linux-stable.git/arch/s390/kernel/ipl.c, branch linux-rolling-stable

s390/kexec: Disable stack protector in s390_reset_system()

2026-03-12T11:09:20+00:00

[ Upstream commit 1623a554c68f352c17d0a358bc62580dc187f06b ]

s390_reset_system() calls set_prefix(0), which switches back to the
absolute lowcore. At that point the stack protector canary no longer
matches the canary from the lowcore the function was entered with, so
the stack check fails.

Mark s390_reset_system() __no_stack_protector. This is safe here since
its callers (__do_machine_kdump() and __do_machine_kexec()) are
effectively no-return and fall back to disabled_wait() on failure.

Fixes: f5730d44e05e ("s390: Add stackprotector support")
Reported-by: Nikita Dubrovskii 
Reviewed-by: Heiko Carstens 
Acked-by: Alexander Gordeev 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Sasha Levin

s390/ipl: Clear SBP flag when bootprog is set

2025-12-14T10:03:57+00:00

With z16 a new flag 'search boot program' was introduced for
list-directed IPL (SCSI, NVMe, ECKD DASD). If this flag is set,
e.g. via selecting the "Automatic" value for the "Boot program
selector" control on an HMC load panel, it is copied to the reipl
structure from the initial ipl structure. When a user now sets a
boot prog via sysfs, the flag is not cleared and the bootloader
will again automatically select the boot program, ignoring user
configuration.

To avoid that, clear the SBP flag when a bootprog sysfs file is
written.

Cc: stable@vger.kernel.org
Reviewed-by: Peter Oberparleiter 
Reviewed-by: Heiko Carstens 
Signed-off-by: Sven Schnelle 
Signed-off-by: Heiko Carstens

sysfs: treewide: switch back to attribute_group::bin_attrs

2025-06-17T08:44:15+00:00

The normal bin_attrs field can now handle const pointers.
This makes the _new variant unnecessary.
Switch all users back.

Signed-off-by: Thomas Weißschuh 
Link: https://lore.kernel.org/r/20250530-sysfs-const-bin_attr-final-v3-4-724bfcf05b99@weissschuh.net
Signed-off-by: Greg Kroah-Hartman

s390: Remove optional third argument of strscpy() if possible

2025-04-17T13:16:10+00:00

The third argument of strscpy() is optional and can be left away iff
the destination is an array and the maximum size of the copy is the
size of destination.
Remove the third argument for those cases where this is possible.

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

s390/ipl: Rename and change strncpy_skip_quote()

2025-04-17T13:16:10+00:00

Rename strncpy_skip_quote() to strscpy_skip_quote() and change its
implementation so that the destination string is always NUL terminated.

Signed-off-by: Heiko Carstens

s390: Use inline qualifier for all EX_TABLE and ALTERNATIVE inline assemblies

2025-03-18T16:13:51+00:00

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 
Reviewed-by: Juergen Christ 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: Convert MACHINE_IS_[LPAR|VM|KVM], etc, machine_is_[lpar|vm|kvm]()

2025-03-04T16:18:07+00:00

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 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

Merge tag 's390-6.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2025-01-21T05:14:49+00:00

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  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
  ...

s390/ipl: Constify 'struct bin_attribute'

2025-01-07T09:05:35+00:00

The sysfs core now allows instances of 'struct bin_attribute' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.

Signed-off-by: Thomas Weißschuh 
Acked-by: Alexander Gordeev 
Link: https://lore.kernel.org/r/20241211-sysfs-const-bin_attr-s390-v1-2-be01f66bfcf7@weissschuh.net
Signed-off-by: Alexander Gordeev

s390/ipl: Fix never less than zero warning

2024-12-11T17:05:49+00:00

DEFINE_IPL_ATTR_STR_RW() macro produces "unsigned 'len' is never less
than zero." warning when sys_vmcmd_on_*_store() callbacks are defined.

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202412081614.5uel8F6W-lkp@intel.com/
Fixes: 247576bf624a ("s390/ipl: Do not accept z/VM CP diag X'008' cmds longer than max length")
Reviewed-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev