linux.git/arch/mips/kernel, branch v6.12.80

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

2026-03-04T12:20:46+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: ftrace: Fix memory corruption when kernel is located beyond 32 bits

2026-01-08T09:14:13+00:00

[ Upstream commit 36dac9a3dda1f2bae343191bc16b910c603cac25 ]

Since commit e424054000878 ("MIPS: Tracing: Reduce the overhead of
dynamic Function Tracer"), the macro UASM_i_LA_mostly has been used,
and this macro can generate more than 2 instructions. At the same
time, the code in ftrace assumes that no more than 2 instructions can
be generated, which is why it stores them in an int[2] array. However,
as previously noted, the macro UASM_i_LA_mostly (and now UASM_i_LA)
causes a buffer overflow when _mcount is beyond 32 bits. This leads to
corruption of the variables located in the __read_mostly section.

This corruption was observed because the variable
__cpu_primary_thread_mask was corrupted, causing a hang very early
during boot.

This fix prevents the corruption by avoiding the generation of
instructions if they could exceed 2 instructions in
length. Fortunately, insn_la_mcount is only used if the instrumented
code is located outside the kernel code section, so dynamic ftrace can
still be used, albeit in a more limited scope. This is still
preferable to corrupting memory and/or crashing the kernel.

Signed-off-by: Gregory CLEMENT 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

arch: Add the macro COMPILE_OFFSETS to all the asm-offsets.c

2025-11-02T13:15:22+00:00

[ Upstream commit 35561bab768977c9e05f1f1a9bc00134c85f3e28 ]

The include/generated/asm-offsets.h is generated in Kbuild during
compiling from arch/SRCARCH/kernel/asm-offsets.c. When we want to
generate another similar offset header file, circular dependency can
happen.

For example, we want to generate a offset file include/generated/test.h,
which is included in include/sched/sched.h. If we generate asm-offsets.h
first, it will fail, as include/sched/sched.h is included in asm-offsets.c
and include/generated/test.h doesn't exist; If we generate test.h first,
it can't success neither, as include/generated/asm-offsets.h is included
by it.

In x86_64, the macro COMPILE_OFFSETS is used to avoid such circular
dependency. We can generate asm-offsets.h first, and if the
COMPILE_OFFSETS is defined, we don't include the "generated/test.h".

And we define the macro COMPILE_OFFSETS for all the asm-offsets.c for this
purpose.

Signed-off-by: Menglong Dong 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Sasha Levin

MIPS: Don't crash in stack_top() for tasks without ABI or vDSO

2025-08-20T16:30:43+00:00

[ Upstream commit e9f4a6b3421e936c3ee9d74710243897d74dbaa2 ]

Not all tasks have an ABI associated or vDSO mapped,
for example kthreads never do.
If such a task ever ends up calling stack_top(), it will derefence the
NULL ABI pointer and crash.

This can for example happen when using kunit:

    mips_stack_top+0x28/0xc0
    arch_pick_mmap_layout+0x190/0x220
    kunit_vm_mmap_init+0xf8/0x138
    __kunit_add_resource+0x40/0xa8
    kunit_vm_mmap+0x88/0xd8
    usercopy_test_init+0xb8/0x240
    kunit_try_run_case+0x5c/0x1a8
    kunit_generic_run_threadfn_adapter+0x28/0x50
    kthread+0x118/0x240
    ret_from_kernel_thread+0x14/0x1c

Only dereference the ABI point if it is set.

The GIC page is also included as it is specific to the vDSO.
Also move the randomization adjustment into the same conditional.

Signed-off-by: Thomas Weißschuh 
Reviewed-by: David Gow 
Reviewed-by: Huacai Chen 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

MIPS: pm-cps: Use per-CPU variables as per-CPU, not per-core

2025-05-29T09:02:41+00:00

[ Upstream commit 00a134fc2bb4a5f8fada58cf7ff4259149691d64 ]

The pm-cps code has up until now used per-CPU variables indexed by core,
rather than CPU number, in order to share data amongst sibling CPUs (ie.
VPs/threads in a core). This works fine for single cluster systems, but
with multi-cluster systems a core number is no longer unique in the
system, leading to sharing between CPUs that are not actually siblings.

Avoid this issue by using per-CPU variables as they are more generally
used - ie. access them using CPU numbers rather than core numbers.
Sharing between siblings is then accomplished by:
 - Assigning the same pointer to entries for each sibling CPU for the
   nc_asm_enter & ready_count variables, which allow this by virtue of
   being per-CPU pointers.

 - Indexing by the first CPU set in a CPUs cpu_sibling_map in the case
   of pm_barrier, for which we can't use the previous approach because
   the per-CPU variable is not a pointer.

Signed-off-by: Paul Burton 
Signed-off-by: Dragan Mladjenovic 
Signed-off-by: Aleksandar Rikalo 
Tested-by: Serge Semin 
Tested-by: Gregory CLEMENT 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

MIPS: cm: Detect CM quirks from device tree

2025-05-02T05:59:14+00:00

[ Upstream commit e27fbe16af5cfc40639de4ced67d1a866a1953e9 ]

Some information that should be retrieved at runtime for the Coherence
Manager can be either absent or wrong. This patch allows checking if
some of this information is available from the device tree and updates
the internal variable accordingly.

For now, only the compatible string associated with the broken HCI is
being retrieved.

Signed-off-by: Gregory CLEMENT 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

MIPS: cevt-ds1287: Add missing ds1287.h include

2025-04-25T08:48:07+00:00

commit f3be225f338a578851a7b607a409f476354a8deb upstream.

Address the issue of cevt-ds1287.c not including the ds1287.h header
file.

Fix follow errors with gcc-14 when -Werror:

arch/mips/kernel/cevt-ds1287.c:15:5: error: no previous prototype for ‘ds1287_timer_state’ [-Werror=missing-prototypes]
   15 | int ds1287_timer_state(void)
      |     ^~~~~~~~~~~~~~~~~~
arch/mips/kernel/cevt-ds1287.c:20:5: error: no previous prototype for ‘ds1287_set_base_clock’ [-Werror=missing-prototypes]
   20 | int ds1287_set_base_clock(unsigned int hz)
      |     ^~~~~~~~~~~~~~~~~~~~~
arch/mips/kernel/cevt-ds1287.c:103:12: error: no previous prototype for ‘ds1287_clockevent_init’ [-Werror=missing-prototypes]
  103 | int __init ds1287_clockevent_init(int irq)
      |            ^~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[7]: *** [scripts/Makefile.build:207: arch/mips/kernel/cevt-ds1287.o] Error 1
make[7]: *** Waiting for unfinished jobs....
make[6]: *** [scripts/Makefile.build:465: arch/mips/kernel] Error 2
make[6]: *** Waiting for unfinished jobs....

Signed-off-by: WangYuli 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Greg Kroah-Hartman

MIPS: ftrace: Declare ftrace_get_parent_ra_addr() as static

2025-02-17T09:05:44+00:00

commit ddd068d81445b17ac0bed084dfeb9e58b4df3ddd upstream.

Declare ftrace_get_parent_ra_addr() as static to suppress clang
compiler warning that 'no previous prototype'. This function is
not intended to be called from other parts.

Fix follow error with clang-19:

arch/mips/kernel/ftrace.c:251:15: error: no previous prototype for function 'ftrace_get_parent_ra_addr' [-Werror,-Wmissing-prototypes]
  251 | unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
      |               ^
arch/mips/kernel/ftrace.c:251:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
  251 | unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
      | ^
      | static
1 error generated.

Signed-off-by: WangYuli 
Acked-by: Masami Hiramatsu (Google) 
Reviewed-by: Philippe Mathieu-Daudé 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Greg Kroah-Hartman

of/fdt: add dt_phys arg to early_init_dt_scan and early_init_dt_verify

2024-12-05T13:01:32+00:00

[ Upstream commit b2473a359763e27567993e7d8f37de82f57a0829 ]

 __pa() is only intended to be used for linear map addresses and using
it for initial_boot_params which is in fixmap for arm64 will give an
incorrect value. Hence save the physical address when it is known at
boot time when calling early_init_dt_scan for arm64 and use it at kexec
time instead of converting the virtual address using __pa().

Note that arm64 doesn't need the FDT region reserved in the DT as the
kernel explicitly reserves the passed in FDT. Therefore, only a debug
warning is fixed with this change.

Reported-by: Breno Leitao 
Suggested-by: Mark Rutland 
Signed-off-by: Usama Arif 
Fixes: ac10be5cdbfa ("arm64: Use common of_kexec_alloc_and_setup_fdt()")
Link: https://lore.kernel.org/r/20241023171426.452688-1-usamaarif642@gmail.com
Signed-off-by: Rob Herring (Arm) 
Signed-off-by: Sasha Levin

Merge tag 'for-6.12-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

2024-11-01T17:31:47+00:00

Pull btrfs fixes from David Sterba:
 "A few more stability fixes. There's one patch adding export of MIPS
  cmpxchg helper, used in the error propagation fix.

   - fix error propagation from split bios to the original btrfs bio

   - fix merging of adjacent extents (normal operation, defragmentation)

   - fix potential use after free after freeing btrfs device structures"

* tag 'for-6.12-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix defrag not merging contiguous extents due to merged extent maps
  btrfs: fix extent map merging not happening for adjacent extents
  btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()
  btrfs: fix error propagation of split bios
  MIPS: export __cmpxchg_small()