linux-stable.git/arch/mips, branch linux-rolling-lts

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

2026-04-18T08:44:57+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

2026-04-18T08:44:57+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

2026-04-18T08:44:57+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

2026-04-11T12:26:35+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

2026-04-11T12:26:35+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

MIPS: SiByte: Bring back cache initialisation

2026-04-11T12:26:35+00:00

commit d62cf1511743526f530a4c169424e50c757f5a5e upstream.

Bring back cache initialisation for Broadcom SiByte SB1 cores, which has
been removed causing the kernel to hang at bootstrap right after:

Dentry cache hash table entries: 524288 (order: 8, 4194304 bytes, linear)
Inode-cache hash table entries: 262144 (order: 7, 2097152 bytes, linear)

The cause of the problem is R4k cache handlers are also used by Broadcom
SiByte SB1 cores, however with a different cache error exception handler
and therefore not using CPU_R4K_CACHE_TLB:

obj-$(CONFIG_CPU_R4K_CACHE_TLB) += c-r4k.o cex-gen.o tlb-r4k.o
obj-$(CONFIG_CPU_SB1)           += c-r4k.o cerr-sb1.o cex-sb1.o tlb-r4k.o

(from arch/mips/mm/Makefile).

Fixes: bbe4f634f48c ("mips: fix r3k_cache_init build regression")
Signed-off-by: Maciej W. Rozycki 
Cc: stable@vger.kernel.org # v6.8+
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Greg Kroah-Hartman

mips: ralink: update CPU clock index

2026-04-11T12:26:32+00:00

[ Upstream commit 43985a62bab9d35e5e9af41118ce2f44c01b97d2 ]

Update CPU clock index to match the clock driver changes.

Fixes: d34db686a3d7 ("clk: ralink: mtmips: fix clocks probe order in oldest ralink SoCs")
Signed-off-by: Mieczyslaw Nalewaj 
Signed-off-by: Shiji Yang 
Reviewed-by: Sergio Paracuellos 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

kbuild: Split .modinfo out from ELF_DETAILS

2026-03-12T11:09:44+00:00

commit 8678591b47469fe16357234efef9b260317b8be4 upstream.

Commit 3e86e4d74c04 ("kbuild: keep .modinfo section in
vmlinux.unstripped") added .modinfo to ELF_DETAILS while removing it
from COMMON_DISCARDS, as it was needed in vmlinux.unstripped and
ELF_DETAILS was present in all architecture specific vmlinux linker
scripts. While this shuffle is fine for vmlinux, ELF_DETAILS and
COMMON_DISCARDS may be used by other linker scripts, such as the s390
and x86 compressed boot images, which may not expect to have a .modinfo
section. In certain circumstances, this could result in a bootloader
failing to load the compressed kernel [1].

Commit ddc6cbef3ef1 ("s390/boot/vmlinux.lds.S: Ensure bzImage ends with
SecureBoot trailer") recently addressed this for the s390 bzImage but
the same bug remains for arm, parisc, and x86. The presence of .modinfo
in the x86 bzImage was the root cause of the issue worked around with
commit d50f21091358 ("kbuild: align modinfo section for Secureboot
Authenticode EDK2 compat"). misc.c in arch/x86/boot/compressed includes
lib/decompress_unzstd.c, which in turn includes lib/xxhash.c and its
MODULE_LICENSE / MODULE_DESCRIPTION macros due to the STATIC definition.

Split .modinfo out from ELF_DETAILS into its own macro and handle it in
all vmlinux linker scripts. Discard .modinfo in the places where it was
previously being discarded from being in COMMON_DISCARDS, as it has
never been necessary in those uses.

Cc: stable@vger.kernel.org
Fixes: 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped")
Reported-by: Ed W 
Closes: https://lore.kernel.org/587f25e0-a80e-46a5-9f01-87cb40cfa377@wildgooses.com/ [1]
Tested-by: Ed W  # x86_64
Link: https://patch.msgid.link/20260225-separate-modinfo-from-elf-details-v1-1-387ced6baf4b@kernel.org
Signed-off-by: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman

MIPS: rb532: Fix MMIO UART resource registration

2026-03-04T12:21:25+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: Loongson2ef: Use pcibios_align_resource() to block io range

2026-03-04T12:21:23+00:00

[ Upstream commit 32ec465103527ede09b640cd0ab0636dc58827fb ]

Loongson2ef reserves io range below 0x4000 (LOONGSON_PCI_IO_START) while
ISA-mode only IDE controller on the south bridge still has a hard
dependency on ISA IO ports.

The reservation was done by lifting loongson_pci_io_resource.start onto
0x4000. Prior to commit ae81aad5c2e1 ("MIPS: PCI: Use
pci_enable_resources()"), the arch specific pcibios_enable_resources()
did not check if the resources were claimed, which diverges from what
PCI core checks, effectively hiding the fact that IDE IO resources were
not properly within the resource tree. After starting to use
pcibios_enable_resources() from PCI core, enabling IDE controller fails:

  pata_cs5536 0000:00:0e.2: BAR 0 [io  0x01f0-0x01f7]: not claimed; can't enable device
  pata_cs5536 0000:00:0e.2: probe with driver pata_cs5536 failed with error -22

MIPS PCI code already has support for enforcing lower bounds using
PCIBIOS_MIN_IO in pcibios_align_resource() without altering the IO
window start address itself. Make Loongson2ef PCI code use
PCIBIOS_MIN_IO too.

Fixes: ae81aad5c2e1 ("MIPS: PCI: Use pci_enable_resources()")
Cc: stable@vger.kernel.org
Tested-by: Beiyan Yun 
Tested-by: Yao Zi 
Signed-off-by: Rong Zhang 
Acked-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin