kernel/linux.git/arch/mips, branch v6.1.174

MIPS: mm: Rewrite TLB uniquification for the hidden bit feature

2026-04-18T08:35:56+00:00

commit 540760b77b8fc49d39d1b2b76196e5ec57711a32 upstream. Before the introduction of the EHINV feature, which lets software mark TLB entries invalid, certain older implementations of the MIPS ISA were equipped with an analogous bit, as a vendor extension, which however is hidden from software and only ever set at reset, and then any software write clears it, making the intended TLB entry valid. This feature makes it unsafe to read a TLB entry with TLBR, modify the page mask, and write the entry back with TLBWI, because this operation will implicitly clear the hidden bit and this may create a duplicate entry, as with the presence of the hidden bit there is no guarantee all the entries across the TLB are unique each. Usually the firmware has already uniquified TLB entries before handing control over, in which case we only need to guarantee at bootstrap no clash will happen with the VPN2 values chosen in local_flush_tlb_all(). However with systems such as Mikrotik RB532 we get handed the TLB as at reset, with the hidden bit set across the entries and possibly duplicate entries present. This then causes a machine check exception when page sizes are reset in r4k_tlb_uniquify() and prevents the system from booting. Rewrite the algorithm used in r4k_tlb_uniquify() then such as to avoid the reuse of ASID/VPN values across the TLB. Get rid of global entries first as they may be blocking the entire address space, e.g. 16 256MiB pages will exhaust the whole address space of a 32-bit CPU and a single big page can exhaust the 32-bit compatibility space on a 64-bit CPU. Details of the algorithm chosen are given across the code itself. Fixes: 9f048fa48740 ("MIPS: mm: Prevent a TLB shutdown on initial uniquification") Signed-off-by: Maciej W. Rozycki Cc: stable@vger.kernel.org # v6.18+ Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin

MIPS: mm: Suppress TLB uniquification on EHINV hardware

2026-04-18T08:35:56+00:00

commit 74283cfe216392c7b776ebf6045b5b15ed9dffcd upstream. Hardware that supports the EHINV feature, mandatory for R6 ISA and FTLB implementation, lets software mark TLB entries invalid, which eliminates the need to ensure no duplicate matching entries are ever created. This feature is already used by local_flush_tlb_all(), via the UNIQUE_ENTRYHI macro, making the preceding call to r4k_tlb_uniquify() superfluous. The next change will also modify uniquification code such that it'll become incompatible with the FTLB and MMID features, as well as MIPSr6 CPUs that do not implement 4KiB pages. Therefore prevent r4k_tlb_uniquify() from being used on EHINV hardware, as denoted by `cpu_has_tlbinv'. Signed-off-by: Maciej W. Rozycki Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin

MIPS: Always record SEGBITS in cpu_data.vmbits

2026-04-18T08:35:56+00:00

commit 8374c2cb83b95b3c92f129fd56527225c20a058c upstream. With a 32-bit kernel running on 64-bit MIPS hardware the hardcoded value of `cpu_vmbits' only records the size of compatibility useg and does not reflect the size of native xuseg or the complete range of values allowed in the VPN2 field of TLB entries. An upcoming change will need the actual VPN2 value range permitted even in 32-bit kernel configurations, so always include the `vmbits' member in `struct cpuinfo_mips' and probe for SEGBITS when running on 64-bit hardware and resorting to the currently hardcoded value of 31 on 32-bit processors. No functional change for users of `cpu_vmbits'. Signed-off-by: Maciej W. Rozycki Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin

mips: mm: Allocate tlb_vpn array atomically

2026-04-11T12:16:26+00:00

commit 01cc50ea5167bb14117257ec084637abe9e5f691 upstream. Found by DEBUG_ATOMIC_SLEEP: BUG: sleeping function called from invalid context at /include/linux/sched/mm.h:306 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 no locks held by swapper/1/0. irq event stamp: 0 hardirqs last enabled at (0): [<0000000000000000>] 0x0 hardirqs last disabled at (0): [] copy_process+0x75c/0x1b68 softirqs last enabled at (0): [] copy_process+0x75c/0x1b68 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.6.119-d79e757675ec-fct #1 Stack : 800000000290bad8 0000000000000000 0000000000000008 800000000290bae8 800000000290bae8 800000000290bc78 0000000000000000 0000000000000000 ffffffff80c80000 0000000000000001 ffffffff80d8dee8 ffffffff810d09c0 784bb2a7ec10647d 0000000000000010 ffffffff80a6fd60 8000000001d8a9c0 0000000000000000 0000000000000000 ffffffff80d90000 0000000000000000 ffffffff80c9e0e8 0000000007ffffff 0000000000000cc0 0000000000000400 ffffffffffffffff 0000000000000001 0000000000000002 ffffffffc0149ed8 fffffffffffffffe 8000000002908000 800000000290bae0 ffffffff80a81b74 ffffffff80129fb0 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 ffffffff80129fd0 0000000000000000 ... Call Trace: [] show_stack+0x60/0x158 [] dump_stack_lvl+0x88/0xbc [] __might_resched+0x268/0x288 [] __kmem_cache_alloc_node+0x2e0/0x330 [] __kmalloc+0x58/0xd0 [] r4k_tlb_uniquify+0x7c/0x428 [] tlb_init+0x7c/0x110 [] per_cpu_trap_init+0x16c/0x1d0 [] start_secondary+0x28/0x128 Fixes: 231ac951faba ("MIPS: mm: kmalloc tlb_vpn array to avoid stack overflow") Signed-off-by: Stefan Wiehler Cc: stable@vger.kernel.org Signed-off-by: Thomas Bogendoerfer Signed-off-by: Greg Kroah-Hartman

MIPS: Fix the GCC version check for `__multi3' workaround

2026-04-11T12:16:26+00:00

commit ec8bf18814915460d9c617b556bf024efef26613 upstream. It was only GCC 10 that fixed a MIPS64r6 code generation issue with a `__multi3' libcall inefficiently produced to perform 64-bit widening multiplication while suitable machine instructions exist to do such a calculation. The fix went in with GCC commit 48b2123f6336 ("re PR target/82981 (unnecessary __multi3 call for mips64r6 linux kernel)"). Adjust our code accordingly, removing build failures such as: mips64-linux-ld: lib/math/div64.o: in function `mul_u64_add_u64_div_u64': div64.c:(.text+0x84): undefined reference to `__multi3' with the GCC versions affected. Fixes: ebabcf17bcd7 ("MIPS: Implement __multi3 for GCC7 MIPS64r6 builds") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202601140146.hMLODc6v-lkp@intel.com/ Signed-off-by: Maciej W. Rozycki Cc: stable@vger.kernel.org # v4.15+ Reviewed-by: David Laight Signed-off-by: Greg Kroah-Hartman

PCI: Introduce pci_dev_for_each_resource()

2026-03-25T10:02:54+00:00

[ Upstream commit 09cc900632400079619e9154604fd299c2cc9a5a ] Instead of open-coding it everywhere introduce a tiny helper that can be used to iterate over each resource of a PCI device, and convert the most obvious users into it. While at it drop doubled empty line before pdev_sort_resources(). No functional changes intended. Suggested-by: Andy Shevchenko Link: https://lore.kernel.org/r/20230330162434.35055-4-andriy.shevchenko@linux.intel.com Signed-off-by: Mika Westerberg Signed-off-by: Andy Shevchenko Signed-off-by: Bjorn Helgaas Reviewed-by: Krzysztof Wilczyński Stable-dep-of: 11721c45a826 ("PCI: Use resource_set_range() that correctly sets ->end") Signed-off-by: Sasha Levin

MIPS: rb532: Fix MMIO UART resource registration

2026-03-04T12:20:53+00:00

[ Upstream commit e93bb4b76cfefb302534246e892c7667491cb8cc ] Since commit 6e690d54cfa8 ("serial: 8250: fix return error code in serial8250_request_std_resource()"), registering an 8250 MMIO port without mapbase no longer works, as the resource range is derived from mapbase/mapsize. Populate mapbase and mapsize accordingly. Also drop ugly membase KSEG1 pointer and set UPF_IOREMAP instead, letting the 8250 core perform the ioremap. Fixes: 6e690d54cfa8 ("serial: 8250: fix return error code in serial8250_request_std_resource()") Cc: stable@vger.kernel.org Reported-by: Waldemar Brodkorb Link: https://lore.kernel.org/linux-mips/aX-d0ShTplHKZT33@waldemar-brodkorb.de/ Signed-off-by: Jiaxun Yang Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin

MIPS: Loongson: Make cpumask_of_node() robust against NUMA_NO_NODE

2026-03-04T12:20:35+00:00

[ Upstream commit d55d3fe2d1470ac5b6e93efe7998b728013c9fc8 ] The arch definition of cpumask_of_node() cannot handle NUMA_NO_NODE - which is a valid index - so add a check for this. Signed-off-by: John Garry Reviewed-by: Huacai Chen Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin

MIPS: Work around LLVM bug when gp is used as global register variable

2026-03-04T12:19:54+00:00

commit 30bfc2d6a1132a89a5f1c3b96c59cf3e4d076ea3 upstream. On MIPS, __current_thread_info is defined as global register variable locating in $gp, and is simply assigned with new address during kernel relocation. This however is broken with LLVM, which always restores $gp if it finds $gp is clobbered in any form, including when intentionally through a global register variable. This is against GCC's documentation[1], which requires a callee-saved register used as global register variable not to be restored if it's clobbered. As a result, $gp will continue to point to the unrelocated kernel after the epilog of relocate_kernel(), leading to an early crash in init_idle, [ 0.000000] CPU 0 Unable to handle kernel paging request at virtual address 0000000000000000, epc == ffffffff81afada8, ra == ffffffff81afad90 [ 0.000000] Oops[#1]: [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper Tainted: G W 6.19.0-rc5-00262-gd3eeb99bbc99-dirty #188 VOLUNTARY [ 0.000000] Tainted: [W]=WARN [ 0.000000] Hardware name: loongson,loongson64v-4core-virtio [ 0.000000] $ 0 : 0000000000000000 0000000000000000 0000000000000001 0000000000000000 [ 0.000000] $ 4 : ffffffff80b80ec0 ffffffff80b53d48 0000000000000000 00000000000f4240 [ 0.000000] $ 8 : 0000000000000100 ffffffff81d82f80 ffffffff81d82f80 0000000000000001 [ 0.000000] $12 : 0000000000000000 ffffffff81776f58 00000000000005da 0000000000000002 [ 0.000000] $16 : ffffffff80b80e40 0000000000000000 ffffffff80b81614 9800000005dfbe80 [ 0.000000] $20 : 00000000540000e0 ffffffff81980000 0000000000000000 ffffffff80f81c80 [ 0.000000] $24 : 0000000000000a26 ffffffff8114fb90 [ 0.000000] $28 : ffffffff80b50000 ffffffff80b53d40 0000000000000000 ffffffff81afad90 [ 0.000000] Hi : 0000000000000000 [ 0.000000] Lo : 0000000000000000 [ 0.000000] epc : ffffffff81afada8 init_idle+0x130/0x270 [ 0.000000] ra : ffffffff81afad90 init_idle+0x118/0x270 [ 0.000000] Status: 540000e2 KX SX UX KERNEL EXL [ 0.000000] Cause : 00000008 (ExcCode 02) [ 0.000000] BadVA : 0000000000000000 [ 0.000000] PrId : 00006305 (ICT Loongson-3) [ 0.000000] Process swapper (pid: 0, threadinfo=(____ptrval____), task=(____ptrval____), tls=0000000000000000) [ 0.000000] Stack : 9800000005dfbf00 ffffffff8178e950 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 ffffffff81970000 000000000000003f ffffffff810a6528 [ 0.000000] 0000000000000001 9800000005dfbe80 9800000005dfbf00 ffffffff81980000 [ 0.000000] ffffffff810a6450 ffffffff81afb6c0 0000000000000000 ffffffff810a2258 [ 0.000000] ffffffff81d82ec8 ffffffff8198d010 ffffffff81b67e80 ffffffff8197dd98 [ 0.000000] ffffffff81d81c80 ffffffff81930000 0000000000000040 0000000000000000 [ 0.000000] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 000000000000009e ffffffff9fc01000 0000000000000000 [ 0.000000] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 ffffffff81ae86dc ffffffff81b3c741 0000000000000002 [ 0.000000] ... [ 0.000000] Call Trace: [ 0.000000] [] init_idle+0x130/0x270 [ 0.000000] [] sched_init+0x5c8/0x6c0 [ 0.000000] [] start_kernel+0x27c/0x7a8 This bug has been reported to LLVM[2] and affects version from (at least) 18 to 21. Let's work around this by using inline assembly to assign $gp before a fix is widely available. Cc: stable@vger.kernel.org Link: https://gcc.gnu.org/onlinedocs/gcc-15.2.0/gcc/Global-Register-Variables.html # [1] Link: https://github.com/llvm/llvm-project/issues/176546 # [2] Signed-off-by: Yao Zi Acked-by: Nathan Chancellor Signed-off-by: Thomas Bogendoerfer Signed-off-by: Greg Kroah-Hartman

MIPS: Fix a reference leak bug in ip22_check_gio()

2026-01-11T14:18:44+00:00

[ Upstream commit 680ad315caaa2860df411cb378bf3614d96c7648 ] If gio_device_register fails, gio_dev_put() is required to drop the gio_dev device reference. Fixes: e84de0c61905 ("MIPS: GIO bus support for SGI IP22/28") Signed-off-by: Haoxiang Li Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin