b01e8dc343
alpha percpu access requires custom SHIFT_PERCPU_PTR() definition for modules to work around addressing range limitation. This is done via generating inline assembly using C preprocessing which forces the assembler to generate external reference. This happens behind the compiler's back and makes the compiler think that static percpu variables in modules are unused. This used to be worked around by using __unused attribute for percpu variables which prevent the compiler from omitting the variable; however, recent declare/definition attribute unification change broke this as __used can't be used for declaration. Also, in the process, PER_CPU_ATTRIBUTES definition in alpha percpu.h got broken. This patch adds PER_CPU_DEF_ATTRIBUTES which is only used for definitions and make alpha use it to add __used for percpu variables in modules. This also fixes the PER_CPU_ATTRIBUTES double definition bug. Signed-off-by: Tejun Heo <tj@kernel.org> Tested-by: maximilian attems <max@stro.at> Acked-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Richard Henderson <rth@twiddle.net> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
104 lines
2.5 KiB
C
104 lines
2.5 KiB
C
#ifndef _ASM_GENERIC_PERCPU_H_
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#define _ASM_GENERIC_PERCPU_H_
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#include <linux/compiler.h>
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#include <linux/threads.h>
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#include <linux/percpu-defs.h>
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#ifdef CONFIG_SMP
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/*
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* per_cpu_offset() is the offset that has to be added to a
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* percpu variable to get to the instance for a certain processor.
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*
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* Most arches use the __per_cpu_offset array for those offsets but
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* some arches have their own ways of determining the offset (x86_64, s390).
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*/
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#ifndef __per_cpu_offset
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extern unsigned long __per_cpu_offset[NR_CPUS];
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#define per_cpu_offset(x) (__per_cpu_offset[x])
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#endif
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/*
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* Determine the offset for the currently active processor.
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* An arch may define __my_cpu_offset to provide a more effective
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* means of obtaining the offset to the per cpu variables of the
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* current processor.
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*/
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#ifndef __my_cpu_offset
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#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
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#endif
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#ifdef CONFIG_DEBUG_PREEMPT
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#define my_cpu_offset per_cpu_offset(smp_processor_id())
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#else
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#define my_cpu_offset __my_cpu_offset
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#endif
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/*
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* Add a offset to a pointer but keep the pointer as is.
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*
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* Only S390 provides its own means of moving the pointer.
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*/
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#ifndef SHIFT_PERCPU_PTR
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#define SHIFT_PERCPU_PTR(__p, __offset) RELOC_HIDE((__p), (__offset))
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#endif
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/*
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* A percpu variable may point to a discarded regions. The following are
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* established ways to produce a usable pointer from the percpu variable
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* offset.
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*/
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#define per_cpu(var, cpu) \
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(*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu)))
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#define __get_cpu_var(var) \
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(*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset))
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#define __raw_get_cpu_var(var) \
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(*SHIFT_PERCPU_PTR(&per_cpu_var(var), __my_cpu_offset))
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#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
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extern void setup_per_cpu_areas(void);
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#endif
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#else /* ! SMP */
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#define per_cpu(var, cpu) (*((void)(cpu), &per_cpu_var(var)))
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#define __get_cpu_var(var) per_cpu_var(var)
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#define __raw_get_cpu_var(var) per_cpu_var(var)
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#endif /* SMP */
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#ifndef PER_CPU_BASE_SECTION
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#ifdef CONFIG_SMP
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#define PER_CPU_BASE_SECTION ".data.percpu"
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#else
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#define PER_CPU_BASE_SECTION ".data"
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#endif
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#endif
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#ifdef CONFIG_SMP
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#ifdef MODULE
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#define PER_CPU_SHARED_ALIGNED_SECTION ""
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#else
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#define PER_CPU_SHARED_ALIGNED_SECTION ".shared_aligned"
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#endif
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#define PER_CPU_FIRST_SECTION ".first"
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#else
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#define PER_CPU_SHARED_ALIGNED_SECTION ""
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#define PER_CPU_FIRST_SECTION ""
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#endif
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#ifndef PER_CPU_ATTRIBUTES
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#define PER_CPU_ATTRIBUTES
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#endif
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#ifndef PER_CPU_DEF_ATTRIBUTES
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#define PER_CPU_DEF_ATTRIBUTES
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#endif
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#endif /* _ASM_GENERIC_PERCPU_H_ */
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