8-byte big endian value.

To retrieve version string from bzIma

s390: enable detection of kernel version from bzImage

Extend "parmarea" to include an offset of the version string, which is
stored as 8-byte big endian value.

To retrieve version string from bzImage reliably, one should check the
presence of "S390EP" ascii string at 0x10008 (available since v3.2),
then read the version string offset from 0x10428 (which has been 0
since v3.2 up to now). The string is null terminated.

Could be retrieved with the following "file" command magic (requires
file v5.34):
8 string \x02\x00\x00\x18\x60\x00\x00\x50\x02\x00\x00\x68\x60\x00\x00\x50\x40\x40\x40\x40\x40\x40\x40\x40 Linux S390
>0x10008 string S390EP
>>0x10428 bequad >0
>>>(0x10428.Q) string >\0 \b, version %s

Reported-by: Petr Tesarik <ptesarik@suse.com>
Suggested-by: Petr Tesarik <ptesarik@suse.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

show more ...

s390/kernel: introduce .dma sections

With a relocatable kernel that could reside at any place in memory, code
and data that has to stay below 2 GB needs special handling.

This patch introduces .dma

s390/kernel: introduce .dma sections

With a relocatable kernel that could reside at any place in memory, code
and data that has to stay below 2 GB needs special handling.

This patch introduces .dma sections for such text, data and ex_table.
The sections will be part of the decompressor kernel, so they will not
be relocated and stay below 2 GB. Their location is passed over to the
decompressed / relocated kernel via the .boot.preserved.data section.

The duald and aste for control register setup also need to stay below
2 GB, so move the setup code from arch/s390/kernel/head64.S to
arch/s390/boot/head.S. The duct and linkage_stack could reside above
2 GB, but their content has to be preserved for the decompresed kernel,
so they are also moved into the .dma section.

The start and end address of the .dma sections is added to vmcoreinfo,
for crash support, to help debugging in case the kernel crashed there.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/sclp: do not use static sccbs

The sccbs for init/read/sdias/early have to be located below 2 GB, and
they are currently defined as a static buffer.

With a relocatable kernel that could reside

s390/sclp: do not use static sccbs

The sccbs for init/read/sdias/early have to be located below 2 GB, and
they are currently defined as a static buffer.

With a relocatable kernel that could reside at any place in memory, this
will no longer guarantee the location below 2 GB, so use a dynamic
GFP_DMA allocation instead.

The sclp_early_sccb buffer needs special handling, as it can be used
very early, and by both the decompressor and also the decompressed
kernel. Therefore, a fixed 4 KB buffer is introduced at 0x11000, the
former PARMAREA_END. The new PARMAREA_END is now 0x12000, and it is
renamed to HEAD_END, as it is rather the end of head.S and not the end
of the parmarea.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/kexec_file: Simplify parmarea access

Access the parmarea in head.S via a struct instead of individual offsets.

While at it make the fields in the parmarea .quads.

Signed-off-by: Philipp Rudo

s390/kexec_file: Simplify parmarea access

Access the parmarea in head.S via a struct instead of individual offsets.

While at it make the fields in the parmarea .quads.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/head: avoid doubling early boot stack size under KASAN

Early boot stack uses predefined 4 pages of memory 0x8000-0xC000. This
stack is used to run not instumented decompressor/facilities
verifi

s390/head: avoid doubling early boot stack size under KASAN

Early boot stack uses predefined 4 pages of memory 0x8000-0xC000. This
stack is used to run not instumented decompressor/facilities
verification C code. It doesn't make sense to double its size when
the kernel is built with KASAN support. BOOT_STACK_ORDER is introduced
to avoid that.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390: remove decompressor's head.S

Decompressor's head.S provided "data mover" sole purpose of which has
been to safely move uncompressed kernel at 0x100000 and jump to it.

With current bzImage lay

s390: remove decompressor's head.S

Decompressor's head.S provided "data mover" sole purpose of which has
been to safely move uncompressed kernel at 0x100000 and jump to it.

With current bzImage layout entire decompressor's code guaranteed to be
in a safe location under 0x100000, and hence could not be overwritten
during kernel move. For that reason head.S could be replaced with simple
memmove function. To do so introduce early boot code phase which is
executed from arch/s390/boot/head.S after "verify_facilities" and takes
care of optional kernel image decompression and transition to it.

Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390: clean up stacks setup

Replace hard coded stack frame overhead values with STACK_FRAME_OVERHEAD
definition. Avoid unnecessary arithmetic instructions.

Signed-off-by: Vasily Gorbik <gor@linux.i

s390: clean up stacks setup

Replace hard coded stack frame overhead values with STACK_FRAME_OVERHEAD
definition. Avoid unnecessary arithmetic instructions.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390: add initial 64-bit restart PSW

To be able to start a kernel image loaded into memory with a
PSW restart, place a 64-bit restart PSW at 0x1a0 in absolute
lowcore.

Suggested-by: Dominik Klein <

s390: add initial 64-bit restart PSW

To be able to start a kernel image loaded into memory with a
PSW restart, place a 64-bit restart PSW at 0x1a0 in absolute
lowcore.

Suggested-by: Dominik Klein <dominik.klein@linux.ibm.com>
Tested-by: Dominik Klein <dominik.klein@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/boot: block uncompressed vmlinux booting attempts

Since the plain vmlinux ELF file no longer carries all necessary parts
for starting up (like the entry point and decompressor), add a check
whi

s390/boot: block uncompressed vmlinux booting attempts

Since the plain vmlinux ELF file no longer carries all necessary parts
for starting up (like the entry point and decompressor), add a check
which would block boot process and encourage users to use bzImage or
arch/s390/boot/compressed/vmlinux instead.

The check relies on s390 linux entry point ABI definition, which is only
present in bzImage and arch/s390/boot/compressed/vmlinux.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/decompressor: support uncompressed kernel

Implement uncompressed kernel support (when "None" is picked in kernel
compression mode list). In that case an actual decompression code is
skipped and

s390/decompressor: support uncompressed kernel

Implement uncompressed kernel support (when "None" is picked in kernel
compression mode list). In that case an actual decompression code is
skipped and control is passed from boot/head.S to startup_continue in
kernel/head64.S. To achieve that uncompressed kernel payload is
conditionally put at 0x100000 in bzImage.

In reality this is very close to classic uncompressed kernel "image",
but the decompressor has its own build and link process,
kernel/head64.S lives at 0x100000 rather than at 0x11000, and .bss
section is reused for both stages.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/decompressor: rename entry point to startup_decompressor

Rename the decompressor entry point to startup_decompressor to
avoid confusion, leaving startup_continue as the entry point of the
uncom

s390/decompressor: rename entry point to startup_decompressor

Rename the decompressor entry point to startup_decompressor to
avoid confusion, leaving startup_continue as the entry point of the
uncompressed image.

Also remove obsolete comment, as the decompressor code is
unconditionally called from boot/head.S now.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/boot: make head.S and als.c be part of the decompressor only

Since uncompressed kernel image does not have to be bootable anymore,
move head.S, head_kdump.S and als.c to boot/ folder and compil

s390/boot: make head.S and als.c be part of the decompressor only

Since uncompressed kernel image does not have to be bootable anymore,
move head.S, head_kdump.S and als.c to boot/ folder and compile them
in just in the decompressor.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/startup: avoid save_area_sync overflow

Currently we overflow save_area_sync and write over
save_area_async. Although this is not a real problem make
startup_pgm_check_handler co

s390/startup: avoid save_area_sync overflow

Currently we overflow save_area_sync and write over
save_area_async. Although this is not a real problem make
startup_pgm_check_handler consistent with late pgm check handler and
store [%r0,%r7] directly into gpregs_save_area.

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/boot: avoid unnecessary zeroing of .bss section

.bss section is a part of the decompressor's image now, linker fills it
with zeros already. No need do it with memset additionally.

s390/boot: avoid unnecessary zeroing of .bss section

.bss section is a part of the decompressor's image now, linker fills it
with zeros already. No need do it with memset additionally.

Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/boot: enable .bss section for compressed kernel

- Support static uninitialized variables in compressed kernel.
- Remove chkbss script
- Get rid of workarounds for not having .bs

s390/boot: enable .bss section for compressed kernel

- Support static uninitialized variables in compressed kernel.
- Remove chkbss script
- Get rid of workarounds for not having .bss section

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390: fix __EMIT_BUG() macro

Setting a kprobe on getname_flags() failed:

$ echo 'p:tmr1 getname_flags +0(%r2):ustring' > kprobe_events
-bash: echo: write error: Invalid argument

s390: fix __EMIT_BUG() macro

Setting a kprobe on getname_flags() failed:

$ echo 'p:tmr1 getname_flags +0(%r2):ustring' > kprobe_events
-bash: echo: write error: Invalid argument

Debugging the kprobes code showed that the address of
getname_flags() is contained in the __bug_table. Kprobes
doesn't allow to set probes at BUG() locations.

$ objdump -j __bug_table -x build/fs/namei.o
[..]
0000000000000108 R_390_PC32 .text+0x00000000000075a8
000000000000010c R_390_PC32 .L223+0x0000000000000004

I was expecting getname_flags() to start with a BUG(), but:

7598: e3 20 10 00 00 04 lg %r2,0(%r1)
759e: c0 f4 00 00 00 00 jg 759e <putname+0x7e>
75a0: R_390_PLT32DBL kmem_cache_free+0x2
75a4: a7 f4 00 01 j 75a6 <putname+0x86>

00000000000075a8 <getname_flags>:
75a8: c0 04 00 00 00 00 brcl 0,75a8 <getname_flags>
75ae: eb 6f f0 48 00 24 stmg %r6,%r15,72(%r15)
75b4: b9 04 00 ef lgr %r14,%r15
75b8: e3 f0 ff a8 ff 71 lay %r15,-88(%r15)

So the BUG() is actually the last opcode of the previous function.
Fix this by switching to using the MONITOR CALL (MC) instruction,
and set the entry in __bug_table to the beginning of that MC.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/startup: add pgm check info printing

Try to print out startup pgm check info including exact linux kernel
version, pgm interruption code and ilc, psw and general registers. Like

s390/startup: add pgm check info printing

Try to print out startup pgm check info including exact linux kernel
version, pgm interruption code and ilc, psw and general registers. Like
the following:

Linux version 5.3.0-rc7-07282-ge7b4d41d61bd-dirty (gor@tuxmaker) #3 SMP PREEMPT Thu Sep 5 16:07:34 CEST 2019
Kernel fault: interruption code 0005 ilc:2
PSW : 0000000180000000 0000000000012e52
R:0 T:0 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:0 CC:0 PM:0 RI:0 EA:3
GPRS: 0000000000000000 00ffffffffffffff 0000000000000000 0000000000019a58
000000000000bf68 0000000000000000 0000000000000000 0000000000000000
0000000000000000 0000000000000000 000000000001a041 0000000000000000
0000000004c9c000 0000000000010070 0000000000012e42 000000000000beb0

This info makes it apparent that kernel startup failed and might help
to understand what went wrong without actual standalone dump.

Printing code runs on its own stack of 1 page (at unused 0x5000), which
should be sufficient for sclp_early_printk usage (typical stack usage
observed has been around 512 bytes).

The code has pgm check recursion prevention, despite pgm check info
printing failure (follow on pgm check) or success it restores original
faulty psw and gprs and does disabled wait.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

show more ...

s390/startup: add initial pgm check handler

The startup code is getting more complicated with features like kaslr and
secure boot in place. In a potential unexpected startup code crash c

s390/startup: add initial pgm check handler

The startup code is getting more complicated with features like kaslr and
secure boot in place. In a potential unexpected startup code crash case
the system would end up in a pgm check loop at address 0, overwriting
pgm check old psw value and just making debugging more complicated. To
avoid that introduce startup program check handler which is active
immediately after kernel start and until early_pgm_check_handler is set
in kernel/early.c. So it covers kernel relocation phase and transition
to it. This pgm check handler simply saves general/control registers and
psw in the save area which should guarantee that we still have something
to look at when standalone dumper is called without saving registers. And
it does disabled wait with a faulty address in the end.

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390: enable detection of kernel version from bzImage

Extend "parmarea" to include an offset of the version string, which is
stored as 8-byte big endian value.

To retrieve versi

s390: enable detection of kernel version from bzImage

Extend "parmarea" to include an offset of the version string, which is
stored as 8-byte big endian value.

To retrieve version string from bzImage reliably, one should check the
presence of "S390EP" ascii string at 0x10008 (available since v3.2),
then read the version string offset from 0x10428 (which has been 0
since v3.2 up to now). The string is null terminated.

Could be retrieved with the following "file" command magic (requires
file v5.34):
8 string \x02\x00\x00\x18\x60\x00\x00\x50\x02\x00\x00\x68\x60\x00\x00\x50\x40\x40\x40\x40\x40\x40\x40\x40 Linux S390
>0x10008 string S390EP
>>0x10428 bequad >0
>>>(0x10428.Q) string >\0 \b, version %s

Reported-by: Petr Tesarik <ptesarik@suse.com>
Suggested-by: Petr Tesarik <ptesarik@suse.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

show more ...

s390/kernel: introduce .dma sections

With a relocatable kernel that could reside at any place in memory, code
and data that has to stay below 2 GB needs special handling.

This p

s390/kernel: introduce .dma sections

With a relocatable kernel that could reside at any place in memory, code
and data that has to stay below 2 GB needs special handling.

This patch introduces .dma sections for such text, data and ex_table.
The sections will be part of the decompressor kernel, so they will not
be relocated and stay below 2 GB. Their location is passed over to the
decompressed / relocated kernel via the .boot.preserved.data section.

The duald and aste for control register setup also need to stay below
2 GB, so move the setup code from arch/s390/kernel/head64.S to
arch/s390/boot/head.S. The duct and linkage_stack could reside above
2 GB, but their content has to be preserved for the decompresed kernel,
so they are also moved into the .dma section.

The start and end address of the .dma sections is added to vmcoreinfo,
for crash support, to help debugging in case the kernel crashed there.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...

s390/sclp: do not use static sccbs

The sccbs for init/read/sdias/early have to be located below 2 GB, and
they are currently defined as a static buffer.

With a relocatable kerne

s390/sclp: do not use static sccbs

The sccbs for init/read/sdias/early have to be located below 2 GB, and
they are currently defined as a static buffer.

With a relocatable kernel that could reside at any place in memory, this
will no longer guarantee the location below 2 GB, so use a dynamic
GFP_DMA allocation instead.

The sclp_early_sccb buffer needs special handling, as it can be used
very early, and by both the decompressor and also the decompressed
kernel. Therefore, a fixed 4 KB buffer is introduced at 0x11000, the
former PARMAREA_END. The new PARMAREA_END is now 0x12000, and it is
renamed to HEAD_END, as it is rather the end of head.S and not the end
of the parmarea.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

show more ...