linux-toradex.git/arch/s390/kernel/early.c, branch v6.7

s390/cmma: move parsing of cmma kernel parameter to early boot code

2023-11-05T21:34:57+00:00

The "cmma=" kernel command line parameter needs to be parsed early for
upcoming changes. Therefore move the parsing code.

Note that EX_TABLE handling of cmma_test_essa() needs to be open-coded,
since the early boot code doesn't have infrastructure for handling expected
exceptions.

Reviewed-by: Claudio Imbrenda 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: use control register bit defines

2023-09-19T11:26:57+00:00

Use control register bit defines instead of plain numbers where
possible.

Reviewed-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/early: use system_ctl_set_bit() instead of local_ctl_set_bit()

2023-09-19T11:26:57+00:00

Use system_ctl_set_bit() instead of local_ctl_set_bit() to reflect
that the control register changes are supposed to be global. This
change is just for documentation purposes, since it still results only
in local control register contents being changed.

Signed-off-by: Heiko Carstens 
Reviewed-by: Alexander Gordeev 
Signed-off-by: Vasily Gorbik

s390/ctlreg: add local and system prefix to some functions

2023-09-19T11:26:56+00:00

Add local and system prefix to some functions to clarify they change
control register contents on either the local CPU or the on all CPUs.

This results in the following API:

Two defines which load and save multiple control registers.
The defines correlate with the following C prototypes:

void __local_ctl_load(unsigned long *, unsigned int cr_low, unsigned int cr_high);
void __local_ctl_store(unsigned long *, unsigned int cr_low, unsigned int cr_high);

Two functions which locally set or clear one bit for a specified
control register:

void local_ctl_set_bit(unsigned int cr, unsigned int bit);
void local_ctl_clear_bit(unsigned int cr, unsigned int bit);

Two functions which set or clear one bit for a specified control
register on all CPUs:

void system_ctl_set_bit(unsigned int cr, unsigned int bit);
void system_ctl_clear_bit(unsigend int cr, unsigned int bit);

Reviewed-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/smp,mcck: fix early IPI handling

2023-09-19T11:26:55+00:00

Both the external call as well as the emergency signal submask bits in
control register 0 are set before any interrupt handler is registered.

Change the order and first register the interrupt handler and only then
enable the interrupts by setting the corresponding bits in control
register 0.

This prevents that the second part of the machine check handler for
early machine check handling is not executed: the machine check handler
sends an IPI to the CPU it runs on. If the corresponding interrupts are
enabled, but no interrupt handler is present, the interrupt is ignored.

Reviewed-by: Sven Schnelle 
Acked-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/mm: simplify kernel mapping setup

2023-08-30T09:03:27+00:00

The kernel mapping is setup in two stages: in the decompressor map all
pages with RWX permissions, and within the kernel change all mappings to
their final permissions, where most of the mappings are changed from RWX to
RWNX.

Change this and map all pages RWNX from the beginning, however without
enabling noexec via control register modification. This means that
effectively all pages are used with RWX permissions like before. When the
final permissions have been applied to the kernel mapping enable noexec via
control register modification.

This allows to remove quite a bit of non-obvious code.

Reviewed-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens

s390: remove "noexec" option

2023-08-30T09:03:27+00:00

Do the same like x86 with commit 76ea0025a214 ("x86/cpu: Remove "noexec"")
and remove the "noexec" kernel command line option.

Reviewed-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens

s390/kasan: move shadow mapping to decompressor

2023-03-20T10:02:51+00:00

Since regular paging structs are initialized in decompressor already
move KASAN shadow mapping to decompressor as well. This helps to avoid
allocating KASAN required memory in 1 large chunk, de-duplicate paging
structs creation code and start the uncompressed kernel with KASAN
instrumentation right away. This also allows to avoid all pitfalls
accidentally calling KASAN instrumented code during KASAN initialization.

Acked-by: Heiko Carstens 
Reviewed-by: Alexander Gordeev 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens

s390/boot: remove non-functioning image bootable check

2023-03-20T10:02:50+00:00

check_image_bootable() has been introduced with commit 627c9b62058e
("s390/boot: block uncompressed vmlinux booting attempts") to make sure
that users don't try to boot uncompressed vmlinux ELF image in qemu. It
used to be possible quite some time ago. That commit prevented confusion
with uncompressed vmlinux image starting to boot and even printing
kernel messages until it crashed. Users might have tried to report the
problem without realizing they are doing something which was not intended.
Since commit f1d3c5323772 ("s390/boot: move sclp early buffer from fixed
address in asm to C") check_image_bootable() doesn't function properly
anymore, as well as booting uncompressed vmlinux image in qemu doesn't
really produce any output and crashes. Moving forward it doesn't make
sense to fix check_image_bootable() anymore, so simply remove it.

Acked-by: Alexander Gordeev 
Acked-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens

s390/setup: do not complain about parameters handled in decompressor

2023-02-27T14:29:36+00:00

Currently there are several kernel command line parameters which are
only parsed and handled in decompressor and not known to the kernel.
This leads to the following error message during kernel boot:

Unknown kernel command line parameters "mem=3G nokaslr", will be passed
to user space.

To avoid confusion, register those parameters with an empty stub so that
kernel does not complain about them.

Reported-by: Gerald Schaefer 
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens