linux.git/arch/s390/kernel/process.c, branch v6.9

s390/fpu: remove regs member from struct fpu

2024-02-16T13:30:16+00:00

KVM was the only user which modified the regs pointer in struct fpu. Remove
the pointer and convert the rest of the core fpu code to directly access
the save area embedded within struct fpu.

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

s390/fpu: make kernel fpu context preemptible

2024-02-16T13:30:15+00:00

Make the kernel fpu context preemptible. Add another fpu structure to the
thread_struct, and use it to save and restore the kernel fpu context if its
task uses fpu registers when it is preempted.

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

s390/fpu: rename save_fpu_regs() to save_user_fpu_regs(), etc

2024-02-16T13:30:15+00:00

Rename save_fpu_regs(), load_fpu_regs(), and struct thread_struct's fpu
member to save_user_fpu_regs(), load_user_fpu_regs(), and ufpu. This way
the function and variable names reflect for which context they are supposed
to be used.

This large and trivial conversion is a prerequisite for making the kernel
fpu usage preemptible.

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

s390/fpu: convert FPU CIF flag to regular TIF flag

2024-02-16T13:30:15+00:00

The FPU state, as represented by the CIF_FPU flag reflects the FPU state of
a task, not the CPU it is running on. Therefore convert the flag to a
regular TIF flag.

This removes the magic in switch_to() where a save_fpu_regs() call for the
currently (previous) running task sets the per-cpu CIF_FPU flag, which is
required to restore FPU register contents of the next task, when it returns
to user space.

Signed-off-by: Heiko Carstens

s390/fpu: provide and use lfpc, sfpc, and stfpc inline assemblies

2024-02-16T13:30:15+00:00

Instead of open-coding lfpc, sfpc, and stfpc inline assemblies at
several locations, provide an fpu_* function for each instruction and
use the function instead.

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

s390/fpu: move, rename, and merge header files

2024-02-16T13:30:14+00:00

Move, rename, and merge the fpu and vx header files. This way fpu header
files have a consistent naming scheme (fpu*.h).

Also get rid of the fpu subdirectory and move header files to asm
directory, so that all fpu and vx header files can be found at the same
location.

Merge internal.h header file into other header files, since the internal
helpers are used at many locations. so those helper functions are really
not internal.

Signed-off-by: Heiko Carstens

s390/switch_to: use generic header file

2024-02-12T14:03:33+00:00

Move the switch_to() implementation to process.c and use the generic
switch_to.h header file instead, like some other architectures.

This addresses also the oddity that the old switch_to() implementation
assigns the return value of __switch_to() to 'prev' instead of 'last',
like it should.

Remove also all includes of switch_to.h from C files, except process.c.

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

s390/fpu: remove ARCH_WANTS_DYNAMIC_TASK_STRUCT support

2023-12-11T13:33:06+00:00

s390 selects ARCH_WANTS_DYNAMIC_TASK_STRUCT in order to make the size of
the task structure dependent on the availability of the vector
facility. This doesn't make sense anymore because since many years all
machines provide the vector facility.

Therefore simplify the code a bit and remove s390 support for
ARCH_WANTS_DYNAMIC_TASK_STRUCT.

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

s390: include linux/io.h instead of asm/io.h

2023-07-03T09:19:40+00:00

Include linux/io.h instead of asm/io.h everywhere. linux/io.h includes
asm/io.h, so this shouldn't cause any problems. Instead this might help for
some randconfig build errors which were reported due to some undefined io
related functions.

Also move the changed include so it stays grouped together with other
includes from the same directory.

For ctcm_mpc.c also remove not needed comments (actually questions).

Acked-by: Christian Borntraeger 
Signed-off-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev

s390: trim ancient junk from copy_thread()

2023-03-13T08:16:42+00:00

Setting and ->psw.addr in childregs of kernel thread is a rudiment of
the old kernel_thread()/kernel_execve() implementation.  Mainline hadn't
been using them since 2012.

And clarify the assignments to frame->sf.gprs - the array stores
grp6..gpr15 values to be set by __switch_to(), so frame->sf.gprs[5]
actually affects grp11, etc.

Better spell that as frame->sf.gprs[11 - 6]...

Signed-off-by: Al Viro 
Link: https://lore.kernel.org/r/ZAU6BYFisE8evmYf@ZenIV
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik