kernel/linux.git/arch, branch v6.6.142

LoongArch: kprobes: Fix handling of fatal unrecoverable recursions

2026-06-01T15:43:16+00:00

[ Upstream commit 1c856e158fd34ef2c4475a81c1dc386329989938 ] 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 Signed-off-by: Sasha Levin

x86/xen: Fix xen_e820_swap_entry_with_ram()

2026-06-01T15:43:13+00:00

[ Upstream commit 28e03f78e69cf6628b81f24777799778528a84c1 ] When swapping a not page-aligned E820 map entry with RAM, the start address of the modified entry is calculated wrong (the offset into the page is subtracted instead of being added to the page address). Fixes: be35d91c8880 ("xen: tolerate ACPI NVS memory overlapping with Xen allocated memory") Reported-by: Jan Beulich Reviewed-by: Jan Beulich Signed-off-by: Juergen Gross Message-ID: <20260505102417.208138-1-jgross@suse.com> Signed-off-by: Sasha Levin

powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()

2026-06-01T15:43:13+00:00

[ Upstream commit 31467b23823ffec1f6fff407f8e3ca9af8b7491a ] A kernel panic is observed when handling machine check exceptions from real mode. BUG: Unable to handle kernel data access on read at 0xc00000006be21300 Oops: Kernel access of bad area, sig: 11 [#1] MSR: 8000000000001003 CR: 88222248 XER: 00000005 CFAR: c00000000003ffc4 DAR: c00000006be21300 DSISR: 40000000 IRQMASK: 0 NIP [c000000000029e40] arch_irq_work_raise+0x10/0x70 LR [c00000000003ffc8] machine_check_queue_event+0xa8/0x150 Call Trace: [c0000000179d3c70] [c00000000003ff64] machine_check_queue_event+0x44/0x150 [c0000000179d3d30] [c0000000000084e0] machine_check_early_common+0x1f0/0x2c0 The crash occurs because arch_irq_work_raise() calls preempt_disable() from machine check exception (MCE) handlers running in real mode. In this context, accessing the preempt_count can fault, leading to the panic. The preempt_disable()/preempt_enable() pair in arch_irq_work_raise() was originally added by commit 0fe1ac48bef0 ("powerpc/perf_event: Fix oops due to perf_event_do_pending call") to avoid races while raising irq work from exception context. Later, commit 471ba0e686cb ("irq_work: Do not raise an IPI when queueing work on the local CPU") added preemption protection in irq_work_queue() path, while commit 20b876918c06 ("irq_work: Use per cpu atomics instead of regular atomics") added equivalent protection in irq_work_queue_on() before reaching arch_irq_work_raise(): irq_work_queue() / irq_work_queue_on() -> preempt_disable() -> __irq_work_queue_local() -> irq_work_raise() -> arch_irq_work_raise() As a result, callers other than mce_irq_work_raise() already execute with preemption disabled, making the additional preempt_disable()/preempt_enable() pair in arch_irq_work_raise() redundant. The arch_irq_work_raise() function executes in NMI context when called from MCE handler. Hence we will not be preempted or scheduled out since we are in NMI context with MSR[EE]=0. Therefore, it is safe to remove the preempt_disable()/preempt_enable() calls from here. Remove it to avoid accessing preempt_count from real mode context. Fixes: cc15ff327569 ("powerpc/mce: Avoid using irq_work_queue() in realmode") Suggested-by: Mahesh Salgaonkar Acked-by: Shrikanth Hegde Reviewed-by: Ritesh Harjani (IBM) Signed-off-by: Sayali Patil [Maddy: Fixed the commit title] Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260513081413.222490-1-sayalip@linux.ibm.com Signed-off-by: Sasha Levin

ARM: integrator: Fix early initialization

2026-06-01T15:43:11+00:00

[ Upstream commit 90d77b30a666049ad24df463f52e5d529c44e8cd ] Starting with commit bdb249fce9ad4 ("ARM: integrator: read counter using syscon/regmap"), intcp_init_early calls syscon_regmap_lookup_by_compatible which in turn calls of_syscon_register. This function allocates memory. Since the memory management code has not been initialized at that time, the call always fails. It either returns -ENOMEM or crashes as follows. Unable to handle kernel NULL pointer dereference at virtual address 0000000c when read [0000000c] *pgd=00000000 Internal error: Oops: 5 [#1] ARM Modules linked in: CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.15.0-rc5-00026-g5fcc9bf84ee5 #1 PREEMPT Hardware name: ARM Integrator/CP (Device Tree) PC is at __kmalloc_cache_noprof+0xec/0x39c LR is at __kmalloc_cache_noprof+0x34/0x39c ... Call trace: __kmalloc_cache_noprof from of_syscon_register+0x7c/0x310 of_syscon_register from device_node_get_regmap+0xa4/0xb0 device_node_get_regmap from intcp_init_early+0xc/0x40 intcp_init_early from start_kernel+0x60/0x688 start_kernel from 0x0 The crash is seen due to a dereferenced pointer which is not supposed to be NULL but is NULL if the memory management subsystem has not been initialized. The crash is not seen with all versions of gcc. Some versions such as gcc 9.x apparently do not dereference the pointer, presumably if tracing is disabled. The problem has been reproduced with gcc 10.x, 11.x, and 13.x. Either case, if the crash is not seen, the call to syscon_regmap_lookup_by_compatible returns -ENOMEM, and sched_clock_register is never called. Fix the problem by moving the early initialization code into the standard machine initialization code. Fixes: bdb249fce9ad4 ("ARM: integrator: read counter using syscon/regmap") Cc: Linus Walleij Signed-off-by: Guenter Roeck Link: https://lore.kernel.org/20250518164118.3859567-1-linux@roeck-us.net Signed-off-by: Linus Walleij Link: https://lore.kernel.org/r/20260505-integrator-fixes-v1-1-56ab9aac59db@kernel.org Signed-off-by: Arnd Bergmann Signed-off-by: Sasha Levin

LoongArch: Remove unused code to avoid build warning

2026-06-01T15:43:09+00:00

commit 0ccc9d47cf020994097ff51827cebd04aa2b0bf4 upstream. 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 Signed-off-by: Greg Kroah-Hartman

KVM: arm64: vgic-its: Reject restored DTE with out-of-range num_eventid_bits

2026-06-01T15:43:08+00:00

commit 9ce754ed8e7ab4e3999767ce1505f85c449ccb07 upstream. Userspace can restore an ITS Device Table Entry whose Size field encodes more EventID bits than the virtual ITS supports. The live MAPD path rejects that state, but vgic_its_restore_dte() accepts it and stores the out-of-range value in dev->num_eventid_bits. Reject restored DTEs with num_eventid_bits > VITS_TYPER_IDBITS before allocating the device. This mirrors the MAPD check and prevents the restored state from reaching vgic_its_restore_itt(), where the unchecked value can be converted into an oversized scan_its_table() range. Fixes: 57a9a117154c ("KVM: arm64: vgic-its: Device table save/restore") Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Link: https://lore.kernel.org/r/20260519132519.2142458-1-michael.bommarito@gmail.com Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

arm64: probes: Handle probes on hinted conditional branch instructions

2026-06-01T15:43:08+00:00

commit 2ccd8ff980b50e842481bae71102fa3883fc4377 upstream. BC.cond instructions introduced by FEAT_HBC cannot be executed out-of-line, like other branch instructions. However, they can be simulated in the same way as B.cond instructions. Extend the B.cond decoder mask to match BC.cond instructions as well, and handle them using the existing B.cond simulation path. Fixes: 7f86d128e437 ("arm64: add HWCAP for FEAT_HBC (hinted conditional branches)") Cc: Signed-off-by: Vladimir Murzin Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

Revert "x86/vdso: Fix output operand size of RDPID"

2026-06-01T15:43:04+00:00

This reverts commit db82a94b0c109e7697a593f36783e7ef36073983. Signed-off-by: Sasha Levin

s390/debug: Reject zero-length input before trimming a newline

2026-06-01T15:43:04+00:00

[ Upstream commit c366a7b5ed7564e41345c380285bd3f6cb98971b ] debug_get_user_string() copies the userspace buffer into a newly allocated NUL-terminated buffer and then unconditionally looks at buffer[user_len - 1] to strip a trailing newline. A zero-length write reaches this helper unchanged, so the newline trim reads before the start of the allocated buffer. Reject empty writes before accessing the last input byte. Fixes: 66a464dbc8e0 ("[PATCH] s390: debug feature changes") Cc: stable@vger.kernel.org Signed-off-by: Pengpeng Hou Reviewed-by: Benjamin Block Reviewed-by: Vasily Gorbik Tested-by: Vasily Gorbik Link: https://lore.kernel.org/r/20260417073530.96002-1-pengpeng@iscas.ac.cn Signed-off-by: Vasily Gorbik Signed-off-by: Alexander Gordeev Signed-off-by: Sasha Levin

powerpc/warp: Fix error handling in pika_dtm_thread

2026-05-23T11:03:33+00:00

commit 108d7f951271cbd36ca36efc5e5d106966f5180c upstream. pika_dtm_thread() acquires client through of_find_i2c_device_by_node() but fails to release it in error handling path. This could result in a reference count leak, preventing proper cleanup and potentially leading to resource exhaustion. Add put_device() to release the reference in the error handling path. Found by code review. Cc: stable@vger.kernel.org Fixes: 3984114f0562 ("powerpc/warp: Platform fix for i2c change") Signed-off-by: Ma Ke Reviewed-by: Christophe Leroy Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20251116024411.21968-1-make24@iscas.ac.cn Signed-off-by: Greg Kroah-Hartman