forked from Minki/linux
9b8de7479d
In non-SMP mode, the variable section attribute specified by DECLARE_PER_CPU() does not agree with that specified by DEFINE_PER_CPU(). This means that architectures that have a small data section references relative to a base register may throw up linkage errors due to too great a displacement between where the base register points and the per-CPU variable. On FRV, the .h declaration says that the variable is in the .sdata section, but the .c definition says it's actually in the .data section. The linker throws up the following errors: kernel/built-in.o: In function `release_task': kernel/exit.c:78: relocation truncated to fit: R_FRV_GPREL12 against symbol `per_cpu__process_counts' defined in .data section in kernel/built-in.o kernel/exit.c:78: relocation truncated to fit: R_FRV_GPREL12 against symbol `per_cpu__process_counts' defined in .data section in kernel/built-in.o To fix this, DECLARE_PER_CPU() should simply apply the same section attribute as does DEFINE_PER_CPU(). However, this is made slightly more complex by virtue of the fact that there are several variants on DEFINE, so these need to be matched by variants on DECLARE. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
#ifndef __ALPHA_PERCPU_H
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#define __ALPHA_PERCPU_H
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#include <linux/compiler.h>
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#include <linux/threads.h>
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/*
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* Determine the real variable name from the name visible in the
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* kernel sources.
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*/
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#define per_cpu_var(var) per_cpu__##var
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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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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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#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
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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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#ifndef MODULE
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#define SHIFT_PERCPU_PTR(var, offset) RELOC_HIDE(&per_cpu_var(var), (offset))
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#define PER_CPU_ATTRIBUTES
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#else
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/*
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* To calculate addresses of locally defined variables, GCC uses 32-bit
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* displacement from the GP. Which doesn't work for per cpu variables in
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* modules, as an offset to the kernel per cpu area is way above 4G.
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*
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* This forces allocation of a GOT entry for per cpu variable using
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* ldq instruction with a 'literal' relocation.
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*/
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#define SHIFT_PERCPU_PTR(var, offset) ({ \
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extern int simple_identifier_##var(void); \
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unsigned long __ptr, tmp_gp; \
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asm ( "br %1, 1f \n\
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1: ldgp %1, 0(%1) \n\
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ldq %0, per_cpu__" #var"(%1)\t!literal" \
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: "=&r"(__ptr), "=&r"(tmp_gp)); \
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(typeof(&per_cpu_var(var)))(__ptr + (offset)); })
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#define PER_CPU_ATTRIBUTES __used
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#endif /* MODULE */
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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(var, per_cpu_offset(cpu)))
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#define __get_cpu_var(var) \
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(*SHIFT_PERCPU_PTR(var, my_cpu_offset))
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#define __raw_get_cpu_var(var) \
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(*SHIFT_PERCPU_PTR(var, __my_cpu_offset))
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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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#define PER_CPU_ATTRIBUTES
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#endif /* SMP */
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#include <asm-generic/percpu.h>
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#endif /* __ALPHA_PERCPU_H */
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