TIF_FPU is unused - remove it.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

The first invocation of kernel_fpu_begin() after switching from user to
kernel context will save all vector registers, even if only parts of the
vector registers are used within the kernel fpu context. Given that save
and restore of all vector registers is quite expensive change the current
approach in several ways:

- Instead of saving and restoring all user registers limit this to those
  registers which are actually used within an kernel fpu context.

- On context switch save all remaining user fpu registers, so they can be
  restored when the task is rescheduled.

- Saving user registers within kernel_fpu_begin() is done without disabling
  and enabling interrupts - which also slightly reduces runtime. In worst
  case (e.g. interrupt context uses the same registers) this may lead to
  the situation that registers are saved several times, however the
  assumption is that this will not happen frequently, so that the new
  method is faster in nearly all cases.

- save_user_fpu_regs() can still be called from all contexts and saves all
  (or all remaining) user registers to a tasks ufpu user fpu save area.

Overall this reduces the time required to save and restore the user fpu
context for nearly all cases.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

The kernel_fpu structure has a quite large size of 520 bytes. In order to
reduce stack footprint introduce several kernel fpu structures with
different and also smaller sizes. This way every kernel fpu user must use
the correct variant. A compile time check verifies that the correct variant
is used.

There are several users which use only 16 instead of all 32 vector
registers. For those users the new kernel_fpu_16 structure with a size of
only 266 bytes can be used.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Let fpu_vlm() and fpu_vstm() macros return the number of registers saved /
loaded. This is helpful to read easy to read code in case there are several
subsequent fpu_vlm() or fpu_vstm() calls:

	__vector128 *vxrs = ....

	vxrs += fpu_vstm(0, 15, vxrs);
	vxrs += fpu_vstm(16, 31, vxrs);
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

The anonymous union within struct fpu contains a floating point register
array and a vector register array. Given that the vector register is always
present remove the floating point register array. For configurations
without vector registers save the floating point register contents within
their corresponding vector register location.

This allows to remove the union, and also to simplify ptrace and perf code.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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 <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

KVM modifies the kernel fpu's regs pointer to its own area to implement its
custom version of preemtible kernel fpu context. With general support for
preemptible kernel fpu context there is no need for the extra complexity in
KVM code anymore.

Therefore convert KVM to a regular kernel fpu user. In particular this
means that all TIF_FPU checks can be removed, since the fpu register
context will never be changed by other kernel fpu users, and also the fpu
register context will be restored if a thread is preempted.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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 <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Change type of fpu mask consistently from u32 to int. This is a
prerequisite to make the kernel fpu usage preemptible. Upcoming code
uses __atomic* ops which work with int pointers.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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 <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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 <hca@linux.ibm.com>

Convert the rather large __kernel_fpu_begin()/__kernel_fpu_end() inline
assemblies to C. The C variant is much more readable, and this also allows
to get rid of the non-obvious usage of KERNEL_VXR_* constants within the
inline assemblies. E.g. "tmll %[m],6" correlates with the two bits set in
KERNEL_VXR_LOW. If the corresponding defines would be changed, the inline
assembles would break in a subtle way.

Therefore convert to C, use the proper defines, and allow the compiler to
generate code using the (hopefully) most efficient instructions.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Instead of open-coding vlm and vstm inline assemblies at several locations,
provide an fpu_* function for each instruction, and use them in the new
save_vx_regs() and load_vx_regs() helper functions.

Note that "O" and "R" inline assembly operand modifiers are used in order
to pass the displacement and base register of the memory operands to the
existing VLM and VSTM macros. The two operand modifiers are not available
for clang. Therefore provide two variants of each inline assembly.

The clang variant always uses and clobbers general purpose register 1, like
in the previous inline assemblies, so it can be used as base register with
a zero displacement. This generates slightly less efficient code, but can
be removed as soon as clang has support for the used operand modifiers.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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 <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Deduplicate the 64 ld and std inline assemblies. Provide an fpu inline
assembly for both instructions, and use them in the new save_fp_regs()
and load_fp_regs() helper functions.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

The only user of sfpc_safe() needs to read the new fpc register value
from memory before it is set with sfpc.

Avoid this indirection and use lfpc, which reads the new value from
memory. Also add the "fpu_" prefix to have a common name space for fpu
related inline assemblies, and provide memory access instrumentation.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Add documentation which describes what the fpu helper functions are
good for, and why they should be used.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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 <hca@linux.ibm.com>

Address various checkpatch warnings, adjust whitespace, and try to increase
readability. This is just preparation, in order to avoid that subsequent
patches contain any distracting drive-by coding style changes.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Use KERNEL_VXR_LOW instead of KERNEL_VXR_V0V7 for configurations without
vector registers in order to decide if floating point registers need to be
saved and restored.

Kernel FPU areas which use floating point registers are supposed to use the
KERNEL_FPR mask, however users may also open-code this and specify
KERNEL_VXR_V0V7 and/or KERNEL_VXR_V8V15. If only KERNEL_VXR_V8V15 is
specified floating point registers wouldn't be saved and restored. Improve
this and check for both bits.

There are currently no users where this would fix a bug.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Remove the historic machine check handler code which validates registers.
Registers are automatically validated as part of the machine check handling
sequence (see Principles of Operation, Machine-Check Handling chapter,
Validation).
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

The v1, v2, v3, and v4 parameters of the RXB macro are a bit misleading,
since the reader can assume that the parameters always correlate with the
instructions format fields V1, V2, V3, and V4 as defined in the Principles
of Operation.

This is not the case for a couple of instructions, therefore improve the
description of the macro.

Suggested by Jens Remus, who also provided the improved description.
Suggested-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

The VLGV macro generates the VLGV instruction and has a vr parameter which
correlates to the V3 vector register field of the instruction (bits 12-15).
Due to its position in the VRS-c instruction format of the VLGV
instruction, this field correlates to the second bit of the RXB byte of the
instruction (see Principles of Operation, Chapter "Vector Overview and
Support Instructions").

Within the VLGV macro the MRXBOPC macro is used to generate the RXB field
of the instruction. The usage of the MRXBOPC macro is incorrect, since the
vector register number is passed as third parameter (which correlates to
the first bit of the RXB byte), while it should be passed as fourth
parameter (second bit of the RXB byte). In result an incorrect instruction
would be generated if the VLGV macro would be used for vector register
numbers larger than 15.

Fix this and pass the vector register number as fourth parameter.

Currently there are no users within the kernel which use the macro in a way
that broken code would be generated.
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

This patch introduces dynamic debug hexdump invocation
possibilities to be able to:
- dump an CCA or EP11 CPRB request as early as possible
  when received via ioctl from userspace but after the
  ap message has been collected together.
- dump an CCA or EP11 CPRB reply short before it is
  transferred via ioctl into userspace.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

This patch introduces two dynamic debug hexdump
invocation possibilities to be able to a) dump an
AP message immediately before it goes into the
firmware queue and b) dump a fresh from the
firmware queue received AP message.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

This patch replaces all the s390 debug feature calls with
debug level by dynamic debug calls pr_debug. These calls
are much more flexible and each single invocation can get
enabled/disabled at runtime wheres the s390 debug feature
debug calls have only one knob - enable or disable all in
one bunch.

This patch follows a similar change for the AP bus and
zcrypt device driver code. All this code uses dynamic
debugging with pr_debug and friends for emitting debug
traces now.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Cleanup and harmonize the s390 debug feature calls
and defines for the pkey module to be similar to
the debug feature as it is used in the zcrypt device
driver and AP bus.

More or less only renaming but no functional changes.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

This patch replaces all the s390 debug feature calls with
debug level by dynamic debug calls pr_debug. These calls
are much more flexible and each single invocation can get
enabled/disabled at runtime wheres the s390 debug feature
debug calls have only one knob - enable or disable all in
one bunch. The benefit is especially significant with
high frequency called functions like the AP bus scan. In
most debugging scenarios you don't want and need them, but
sometimes it is crucial to know exactly when and how long
the AP bus scan took.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

This patch harmonizes the calls and defines around the
s390 debug feature as it is used in the AP bus and
zcrypt device driver code.

More or less cleanup and renaming, no functional changes.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Fix virtual vs physical address confusion. This does not fix a bug
since virtual and physical address spaces are currently the same.

/proc/iomem should report the physical address ranges, so use __pa_symbol()
for resource registration, similar to other architectures.
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

When building 'ARCH=s390 defconfig compat.config' with GCC and
LD=ld.lld, there is an error when attempting to link the compat vDSO:

  ld.lld: error: unknown emulation: elf_s390
  make[4]: *** [arch/s390/kernel/vdso32/Makefile:48: arch/s390/kernel/vdso32/vdso32.so.dbg] Error 1

Much like clang, ld.lld only supports the 64-bit s390 emulation. Add a
dependency on not using LLD to CONFIG_COMPAT to avoid breaking the build
with this toolchain combination.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20240214-s390-compat-lld-dep-v1-1-abf1f4b5e514@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>

When linking vdso64.so.dbg with ld.lld, there is a warning about not
finding _start for the starting address:

  ld.lld: warning: cannot find entry symbol _start; not setting start address

Fix this by removing the unused ENTRY in both vdso linker scripts. See
commit e2471728 ("powerpc/vdso: Remove unused ENTRY in linker
scripts"), which solved the same problem for powerpc, for further details.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Commit e21f8baf ("s390/bug: add entry size to the __bug_table section")
changed the __EMIT_BUG() inline assembly to emit mergeable __bug_table
entries. This is at least currently not needed, but causes problems with
the upcoming s390 ld.lld support:

  ld.lld: error: drivers/nvme/host/fc.o:(__bug_table): writable SHF_MERGE section is not supported

Therefore revert the change for now.
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/all/20240207-s390-lld-and-orphan-warn-v1-0-8a665b3346ab@kernel.org/Suggested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

ld.bfd defaults to '-z notext' (although it is customizable with the
'--enable-textrel-check' configure option) but ld.lld defaults to '-z
text', which causes issues with building the kernel due to the presence
of dynamic relocations in sections that are not writable.

  ld.lld: error: relocation R_390_64 cannot be used against local symbol; recompile with -fPIC

Add '-z notext' to avoid these errors, as this is expected, which
matches other architectures.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-11-8a665b3346ab@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>

Now that all sections have been properly accounted for in the s390
linker scripts, select CONFIG_ARCH_WANT_LD_ORPHAN_WARN so that
'--orphan-handling' is added to LDFLAGS to catch any future sections
that are added without being described in linker scripts.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-10-8a665b3346ab@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>

When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are several series of warnings
from the various discardable sections that the kernel adds for build
purposes that are not needed at runtime:

  s390-linux-ld: warning: orphan section `.export_symbol' from `arch/s390/boot/decompressor.o' being placed in section `.export_symbol'
  s390-linux-ld: warning: orphan section `.discard.addressable' from `arch/s390/boot/decompressor.o' being placed in section `.discard.addressable'
  s390-linux-ld: warning: orphan section `.modinfo' from `arch/s390/boot/decompressor.o' being placed in section `.modinfo'

include/asm-generic/vmlinux.lds.h has a macro for easily discarding
these sections across the kernel named COMMON_DISCARDS, use it to clear
up the warnings.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-9-8a665b3346ab@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>

When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there is a warning around the '.comment'
section for each file in arch/s390/boot

  s390-linux-ld: warning: orphan section `.comment' from `arch/s390/boot/als.o' being placed in section `.comment'
  s390-linux-ld: warning: orphan section `.comment' from `arch/s390/boot/startup.o' being placed in section `.comment'
  s390-linux-ld: warning: orphan section `.comment' from `arch/s390/boot/physmem_info.o' being placed in section `.comment'

include/asm-generic/vmlinux.lds.h has a macro for required ELF sections
not related to debugging named ELF_DETAILS, use it to clear up the
warnings.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-8-8a665b3346ab@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>

When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are several series of warnings for
each file in arch/s390/boot due to the boot linker script not handling
the DWARF debug sections:

  s390-linux-ld: warning: orphan section `.debug_line' from `arch/s390/boot/head.o' being placed in section `.debug_line'
  s390-linux-ld: warning: orphan section `.debug_info' from `arch/s390/boot/head.o' being placed in section `.debug_info'
  s390-linux-ld: warning: orphan section `.debug_abbrev' from `arch/s390/boot/head.o' being placed in section `.debug_abbrev'
  s390-linux-ld: warning: orphan section `.debug_aranges' from `arch/s390/boot/head.o' being placed in section `.debug_aranges'
  s390-linux-ld: warning: orphan section `.debug_str' from `arch/s390/boot/head.o' being placed in section `.debug_str'

include/asm-generic/vmlinux.lds.h has a macro for DWARF debug sections
named DWARF_DEBUG, use it to clear up the warnings.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-7-8a665b3346ab@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>

When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are several warnings from
arch/s390/boot/head.o due to the unhandled presence of '.rela' sections:

  s390-linux-ld: warning: orphan section `.rela.iplt' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.head.text' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.got' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.data' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.data.rel.ro' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.iplt' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.head.text' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.got' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.data' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.data.rel.ro' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'

These sections are unneeded for the decompressor and they are not
emitted in the binary currently. In a manner similar to other
architectures, coalesce the sections into '.rela.dyn' and ensure it is
zero sized, which is a safe/tested approach versus full discard.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-6-8a665b3346ab@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>

When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there is a warning about the presence of
an '.init.text' section in arch/s390/boot:

  s390-linux-ld: warning: orphan section `.init.text' from `arch/s390/boot/sclp_early_core.o' being placed in section `.init.text'

arch/s390/boot/sclp_early_core.c includes a file from the main kernel
build, which picks up a usage of '__init' somewhere. For the
decompressed image, this section can just be coalesced into '.text'.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-5-8a665b3346ab@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>