linux.git/arch/arc, branch v6.1.168

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

2025-12-06T21:12:15+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

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

2025-12-06T21:12:09+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

ARC: build: Try to guess GCC variant of cross compiler

2025-01-09T12:30:05+00:00

[ Upstream commit 824927e88456331c7a999fdf5d9d27923b619590 ]

ARC GCC compiler is packaged starting from Fedora 39i and the GCC
variant of cross compile tools has arc-linux-gnu- prefix and not
arc-linux-. This is causing that CROSS_COMPILE variable is left unset.

This change allows builds without need to supply CROSS_COMPILE argument
if distro package is used.

Before this change:
$ make -j 128 ARCH=arc W=1 drivers/infiniband/hw/mlx4/
  gcc: warning: ‘-mcpu=’ is deprecated; use ‘-mtune=’ or ‘-march=’ instead
  gcc: error: unrecognized command-line option ‘-mmedium-calls’
  gcc: error: unrecognized command-line option ‘-mlock’
  gcc: error: unrecognized command-line option ‘-munaligned-access’

[1] https://packages.fedoraproject.org/pkgs/cross-gcc/gcc-arc-linux-gnu/index.html
Signed-off-by: Leon Romanovsky 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

mm: remove kern_addr_valid() completely

2024-11-08T15:26:39+00:00

[ Upstream commit e025ab842ec35225b1a8e163d1f311beb9e38ce9 ]

Most architectures (except arm64/x86/sparc) simply return 1 for
kern_addr_valid(), which is only used in read_kcore(), and it calls
copy_from_kernel_nofault() which could check whether the address is a
valid kernel address.  So as there is no need for kern_addr_valid(), let's
remove it.

Link: https://lkml.kernel.org/r/20221018074014.185687-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Acked-by: Geert Uytterhoeven 	[m68k]
Acked-by: Heiko Carstens 		[s390]
Acked-by: Christoph Hellwig 
Acked-by: Helge Deller 			[parisc]
Acked-by: Michael Ellerman 		[powerpc]
Acked-by: Guo Ren 			[csky]
Acked-by: Catalin Marinas 	[arm64]
Cc: Alexander Gordeev 
Cc: Andy Lutomirski 
Cc: Anton Ivanov 
Cc: 
Cc: Borislav Petkov 
Cc: Christian Borntraeger 
Cc: Christophe Leroy 
Cc: Chris Zankel 
Cc: Dave Hansen 
Cc: David S. Miller 
Cc: Dinh Nguyen 
Cc: Greg Ungerer 
Cc: H. Peter Anvin 
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: Ivan Kokshaysky 
Cc: James Bottomley 
Cc: Johannes Berg 
Cc: Jonas Bonn 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michal Simek 
Cc: Nicholas Piggin 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Peter Zijlstra 
Cc: Richard Henderson 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Russell King 
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: Sven Schnelle 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Vineet Gupta 
Cc: Will Deacon 
Cc: Xuerui Wang 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Stable-dep-of: 3d5854d75e31 ("fs/proc/kcore.c: allow translation of physical memory addresses")
Signed-off-by: Sasha Levin

ARC: [plat-hsdk]: Remove misplaced interrupt-cells property

2024-05-02T14:29:23+00:00

[ Upstream commit 61231eb8113ce47991f35024f9c20810b37996bf ]

"gmac" node stands for just an ordinary Ethernet controller,
which is by no means a provider of interrupts, i.e. it doesn't serve
as an interrupt controller, thus "#interrupt-cells" property doesn't
belong to it and so we remove it.

Fixes:
------------>8------------
  DTC     arch/arc/boot/dts/hsdk.dtb
arch/arc/boot/dts/hsdk.dts:207.23-235.5: Warning (interrupt_provider): /soc/ethernet@8000: '#interrupt-cells' found, but node is not an interrupt provider
arch/arc/boot/dts/hsdk.dtb: Warning (interrupt_map): Failed prerequisite 'interrupt_provider'
------------>8------------

Reported-by: Vineet Gupta 
Signed-off-by: Alexey Brodkin 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

work around gcc bugs with 'asm goto' with outputs

2024-02-23T08:12:28+00:00

commit 68fb3ca0e408e00db1c3f8fccdfa19e274c033be upstream.

We've had issues with gcc and 'asm goto' before, and we created a
'asm_volatile_goto()' macro for that in the past: see commits
3f0116c3238a ("compiler/gcc4: Add quirk for 'asm goto' miscompilation
bug") and a9f180345f53 ("compiler/gcc4: Make quirk for
asm_volatile_goto() unconditional").

Then, much later, we ended up removing the workaround in commit
43c249ea0b1e ("compiler-gcc.h: remove ancient workaround for gcc PR
58670") because we no longer supported building the kernel with the
affected gcc versions, but we left the macro uses around.

Now, Sean Christopherson reports a new version of a very similar
problem, which is fixed by re-applying that ancient workaround.  But the
problem in question is limited to only the 'asm goto with outputs'
cases, so instead of re-introducing the old workaround as-is, let's
rename and limit the workaround to just that much less common case.

It looks like there are at least two separate issues that all hit in
this area:

 (a) some versions of gcc don't mark the asm goto as 'volatile' when it
     has outputs:

        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619
        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420

     which is easy to work around by just adding the 'volatile' by hand.

 (b) Internal compiler errors:

        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422

     which are worked around by adding the extra empty 'asm' as a
     barrier, as in the original workaround.

but the problem Sean sees may be a third thing since it involves bad
code generation (not an ICE) even with the manually added 'volatile'.

The same old workaround works for this case, even if this feels a
bit like voodoo programming and may only be hiding the issue.

Reported-and-tested-by: Sean Christopherson 
Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/
Cc: Nick Desaulniers 
Cc: Uros Bizjak 
Cc: Jakub Jelinek 
Cc: Andrew Pinski 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

ARC: fix spare error

2024-01-20T10:50:08+00:00

[ Upstream commit aca02d933f63ba8bc84258bf35f9ffaf6b664336 ]

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202312082320.VDN5A9hb-lkp@intel.com/
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: atomics: Add compiler barrier to atomic operations...

2023-09-19T10:28:04+00:00

commit 42f51fb24fd39cc547c086ab3d8a314cc603a91c upstream.

... to avoid unwanted gcc optimizations

SMP kernels fail to boot with commit 596ff4a09b89
("cpumask: re-introduce constant-sized cpumask optimizations").

|
| percpu: BUG: failure at mm/percpu.c:2981/pcpu_build_alloc_info()!
|

The write operation performed by the SCOND instruction in the atomic
inline asm code is not properly passed to the compiler. The compiler
cannot correctly optimize a nested loop that runs through the cpumask
in the pcpu_build_alloc_info() function.

Fix this by add a compiler barrier (memory clobber in inline asm).

Apparently atomic ops used to have memory clobber implicitly via
surrounding smp_mb(). However commit b64be6836993c431e
("ARC: atomics: implement relaxed variants") removed the smp_mb() for
the relaxed variants, but failed to add the explicit compiler barrier.

Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/135
Cc:  # v6.3+
Fixes: b64be6836993c43 ("ARC: atomics: implement relaxed variants")
Signed-off-by: Pavel Kozlov 
Signed-off-by: Vineet Gupta 
[vgupta: tweaked the changelog and added Fixes tag]
Signed-off-by: Greg Kroah-Hartman

ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef ASSEMBLY guard

2023-07-19T14:21:42+00:00

[ Upstream commit 92e2921eeafdfca9acd9b83f07d2b7ca099bac24 ]

ASM_NL is useful not only in *.S files but also in .c files for using
inline assembler in C code.

On ARC, however, ASM_NL is evaluated inconsistently. It is expanded to
a backquote (`) in *.S files, but a semicolon (;) in *.c files because
arch/arc/include/asm/linkage.h defines it inside #ifdef __ASSEMBLY__,
so the definition for C code falls back to the default value defined in
include/linux/linkage.h.

If ASM_NL is used in inline assembler in .c files, it will result in
wrong assembly code because a semicolon is not an instruction separator,
but the start of a comment for ARC.

Move ASM_NL (also __ALIGN and __ALIGN_STR) out of the #ifdef.

Fixes: 9df62f054406 ("arch: use ASM_NL instead of ';' for assembler new line character in the macro")
Fixes: 8d92e992a785 ("ARC: define __ALIGN_STR and __ALIGN symbols for ARC")
Signed-off-by: Masahiro Yamada 
Signed-off-by: Sasha Levin

mm/fault: convert remaining simple cases to lock_mm_and_find_vma()

2023-07-01T11:16:25+00:00

commit a050ba1e7422f2cc60ff8bfde3f96d34d00cb585 upstream.

This does the simple pattern conversion of alpha, arc, csky, hexagon,
loongarch, nios2, sh, sparc32, and xtensa to the lock_mm_and_find_vma()
helper.  They all have the regular fault handling pattern without odd
special cases.

The remaining architectures all have something that keeps us from a
straightforward conversion: ia64 and parisc have stacks that can grow
both up as well as down (and ia64 has special address region checks).

And m68k, microblaze, openrisc, sparc64, and um end up having extra
rules about only expanding the stack down a limited amount below the
user space stack pointer.  That is something that x86 used to do too
(long long ago), and it probably could just be skipped, but it still
makes the conversion less than trivial.

Note that this conversion was done manually and with the exception of
alpha without any build testing, because I have a fairly limited cross-
building environment.  The cases are all simple, and I went through the
changes several times, but...

Signed-off-by: Linus Torvalds 
Signed-off-by: Samuel Mendoza-Jonas 
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman