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The s390 specific diag288_wdt watchdog driver makes use of the virtual
watchdog timer, which is available in most machine configurations.
If executing the diagnose instruction with subcode 0x288 results in an
exception the watchdog timer is not available, otherwise it is available.
In order to allow module autoload of the diag288_wdt module, move the
detection of the virtual watchdog timer to early boot code, and provide
its availability as a cpu feature.
This allows to make use of module_cpu_feature_match() to automatically load
the module iff the virtual watchdog timer is available.
Suggested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Tested-by: Mete Durlu <meted@linux.ibm.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20250410095036.1525057-1-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Use asm_inline for all inline assemblies which make use of the EX_TABLE or
ALTERNATIVE macros.
These macros expand to many lines and the compiler assumes the number of
lines within an inline assembly is the same as the number of instructions
within an inline assembly. This has an effect on inlining and loop
unrolling decisions.
In order to avoid incorrect assumptions use asm_inline, which tells the
compiler that an inline assembly has the smallest possible size.
In order to avoid confusion when asm_inline should be used or not, since a
couple of inline assemblies are quite large: the rule is to always use
asm_inline whenever the EX_TABLE or ALTERNATIVE macro is used. In specific
cases there may be reasons to not follow this guideline, but that should
be documented with the corresponding code.
Using the inline qualifier everywhere has only a small effect on the kernel
image size:
add/remove: 0/10 grow/shrink: 19/8 up/down: 1492/-1858 (-366)
The only location where this seems to matter is load_unaligned_zeropad()
from word-at-a-time.h where the compiler inlines more functions within the
dcache code, which is indeed code where performance matters.
Suggested-by: Juergen Christ <jchrist@linux.ibm.com>
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Shorten detect_diag9c() and use regular EX_TABLE program check handling.
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Shorten cmma_test_essa() and use regular EX_TABLE program check handling.
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Instead of having a private cpu_has_vx() implementation use the new common
cpu feature method. Move the facility detection to the decompressor so it
matches all other cpu features.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Move machine type detection to the decompressor and use static branches
to implement and use machine_is_[lpar|vm|kvm]() instead of a runtime check
via MACHINE_IS_[LPAR|VM|KVM].
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use static branch(es) to implement and use machine_has_diag9c() instead of
a runtime check via MACHINE_HAS_DIAG9C.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use static branch(es) to implement and use machine_has_tx() instead of
a runtime check with MACHINE_HAS_TE.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use static branch(es) to implement and use machine_has_tlb_guest()
instead of a runtime check via MACHINE_HAS_TLB_GUEST.
Also add sclp_early_detect_machine_features() in order to allow for
feature detection from the decompressor.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use static branch(es) to implement and use machine_has_scc() instead
of a runtime check via MACHINE_HAS_SCC.
This comes with a cleanup of early time initialization: the initial
tod_clock_base value is now passed via the bootdata mechanism, instead
of using absolute lowcore as transport vehicle from the decompressor
to the kernel.
Also the early tod clock initialization is moved to the decompressor
which allows to use a static branch with machine_has_scc() within the
kernel.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Remove MACHINE_FLAG_PCI_MIO/MACHINE_HAS_PCI_MIO and implement the identical
functionality with set_machine_feature(), clear_machine_feature() and
test_machine_feature().
Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Convert the explicit relocated lowcore alternative type to a more
generic machine feature. This only reduces the number of alternative
types, but has no impact on code generation.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Convert MACHINE_HAS_... to cpu_has_...() which uses test_facility() instead
of testing the machine_flags lowcore member if the feature is present.
test_facility() generates better code since it results in a static branch
without accessing memory. The branch is patched via alternatives by the
decompressor depending on the availability of the required facility.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Convert MACHINE_HAS_... to cpu_has_...() which uses test_facility() instead
of testing the machine_flags lowcore member if the feature is present.
test_facility() generates better code since it results in a static branch
without accessing memory. The branch is patched via alternatives by the
decompressor depending on the availability of the required facility.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Convert MACHINE_HAS_... to cpu_has_...() which uses test_facility() instead
of testing the machine_flags lowcore member if the feature is present.
test_facility() generates better code since it results in a static branch
without accessing memory. The branch is patched via alternatives by the
decompressor depending on the availability of the required facility.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull more s390 updates from Alexander Gordeev:
- The rework that uncoupled physical and virtual address spaces
inadvertently prevented KASAN shadow mappings from using large pages.
Restore large page mappings for KASAN shadows
- Add decompressor routine physmem_alloc() that may fail, unlike
physmem_alloc_or_die(). This allows callers to implement fallback
paths
- Allow falling back from large pages to smaller pages (1MB or 4KB) if
the allocation of 2GB pages in the decompressor can not be fulfilled
- Add to the decompressor boot print support of "%%" format string,
width and padding hadnling, length modifiers and decimal conversion
specifiers
- Add to the decompressor message severity levels similar to kernel
ones. Support command-line options that control console output
verbosity
- Replaces boot_printk() calls with appropriate loglevel- specific
helpers such as boot_emerg(), boot_warn(), and boot_debug().
- Collect all boot messages into a ring buffer independent of the
current log level. This is particularly useful for early crash
analysis
- If 'earlyprintk' command line parameter is not specified, store
decompressor boot messages in a ring buffer to be printed later by
the kernel, once the console driver is registered
- Add 'bootdebug' command line parameter to enable printing of
decompressor debug messages when needed. That parameters allows
message suppressing and filtering
- Dump boot messages on a decompressor crash, but only if 'bootdebug'
command line parameter is enabled
- When CONFIG_PRINTK_TIME is enabled, add timestamps to boot messages
in the same format as regular printk()
- Dump physical memory tracking information on boot: online ranges,
reserved areas and vmem allocations
- Dump virtual memory layout and randomization details
- Improve decompression error reporting and dump the message ring
buffer in case the boot failed and system halted
- Add an exception handler which handles exceptions when FPU control
register is attempted to be set to an invalid value. Remove '.fixup'
section as result of this change
- Use 'A', 'O', and 'R' inline assembly format flags, which allows
recent Clang compilers to generate better FPU code
- Rework uaccess code so it reads better and generates more efficient
code
- Cleanup futex inline assembly code
- Disable KMSAN instrumention for futex inline assemblies, which
contain dereferenced user pointers. Otherwise, shadows for the user
pointers would be accessed
- PFs which are not initially configured but in standby create only a
single-function PCI domain. If they are configured later on, sibling
PFs and their child VFs will not be added to their PCI domain
breaking SR-IOV expectations.
Fix that by allowing initially configured but in standby PFs create
multi-function PCI domains
- Add '-std=gnu11' to decompressor and purgatory CFLAGS to avoid
compile errors caused by kernel's own definitions of 'bool', 'false',
and 'true' conflicting with the C23 reserved keywords
- Fix sclp subsystem failure when a sclp console is not present
- Fix misuse of non-NULL terminated strings in vmlogrdr driver
- Various other small improvements, cleanups and fixes
* tag 's390-6.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (53 commits)
s390/vmlogrdr: Use array instead of string initializer
s390/vmlogrdr: Use internal_name for error messages
s390/sclp: Initialize sclp subsystem via arch_cpu_finalize_init()
s390/tools: Use array instead of string initializer
s390/vmem: Fix null-pointer-arithmetic warning in vmem_map_init()
s390: Add '-std=gnu11' to decompressor and purgatory CFLAGS
s390/bitops: Use correct constraint for arch_test_bit() inline assembly
s390/pci: Fix SR-IOV for PFs initially in standby
s390/futex: Avoid KMSAN instrumention for user pointers
s390/uaccess: Rename get_put_user_noinstr_attributes to uaccess_kmsan_or_inline
s390/futex: Cleanup futex_atomic_cmpxchg_inatomic()
s390/futex: Generate futex atomic op functions
s390/uaccess: Remove INLINE_COPY_FROM_USER and INLINE_COPY_TO_USER
s390/uaccess: Use asm goto for put_user()/get_user()
s390/uaccess: Remove usage of the oac specifier
s390/uaccess: Replace EX_TABLE_UA_LOAD_MEM exception handling
s390/uaccess: Cleanup noinstr __put_user()/__get_user() inline assembly constraints
s390/uaccess: Remove __put_user_fn()/__get_user_fn() wrappers
s390/uaccess: Move put_user() / __put_user() close to put_user() asm code
s390/uaccess: Use asm goto for __mvc_kernel_nofault()
...
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Use a zero identity base when CONFIG_RANDOMIZE_IDENTITY_BASE is off,
slightly optimizing __pa/__va calculations.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Add boot_debug() calls to log various memory layout decisions and
randomization details during early startup, improving debugging
capabilities.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Reorder the store_ipl_parmblock(), uv_query_info(), and command line
setup calls to occur earlier. This ensures debug printing covers all
memory tracking activities from the start.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Introduce boot_debug() calls to track memory detection, online ranges,
reserved areas, and allocations (except for VMEM allocations, which are
too frequent). Instead introduce dump_physmem_reserved() function which
prints out full memory tracking information. This helps in debugging
early boot memory handling.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Replaces boot_printk() calls with appropriate loglevel-specific helpers
such as boot_emerg(), boot_warn(), and boot_debug().
Using functions with explicit log levels improves log clarity and aligns
the boot code with standard kernel logging practices. This makes it
easier to filter and manage boot-time messages based on their severity.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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The new name better reflects the function's behavior, emphasizing that
it will terminate execution if allocation fails.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Alexander Gordeev:
- Select config option KASAN_VMALLOC if KASAN is enabled
- Select config option VMAP_STACK unconditionally
- Implement arch_atomic_inc() / arch_atomic_dec() functions which
result in a single instruction if compiled for z196 or newer
architectures
- Make layering between atomic.h and atomic_ops.h consistent
- Comment s390 preempt_count implementation
- Remove pre MARCH_HAS_Z196_FEATURES preempt count implementation
- GCC uses the number of lines of an inline assembly to calculate
number of instructions and decide on inlining. Therefore remove
superfluous new lines from a couple of inline assemblies.
- Provide arch_atomic_*_and_test() implementations that allow the
compiler to generate slightly better code.
- Optimize __preempt_count_dec_and_test()
- Remove __bootdata annotations from declarations in header files
- Add missing include of <linux/smp.h> in abs_lowcore.h to provide
declarations for get_cpu() and put_cpu() used in the code
- Fix suboptimal kernel image base when running make kasan.config
- Remove huge_pte_none() and huge_pte_none_mostly() as are identical to
the generic variants
- Remove unused PAGE_KERNEL_EXEC, SEGMENT_KERNEL_EXEC, and
REGION3_KERNEL_EXEC defines
- Simplify noexec page protection handling and change the page, segment
and region3 protection definitions automatically if the instruction
execution-protection facility is not available
- Save one instruction and prefer EXRL instruction over EX in string,
xor_*(), amode31 and other functions
- Create /dev/diag misc device to fetch diagnose specific information
from the kernel and provide it to userspace
- Retrieve electrical power readings using DIAGNOSE 0x324 ioctl
- Make ccw_device_get_ciw() consistent and use array indices instead of
pointer arithmetic
- s390/qdio: Move memory alloc/pointer arithmetic for slib and sl into
one place
- The sysfs core now allows instances of 'struct bin_attribute' to be
moved into read-only memory. Make use of that in s390 code
- Add missing TLB range adjustment in pud_free_tlb()
- Improve topology setup by adding early polarization detection
- Fix length checks in codepage_convert() function
- The generic bitops implementation is nearly identical to the s390
one. Switch to the generic variant and decrease a bit the kernel
image size
- Provide an optimized arch_test_bit() implementation which makes use
of flag output constraint. This generates slightly better code
- Provide memory topology information obtanied with DIAGNOSE 0x310
using ioctl.
- Various other small improvements, fixes, and cleanups
Also, some changes came in through a merge of 'pci-device-recovery'
branch:
- Add PCI error recovery status mechanism
- Simplify and document debug_next_entry() logic
- Split private data allocation and freeing out of debug file open()
and close() operations
- Add debug_dump() function that gets a textual representation of a
debug info (e.g. PCI recovery hardware error logs)
- Add formatted content of pci_debug_msg_id to the PCI report
* tag 's390-6.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (48 commits)
s390/futex: Fix FUTEX_OP_ANDN implementation
s390/diag: Add memory topology information via diag310
s390/bitops: Provide optimized arch_test_bit()
s390/bitops: Switch to generic bitops
s390/ebcdic: Fix length decrement in codepage_convert()
s390/ebcdic: Fix length check in codepage_convert()
s390/ebcdic: Use exrl instead of ex
s390/amode31: Use exrl instead of ex
s390/stackleak: Use exrl instead of ex in __stackleak_poison()
s390/lib: Use exrl instead of ex in xor functions
s390/topology: Improve topology detection
s390/tlb: Add missing TLB range adjustment
s390/pkey: Constify 'struct bin_attribute'
s390/sclp: Constify 'struct bin_attribute'
s390/pci: Constify 'struct bin_attribute'
s390/ipl: Constify 'struct bin_attribute'
s390/crypto/cpacf: Constify 'struct bin_attribute'
s390/qdio: Move memory alloc/pointer arithmetic for slib and sl into one place
s390/cio: Use array indices instead of pointer arithmetic
s390/qdio: Rename feature flag aif_osa to aif_qdio
...
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By default page protection definitions like PAGE_RX have the _PAGE_NOEXEC
bit set. For older machines without the instruction execution protection
facility this bit is not allowed to be used in page table entries, and
therefore must be removed.
This is done at a couple of page table walkers, but also at some but not
all page table modification functions like ptep_modify_prot_commit(). Avoid
all of this and change the page, segment and region3 protection definitions
so that the noexec bit is masked out automatically if the instruction
execution-protection facility is not available. This is similar to what
also various other architectures do which had to solve the same problem.
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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The calculation determining whether to use three- or four-level paging
didn't account for KMSAN modules metadata. Include this metadata in the
virtual memory size calculation to ensure correct paging mode selection
and avoiding potentially unnecessary physical memory size limitations.
Fixes: 65ca73f9fb36 ("s390/mm: define KMSAN metadata for vmalloc and modules")
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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devices
To support memory devices under QEMU/KVM, such as virtio-mem,
we have to prepare our kernel virtual address space accordingly and
have to know the highest possible physical memory address we might see
later: the storage limit. The good old SCLP interface is not suitable for
this use case.
In particular, memory owned by memory devices has no relationship to
storage increments, it is always detected using the device driver, and
unaware OSes (no driver) must never try making use of that memory.
Consequently this memory is located outside of the "maximum storage
increment"-indicated memory range.
Let's use our new diag500 STORAGE_LIMIT subcode to query this storage
limit that can exceed the "maximum storage increment", and use the
existing interfaces (i.e., SCLP) to obtain information about the initial
memory that is not owned+managed by memory devices.
If a hypervisor does not support such memory devices, the address exposed
through diag500 STORAGE_LIMIT will correspond to the maximum storage
increment exposed through SCLP.
To teach kdump on s390 to include memory owned by memory devices, there
will be ways to query the relevant memory ranges from the device via a
driver running in special kdump mode (like virtio-mem already implements
to filter /proc/vmcore access so we don't end up reading from unplugged
device blocks).
Update setup_ident_map_size(), to clarify that there can be more than
just online and standby memory.
Tested-by: Mario Casquero <mcasquer@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-4-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Run codespell on arch/s390 and drivers/s390 and fix all typos.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Vasily Gorbik:
- Optimize ftrace and kprobes code patching and avoid stop machine for
kprobes if sequential instruction fetching facility is available
- Add hiperdispatch feature to dynamically adjust CPU capacity in
vertical polarization to improve scheduling efficiency and overall
performance. Also add infrastructure for handling warning track
interrupts (WTI), allowing for graceful CPU preemption
- Rework crypto code pkey module and split it into separate,
independent modules for sysfs, PCKMO, CCA, and EP11, allowing modules
to load only when the relevant hardware is available
- Add hardware acceleration for HMAC modes and the full AES-XTS cipher,
utilizing message-security assist extensions (MSA) 10 and 11. It
introduces new shash implementations for HMAC-SHA224/256/384/512 and
registers the hardware-accelerated AES-XTS cipher as the preferred
option. Also add clear key token support
- Add MSA 10 and 11 processor activity instrumentation counters to perf
and update PAI Extension 1 NNPA counters
- Cleanup cpu sampling facility code and rework debug/WARN_ON_ONCE
statements
- Add support for SHA3 performance enhancements introduced with MSA 12
- Add support for the query authentication information feature of MSA
13 and introduce the KDSA CPACF instruction. Provide query and query
authentication information in sysfs, enabling tools like cpacfinfo to
present this data in a human-readable form
- Update kernel disassembler instructions
- Always enable EXPOLINE_EXTERN if supported by the compiler to ensure
kpatch compatibility
- Add missing warning handling and relocated lowcore support to the
early program check handler
- Optimize ftrace_return_address() and avoid calling unwinder
- Make modules use kernel ftrace trampolines
- Strip relocs from the final vmlinux ELF file to make it roughly 2
times smaller
- Dump register contents and call trace for early crashes to the
console
- Generate ptdump address marker array dynamically
- Fix rcu_sched stalls that might occur when adding or removing large
amounts of pages at once to or from the CMM balloon
- Fix deadlock caused by recursive lock of the AP bus scan mutex
- Unify sync and async register save areas in entry code
- Cleanup debug prints in crypto code
- Various cleanup and sanitizing patches for the decompressor
- Various small ftrace cleanups
* tag 's390-6.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (84 commits)
s390/crypto: Display Query and Query Authentication Information in sysfs
s390/crypto: Add Support for Query Authentication Information
s390/crypto: Rework RRE and RRF CPACF inline functions
s390/crypto: Add KDSA CPACF Instruction
s390/disassembler: Remove duplicate instruction format RSY_RDRU
s390/boot: Move boot_printk() code to own file
s390/boot: Use boot_printk() instead of sclp_early_printk()
s390/boot: Rename decompressor_printk() to boot_printk()
s390/boot: Compile all files with the same march flag
s390: Use MARCH_HAS_*_FEATURES defines
s390: Provide MARCH_HAS_*_FEATURES defines
s390/facility: Disable compile time optimization for decompressor code
s390/boot: Increase minimum architecture to z10
s390/als: Remove obsolete comment
s390/sha3: Fix SHA3 selftests failures
s390/pkey: Add AES xts and HMAC clear key token support
s390/cpacf: Add MSA 10 and 11 new PCKMO functions
s390/mm: Add cond_resched() to cmm_alloc/free_pages()
s390/pai_ext: Update PAI extension 1 counters
s390/pai_crypto: Add support for MSA 10 and 11 pai counters
...
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Consistently use boot_printk() everywhere instead of sclp_early_printk() at
some places. For some places it was required (e.g. als.c), in order to stay
in code compiled for the same architecture level, for other places it is
not obvious why sclp_early_printk() was used instead of
decompressor_printk().
Given that the whole decompressor code is compiled for the same
architecture level, there is no requirement left to use different
printk functions.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Rename decompressor_printk() to boot_printk() just to have a shorter
function name, which also makes the code more readable.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Symbol offsets to the KASLR base do not match symbol address in
the vmlinux image. That is the result of setting the KASLR base
to the beginning of .text section as result of an optimization.
Revert that optimization and allocate virtual memory for the
whole kernel image including __START_KERNEL bytes as per the
linker script. That allows keeping the semantics of the KASLR
base offset in sync with other architectures.
Rename __START_KERNEL to TEXT_OFFSET, since it represents the
offset of the .text section within the kernel image, rather than
a virtual address.
Still skip mapping TEXT_OFFSET bytes to save memory on pgtables
and provoke exceptions in case an attempt to access this area is
made, as no kernel symbol may reside there.
In case CONFIG_KASAN is enabled the location counter might exceed
the value of TEXT_OFFSET, while the decompressor linker script
forcefully resets it to TEXT_OFFSET, which leads to a sections
overlap link failure. Use MAX() expression to avoid that.
Reported-by: Omar Sandoval <osandov@osandov.com>
Closes: https://lore.kernel.org/linux-s390/ZnS8dycxhtXBZVky@telecaster.dhcp.thefacebook.com/
Fixes: 56b1069c40c7 ("s390/boot: Rework deployment of the kernel image")
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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When physical memory for the kernel image is allocated it does not
consider extra memory required for offsetting the image start to
match it with the lower 20 bits of KASLR virtual base address. That
might lead to kernel access beyond its memory range.
Suggested-by: Vasily Gorbik <gor@linux.ibm.com>
Fixes: 693d41f7c938 ("s390/mm: Restore mapping of kernel image using large pages")
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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SIE instruction performs faster when the virtual address of
SIE block matches the physical one. Pin the identity mapping
base to zero for the benefit of SIE and other instructions
that have similar performance impact. Still, randomize the
base when DEBUG_VM kernel configuration option is enabled.
Suggested-by: Vasily Gorbik <gor@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The s390 architecture defines two special per-CPU data pages
called the "prefix area". In s390-linux terminology this is usually
called "lowcore". This memory area contains system configuration
data like old/new PSW's for system call/interrupt/machine check
handlers and lots of other data. It is normally mapped to logical
address 0. This area can only be accessed when in supervisor mode.
This means that kernel code can dereference NULL pointers, because
accesses to address 0 are allowed. Parts of lowcore can be write
protected, but read accesses and write accesses outside of the write
protected areas are not caught.
To remove this limitation for debugging and testing, remap lowcore to
another address and define a function get_lowcore() which simply
returns the address where lowcore is mapped at. This would normally
introduce a pointer dereference (=memory read). As lowcore is used
for several very often used variables, add code to patch this function
during runtime, so we avoid the memory reads.
For C code get_lowcore() has to be used, for assembly code it is
the GET_LC macro. When using this macro/function a reference is added
to alternative patching. All these locations will be patched to the
actual lowcore location when the kernel is booted or a module is loaded.
To make debugging/bisecting problems easier, this patch adds all the
infrastructure but the lowcore address is still hardwired to 0. This
way the code can be converted on a per function basis, and the
functionality is enabled in a patch after all the functions have
been converted.
Note that this requires at least z16 because the old lpsw instruction
only allowed a 12 bit displacement. z16 introduced lpswey which allows
20 bits (signed), so the lowcore can effectively be mapped from
address 0 - 0x7e000. To use 0x7e000 as address, a 6 byte lgfi
instruction would have to be used in the alternative. To save two
bytes, llilh can be used, but this only allows to set bits 16-31 of
the address. In order to use the llilh instruction, use 0x70000 as
alternative lowcore address. This is still large enough to catch
NULL pointer dereferences into large arrays.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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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 <agordeev@linux.ibm.com>
Co-developed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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When allocating a random memory range for .amode31 sections
the minimal randomization address is 0. That does not lead
to a possible overlap with the decompressor image (which also
starts from 0) since by that time the image range is already
reserved.
Do not assume the decompressor range is reserved and always
provide the minimal randomization address for .amode31
sections beyond the decompressor. That is a prerequisite
for moving the lowcore memory address from NULL elsewhere.
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- In the series "mm: Avoid possible overflows in dirty throttling" Jan
Kara addresses a couple of issues in the writeback throttling code.
These fixes are also targetted at -stable kernels.
- Ryusuke Konishi's series "nilfs2: fix potential issues related to
reserved inodes" does that. This should actually be in the
mm-nonmm-stable tree, along with the many other nilfs2 patches. My
bad.
- More folio conversions from Kefeng Wang in the series "mm: convert to
folio_alloc_mpol()"
- Kemeng Shi has sent some cleanups to the writeback code in the series
"Add helper functions to remove repeated code and improve readability
of cgroup writeback"
- Kairui Song has made the swap code a little smaller and a little
faster in the series "mm/swap: clean up and optimize swap cache
index".
- In the series "mm/memory: cleanly support zeropage in
vm_insert_page*(), vm_map_pages*() and vmf_insert_mixed()" David
Hildenbrand has reworked the rather sketchy handling of the use of
the zeropage in MAP_SHARED mappings. I don't see any runtime effects
here - more a cleanup/understandability/maintainablity thing.
- Dev Jain has improved selftests/mm/va_high_addr_switch.c's handling
of higher addresses, for aarch64. The (poorly named) series is
"Restructure va_high_addr_switch".
- The core TLB handling code gets some cleanups and possible slight
optimizations in Bang Li's series "Add update_mmu_tlb_range() to
simplify code".
- Jane Chu has improved the handling of our
fake-an-unrecoverable-memory-error testing feature MADV_HWPOISON in
the series "Enhance soft hwpoison handling and injection".
- Jeff Johnson has sent a billion patches everywhere to add
MODULE_DESCRIPTION() to everything. Some landed in this pull.
- In the series "mm: cleanup MIGRATE_SYNC_NO_COPY mode", Kefeng Wang
has simplified migration's use of hardware-offload memory copying.
- Yosry Ahmed performs more folio API conversions in his series "mm:
zswap: trivial folio conversions".
- In the series "large folios swap-in: handle refault cases first",
Chuanhua Han inches us forward in the handling of large pages in the
swap code. This is a cleanup and optimization, working toward the end
objective of full support of large folio swapin/out.
- In the series "mm,swap: cleanup VMA based swap readahead window
calculation", Huang Ying has contributed some cleanups and a possible
fixlet to his VMA based swap readahead code.
- In the series "add mTHP support for anonymous shmem" Baolin Wang has
taught anonymous shmem mappings to use multisize THP. By default this
is a no-op - users must opt in vis sysfs controls. Dramatic
improvements in pagefault latency are realized.
- David Hildenbrand has some cleanups to our remaining use of
page_mapcount() in the series "fs/proc: move page_mapcount() to
fs/proc/internal.h".
- David also has some highmem accounting cleanups in the series
"mm/highmem: don't track highmem pages manually".
- Build-time fixes and cleanups from John Hubbard in the series
"cleanups, fixes, and progress towards avoiding "make headers"".
- Cleanups and consolidation of the core pagemap handling from Barry
Song in the series "mm: introduce pmd|pte_needs_soft_dirty_wp helpers
and utilize them".
- Lance Yang's series "Reclaim lazyfree THP without splitting" has
reduced the latency of the reclaim of pmd-mapped THPs under fairly
common circumstances. A 10x speedup is seen in a microbenchmark.
It does this by punting to aother CPU but I guess that's a win unless
all CPUs are pegged.
- hugetlb_cgroup cleanups from Xiu Jianfeng in the series
"mm/hugetlb_cgroup: rework on cftypes".
- Miaohe Lin's series "Some cleanups for memory-failure" does just that
thing.
- Someone other than SeongJae has developed a DAMON feature in Honggyu
Kim's series "DAMON based tiered memory management for CXL memory".
This adds DAMON features which may be used to help determine the
efficiency of our placement of CXL/PCIe attached DRAM.
- DAMON user API centralization and simplificatio work in SeongJae
Park's series "mm/damon: introduce DAMON parameters online commit
function".
- In the series "mm: page_type, zsmalloc and page_mapcount_reset()"
David Hildenbrand does some maintenance work on zsmalloc - partially
modernizing its use of pageframe fields.
- Kefeng Wang provides more folio conversions in the series "mm: remove
page_maybe_dma_pinned() and page_mkclean()".
- More cleanup from David Hildenbrand, this time in the series
"mm/memory_hotplug: use PageOffline() instead of PageReserved() for
!ZONE_DEVICE". It "enlightens memory hotplug more about PageOffline()
pages" and permits the removal of some virtio-mem hacks.
- Barry Song's series "mm: clarify folio_add_new_anon_rmap() and
__folio_add_anon_rmap()" is a cleanup to the anon folio handling in
preparation for mTHP (multisize THP) swapin.
- Kefeng Wang's series "mm: improve clear and copy user folio"
implements more folio conversions, this time in the area of large
folio userspace copying.
- The series "Docs/mm/damon/maintaier-profile: document a mailing tool
and community meetup series" tells people how to get better involved
with other DAMON developers. From SeongJae Park.
- A large series ("kmsan: Enable on s390") from Ilya Leoshkevich does
that.
- David Hildenbrand sends along more cleanups, this time against the
migration code. The series is "mm/migrate: move NUMA hinting fault
folio isolation + checks under PTL".
- Jan Kara has found quite a lot of strangenesses and minor errors in
the readahead code. He addresses this in the series "mm: Fix various
readahead quirks".
- SeongJae Park's series "selftests/damon: test DAMOS tried regions and
{min,max}_nr_regions" adds features and addresses errors in DAMON's
self testing code.
- Gavin Shan has found a userspace-triggerable WARN in the pagecache
code. The series "mm/filemap: Limit page cache size to that supported
by xarray" addresses this. The series is marked cc:stable.
- Chengming Zhou's series "mm/ksm: cmp_and_merge_page() optimizations
and cleanup" cleans up and slightly optimizes KSM.
- Roman Gushchin has separated the memcg-v1 and memcg-v2 code - lots of
code motion. The series (which also makes the memcg-v1 code
Kconfigurable) are "mm: memcg: separate legacy cgroup v1 code and put
under config option" and "mm: memcg: put cgroup v1-specific memcg
data under CONFIG_MEMCG_V1"
- Dan Schatzberg's series "Add swappiness argument to memory.reclaim"
adds an additional feature to this cgroup-v2 control file.
- The series "Userspace controls soft-offline pages" from Jiaqi Yan
permits userspace to stop the kernel's automatic treatment of
excessive correctable memory errors. In order to permit userspace to
monitor and handle this situation.
- Kefeng Wang's series "mm: migrate: support poison recover from
migrate folio" teaches the kernel to appropriately handle migration
from poisoned source folios rather than simply panicing.
- SeongJae Park's series "Docs/damon: minor fixups and improvements"
does those things.
- In the series "mm/zsmalloc: change back to per-size_class lock"
Chengming Zhou improves zsmalloc's scalability and memory
utilization.
- Vivek Kasireddy's series "mm/gup: Introduce memfd_pin_folios() for
pinning memfd folios" makes the GUP code use FOLL_PIN rather than
bare refcount increments. So these paes can first be moved aside if
they reside in the movable zone or a CMA block.
- Andrii Nakryiko has added a binary ioctl()-based API to
/proc/pid/maps for much faster reading of vma information. The series
is "query VMAs from /proc/<pid>/maps".
- In the series "mm: introduce per-order mTHP split counters" Lance
Yang improves the kernel's presentation of developer information
related to multisize THP splitting.
- Michael Ellerman has developed the series "Reimplement huge pages
without hugepd on powerpc (8xx, e500, book3s/64)". This permits
userspace to use all available huge page sizes.
- In the series "revert unconditional slab and page allocator fault
injection calls" Vlastimil Babka removes a performance-affecting and
not very useful feature from slab fault injection.
* tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (411 commits)
mm/mglru: fix ineffective protection calculation
mm/zswap: fix a white space issue
mm/hugetlb: fix kernel NULL pointer dereference when migrating hugetlb folio
mm/hugetlb: fix possible recursive locking detected warning
mm/gup: clear the LRU flag of a page before adding to LRU batch
mm/numa_balancing: teach mpol_to_str about the balancing mode
mm: memcg1: convert charge move flags to unsigned long long
alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting
lib: reuse page_ext_data() to obtain codetag_ref
lib: add missing newline character in the warning message
mm/mglru: fix overshooting shrinker memory
mm/mglru: fix div-by-zero in vmpressure_calc_level()
mm/kmemleak: replace strncpy() with strscpy()
mm, page_alloc: put should_fail_alloc_page() back behing CONFIG_FAIL_PAGE_ALLOC
mm, slab: put should_failslab() back behind CONFIG_SHOULD_FAILSLAB
mm: ignore data-race in __swap_writepage
hugetlbfs: ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr
mm: shmem: rename mTHP shmem counters
mm: swap_state: use folio_alloc_mpol() in __read_swap_cache_async()
mm/migrate: putback split folios when numa hint migration fails
...
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Vasily Gorbik:
- Remove restrictions on PAI NNPA and crypto counters, enabling
concurrent per-task and system-wide sampling and counting events
- Switch to GENERIC_CPU_DEVICES by setting up the CPU present mask in
the architecture code and letting the generic code handle CPU
bring-up
- Add support for the diag204 busy indication facility to prevent
undesirable blocking during hypervisor logical CPU utilization
queries. Implement results caching
- Improve the handling of Store Data SCLP events by suppressing
unnecessary warning, preventing buffer release in I/O during
failures, and adding timeout handling for Store Data requests to
address potential firmware issues
- Provide optimized __arch_hweight*() implementations
- Remove the unnecessary CPU KOBJ_CHANGE uevents generated during
topology updates, as they are unused and also not present on other
architectures
- Cleanup atomic_ops, optimize __atomic_set() for small values and
__atomic_cmpxchg_bool() for compilers supporting flag output
constraint
- Couple of cleanups for KVM:
- Move and improve KVM struct definitions for DAT tables from
gaccess.c to a new header
- Pass the asce as parameter to sie64a()
- Make the crdte() and cspg() page table handling wrappers return a
boolean to indicate success, like the other existing "compare and
swap" wrappers
- Add documentation for HWCAP flags
- Switch to obtaining total RAM pages from memblock instead of
totalram_pages() during mm init, to ensure correct calculation of
zero page size, when defer_init is enabled
- Refactor lowcore access and switch to using the get_lowcore()
function instead of the S390_lowcore macro
- Cleanups for PG_arch_1 and folio handling in UV and hugetlb code
- Add missing MODULE_DESCRIPTION() macros
- Fix VM_FAULT_HWPOISON handling in do_exception()
* tag 's390-6.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (54 commits)
s390/mm: Fix VM_FAULT_HWPOISON handling in do_exception()
s390/kvm: Move bitfields for dat tables
s390/entry: Pass the asce as parameter to sie64a()
s390/sthyi: Use cached data when diag is busy
s390/sthyi: Move diag operations
s390/hypfs_diag: Diag204 busy loop
s390/diag: Add busy-indication-facility requirements
s390/diag: Diag204 add busy return errno
s390/diag: Return errno's from diag204
s390/sclp: Diag204 busy indication facility detection
s390/atomic_ops: Make use of flag output constraint
s390/atomic_ops: Improve __atomic_set() for small values
s390/atomic_ops: Use symbolic names
s390/smp: Switch to GENERIC_CPU_DEVICES
s390/hwcaps: Add documentation for HWCAP flags
s390/pgtable: Make crdte() and cspg() return a value
s390/topology: Remove CPU KOBJ_CHANGE uevents
s390/sclp: Add timeout to Store Data requests
s390/sclp: Prevent release of buffer in I/O
s390/sclp: Suppress unnecessary Store Data warning
...
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The pages for the KMSAN metadata associated with most kernel mappings are
taken from memblock by the common code. However, vmalloc and module
metadata needs to be defined by the architectures.
Be a little bit more careful than x86: allocate exactly MODULES_LEN for
the module shadow and origins, and then take 2/3 of vmalloc for the
vmalloc shadow and origins. This ensures that users passing small
vmalloc= values on the command line do not cause module metadata
collisions.
Link: https://lkml.kernel.org/r/20240621113706.315500-32-iii@linux.ibm.com
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <kasan-dev@googlegroups.com>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Since commit 778666df60f0 ("s390: compile relocatable kernel without
-fPIE") and commit 00cda11d3b2e ("s390: Compile kernel with -fPIC and
link with -no-pie") the kernel on s390x may have a Global Offset Table
(GOT) whose entries are adjusted for KASLR in kaslr_adjust_got().
The GOT may contain entries for undefined weak symbols that resolved to
zero. That is the resulting GOT entry value is zero. Adjusting those
entries unconditionally in kaslr_adjust_got() is wrong. Otherwise the
following sample code would erroneously assume foo to be defined, due to
the adjustment changing the zero-value to a non-zero one:
extern int foo __attribute__((weak));
if (*foo)
/* foo is defined [or undefined and erroneously adjusted] */
The vmlinux build at commit 00cda11d3b2e ("s390: Compile kernel with
-fPIC and link with -no-pie") with defconfig actually had two GOT
entries for the undefined weak symbols __start_BTF and __stop_BTF:
$ objdump -tw vmlinux | grep -F "*UND*"
0000000000000000 w *UND* 0000000000000000 __stop_BTF
0000000000000000 w *UND* 0000000000000000 __start_BTF
$ readelf -rw vmlinux | grep -E "R_390_GOTENT +0{16}"
000000345760 2776a0000001a R_390_GOTENT 0000000000000000 __stop_BTF + 2
000000345766 2d5480000001a R_390_GOTENT 0000000000000000 __start_BTF + 2
The s390-specific vmlinux linker script sets the section start to
__START_KERNEL, which is currently defined as 0x100000 on s390x. Access
to lowcore is performed via a pointer of 0 and not a symbol in a section
starting at 0. The first 64K are reserved for the loader on s390x. Thus
it is safe to assume that __START_KERNEL will never be 0. As a result
there cannot be any defined symbols resolving to zero in the kernel.
Note that the first three GOT entries are reserved for the dynamic
loader on s390x. [1] In the kernel they are zero. Therefore no extra
handling is required to skip these.
Skip adjusting GOT entries with a value of zero in kaslr_adjust_got().
While at it update the comment when a GOT exists on s390x. Since commit
00cda11d3b2e ("s390: Compile kernel with -fPIC and link with -no-pie")
it no longer only exists when compiling with Clang, but also with GCC.
[1]: s390x ELF ABI, section "Global Offset Table",
https://github.com/IBM/s390x-abi/releases
Fixes: 778666df60f0 ("s390: compile relocatable kernel without -fPIE")
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Replace all S390_lowcore usages in arch/s390/boot by get_lowcore().
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Since physical and virtual kernel address spaces are uncoupled
the kernel image is not mapped using large segment pages anymore,
which is a regression.
Put the kernel image at the same large segment page offset in
physical memory as in virtual memory. Such approach preserves
the existing number of bits of entropy used for randomization
of the kernel location in virtual memory when KASLR is on.
As result, the kernel is mapped using large segment pages.
Fixes: c98d2ecae08f ("s390/mm: Uncouple physical vs virtual address spaces")
Reported-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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It is nowhere used in the decompressor, therefore remove it.
Fixes: 17e89e1340a3 ("s390/facilities: move stfl information from lowcore to global data")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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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 <ulrich.weigand@de.ibm.com>
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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The .vmlinux.relocs section is moved in front of the compressed
kernel. The interim section rescue step is avoided as result.
Suggested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Rework deployment of kernel image for both compressed and
uncompressed variants as defined by CONFIG_KERNEL_UNCOMPRESSED
kernel configuration variable.
In case CONFIG_KERNEL_UNCOMPRESSED is disabled avoid uncompressing
the kernel to a temporary buffer and copying it to the target
address. Instead, uncompress it directly to the target destination.
In case CONFIG_KERNEL_UNCOMPRESSED is enabled avoid moving the
kernel to default 0x100000 location when KASLR is disabled or
failed. Instead, use the uncompressed kernel image directly.
In case KASLR is disabled or failed .amode31 section location in
memory is not randomized and precedes the kernel image. In case
CONFIG_KERNEL_UNCOMPRESSED is disabled that location overlaps the
area used by the decompression algorithm. That is fine, since that
area is not used after the decompression finished and the size of
.amode31 section is not expected to exceed BOOT_HEAP_SIZE ever.
There is no decompression in case CONFIG_KERNEL_UNCOMPRESSED is
enabled. Therefore, rename decompress_kernel() to deploy_kernel(),
which better describes both uncompressed and compressed cases.
Introduce AMODE31_SIZE macro to avoid immediate value of 0x3000
(the size of .amode31 section) in the decompressor linker script.
Modify the vmlinux linker script to force the size of .amode31
section to AMODE31_SIZE (the value of (_eamode31 - _samode31)
could otherwise differ as result of compiler options used).
Introduce __START_KERNEL macro that defines the kernel ELF image
entry point and set it to the currrent value of 0x100000.
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Since kernel virtual and physical address spaces are
uncoupled the kernel is mapped at the top of the virtual
address space in case KASLR is disabled.
That does not pose any issue with regard to the kernel
booting and operation, but makes it difficult to use a
generated vmlinux with some debugging tools (e.g. gdb),
because the exact location of the kernel image in virtual
memory is unknown. Make that location known and introduce
CONFIG_KERNEL_IMAGE_BASE configuration option.
A custom CONFIG_KERNEL_IMAGE_BASE value that would break
the virtual memory layout leads to a build error.
The kernel image size is defined by KERNEL_IMAGE_SIZE
macro and set to 512 MB, by analogy with x86.
Suggested-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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The uncoupling physical vs virtual address spaces brings
the following benefits to s390:
- virtual memory layout flexibility;
- closes the address gap between kernel and modules, it
caused s390-only problems in the past (e.g. 'perf' bugs);
- allows getting rid of trampolines used for module calls
into kernel;
- allows simplifying BPF trampoline;
- minor performance improvement in branch prediction;
- kernel randomization entropy is magnitude bigger, as it is
derived from the amount of available virtual, not physical
memory;
The whole change could be described in two pictures below:
before and after the change.
Some aspects of the virtual memory layout setup are not
clarified (number of page levels, alignment, DMA memory),
since these are not a part of this change or secondary
with regard to how the uncoupling itself is implemented.
The focus of the pictures is to explain why __va() and __pa()
macros are implemented the way they are.
Memory layout in V==R mode:
| Physical | Virtual |
+- 0 --------------+- 0 --------------+ identity mapping start
| | S390_lowcore | Low-address memory
| +- 8 KB -----------+
| | |
| | identity | phys == virt
| | mapping | virt == phys
| | |
+- AMODE31_START --+- AMODE31_START --+ .amode31 rand. phys/virt start
|.amode31 text/data|.amode31 text/data|
+- AMODE31_END ----+- AMODE31_END ----+ .amode31 rand. phys/virt start
| | |
| | |
+- __kaslr_offset, __kaslr_offset_phys| kernel rand. phys/virt start
| | |
| kernel text/data | kernel text/data | phys == kvirt
| | |
+------------------+------------------+ kernel phys/virt end
| | |
| | |
| | |
| | |
+- ident_map_size -+- ident_map_size -+ identity mapping end
| |
| ... unused gap |
| |
+---- vmemmap -----+ 'struct page' array start
| |
| virtually mapped |
| memory map |
| |
+- __abs_lowcore --+
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| Absolute Lowcore |
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+- __memcpy_real_area
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| Real Memory Copy|
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+- VMALLOC_START --+ vmalloc area start
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| vmalloc area |
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+- MODULES_VADDR --+ modules area start
| |
| modules area |
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+------------------+ UltraVisor Secure Storage limit
| |
| ... unused gap |
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+KASAN_SHADOW_START+ KASAN shadow memory start
| |
| KASAN shadow |
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+------------------+ ASCE limit
Memory layout in V!=R mode:
| Physical | Virtual |
+- 0 --------------+- 0 --------------+
| | S390_lowcore | Low-address memory
| +- 8 KB -----------+
| | |
| | |
| | ... unused gap |
| | |
+- AMODE31_START --+- AMODE31_START --+ .amode31 rand. phys/virt start
|.amode31 text/data|.amode31 text/data|
+- AMODE31_END ----+- AMODE31_END ----+ .amode31 rand. phys/virt end (<2GB)
| | |
| | |
+- __kaslr_offset_phys | kernel rand. phys start
| | |
| kernel text/data | |
| | |
+------------------+ | kernel phys end
| | |
| | |
| | |
| | |
+- ident_map_size -+ |
| |
| ... unused gap |
| |
+- __identity_base + identity mapping start (>= 2GB)
| |
| identity | phys == virt - __identity_base
| mapping | virt == phys + __identity_base
| |
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+---- vmemmap -----+ 'struct page' array start
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| virtually mapped |
| memory map |
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+- __abs_lowcore --+
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| Absolute Lowcore |
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+- __memcpy_real_area
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| Real Memory Copy|
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+- VMALLOC_START --+ vmalloc area start
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| vmalloc area |
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+- MODULES_VADDR --+ modules area start
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| modules area |
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+- __kaslr_offset -+ kernel rand. virt start
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| kernel text/data | phys == (kvirt - __kaslr_offset) +
| | __kaslr_offset_phys
+- kernel .bss end + kernel rand. virt end
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| ... unused gap |
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+------------------+ UltraVisor Secure Storage limit
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| ... unused gap |
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+KASAN_SHADOW_START+ KASAN shadow memory start
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| KASAN shadow |
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+------------------+ ASCE limit
Unused gaps in the virtual memory layout could be present
or not - depending on how partucular system is configured.
No page tables are created for the unused gaps.
The relative order of vmalloc, modules and kernel image in
virtual memory is defined by following considerations:
- start of the modules area and end of the kernel should reside
within 4GB to accommodate relative 32-bit jumps. The best way
to achieve that is to place kernel next to modules;
- vmalloc and module areas should locate next to each other
to prevent failures and extra reworks in user level tools
(makedumpfile, crash, etc.) which treat vmalloc and module
addresses similarily;
- kernel needs to be the last area in the virtual memory
layout to easily distinguish between kernel and non-kernel
virtual addresses. That is needed to (again) simplify
handling of addresses in user level tools and make __pa()
macro faster (see below);
Concluding the above, the relative order of the considered
virtual areas in memory is: vmalloc - modules - kernel.
Therefore, the only change to the current memory layout is
moving kernel to the end of virtual address space.
With that approach the implementation of __pa() macro is
straightforward - all linear virtual addresses less than
kernel base are considered identity mapping:
phys == virt - __identity_base
All addresses greater than kernel base are kernel ones:
phys == (kvirt - __kaslr_offset) + __kaslr_offset_phys
By contrast, __va() macro deals only with identity mapping
addresses:
virt == phys + __identity_base
.amode31 section is mapped separately and is not covered by
__pa() macro. In fact, it could have been handled easily by
checking whether a virtual address is within the section or
not, but there is no need for that. Thus, let __pa() code
do as little machine cycles as possible.
The KASAN shadow memory is located at the very end of the
virtual memory layout, at addresses higher than the kernel.
However, that is not a linear mapping and no code other than
KASAN instrumentation or API is expected to access it.
When KASLR mode is enabled the kernel base address randomized
within a memory window that spans whole unused virtual address
space. The size of that window depends from the amount of
physical memory available to the system, the limit imposed by
UltraVisor (if present) and the vmalloc area size as provided
by vmalloc= kernel command line parameter.
In case the virtual memory is exhausted the minimum size of
the randomization window is forcefully set to 2GB, which
amounts to in 15 bits of entropy if KASAN is enabled or 17
bits of entropy in default configuration.
The default kernel offset 0x100000 is used as a magic value
both in the decompressor code and vmlinux linker script, but
it will be removed with a follow-up change.
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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This is a preparatory rework to allow uncoupling virtual
and physical addresses spaces.
Currently __kaslr_offset is the kernel offset in both
physical memory on boot and in virtual memory after DAT
mode is enabled.
Uncouple these offsets and rename the physical address
space variant to __kaslr_offset_phys while keep the name
__kaslr_offset for the offset in virtual address space.
Do not use __kaslr_offset_phys after DAT mode is enabled
just yet, but still make it a persistent boot variable
for later use.
Use __kaslr_offset and __kaslr_offset_phys offsets in
proper contexts and alter handle_relocs() function to
distinguish between the two.
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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This is a preparatory rework to allow uncoupling virtual
and physical addresses spaces.
Put virtual memory layout information into a structure
to improve code generation when accessing the structure
members, which are currently only ident_map_size and
__kaslr_offset.
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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