linux.git/arch/loongarch, branch master

Merge tag 'loongarch-fixes-7.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson

2026-05-23T16:13:00+00:00

Pull LoongArch fixes from Huacai Chen:
 "Rework KASLR to avoid initrd overlap, remove some unused code to avoid
  a build warning, fix some bugs in kprobes and KVM"

* tag 'loongarch-fixes-7.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson:
  LoongArch: KVM: Move some variable declarations to paravirt.h
  LoongArch: kprobes: Fix handling of fatal unrecoverable recursions
  LoongArch: kprobes: Use larch_insn_text_copy() to patch instructions
  LoongArch: Remove unused code to avoid build warning
  LoongArch: Avoid initrd overlap during kernel relocation
  LoongArch: Skip relocation-time KASLR if already applied
  efi/loongarch: Randomize kernel preferred address for KASLR

LoongArch: KVM: Move some variable declarations to paravirt.h

2026-05-22T07:05:12+00:00

Some variables relative with paravirt feature are declared in the header
file asm/qspinlock.h, however this file can be included only when option
CONFIG_SMP is on. There is compiling warnings if CONFIG_SMP is off since
variables are not declared.

Move these variable declarations to header file asm/paravirt.h to avoid
compiling warnings.

Fixes: c43dce6f13fb ("LoongArch: KVM: Make vcpu_is_preempted() as a macro rather than function")
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202605061313.O8Hswm2b-lkp@intel.com/
Signed-off-by: Bibo Mao 
Signed-off-by: Huacai Chen

LoongArch: kprobes: Fix handling of fatal unrecoverable recursions

2026-05-22T07:05:07+00:00

KPROBE_HIT_SS and KPROBE_REENTER are two types of fatal recursions that
can not be safely recovered in kprobes.

KPROBE_HIT_SS means that a kprobe is hit during single-stepping. At
this point, the architecture-specific single-step context is already
active. Nested single-stepping would corrupt the state, as the kprobe
control block (kcb) and hardware registers cannot safely store multiple
levels of stepping state.

KPROBE_REENTER means that a third-level recursion occurs when a probe
is hit while the system is already handling a nested probe (second-
level). The kcb only provides a single slot (prev_kprobe) to backup the
state. When a third probe is hit, there is no more space to save the
state without corrupting the first-level backup.

Kprobes work by replacing instructions with breakpoints. In order to
execute the original instruction and continue, it must be moved to a
temporary "single-step" slot. Since there is no backup space left to
set up this slot safely, the CPU would be forced to return to the same
original breakpoint address, triggering an endless loop.

Currently, the code only prints a warning and returns. This leads to
an infinite re-entry loop as the CPU repeatedly hits the same trap and
a "stuck" CPU core because preemption was disabled at the start of the
handler and never re-enabled in this early return path.

Fix the logic by:
1. Merging KPROBE_HIT_SS and KPROBE_REENTER cases, as both represent
   fatal recursions that cannot be safely recovered.
2. Replacing WARN_ON_ONCE() with BUG() to terminate the system. This
   aligns LoongArch with other architectures (x86, arm64, riscv) and
   prevents stack overflow while providing diagnostic information.

Fixes: 6d4cc40fb5f5 ("LoongArch: Add kprobes support")
Signed-off-by: Tiezhu Yang 
Signed-off-by: Huacai Chen

LoongArch: kprobes: Use larch_insn_text_copy() to patch instructions

2026-05-22T07:05:07+00:00

On SMP systems, kprobe handlers would occasionally fail to execute on
certain CPU cores. The issue is hard to reproduce and typically occurs
randomly under high system load.

The root cause is a software-side instruction hazard. According to the
LoongArch Reference Manual, while the cache coherency is maintained by
hardware, software must explicitly use the "IBAR" instruction to ensure
the instruction fetch unit (IFU) observes the effects of recent stores.

The current arch_arm_kprobe() and arch_disarm_kprobe() only execute the
"IBAR" barrier (via flush_insn_slot -> local_flush_icache_range) on the
local CPU. This leaves a vulnerable window where remote CPU cores may
continue executing stale instructions from their pipelines or prefetch
buffers, as they have not executed an "IBAR" since the code modification.

Switch to larch_insn_text_copy() to fix this:
1. Synchronization: It uses stop_machine_cpuslocked() to synchronize all
   online CPUs, ensuring no CPU is executing the target code area during
   modification.
2. Visibility: By passing cpu_online_mask to stop_machine_cpuslocked(),
   the callback text_copy_cb() is executed on all online cores. Each CPU
   core invokes local_flush_icache_range() to execute "IBAR", clearing
   instruction hazards system-wide and ensuring the "break" instruction
   is visible to the fetch units of all cores.
3. Robustness: It properly manages memory write permissions (ROX/RW) for
   the kernel text segment during patching, ensuring compatibility with
   CONFIG_STRICT_KERNEL_RWX.

Cc:   # 6.18+
Fixes: 6d4cc40fb5f5 ("LoongArch: Add kprobes support")
Signed-off-by: Tiezhu Yang 
Signed-off-by: Huacai Chen

LoongArch: Remove unused code to avoid build warning

2026-05-21T12:58:40+00:00

After commit feee6b2989165631b1 ("mm/memory_hotplug: shrink zones when
offlining memory"), __remove_pages() doesn't need the "zone" parameter
so the "page" variable is also unused. Remove the unused code to avoid
such build warning:

arch/loongarch/mm/init.c: In function 'arch_remove_memory':
arch/loongarch/mm/init.c:134:22: warning: variable 'page' set but not used [-Wunused-but-set-variable=]
  134 |         struct page *page = pfn_to_page(start_pfn);

Cc: 
Reviewed-by: Guo Ren 
Signed-off-by: Huacai Chen

LoongArch: Avoid initrd overlap during kernel relocation

2026-05-21T12:58:36+00:00

Validate the relocation address against the initrd region specified via
"initrd=" or "initrdmem=" on the command line. Reject relocation targets
that overlap the initrd to prevent memory corruption during early boot.

Acked-by: Ard Biesheuvel 
Signed-off-by: WANG Rui 
Signed-off-by: Huacai Chen

LoongArch: Skip relocation-time KASLR if already applied

2026-05-21T12:58:36+00:00

When the kernel is relocated during early boot (efistub or kexec_file),
a randomized load address may has already been selected and applied. In
this case, performing KASLR again in relocate.c is unnecessary.

Note: strictly-defined KASLR means the kernel's final runtime address
has a random offset from the kernel's load address, which is implemented
in relocate.c; broadly-defined KALSR means the kernel's final runtime
address has a random offset from the kernel's link address (a.k.a.
VMLINUX_LOAD_ADDRESS), which also include the efistlub implementation,
kexec_file implementation and QEMU direct kernel boot. kaslr_disabled()
return true only means strictly-defined KASLR is disabled.

Acked-by: Ard Biesheuvel 
Signed-off-by: WANG Rui 
Signed-off-by: Huacai Chen

efi/loongarch: Randomize kernel preferred address for KASLR

2026-05-21T12:58:36+00:00

Introduce efi_get_kimg_kaslr_address() helper to compute the preferred
kernel image load address dynamically when CONFIG_RANDOMIZE_BASE is
enabled. The function derives a random offset by using the EFI-provided
randomness combined with the timer tick value, and constrains it within
CONFIG_RANDOMIZE_BASE_MAX_OFFSET.

Update EFI_KIMG_PREFERRED_ADDRESS to call this helper so that the EFI
stub can select a randomized load address when KASLR is active, while
preserving the original base address behavior when KASLR is disabled or
"nokaslr" is specified.

Note: LoongArch can't KASLR for hibernation, so set efi_nokaslr to true
if "resume=" is explicitly specified in cmdline.

Acked-by: Ard Biesheuvel 
Signed-off-by: WANG Rui 
Signed-off-by: Huacai Chen

ring-buffer: Flush and stop persistent ring buffer on panic

2026-05-21T12:20:58+00:00

On real hardware, panic and machine reboot may not flush hardware cache
to memory. This means the persistent ring buffer, which relies on a
coherent state of memory, may not have its events written to the buffer
and they may be lost. Moreover, there may be inconsistency with the
counters which are used for validation of the integrity of the
persistent ring buffer which may cause all data to be discarded.

To avoid this issue, stop recording of the ring buffer on panic and
flush the cache of the ring buffer's memory.

Fixes: e645535a954a ("tracing: Add option to use memmapped memory for trace boot instance")
Cc: stable@vger.kernel.org
Cc: Will Deacon 
Cc: Mathieu Desnoyers 
Cc: Ian Rogers 
Link: https://patch.msgid.link/177751969602.2136606.12031934362587643488.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) 
Acked-by: Catalin Marinas 
Acked-by: Geert Uytterhoeven 
Signed-off-by: Steven Rostedt

LoongArch: KVM: Move unconditional delay into timer clear scenery

2026-05-04T01:00:48+00:00

When timer interrupt arrives in guest kernel, guest kernel clears the
timer interrupt and program timer with the next incoming event.

During this stage, timer tick is -1 and timer interrupt status is
disabled in ESTAT register. KVM hypervisor need write zero with timer
tick register and wait timer interrupt injection from HW side, and
then clear timer interrupt.

So there is 2 cycle delay in KVM hypervisor to emulate such scenery,
and the delay is unnecessary if there is no need to clear the timer
interrupt.

Here move 2 cycle delay into timer clear scenery and add timer ESTAT
checking after delay, and set max timer expire value if timer interrupt
does not arrive still.

Cc: stable@vger.kernel.org
Signed-off-by: Bibo Mao 
Signed-off-by: Huacai Chen