linux-stable.git/arch/arc/include, branch linux-6.17.y

arc: Fix fls() const-foldability via builtin_clzl()

2025-11-13T20:36:48+00:00

[ Upstream commit a3fecb9160482367365cc384c59dd220b162b066 ]

While tracking down a problem where constant expressions used by
BUILD_BUG_ON() suddenly stopped working[1], we found that an added static
initializer was convincing the compiler that it couldn't track the state
of the prior statically initialized value. Tracing this down found that
ffs() was used in the initializer macro, but since it wasn't marked with
__attribute__const__, the compiler had to assume the function might
change variable states as a side-effect (which is not true for ffs(),
which provides deterministic math results).

For arc architecture with CONFIG_ISA_ARCV2=y, the __fls() function
uses __builtin_arc_fls() which lacks GCC's const attribute, preventing
compile-time constant folding, and KUnit testing of ffs/fls fails on
arc[3]. A patch[2] to GCC to solve this has been sent.

Add a fix for this by handling compile-time constants with the standard
__builtin_clzl() builtin (which has const attribute) while preserving
the optimized arc-specific builtin for runtime cases. This has the added
benefit of skipping runtime calculation of compile-time constant values.
Even with the GCC bug fixed (which is about "attribute const") this is a
good change to avoid needless runtime costs, and should be done
regardless of the state of GCC's bug.

Build tested ARCH=arc allyesconfig with GCC arc-linux 15.2.0.

Link: https://github.com/KSPP/linux/issues/364 [1]
Link: https://gcc.gnu.org/pipermail/gcc-patches/2025-August/693273.html
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202508031025.doWxtzzc-lkp@intel.com/ [3]
Signed-off-by: Kees Cook 
Acked-by: Vineet Gupta 
Signed-off-by: Yury Norov (NVIDIA) 
Signed-off-by: Sasha Levin

Merge tag 'arc-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

2025-06-12T15:17:56+00:00

Pull ARC fixes from Vineet Gupta:

 - arch_atomic64_cmpxchg relaxed variant [Jason]

 - use of inbuilt swap in stack unwinder  [Yu-Chun Lin]

 - use of __ASSEMBLER__ in kernel headers [Thomas Huth]

* tag 'arc-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: Replace __ASSEMBLY__ with __ASSEMBLER__ in the non-uapi headers
  ARC: Replace __ASSEMBLY__ with __ASSEMBLER__ in uapi headers
  ARC: unwind: Use built-in sort swap to reduce code size and improve performance
  ARC: atomics: Implement arch_atomic64_cmpxchg using _relaxed

mm: pgtable: fix pte_swp_exclusive

2025-06-11T21:52:08+00:00

Make pte_swp_exclusive return bool instead of int.  This will better
reflect how pte_swp_exclusive is actually used in the code.

This fixes swap/swapoff problems on Alpha due pte_swp_exclusive not
returning correct values when _PAGE_SWP_EXCLUSIVE bit resides in upper
32-bits of PTE (like on alpha).

Suggested-by: Al Viro 
Signed-off-by: Magnus Lindholm 
Cc: Sam James 
Link: https://lore.kernel.org/lkml/20250218175735.19882-2-linmag7@gmail.com/
Link: https://lore.kernel.org/lkml/20250602041118.GA2675383@ZenIV/
[ Applied as the 'sed' script Al suggested   - Linus ]
Signed-off-by: Linus Torvalds

ARC: Replace ASSEMBLY with ASSEMBLER in the non-uapi headers

2025-06-09T16:18:12+00:00

While the GCC and Clang compilers already define __ASSEMBLER__
automatically when compiling assembly code, __ASSEMBLY__ is a
macro that only gets defined by the Makefiles in the kernel.
This can be very confusing when switching between userspace
and kernelspace coding, or when dealing with uapi headers that
rather should use __ASSEMBLER__ instead. So let's standardize on
the __ASSEMBLER__ macro that is provided by the compilers now.

This is a completely mechanical patch (done with a simple "sed -i"
statement).

Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: Thomas Huth 
Signed-off-by: Vineet Gupta

ARC: Replace ASSEMBLY with ASSEMBLER in uapi headers

2025-06-09T16:18:12+00:00

__ASSEMBLY__ is only defined by the Makefile of the kernel, so
this is not really useful for uapi headers (unless the userspace
Makefile defines it, too). Let's switch to __ASSEMBLER__ which
gets set automatically by the compiler when compiling assembly
code.

Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: Thomas Huth 
Signed-off-by: Vineet Gupta

ARC: atomics: Implement arch_atomic64_cmpxchg using _relaxed

2025-06-09T16:18:12+00:00

The core atomic code has a number of macros where it elaborates
architecture primitives into more functions. ARC uses
arch_atomic64_cmpxchg() as it's architecture primitive which disable alot
of the additional functions.

Instead provide arch_cmpxchg64_relaxed() as the primitive and rely on the
core macros to create arch_cmpxchg64().

The macros will also provide other functions, for instance,
try_cmpxchg64_release(), giving a more complete implementation.

Suggested-by: Mark Rutland 
Link: https://lore.kernel.org/r/Z0747n5bSep4_1VX@J2N7QTR9R3
Signed-off-by: Jason Gunthorpe 
Signed-off-by: Vineet Gupta

syscall.h: introduce syscall_set_nr()

2025-05-12T00:48:15+00:00

Similar to syscall_set_arguments() that complements
syscall_get_arguments(), introduce syscall_set_nr() that complements
syscall_get_nr().

syscall_set_nr() is going to be needed along with syscall_set_arguments()
on all HAVE_ARCH_TRACEHOOK architectures to implement
PTRACE_SET_SYSCALL_INFO API.

Link: https://lkml.kernel.org/r/20250303112020.GD24170@strace.io
Signed-off-by: Dmitry V. Levin 
Tested-by: Charlie Jenkins 
Reviewed-by: Charlie Jenkins 
Acked-by: Helge Deller  # parisc
Reviewed-by: Maciej W. Rozycki  # mips
Cc: Alexander Gordeev 
Cc: Alexey Gladkov (Intel) 
Cc: Andreas Larsson 
Cc: anton ivanov 
Cc: Arnd Bergmann 
Cc: Borislav Betkov 
Cc: Brian Cain 
Cc: Christian Borntraeger 
Cc: Christian Zankel 
Cc: Christophe Leroy 
Cc: Dave Hansen 
Cc: Davide Berardi 
Cc: David S. Miller 
Cc: Dinh Nguyen 
Cc: Eugene Syromiatnikov 
Cc: Eugene Syromyatnikov 
Cc: Geert Uytterhoeven 
Cc: Guo Ren 
Cc: Heiko Carstens 
Cc: "H. Peter Anvin" 
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: Johannes Berg 
Cc: John Paul Adrian Glaubitz 
Cc: Jonas Bonn 
Cc: Madhavan Srinivasan 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Mike Frysinger 
Cc: Naveen N Rao 
Cc: Nicholas Piggin 
Cc: Oleg Nesterov 
Cc: Renzo Davoi 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Russel King 
Cc: Shuah Khan 
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: Sven Schnelle 
Cc: Thomas Gleinxer 
Cc: Vasily Gorbik 
Cc: Vineet Gupta 
Cc: WANG Xuerui 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton

syscall.h: add syscall_set_arguments()

2025-05-12T00:48:15+00:00

This function is going to be needed on all HAVE_ARCH_TRACEHOOK
architectures to implement PTRACE_SET_SYSCALL_INFO API.

This partially reverts commit 7962c2eddbfe ("arch: remove unused function
syscall_set_arguments()") by reusing some of old syscall_set_arguments()
implementations.

[nathan@kernel.org: fix compile time fortify checks]
  Link: https://lkml.kernel.org/r/20250408213131.GA2872426@ax162
Link: https://lkml.kernel.org/r/20250303112009.GC24170@strace.io
Signed-off-by: Dmitry V. Levin 
Signed-off-by: Nathan Chancellor 
Tested-by: Charlie Jenkins 
Reviewed-by: Charlie Jenkins 
Acked-by: Helge Deller  # parisc
Reviewed-by: Maciej W. Rozycki 	[mips]
Cc: Alexander Gordeev 
Cc: Alexey Gladkov (Intel) 
Cc: Andreas Larsson 
Cc: anton ivanov 
Cc: Arnd Bergmann 
Cc: Borislav Betkov 
Cc: Brian Cain 
Cc: Christian Borntraeger 
Cc: Christian Zankel 
Cc: Christophe Leroy 
Cc: Dave Hansen 
Cc: Davide Berardi 
Cc: David S. Miller 
Cc: Dinh Nguyen 
Cc: Eugene Syromiatnikov 
Cc: Eugene Syromyatnikov 
Cc: Geert Uytterhoeven 
Cc: Guo Ren 
Cc: Heiko Carstens 
Cc: "H. Peter Anvin" 
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: Johannes Berg 
Cc: John Paul Adrian Glaubitz 
Cc: Jonas Bonn 
Cc: Madhavan Srinivasan 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Mike Frysinger 
Cc: Naveen N Rao 
Cc: Nicholas Piggin 
Cc: Oleg Nesterov 
Cc: Renzo Davoi 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Russel King 
Cc: Shuah Khan 
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: Sven Schnelle 
Cc: Thomas Gleinxer 
Cc: Vasily Gorbik 
Cc: Vineet Gupta 
Cc: WANG Xuerui 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton

arch: remove mk_pmd()

2025-05-12T00:48:04+00:00

There are now no callers of mk_huge_pmd() and mk_pmd().  Remove them.

Link: https://lkml.kernel.org/r/20250402181709.2386022-12-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Cc: Zi Yan 
Cc: Alexander Gordeev 
Cc: Andreas Larsson 
Cc: Anton Ivanov 
Cc: Dave Hansen 
Cc: David Hildenbrand 
Cc: "David S. Miller" 
Cc: Geert Uytterhoeven 
Cc: Johannes Berg 
Cc: Muchun Song 
Cc: Richard Weinberger 
Cc: 
Signed-off-by: Andrew Morton

mm: introduce a common definition of mk_pte()

2025-05-12T00:48:02+00:00

Most architectures simply call pfn_pte().  Centralise that as the normal
definition and remove the definition of mk_pte() from the architectures
which have either that exact definition or something similar.

Link: https://lkml.kernel.org/r/20250402181709.2386022-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Acked-by: Geert Uytterhoeven  # m68k
Acked-by: David Hildenbrand 
Reviewed-by: Alexander Gordeev  # s390
Cc: Zi Yan 
Cc: Andreas Larsson 
Cc: Anton Ivanov 
Cc: Dave Hansen 
Cc: "David S. Miller" 
Cc: Johannes Berg 
Cc: Muchun Song 
Cc: Richard Weinberger 
Cc: 
Signed-off-by: Andrew Morton

linux-stable.git/arch/arc/include, branch linux-6.17.y

arc: Fix __fls() const-foldability via __builtin_clzl()

Merge tag 'arc-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

mm: pgtable: fix pte_swp_exclusive

ARC: Replace __ASSEMBLY__ with __ASSEMBLER__ in the non-uapi headers

ARC: Replace __ASSEMBLY__ with __ASSEMBLER__ in uapi headers

ARC: atomics: Implement arch_atomic64_cmpxchg using _relaxed

syscall.h: introduce syscall_set_nr()

syscall.h: add syscall_set_arguments()

arch: remove mk_pmd()

mm: introduce a common definition of mk_pte()

arc: Fix fls() const-foldability via builtin_clzl()

ARC: Replace ASSEMBLY with ASSEMBLER in the non-uapi headers

ARC: Replace ASSEMBLY with ASSEMBLER in uapi headers