kernel/linux.git/arch/s390/include/asm/percpu.h, branch linux-7.0.y

s390/percpu: Get rid of ARCH_MODULE_NEEDS_WEAK_PER_CPU

2025-11-24T10:45:20+00:00

Since the rework of the kernel virtual address space [1] the module area and the kernel image are within the same 4GB area. Therefore there is no need for the weak per cpu workaround for modules anymore. Remove it. [1] commit c98d2ecae08f ("s390/mm: Uncouple physical vs virtual address spaces") Acked-by: Alexander Gordeev Signed-off-by: Heiko Carstens

s390: Remove superfluous newlines from inline assemblies

2025-09-29T11:52:08+00:00

Remove superfluous newlines from inline assemblies. Compilers use the number of lines of inline assemblies as heuristic for the complexity and inline decisions. Therefore inline assemblies should only contain as many lines as required. A lot of inline assemblies contain a superfluous newline for the last line. Remove such newlines to improve compiler inlining decisions. Suggested-by: Juergen Christ Signed-off-by: Heiko Carstens Reviewed-by: Alexander Gordeev Reviewed-by: Juergen Christ Signed-off-by: Alexander Gordeev

mm/percpu: conditionally define _shared_alloc_tag via CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU

2025-07-10T05:42:15+00:00

Recently discovered this entry while checking kallsyms on ARM64: ffff800083e509c0 D _shared_alloc_tag If ARCH_NEEDS_WEAK_PER_CPU is not defined(it is only defined for s390 and alpha architectures), there's no need to statically define the percpu variable _shared_alloc_tag. Therefore, we need to implement isolation for this purpose. When building the core kernel code for s390 or alpha architectures, ARCH_NEEDS_WEAK_PER_CPU remains undefined (as it is gated by #if defined(MODULE)). However, when building modules for these architectures, the macro is explicitly defined. Therefore, we remove all instances of ARCH_NEEDS_WEAK_PER_CPU from the code and introduced CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU to replace the relevant logic. We can now conditionally define the perpcu variable _shared_alloc_tag based on CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU. This allows architectures (such as s390/alpha) that require weak definitions for percpu variables in modules to include the definition, while others can omit it via compile-time exclusion. Link: https://lkml.kernel.org/r/20250618015809.1235761-1-hao.ge@linux.dev Signed-off-by: Hao Ge Suggested-by: Suren Baghdasaryan Acked-by: Alexander Gordeev [s390] Acked-by: Mike Rapoport (Microsoft) Cc: Chistoph Lameter Cc: Christian Borntraeger Cc: David Hildenbrand Cc: Dennis Zhou Cc: Heiko Carstens Cc: Kent Overstreet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Matt Turner Cc: Richard Henderson Cc: Sven Schnelle Cc: Tejun Heo Cc: Vasily Gorbik Cc: Vlastimil Babka Signed-off-by: Andrew Morton

s390: Use MARCH_HAS_*_FEATURES defines

2024-09-07T15:12:42+00:00

Replace CONFIG_HAVE_MARCH_*_FEATURES with MARCH_HAS_*_FEATURES everywhere so code gets compiled correctly depending on if the target is the kernel or the decompressor. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens

s390: Replace S390_lowcore by get_lowcore()

2024-06-18T15:01:33+00:00

Replace all S390_lowcore usages in arch/s390/ by get_lowcore(). Acked-by: Heiko Carstens Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik

arch: Remove cmpxchg_double

2023-06-05T07:36:39+00:00

No moar users, remove the monster. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Arnd Bergmann Reviewed-by: Mark Rutland Acked-by: Heiko Carstens Tested-by: Mark Rutland Link: https://lore.kernel.org/r/20230531132323.991907085@infradead.org

percpu: Wire up cmpxchg128

2023-06-05T07:36:37+00:00

In order to replace cmpxchg_double() with the newly minted cmpxchg128() family of functions, wire it up in this_cpu_cmpxchg(). Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Mark Rutland Tested-by: Mark Rutland Link: https://lore.kernel.org/r/20230531132323.654945124@infradead.org

s390/percpu: add READ_ONCE() to arch_this_cpu_to_op_simple()

2023-01-11T14:28:47+00:00

Make sure that *ptr__ within arch_this_cpu_to_op_simple() is only dereferenced once by using READ_ONCE(). Otherwise the compiler could generate incorrect code. Cc: Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens

s390/cmpxchg: use register pair instead of register asm

2021-06-28T09:18:28+00:00

Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: don't trace preemption in percpu macros

2020-08-26T16:07:04+00:00

Since commit a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables") the lockdep code itself uses percpu variables. This leads to recursions because the percpu macros are calling preempt_enable() which might call trace_preempt_on(). Signed-off-by: Sven Schnelle Reviewed-by: Vasily Gorbik Signed-off-by: Vasily Gorbik