kernel/linux.git/arch/loongarch, branch v6.6.132

LoongArch: Workaround LS2K/LS7A GPU DMA hang bug

2026-04-02T11:07:27+00:00

commit 95db0c9f526d583634cddb2e5914718570fbac87 upstream. 1. Hardware limitation: GPU, DC and VPU are typically PCI device 06.0, 06.1 and 06.2. They share some hardware resources, so when configure the PCI 06.0 device BAR1, DMA memory access cannot be performed through this BAR, otherwise it will cause hardware abnormalities. 2. In typical scenarios of reboot or S3/S4, DC access to memory through BAR is not prohibited, resulting in GPU DMA hangs. 3. Workaround method: When configuring the 06.0 device BAR1, turn off the memory access of DC, GPU and VPU (via DC's CRTC registers). Cc: stable@vger.kernel.org Signed-off-by: Qianhai Wu Signed-off-by: Huacai Chen Signed-off-by: Greg Kroah-Hartman

LoongArch: Give more information if kmem access failed

2026-03-25T10:06:02+00:00

commit a47f0754bdd01f971c9715acdbdd3a07515c8f83 upstream. If memory access such as copy_{from, to}_kernel_nofault() failed, its users do not know what happened, so it is very useful to print the exception code for such cases. Furthermore, it is better to print the caller function to know where is the entry. Here are the low level call chains: copy_from_kernel_nofault() copy_from_kernel_nofault_loop() __get_kernel_nofault() copy_to_kernel_nofault() copy_to_kernel_nofault_loop() __put_kernel_nofault() Cc: stable@vger.kernel.org Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen Signed-off-by: Greg Kroah-Hartman

LoongArch: Disable instrumentation for setup_ptwalker()

2026-03-04T12:21:17+00:00

[ Upstream commit 7cb37af61f09c9cfd90c43c9275307c16320cbf2 ] According to Documentation/dev-tools/kasan.rst, software KASAN modes use compiler instrumentation to insert validity checks. Such instrumentation might be incompatible with some parts of the kernel, and therefore needs to be disabled, just use the attribute __no_sanitize_address to disable instrumentation for the low level function setup_ptwalker(). Otherwise bringing up the secondary CPUs failed when CONFIG_KASAN is set (especially when PTW is enabled), here are the call chains: smpboot_entry() start_secondary() cpu_probe() per_cpu_trap_init() tlb_init() setup_tlb_handler() setup_ptwalker() The reason is the PGD registers are configured in setup_ptwalker(), but KASAN instrumentation may cause TLB exceptions before that. Cc: stable@vger.kernel.org Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen Signed-off-by: Sasha Levin

LoongArch: Guard percpu handler under !CONFIG_PREEMPT_RT

2026-03-04T12:21:16+00:00

[ Upstream commit 70b0faae3590c628a98a627a10e5d211310169d4 ] After commit 88fd2b70120d ("LoongArch: Fix sleeping in atomic context for PREEMPT_RT"), it should guard percpu handler under !CONFIG_PREEMPT_RT to avoid redundant operations. Cc: stable@vger.kernel.org Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen Signed-off-by: Sasha Levin

LoongArch: Prefer top-down allocation after arch_mem_init()

2026-03-04T12:21:16+00:00

[ Upstream commit 2172d6ebac9372eb01fe4505a53e18cb061e103b ] Currently we use bottom-up allocation after sparse_init(), the reason is sparse_init() need a lot of memory, and bottom-up allocation may exhaust precious low memory (below 4GB). On the other hand, SWIOTLB and CMA need low memories for DMA32, so swiotlb_init() and dma_contiguous_reserve() need bottom-up allocation. Since swiotlb_init() and dma_contiguous_reserve() are both called in arch_mem_init(), we no longer need bottom-up allocation after that. So we set the allocation policy to top-down at the end of arch_mem_init(), in order to avoid later memory allocations (such as KASAN) exhaust low memory. This solve at least two problems: 1. Some buggy BIOSes use 0xfd000000~0xfe000000 for secondary CPUs, but didn't reserve this range, which causes smpboot failures. 2. Some DMA32 devices, such as Loongson-DRM and OHCI, cannot work with KASAN enabled. Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen Signed-off-by: Sasha Levin

LoongArch: Make cpumask_of_node() robust against NUMA_NO_NODE

2026-03-04T12:21:16+00:00

[ Upstream commit 94b0c831eda778ae9e4f2164a8b3de485d8977bb ] The arch definition of cpumask_of_node() cannot handle NUMA_NO_NODE - which is a valid index - so add a check for this. Cc: stable@vger.kernel.org Signed-off-by: John Garry Signed-off-by: Huacai Chen Signed-off-by: Sasha Levin

LoongArch: Add writecombine support for DMW-based ioremap()

2026-02-19T15:28:26+00:00

commit 8e02c3b782ec64343f3cccc8dc5a8be2b379e80b upstream. Currently, only TLB-based ioremap() support writecombine, so add the counterpart for DMW-based ioremap() with help of DMW2. The base address (WRITECOMBINE_BASE) is configured as 0xa000000000000000. DMW3 is unused by kernel now, however firmware may leave garbage in them and interfere kernel's address mapping. So clear it as necessary. BTW, centralize the DMW configuration to macro SETUP_DMWINS. Signed-off-by: Jiaxun Yang Signed-off-by: Huacai Chen Signed-off-by: Greg Kroah-Hartman

LoongArch: Rework KASAN initialization for PTW-enabled systems

2026-02-19T15:28:25+00:00

commit 5ec5ac4ca27e4daa234540ac32f9fc5219377d53 upstream. kasan_init_generic() indicates that kasan is fully initialized, so it should be put at end of kasan_init(). Otherwise bringing up the primary CPU failed when CONFIG_KASAN is set on PTW-enabled systems, here are the call chains: kernel_entry() start_kernel() setup_arch() kasan_init() kasan_init_generic() The reason is PTW-enabled systems have speculative accesses which means memory accesses to the shadow memory after kasan_init() may be executed by hardware before. However, accessing shadow memory is safe only after kasan fully initialized because kasan_init() uses a temporary PGD table until we have populated all levels of shadow page tables and writen the PGD register. Moving kasan_init_generic() later can defer the occasion of kasan_enabled(), so as to avoid speculative accesses on shadow pages. After moving kasan_init_generic() to the end, kasan_init() can no longer call kasan_mem_to_shadow() for shadow address conversion because it will always return kasan_early_shadow_page. On the other hand, we should keep the current logic of kasan_mem_to_shadow() for both the early and final stage because there may be instrumentation before kasan_init(). To solve this, we factor out a new mem_to_shadow() function from current kasan_mem_to_shadow() for the shadow address conversion in kasan_init(). Cc: stable@vger.kernel.org Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen [ Huacai: To backport from upstream to 6.6 & 6.12, kasan_enabled() is replaced with kasan_arch_is_ready() and kasan_init_generic() is replaced with "kasan_early_stage = false". ] Signed-off-by: Greg Kroah-Hartman

LoongArch: Add WriteCombine shadow mapping in KASAN

2026-02-19T15:28:25+00:00

commit 139d42ca51018c1d43ab5f35829179f060d1ab31 upstream. Currently, the kernel couldn't boot when ARCH_IOREMAP, ARCH_WRITECOMBINE and KASAN are enabled together. Because DMW2 is used by kernel now which is configured as 0xa000000000000000 for WriteCombine, but KASAN has no segment mapping for it. This patch fix this issue. Solution: Add the relevant definitions for WriteCombine (DMW2) in KASAN. Cc: stable@vger.kernel.org Fixes: 8e02c3b782ec ("LoongArch: Add writecombine support for DMW-based ioremap()") Signed-off-by: Kanglong Wang Signed-off-by: Huacai Chen Signed-off-by: Greg Kroah-Hartman

LoongArch: Enable exception fixup for specific ADE subcode

2026-02-11T12:39:10+00:00

[ Upstream commit 9bdc1ab5e4ce6f066119018d8f69631a46f9c5a0 ] This patch allows the LoongArch BPF JIT to handle recoverable memory access errors generated by BPF_PROBE_MEM* instructions. When a BPF program performs memory access operations, the instructions it executes may trigger ADEM exceptions. The kernel’s built-in BPF exception table mechanism (EX_TYPE_BPF) will generate corresponding exception fixup entries in the JIT compilation phase; however, the architecture-specific trap handling function needs to proactively call the common fixup routine to achieve exception recovery. do_ade(): fix EX_TYPE_BPF memory access exceptions for BPF programs, ensure safe execution. Relevant test cases: illegal address access tests in module_attach and subprogs_extable of selftests/bpf. Signed-off-by: Chenghao Duan Signed-off-by: Huacai Chen Signed-off-by: Sasha Levin