s390/boot: Add exception table support

The early boot code contains various open-coded inline assemblies with
exception handling. In order to handle possible exceptions each of them
changes the prog

s390/boot: Add exception table support

The early boot code contains various open-coded inline assemblies with
exception handling. In order to handle possible exceptions each of them
changes the program check new psw, and restores it.

In order to simplify the various inline assemblies add simple exception
table support: the program check handler is called with a fully populated
pt_regs on the stack and may change the psw and register members. When the
program check handler returns the psw and registers from pt_regs will be
used to continue execution.

The program check handler searches the exception table for an entry which
matches the address of the program check. If such an entry is found the psw
address within pt_regs on the stack is replaced with a fixup address, and
execution continues at the new address.

If no entry is found the psw is changed to a disabled wait psw and
execution stops.

Before entering the C part of the program check handler the address of the
program check new psw is replaced to a minimalistic handler.
This is supposed to help against program check loops. If an exception
happens while in program check processing the register contents of the
original exception are restored and a disabled wait psw is loaded.

Acked-by: Alexander Gordeev <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>

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s390/boot: Move boot_printk() code to own file

Keep the printk code separate from the program check code and move
boot_printk() and helper functions to own printk.c file.

Reviewed-by: Sven Schnelle

s390/boot: Move boot_printk() code to own file

Keep the printk code separate from the program check code and move
boot_printk() and helper functions to own printk.c file.

Reviewed-by: Sven Schnelle <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390/boot: Compile all files with the same march flag

Only a couple of files of the decompressor are compiled with the
minimum architecture level. This is problematic for potential function
calls be

s390/boot: Compile all files with the same march flag

Only a couple of files of the decompressor are compiled with the
minimum architecture level. This is problematic for potential function
calls between compile units, especially if a target function is within
a compile until compiled for a higher architecture level, since that
may lead to an unexpected operation exception.

Therefore compile all files of the decompressor for the same (minimum)
architecture level.

Reviewed-by: Sven Schnelle <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390/boot: Increase minimum architecture to z10

The decompressor code is partially compiled with march=z900 so it is
possible to print an error message in case a kernel is booted on a
machine which

s390/boot: Increase minimum architecture to z10

The decompressor code is partially compiled with march=z900 so it is
possible to print an error message in case a kernel is booted on a
machine which misses facilities to execute the kernel.

Given that the decompressor code also includes header files from the
core kernel this causes problems for inline assemblies and other code
where the minimum assumed architecture level is set to z10 in the
meantime. If such code is also used in the decompressor (e.g. inline
functions) z900 support must be implemented again.

In order to avoid this and to keep things simple just raise the
minimum architecture level to z10 for the decompressor just like for
the kernel.

Reviewed-by: Sven Schnelle <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390/build: Avoid relocation information in final vmlinux

Since commit 778666df60f0 ("s390: compile relocatable kernel without
-fPIE") the kernel vmlinux ELF file is linked with --emit-relocs to
pre

s390/build: Avoid relocation information in final vmlinux

Since commit 778666df60f0 ("s390: compile relocatable kernel without
-fPIE") the kernel vmlinux ELF file is linked with --emit-relocs to
preserve all relocations, so that all absolute relocations can be
extracted using the 'relocs' tool to adjust them during boot.

Port and adapt Petr Pavlu's x86 commit 9d9173e9ceb6 ("x86/build: Avoid
relocation information in final vmlinux") to s390 to strip all
relocations from the final vmlinux ELF file to optimize its size.
Following is his original commit message with minor adaptions for s390:

The Linux build process on s390 roughly consists of compiling all input
files, statically linking them into a vmlinux ELF file, and then taking
and turning this file into an actual bzImage bootable file.

vmlinux has in this process two main purposes:
1) It is an intermediate build target on the way to produce the final
bootable image.
2) It is a file that is expected to be used by debuggers and standard
ELF tooling to work with the built kernel.

For the second purpose, a vmlinux file is typically collected by various
package build recipes, such as distribution spec files, including the
kernel's own tar-pkg target.

When building the kernel vmlinux contains also relocation information
produced by using the --emit-relocs linker option. This is utilized by
subsequent build steps to create relocs.S and produce a relocatable
image. However, the information is not needed by debuggers and other
standard ELF tooling.

The issue is then that the collected vmlinux file and hence distribution
packages end up unnecessarily large because of this extra data. The
following is a size comparison of vmlinux v6.10 with and without the
relocation information:

| Configuration | With relocs | Stripped relocs |
| defconfig | 696 MB | 320 MB |
| -CONFIG_DEBUG_INFO | 48 MB | 32 MB |

Optimize a resulting vmlinux by adding a postlink step that splits the
relocation information into relocs.S and then strips it from the vmlinux
binary.

Reviewed-by: Vasily Gorbik <[email protected]>
Signed-off-by: Jens Remus <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>

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s390: Remove protvirt and kvm config guards for uv code

Removing the CONFIG_PROTECTED_VIRTUALIZATION_GUEST ifdefs and config
option as well as CONFIG_KVM ifdefs in uv files.

Having this configurabl

s390: Remove protvirt and kvm config guards for uv code

Removing the CONFIG_PROTECTED_VIRTUALIZATION_GUEST ifdefs and config
option as well as CONFIG_KVM ifdefs in uv files.

Having this configurable has been more of a pain than a help.
It's time to remove the ifdefs and the config option.

Signed-off-by: Janosch Frank <[email protected]>
Acked-by: Christian Borntraeger <[email protected]>
Acked-by: Heiko Carstens <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>

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s390/alternatives: Allow early alternative patching in decompressor

Add the required code to patch alternatives early in the decompressor.
This is required for the upcoming lowcore relocation change

s390/alternatives: Allow early alternative patching in decompressor

Add the required code to patch alternatives early in the decompressor.
This is required for the upcoming lowcore relocation changes, where
alternatives for facility 193 need to get patched before lowcore
alternatives.

Reviewed-by: Alexander Gordeev <[email protected]>
Co-developed-by: Heiko Carstens <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>
Signed-off-by: Sven Schnelle <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>

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s390/boot: add the KMSAN runtime stub

It should be possible to have inline functions in the s390 header files,
which call kmsan_unpoison_memory(). The problem is that these header
files might be in

s390/boot: add the KMSAN runtime stub

It should be possible to have inline functions in the s390 header files,
which call kmsan_unpoison_memory(). The problem is that these header
files might be included by the decompressor, which does not contain KMSAN
runtime, causing linker errors.

Not compiling these calls if __SANITIZE_MEMORY__ is not defined - either
by changing kmsan-checks.h or at the call sites - may cause unintended
side effects, since calling these functions from an uninstrumented code
that is linked into the kernel is valid use case.

One might want to explicitly distinguish between the kernel and the
decompressor. Checking for a decompressor-specific #define is quite
heavy-handed, and will have to be done at all call sites.

A more generic approach is to provide a dummy kmsan_unpoison_memory()
definition. This produces some runtime overhead, but only when building
with CONFIG_KMSAN. The benefit is that it does not disturb the existing
KMSAN build logic and call sites don't need to be changed.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ilya Leoshkevich <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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s390/boot: turn off KMSAN

All other sanitizers are disabled for boot as well. While at it, add a
comment explaining why we need this.

Link: https://lkml.kernel.org/r/20240621113706.315500-23-iii@l

s390/boot: turn off KMSAN

All other sanitizers are disabled for boot as well. While at it, add a
comment explaining why we need this.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ilya Leoshkevich <[email protected]>
Reviewed-by: Alexander Gordeev <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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s390: Compile kernel with -fPIC and link with -no-pie

When the kernel is built with CONFIG_PIE_BUILD option enabled it
uses dynamic symbols, for which the linker does not allow more
than 64K number

s390: Compile kernel with -fPIC and link with -no-pie

When the kernel is built with CONFIG_PIE_BUILD option enabled it
uses dynamic symbols, for which the linker does not allow more
than 64K number of entries. This can break features like kpatch.

Hence, whenever possible the kernel is built with CONFIG_PIE_BUILD
option disabled. For that support of unaligned symbols generated by
linker scripts in the compiler is necessary.

However, older compilers might lack such support. In that case the
build process resorts to CONFIG_PIE_BUILD option-enabled build.

Compile object files with -fPIC option and then link the kernel
binary with -no-pie linker option.

As result, the dynamic symbols are not generated and not only kpatch
feature succeeds, but also the whole CONFIG_PIE_BUILD option-enabled
code could be dropped.

[ agordeev: Reworded the commit message ]

Suggested-by: Ulrich Weigand <[email protected]>
Signed-off-by: Sumanth Korikkar <[email protected]>
Reviewed-by: Alexander Gordeev <[email protected]>
Signed-off-by: Alexander Gordeev <[email protected]>

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s390: adjust indentation of RELOCS command build step out

Common pattern in non-verbose build output for quiet commands is that the
shorthand of a command including whitespace contains at least eigh

s390: adjust indentation of RELOCS command build step out

Common pattern in non-verbose build output for quiet commands is that the
shorthand of a command including whitespace contains at least eight
characters. Adjust this for the RELOCS command, which comes only with seven
characters.

Before:
SORTTAB vmlinux
CC arch/s390/boot/version.o
RELOCS arch/s390/boot/relocs.S
OBJCOPY arch/s390/boot/info.bin

After:
SORTTAB vmlinux
CC arch/s390/boot/version.o
RELOCS arch/s390/boot/relocs.S
OBJCOPY arch/s390/boot/info.bin

Signed-off-by: Heiko Carstens <[email protected]>
Signed-off-by: Alexander Gordeev <[email protected]>

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s390/boot: workaround current 'llvm-objdump -t -j ...' behavior

When building with OBJDUMP=llvm-objdump, there are a series of warnings
from the section comparisons that arch/s390/boot/Makefile perf

s390/boot: workaround current 'llvm-objdump -t -j ...' behavior

When building with OBJDUMP=llvm-objdump, there are a series of warnings
from the section comparisons that arch/s390/boot/Makefile performs
between vmlinux and arch/s390/boot/vmlinux:

llvm-objdump: warning: section '.boot.preserved.data' mentioned in a -j/--section option, but not found in any input file
llvm-objdump: warning: section '.boot.data' mentioned in a -j/--section option, but not found in any input file
llvm-objdump: warning: section '.boot.preserved.data' mentioned in a -j/--section option, but not found in any input file
llvm-objdump: warning: section '.boot.data' mentioned in a -j/--section option, but not found in any input file

The warning is a little misleading, as these sections do exist in the
input files. It is really pointing out that llvm-objdump does not match
GNU objdump's behavior of respecting '-j' / '--section' in combination
with '-t' / '--syms':

$ s390x-linux-gnu-objdump -t -j .boot.data vmlinux.full

vmlinux.full: file format elf64-s390

SYMBOL TABLE:
0000000001951000 l O .boot.data 0000000000003000 sclp_info_sccb
00000000019550e0 l O .boot.data 0000000000000001 sclp_info_sccb_valid
00000000019550e2 g O .boot.data 0000000000001000 early_command_line
...

$ llvm-objdump -t -j .boot.data vmlinux.full

vmlinux.full: file format elf64-s390

SYMBOL TABLE:
0000000000100040 l O .text 0000000000000010 dw_psw
0000000000000000 l df *ABS* 0000000000000000 main.c
00000000001001b0 l F .text 00000000000000c6 trace_event_raw_event_initcall_level
0000000000100280 l F .text 0000000000000100 perf_trace_initcall_level
...

It may be possible to change llvm-objdump's behavior to match GNU
objdump's behavior but the difficulty of that task has not yet been
explored. The combination of '$(OBJDUMP) -t -j' is not common in the
kernel tree on a whole, so workaround this tool difference by grepping
for the sections in the full symbol table output in a similar manner to
the sed invocation. This results in no visible change for GNU objdump
users while fixing the warnings for OBJDUMP=llvm-objdump, further
enabling use of LLVM=1 for ARCH=s390 with versions of LLVM that have
support for s390 in ld.lld and llvm-objcopy.

Reported-by: Heiko Carstens <[email protected]>
Closes: https://lore.kernel.org/[email protected]/
Link: https://github.com/ClangBuiltLinux/linux/issues/859
Signed-off-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/20240220-s390-work-around-llvm-objdump-t-j-v1-1-47bb0366a831@kernel.org
Signed-off-by: Heiko Carstens <[email protected]>

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s390: compile relocatable kernel without -fPIE

On s390, currently kernel uses the '-fPIE' compiler flag for compiling
vmlinux. This has a few problems:

- It uses dynamic symbols (.dynsym), for w

s390: compile relocatable kernel without -fPIE

On s390, currently kernel uses the '-fPIE' compiler flag for compiling
vmlinux. This has a few problems:

- It uses dynamic symbols (.dynsym), for which the linker refuses to
allow more than 64k sections. This can break features which use
'-ffunction-sections' and '-fdata-sections', including kpatch-build
[1] and Function Granular KASLR.

- It unnecessarily uses GOT relocations, adding an extra layer of
indirection for many memory accesses.

Instead of using '-fPIE', resolve all the relocations at link time and
then manually adjust any absolute relocations (R_390_64) during boot.

This is done by first telling the linker to preserve all relocations
during the vmlinux link. (Note this is harmless: they are later
stripped in the vmlinux.bin link.)

Then use the 'relocs' tool to find all absolute relocations (R_390_64)
which apply to allocatable sections. The offsets of those relocations
are saved in a special section which is then used to adjust the
relocations during boot.

(Note: For some reason, Clang occasionally creates a GOT reference, even
without '-fPIE'. So Clang-compiled kernels have a GOT, which needs to
be adjusted.)

On my mostly-defconfig kernel, this reduces kernel text size by ~1.3%.

[1] https://github.com/dynup/kpatch/issues/1284
[2] https://gcc.gnu.org/pipermail/gcc-patches/2023-June/622872.html
[3] https://gcc.gnu.org/pipermail/gcc-patches/2023-August/625986.html

Compiler consideration:

Gcc recently implemented an optimization [2] for loading symbols without
explicit alignment, aligning with the IBM Z ELF ABI. This ABI mandates
symbols to reside on a 2-byte boundary, enabling the use of the larl
instruction. However, kernel linker scripts may still generate unaligned
symbols. To address this, a new -munaligned-symbols option has been
introduced [3] in recent gcc versions. This option has to be used with
future gcc versions.

Older Clang lacks support for handling unaligned symbols generated
by kernel linker scripts when the kernel is built without -fPIE. However,
future versions of Clang will include support for the -munaligned-symbols
option. When the support is unavailable, compile the kernel with -fPIE
to maintain the existing behavior.

In addition to it:
move vmlinux.relocs to safe relocation

When the kernel is built with CONFIG_KERNEL_UNCOMPRESSED, the entire
uncompressed vmlinux.bin is positioned in the bzImage decompressor
image at the default kernel LMA of 0x100000, enabling it to be executed
in-place. However, the size of .vmlinux.relocs could be large enough to
cause an overlap with the uncompressed kernel at the address 0x100000.
To address this issue, .vmlinux.relocs is positioned after the
.rodata.compressed in the bzImage. Nevertheless, in this configuration,
vmlinux.relocs will overlap with the .bss section of vmlinux.bin. To
overcome that, move vmlinux.relocs to a safe location before clearing
.bss and handling relocs.

Compile warning fix from Sumanth Korikkar:

When kernel is built with CONFIG_LD_ORPHAN_WARN and -fno-PIE, there are
several warnings:

ld: warning: orphan section `.rela.iplt' from
`arch/s390/kernel/head64.o' being placed in section `.rela.dyn'
ld: warning: orphan section `.rela.head.text' from
`arch/s390/kernel/head64.o' being placed in section `.rela.dyn'
ld: warning: orphan section `.rela.init.text' from
`arch/s390/kernel/head64.o' being placed in section `.rela.dyn'
ld: warning: orphan section `.rela.rodata.cst8' from
`arch/s390/kernel/head64.o' being placed in section `.rela.dyn'

Orphan sections are sections that exist in an object file but don't have
a corresponding output section in the final executable. ld raises a
warning when it identifies such sections.

Eliminate the warning by placing all .rela orphan sections in .rela.dyn
and raise an error when size of .rela.dyn is greater than zero. i.e.
Dont just neglect orphan sections.

This is similar to adjustment performed in x86, where kernel is built
with -fno-PIE.
commit 5354e84598f2 ("x86/build: Add asserts for unwanted sections")

[[email protected]: rebased Josh Poimboeuf patches and move
vmlinux.relocs to safe location]
[[email protected]: merged compile warning fix from Sumanth]
Tested-by: Sumanth Korikkar <[email protected]>
Acked-by: Vasily Gorbik <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Sumanth Korikkar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Heiko Carstens <[email protected]>

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s390/boot: add 'alloc' to info.bin .vmlinux.info section flags

When attempting to boot a kernel compiled with OBJCOPY=llvm-objcopy,
there is a crash right at boot:

Out of memory allocating 6d7800

s390/boot: add 'alloc' to info.bin .vmlinux.info section flags

When attempting to boot a kernel compiled with OBJCOPY=llvm-objcopy,
there is a crash right at boot:

Out of memory allocating 6d7800 bytes 8 aligned in range 0:20000000
Reserved memory ranges:
0000000000000000 a394c3c30d90cdaf DECOMPRESSOR
Usable online memory ranges (info source: sclp read info [3]):
0000000000000000 0000000020000000
Usable online memory total: 20000000 Reserved: a394c3c30d90cdaf Free: 0
Call Trace:
(sp:0000000000033e90 [<0000000000012fbc>] physmem_alloc_top_down+0x5c/0x104)
sp:0000000000033f00 [<0000000000011d56>] startup_kernel+0x3a6/0x77c
sp:0000000000033f60 [<00000000000100f4>] startup_normal+0xd4/0xd4

GNU objcopy does not have any issues. Looking at differences between the
object files in each build reveals info.bin does not get properly
populated with llvm-objcopy, which results in an empty .vmlinux.info
section.

$ file {gnu,llvm}-objcopy/arch/s390/boot/info.bin
gnu-objcopy/arch/s390/boot/info.bin: data
llvm-objcopy/arch/s390/boot/info.bin: empty

$ llvm-readelf --section-headers {gnu,llvm}-objcopy/arch/s390/boot/vmlinux | rg 'File:|\.vmlinux\.info|\.decompressor\.syms'
File: gnu-objcopy/arch/s390/boot/vmlinux
[12] .vmlinux.info PROGBITS 0000000000034000 035000 000078 00 WA 0 0 1
[13] .decompressor.syms PROGBITS 0000000000034078 035078 000b00 00 WA 0 0 1
File: llvm-objcopy/arch/s390/boot/vmlinux
[12] .vmlinux.info PROGBITS 0000000000034000 035000 000000 00 WA 0 0 1
[13] .decompressor.syms PROGBITS 0000000000034000 035000 000b00 00 WA 0 0 1

Ulrich points out that llvm-objcopy only copies sections marked as alloc
with a binary output target, whereas the .vmlinux.info section is only
marked as load. Add 'alloc' in addition to 'load', so that both objcopy
implementations work properly:

$ file {gnu,llvm}-objcopy/arch/s390/boot/info.bin
gnu-objcopy/arch/s390/boot/info.bin: data
llvm-objcopy/arch/s390/boot/info.bin: data

$ llvm-readelf --section-headers {gnu,llvm}-objcopy/arch/s390/boot/vmlinux | rg 'File:|\.vmlinux\.info|\.decompressor\.syms'
File: gnu-objcopy/arch/s390/boot/vmlinux
[12] .vmlinux.info PROGBITS 0000000000034000 035000 000078 00 WA 0 0 1
[13] .decompressor.syms PROGBITS 0000000000034078 035078 000b00 00 WA 0 0 1
File: llvm-objcopy/arch/s390/boot/vmlinux
[12] .vmlinux.info PROGBITS 0000000000034000 035000 000078 00 WA 0 0 1
[13] .decompressor.syms PROGBITS 0000000000034078 035078 000b00 00 WA 0 0 1

Closes: https://github.com/ClangBuiltLinux/linux/issues/1996
Link: https://github.com/llvm/llvm-project/commit/3c02cb7492fc78fb678264cebf57ff88e478e14f
Suggested-by: Ulrich Weigand <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/20240216-s390-fix-boot-with-llvm-objcopy-v1-1-0ac623daf42b@kernel.org
Signed-off-by: Heiko Carstens <[email protected]>

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s390/boot: add support for CONFIG_LD_ORPHAN_WARN

arch/s390/boot/vmlinux uses a different linker script and build rules
than the main vmlinux, so the '--orphan-handling' flag is not applied to
it. Ad

s390/boot: add support for CONFIG_LD_ORPHAN_WARN

arch/s390/boot/vmlinux uses a different linker script and build rules
than the main vmlinux, so the '--orphan-handling' flag is not applied to
it. Add support for '--orphan-handling' so that all sections are
properly described in the linker script, which helps eliminate bugs
between linker implementations having different orphan section
heuristics.

Signed-off-by: Nathan Chancellor <[email protected]>
Tested-by: Justin Stitt <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Heiko Carstens <[email protected]>

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s390/boot: rename mem_detect to physmem_info

In preparation to extending mem_detect with additional information like
reserved ranges rename it to more generic physmem_info. This new naming
also help

s390/boot: rename mem_detect to physmem_info

In preparation to extending mem_detect with additional information like
reserved ranges rename it to more generic physmem_info. This new naming
also help to avoid confusion by using more exact terms like "physmem
online ranges", etc.

Acked-by: Heiko Carstens <[email protected]>
Reviewed-by: Alexander Gordeev <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390/decompressor: add link map saving

Produce arch/s390/boot/vmlinux.map link map for the decompressor, when
CONFIG_VMLINUX_MAP option is enabled.

Link map is quite useful during making kernel cha

s390/decompressor: add link map saving

Produce arch/s390/boot/vmlinux.map link map for the decompressor, when
CONFIG_VMLINUX_MAP option is enabled.

Link map is quite useful during making kernel changes related to how
the decompressor is composed and debugging linker scripts.

Acked-by: Heiko Carstens <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390/mm: start kernel with DAT enabled

The setup of the kernel virtual address space is spread
throughout the sources, boot stages and config options
like this:

1. The available physical memory reg

s390/mm: start kernel with DAT enabled

The setup of the kernel virtual address space is spread
throughout the sources, boot stages and config options
like this:

1. The available physical memory regions are queried
and stored as mem_detect information for later use
in the decompressor.

2. Based on the physical memory availability the virtual
memory layout is established in the decompressor;

3. If CONFIG_KASAN is disabled the kernel paging setup
code populates kernel pgtables and turns DAT mode on.
It uses the information stored at step [1].

4. If CONFIG_KASAN is enabled the kernel early boot
kasan setup populates kernel pgtables and turns DAT
mode on. It uses the information stored at step [1].

The kasan setup creates early_pg_dir directory and
directly overwrites swapper_pg_dir entries to make
shadow memory pages available.

Move the kernel virtual memory setup to the decompressor
and start the kernel with DAT turned on right from the
very first istruction. That completely eliminates the
boot phase when the kernel runs in DAT-off mode, simplies
the overall design and consolidates pgtables setup.

The identity mapping is created in the decompressor, while
kasan shadow mappings are still created by the early boot
kernel code.

Share with decompressor the existing kasan memory allocator.
It decreases the size of a newly requested memory block from
pgalloc_pos and ensures that kernel image is not overwritten.
pgalloc_low and pgalloc_pos pointers are made preserved boot
variables for that.

Use the bootdata infrastructure to setup swapper_pg_dir
and invalid_pg_dir directories used by the kernel later.
The interim early_pg_dir directory established by the
kasan initialization code gets eliminated as result.

As the kernel runs in DAT-on mode only the PSW_KERNEL_BITS
define gets PSW_MASK_DAT bit by default. Additionally, the
setup_lowcore_dat_off() and setup_lowcore_dat_on() routines
get merged, since there is no DAT-off mode stage anymore.

The memory mappings are created with RW+X protection that
allows the early boot code setting up all necessary data
and services for the kernel being booted. Just before the
paging is enabled the memory protection is changed to
RO+X for text, RO+NX for read-only data and RW+NX for
kernel data and the identity mapping.

Reviewed-by: Heiko Carstens <[email protected]>
Signed-off-by: Alexander Gordeev <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390: always build relocatable kernel

Nathan Chancellor reported several link errors on s390 with
CONFIG_RELOCATABLE disabled, after binutils commit 906f69cf65da ("IBM
zSystems: Issue error for *DBL

s390: always build relocatable kernel

Nathan Chancellor reported several link errors on s390 with
CONFIG_RELOCATABLE disabled, after binutils commit 906f69cf65da ("IBM
zSystems: Issue error for *DBL relocs on misaligned symbols"). The binutils
commit reveals potential miscompiles that might have happened already
before with linker script defined symbols at odd addresses.

A similar bug was recently fixed in the kernel with commit c9305b6c1f52
("s390: fix nospec table alignments").

See https://github.com/ClangBuiltLinux/linux/issues/1747 for an analysis
from Ulich Weigand.

Therefore always build a relocatable kernel to avoid this problem. There is
hardly any use-case for non-relocatable kernels, so this shouldn't be
controversial.

Link: https://github.com/ClangBuiltLinux/linux/issues/1747
Signed-off-by: Heiko Carstens <[email protected]>
Reported-by: Nathan Chancellor <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexander Gordeev <[email protected]>

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s390/boot: convert initial lowcore to C

Convert initial lowcore to C and use proper defines and structures to
initialize it. This should make the z/VM ipl procedure a bit less magic.

Acked-by: Pete

s390/boot: convert initial lowcore to C

Convert initial lowcore to C and use proper defines and structures to
initialize it. This should make the z/VM ipl procedure a bit less magic.

Acked-by: Peter Oberparleiter <[email protected]>
Reviewed-by: Vasily Gorbik <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390/boot: get rid of startup archive

The final kernel image is created by linking decompressor object files with
a startup archive. The startup archive file however does not contain only
optional c

s390/boot: get rid of startup archive

The final kernel image is created by linking decompressor object files with
a startup archive. The startup archive file however does not contain only
optional code and data which can be discarded if not referenced. It also
contains mandatory object data like head.o which must never be discarded,
even if not referenced.

Move the decompresser code and linker script to the boot directory and get
rid of the startup archive so everything is kept during link time.

Acked-by: Vasily Gorbik <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390: move the install rule to arch/s390/Makefile

Currently, the install target in arch/s390/Makefile descends into
arch/s390/boot/Makefile to invoke the shell script, but there is no
good reason to

s390: move the install rule to arch/s390/Makefile

Currently, the install target in arch/s390/Makefile descends into
arch/s390/boot/Makefile to invoke the shell script, but there is no
good reason to do so.

arch/s390/Makefile can run the shell script directly.

Signed-off-by: Masahiro Yamada <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Heiko Carstens <[email protected]>

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s390: enable KCSAN

s390x GCC and SystemZ Clang have ThreadSanitizer support now [1] [2],
so enable KCSAN for s390.

[1] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=ea22954e7c58
[2] https://reviews

s390: enable KCSAN

s390x GCC and SystemZ Clang have ThreadSanitizer support now [1] [2],
so enable KCSAN for s390.

[1] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=ea22954e7c58
[2] https://reviews.llvm.org/D105629

Signed-off-by: Ilya Leoshkevich <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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s390/boot: move dma sections from decompressor to decompressed kernel

This change simplifies the task of making the decompressor relocatable.

The decompressor's image contains special DMA sections

s390/boot: move dma sections from decompressor to decompressed kernel

This change simplifies the task of making the decompressor relocatable.

The decompressor's image contains special DMA sections between _sdma and
_edma. This DMA segment is loaded at boot as part of the decompressor and
then simply handed over to the decompressed kernel. The decompressor itself
never uses it in any way. The primary reason for this is the need to keep
the aforementioned DMA segment below 2GB which is required by architecture,
and because the decompressor is always loaded at a fixed low physical
address, it is guaranteed that the DMA region will not cross the 2GB
memory limit. If the DMA region had been placed in the decompressed kernel,
then KASLR would make this guarantee impossible to fulfill or it would
be restricted to the first 2GB of memory address space.

This commit moves all DMA sections between _sdma and _edma from
the decompressor's image to the decompressed kernel's image. The complete
DMA region is placed in the init section of the decompressed kernel and
immediately relocated below 2GB at start-up before it is needed by other
parts of the decompressed kernel. The relocation of the DMA region happens
even if the decompressed kernel is already located below 2GB in order
to keep the first implementation simple. The relocation should not have
any noticeable impact on boot time because the DMA segment is only a couple
of pages.

After relocating the DMA sections, the kernel has to fix all references
which point into it. In order to automate this, place all variables
pointing into the DMA sections in a special .dma.refs section. All such
variables must be defined using the new __dma_ref macro. Only variables
containing addresses within the DMA sections must be placed in the new
.dma.refs section.

Furthermore, move the initialization of control registers from
the decompressor to the decompressed kernel because some control registers
reference tables that must be placed in the DMA data section to
guarantee that their addresses are below 2G. Because the decompressed
kernel relocates the DMA sections at startup, the content of control
registers CR2, CR5 and CR15 must be updated with new addresses after
the relocation. The decompressed kernel initializes all control registers
early at boot and then updates the content of CR2, CR5 and CR15
as soon as the DMA relocation has occurred. This practically reverts
the commit a80313ff91ab ("s390/kernel: introduce .dma sections").

Signed-off-by: Alexander Egorenkov <[email protected]>
Acked-by: Heiko Carstens <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

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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 <[email protected]>
Reviewed-by: Vasily Gorbik <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>

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