kernel/linux.git/arch/arm, branch v6.12.94

ARM: 9475/1: entry: use byte load for KASAN VMAP stack shadow

2026-06-19T11:42:30+00:00

commit 77a1f6883dc6e837bb2cb30b9b02e2f94338e2c6 upstream. Commit 44e9a3bb76e5 ("ARM: 9430/1: entry: Do a dummy read from VMAP shadow") added a dummy read from the KASAN VMAP stack shadow in __switch_to(). The read uses ldr, but the KASAN shadow address is byte-granular and is not guaranteed to be word aligned. ARMv5 faults unaligned word loads. With CONFIG_KASAN_VMALLOC and CONFIG_VMAP_STACK enabled, ARM926/VersatilePB crashes in __switch_to() with an alignment exception before reaching init. Use ldrb for the dummy shadow access. The code only needs to fault in the shadow mapping if the stack shadow is missing, so a byte load is sufficient and matches the granularity of KASAN shadow memory. Fixes: 44e9a3bb76e5 ("ARM: 9430/1: entry: Do a dummy read from VMAP shadow") Cc: stable@vger.kernel.org # v6.13+ Signed-off-by: Karl Mehltretter Reviewed-by: Linus Walleij Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

ARM: 9474/1: io: avoid KASAN instrumentation of raw halfword I/O

2026-06-19T11:42:30+00:00

commit d59ed803715a71fb9582e139d648ece8d66dc743 upstream. For CPUs before ARMv6, __raw_readw() and __raw_writew() are implemented as C volatile halfword accesses so the compiler can generate an access sequence that is safe for those machines. With KASAN enabled, those C accesses are instrumented as normal memory accesses. That is not valid for MMIO. On ARM926/VersatilePB with KASAN enabled, PL011 probing traps in __asan_store2() while registering the UART, because the instrumented writew() tries to check KASAN shadow for an MMIO address. Keep the existing volatile halfword access, but move the ARMv5 definitions into __no_kasan_or_inline functions so raw MMIO halfword accesses are not instrumented by KASAN. The ARMv6-and-newer inline assembly path is unchanged. Fixes: 421015713b30 ("ARM: 9017/2: Enable KASan for ARM") Cc: stable@vger.kernel.org # v5.11+ Signed-off-by: Karl Mehltretter Reviewed-by: Linus Walleij Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

ARM: socfpga: Fix OF node refcount leak in SMP setup

2026-06-19T11:42:30+00:00

commit 63838c323924fe4a78b2323bd45aa1030f72ca60 upstream. socfpga_smp_prepare_cpus() looks up the Cortex-A9 SCU node with of_find_compatible_node(), which returns a node reference that must be released with of_node_put(). The function maps the SCU registers and then returns without dropping that reference, leaking the node on both the success path and the of_iomap() failure path. Drop the reference once the mapping attempt is complete. The returned MMIO mapping does not depend on keeping the device node reference held. Fixes: 122694a0c712 ("ARM: socfpga: use of_iomap to map the SCU") Cc: stable@vger.kernel.org Signed-off-by: Yuho Choi Signed-off-by: Dinh Nguyen Signed-off-by: Greg Kroah-Hartman

ARM: fix branch predictor hardening

2026-06-19T11:42:17+00:00

commit fd2dee1c6e2256f726ba33fd3083a7be0efc80d3 upstream. __do_user_fault() may be called with indeterminent interrupt enable state, which means we may be preemptive at this point. This causes problems when calling harden_branch_predictor(). For example, when called from a data abort, do_alignment_fault()->do_bad_area(). Move harden_branch_predictor() out of __do_user_fault() and into the calling contexts. Moving it into do_kernel_address_page_fault(), we can be sure that interrupts will be disabled here. Converting do_translation_fault() to use do_kernel_address_page_fault() rather than do_bad_area() means that we keep branch predictor handling for translation faults. Interrupts will also be disabled at this call site. do_sect_fault() needs special handling, so detect user mode accesses to kernel-addresses, and add an explicit call to branch predictor hardening. Finally, add branch predictor hardening to do_alignment() for the faulting case (user mode accessing kernel addresses) before interrupts are enabled. This should cover all cases where harden_branch_predictor() is called, ensuring that it is always has interrupts disabled, also ensuring that it is called early in each call path. Reviewed-by: Xie Yuanbin Tested-by: Xie Yuanbin Signed-off-by: Russell King (Oracle) Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Sasha Levin

ARM: fix hash_name() fault

2026-06-19T11:42:17+00:00

commit 7733bc7d299d682f2723dc38fc7f370b9bf973e9 upstream. Zizhi Wo reports: "During the execution of hash_name()->load_unaligned_zeropad(), a potential memory access beyond the PAGE boundary may occur. For example, when the filename length is near the PAGE_SIZE boundary. This triggers a page fault, which leads to a call to do_page_fault()->mmap_read_trylock(). If we can't acquire the lock, we have to fall back to the mmap_read_lock() path, which calls might_sleep(). This breaks RCU semantics because path lookup occurs under an RCU read-side critical section." This is seen with CONFIG_DEBUG_ATOMIC_SLEEP=y and CONFIG_KFENCE=y. Kernel addresses (with the exception of the vectors/kuser helper page) do not have VMAs associated with them. If the vectors/kuser helper page faults, then there are two possibilities: 1. if the fault happened while in kernel mode, then we're basically dead, because the CPU won't be able to vector through this page to handle the fault. 2. if the fault happened while in user mode, that means the page was protected from user access, and we want to fault anyway. Thus, we can handle kernel addresses from any context entirely separately without going anywhere near the mmap lock. This gives us an entirely non-sleeping path for all kernel mode kernel address faults. As we handle the kernel address faults before interrupts are enabled, this change has the side effect of improving the branch predictor hardening, but does not completely solve the issue. Reported-by: Zizhi Wo Reported-by: Xie Yuanbin Link: https://lore.kernel.org/r/20251126090505.3057219-1-wozizhi@huaweicloud.com Reviewed-by: Xie Yuanbin Tested-by: Xie Yuanbin Signed-off-by: Russell King (Oracle) Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Sasha Levin

ARM: allow __do_kernel_fault() to report execution of memory faults

2026-06-19T11:42:17+00:00

commit 40b466db1dffb41f0529035c59c5739636d0e5b8 upstream. Allow __do_kernel_fault() to detect the execution of memory, so we can provide the same fault message as do_page_fault() would do. This is required when we split the kernel address fault handling from the main do_page_fault() code path. Reviewed-by: Xie Yuanbin Tested-by: Xie Yuanbin Signed-off-by: Russell King (Oracle) Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Sasha Levin

ARM: group is_permission_fault() with is_translation_fault()

2026-06-19T11:42:17+00:00

commit dea20281ac88226615761c570c8ff7adc18e6ac2 upstream. Group is_permission_fault() with is_translation_fault(), which is needed to use is_permission_fault() in __do_kernel_fault(). As this is static inline, there is no need for this to be under CONFIG_MMU. Signed-off-by: Russell King (Oracle) Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Sasha Levin

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

2026-06-09T10:26:03+00:00

[ Upstream commit a494d3c8d5392bcdff83c2a593df0c160ff9f322 ] 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 Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ARM: integrator: Fix early initialization

2026-06-01T15:46:25+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

ARM: dts: renesas: rskrza1: Drop superfluous cells

2026-06-01T15:46:23+00:00

[ Upstream commit ab83176d3cf1cf1c1f6e604432905bda4515d17f ] Drop superfluous address-cells and size-cells to fix DTC W=1 warning: arch/arm/boot/dts/renesas/r7s72100-rskrza1.dts:32.17-72.4: Warning (avoid_unnecessary_addr_size): /flash@18000000: unnecessary #address-cells/#size-cells without "ranges", "dma-ranges" or child "reg" or "ranges" property Signed-off-by: Marek Vasut Fixes: 98537eb77d3ef185 ("ARM: dts: renesas: rskrza1: Add FLASH nodes") Reviewed-by: Geert Uytterhoeven Link: https://patch.msgid.link/20260327234244.91707-7-marek.vasut+renesas@mailbox.org Signed-off-by: Geert Uytterhoeven Signed-off-by: Sasha Levin