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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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59b5ed409d
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 <gehao@kylinos.cn> Suggested-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> [s390] Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Chistoph Lameter <cl@linux.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Richard Henderson <richard.henderson@linaro.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
186 lines
6.4 KiB
C
186 lines
6.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ARCH_S390_PERCPU__
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#define __ARCH_S390_PERCPU__
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#include <linux/preempt.h>
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#include <asm/cmpxchg.h>
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#include <asm/march.h>
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/*
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* s390 uses its own implementation for per cpu data, the offset of
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* the cpu local data area is cached in the cpu's lowcore memory.
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*/
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#define __my_cpu_offset get_lowcore()->percpu_offset
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/*
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* For 64 bit module code, the module may be more than 4G above the
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* per cpu area, use weak definitions to force the compiler to
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* generate external references.
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* Therefore, we have enabled CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU
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* in the Kconfig.
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*/
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/*
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* We use a compare-and-swap loop since that uses less cpu cycles than
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* disabling and enabling interrupts like the generic variant would do.
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*/
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#define arch_this_cpu_to_op_simple(pcp, val, op) \
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({ \
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typedef typeof(pcp) pcp_op_T__; \
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pcp_op_T__ old__, new__, prev__; \
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pcp_op_T__ *ptr__; \
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preempt_disable_notrace(); \
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ptr__ = raw_cpu_ptr(&(pcp)); \
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prev__ = READ_ONCE(*ptr__); \
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do { \
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old__ = prev__; \
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new__ = old__ op (val); \
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prev__ = cmpxchg(ptr__, old__, new__); \
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} while (prev__ != old__); \
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preempt_enable_notrace(); \
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new__; \
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})
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#define this_cpu_add_1(pcp, val) arch_this_cpu_to_op_simple(pcp, val, +)
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#define this_cpu_add_2(pcp, val) arch_this_cpu_to_op_simple(pcp, val, +)
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#define this_cpu_add_return_1(pcp, val) arch_this_cpu_to_op_simple(pcp, val, +)
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#define this_cpu_add_return_2(pcp, val) arch_this_cpu_to_op_simple(pcp, val, +)
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#define this_cpu_and_1(pcp, val) arch_this_cpu_to_op_simple(pcp, val, &)
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#define this_cpu_and_2(pcp, val) arch_this_cpu_to_op_simple(pcp, val, &)
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#define this_cpu_or_1(pcp, val) arch_this_cpu_to_op_simple(pcp, val, |)
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#define this_cpu_or_2(pcp, val) arch_this_cpu_to_op_simple(pcp, val, |)
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#ifndef MARCH_HAS_Z196_FEATURES
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#define this_cpu_add_4(pcp, val) arch_this_cpu_to_op_simple(pcp, val, +)
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#define this_cpu_add_8(pcp, val) arch_this_cpu_to_op_simple(pcp, val, +)
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#define this_cpu_add_return_4(pcp, val) arch_this_cpu_to_op_simple(pcp, val, +)
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#define this_cpu_add_return_8(pcp, val) arch_this_cpu_to_op_simple(pcp, val, +)
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#define this_cpu_and_4(pcp, val) arch_this_cpu_to_op_simple(pcp, val, &)
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#define this_cpu_and_8(pcp, val) arch_this_cpu_to_op_simple(pcp, val, &)
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#define this_cpu_or_4(pcp, val) arch_this_cpu_to_op_simple(pcp, val, |)
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#define this_cpu_or_8(pcp, val) arch_this_cpu_to_op_simple(pcp, val, |)
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#else /* MARCH_HAS_Z196_FEATURES */
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#define arch_this_cpu_add(pcp, val, op1, op2, szcast) \
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{ \
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typedef typeof(pcp) pcp_op_T__; \
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pcp_op_T__ val__ = (val); \
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pcp_op_T__ old__, *ptr__; \
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preempt_disable_notrace(); \
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ptr__ = raw_cpu_ptr(&(pcp)); \
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if (__builtin_constant_p(val__) && \
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((szcast)val__ > -129) && ((szcast)val__ < 128)) { \
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asm volatile( \
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op2 " %[ptr__],%[val__]\n" \
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: [ptr__] "+Q" (*ptr__) \
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: [val__] "i" ((szcast)val__) \
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: "cc"); \
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} else { \
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asm volatile( \
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op1 " %[old__],%[val__],%[ptr__]\n" \
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: [old__] "=d" (old__), [ptr__] "+Q" (*ptr__) \
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: [val__] "d" (val__) \
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: "cc"); \
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} \
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preempt_enable_notrace(); \
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}
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#define this_cpu_add_4(pcp, val) arch_this_cpu_add(pcp, val, "laa", "asi", int)
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#define this_cpu_add_8(pcp, val) arch_this_cpu_add(pcp, val, "laag", "agsi", long)
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#define arch_this_cpu_add_return(pcp, val, op) \
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({ \
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typedef typeof(pcp) pcp_op_T__; \
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pcp_op_T__ val__ = (val); \
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pcp_op_T__ old__, *ptr__; \
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preempt_disable_notrace(); \
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ptr__ = raw_cpu_ptr(&(pcp)); \
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asm volatile( \
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op " %[old__],%[val__],%[ptr__]\n" \
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: [old__] "=d" (old__), [ptr__] "+Q" (*ptr__) \
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: [val__] "d" (val__) \
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: "cc"); \
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preempt_enable_notrace(); \
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old__ + val__; \
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})
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#define this_cpu_add_return_4(pcp, val) arch_this_cpu_add_return(pcp, val, "laa")
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#define this_cpu_add_return_8(pcp, val) arch_this_cpu_add_return(pcp, val, "laag")
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#define arch_this_cpu_to_op(pcp, val, op) \
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{ \
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typedef typeof(pcp) pcp_op_T__; \
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pcp_op_T__ val__ = (val); \
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pcp_op_T__ old__, *ptr__; \
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preempt_disable_notrace(); \
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ptr__ = raw_cpu_ptr(&(pcp)); \
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asm volatile( \
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op " %[old__],%[val__],%[ptr__]\n" \
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: [old__] "=d" (old__), [ptr__] "+Q" (*ptr__) \
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: [val__] "d" (val__) \
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: "cc"); \
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preempt_enable_notrace(); \
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}
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#define this_cpu_and_4(pcp, val) arch_this_cpu_to_op(pcp, val, "lan")
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#define this_cpu_and_8(pcp, val) arch_this_cpu_to_op(pcp, val, "lang")
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#define this_cpu_or_4(pcp, val) arch_this_cpu_to_op(pcp, val, "lao")
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#define this_cpu_or_8(pcp, val) arch_this_cpu_to_op(pcp, val, "laog")
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#endif /* MARCH_HAS_Z196_FEATURES */
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#define arch_this_cpu_cmpxchg(pcp, oval, nval) \
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({ \
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typedef typeof(pcp) pcp_op_T__; \
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pcp_op_T__ ret__; \
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pcp_op_T__ *ptr__; \
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preempt_disable_notrace(); \
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ptr__ = raw_cpu_ptr(&(pcp)); \
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ret__ = cmpxchg(ptr__, oval, nval); \
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preempt_enable_notrace(); \
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ret__; \
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})
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#define this_cpu_cmpxchg_1(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval)
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#define this_cpu_cmpxchg_2(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval)
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#define this_cpu_cmpxchg_4(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval)
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#define this_cpu_cmpxchg_8(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval)
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#define this_cpu_cmpxchg64(pcp, o, n) this_cpu_cmpxchg_8(pcp, o, n)
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#define this_cpu_cmpxchg128(pcp, oval, nval) \
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({ \
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typedef typeof(pcp) pcp_op_T__; \
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u128 old__, new__, ret__; \
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pcp_op_T__ *ptr__; \
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old__ = oval; \
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new__ = nval; \
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preempt_disable_notrace(); \
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ptr__ = raw_cpu_ptr(&(pcp)); \
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ret__ = cmpxchg128((void *)ptr__, old__, new__); \
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preempt_enable_notrace(); \
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ret__; \
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})
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#define arch_this_cpu_xchg(pcp, nval) \
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({ \
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typeof(pcp) *ptr__; \
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typeof(pcp) ret__; \
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preempt_disable_notrace(); \
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ptr__ = raw_cpu_ptr(&(pcp)); \
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ret__ = xchg(ptr__, nval); \
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preempt_enable_notrace(); \
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ret__; \
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})
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#define this_cpu_xchg_1(pcp, nval) arch_this_cpu_xchg(pcp, nval)
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#define this_cpu_xchg_2(pcp, nval) arch_this_cpu_xchg(pcp, nval)
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#define this_cpu_xchg_4(pcp, nval) arch_this_cpu_xchg(pcp, nval)
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#define this_cpu_xchg_8(pcp, nval) arch_this_cpu_xchg(pcp, nval)
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#include <asm-generic/percpu.h>
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#endif /* __ARCH_S390_PERCPU__ */
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