bb7aa6d47f
The implementation of __builtin_xchg() in at least some versions of avr32 gcc is buggy. Rather than find out exactly which versions that have this bug, let's just avoid the problem altogether by implementing xchg() in inline assembly. Also, in most architectures, xchg() seems to imply a memory barrier, while the existing avr32 implementation did not. This patch also fixes that discrepancy. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
156 lines
3.9 KiB
C
156 lines
3.9 KiB
C
/*
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* Copyright (C) 2004-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_AVR32_SYSTEM_H
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#define __ASM_AVR32_SYSTEM_H
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#include <linux/compiler.h>
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#include <linux/linkage.h>
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#include <linux/types.h>
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#include <asm/ptrace.h>
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#include <asm/sysreg.h>
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#define xchg(ptr,x) \
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((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
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#define nop() asm volatile("nop")
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#define mb() asm volatile("" : : : "memory")
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#define rmb() mb()
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#define wmb() asm volatile("sync 0" : : : "memory")
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#define read_barrier_depends() do { } while(0)
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#define set_mb(var, value) do { var = value; mb(); } while(0)
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/*
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* Help PathFinder and other Nexus-compliant debuggers keep track of
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* the current PID by emitting an Ownership Trace Message each time we
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* switch task.
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*/
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#ifdef CONFIG_OWNERSHIP_TRACE
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#include <asm/ocd.h>
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#define finish_arch_switch(prev) \
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do { \
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__mtdr(DBGREG_PID, prev->pid); \
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__mtdr(DBGREG_PID, current->pid); \
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} while(0)
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#endif
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/*
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* switch_to(prev, next, last) should switch from task `prev' to task
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* `next'. `prev' will never be the same as `next'.
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*
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* We just delegate everything to the __switch_to assembly function,
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* which is implemented in arch/avr32/kernel/switch_to.S
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*
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* mb() tells GCC not to cache `current' across this call.
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*/
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struct cpu_context;
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struct task_struct;
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extern struct task_struct *__switch_to(struct task_struct *,
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struct cpu_context *,
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struct cpu_context *);
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#define switch_to(prev, next, last) \
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do { \
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last = __switch_to(prev, &prev->thread.cpu_context + 1, \
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&next->thread.cpu_context); \
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} while (0)
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#ifdef CONFIG_SMP
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# error "The AVR32 port does not support SMP"
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#else
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# define smp_mb() barrier()
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# define smp_rmb() barrier()
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# define smp_wmb() barrier()
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# define smp_read_barrier_depends() do { } while(0)
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#endif
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#include <linux/irqflags.h>
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extern void __xchg_called_with_bad_pointer(void);
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static inline unsigned long xchg_u32(u32 val, volatile u32 *m)
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{
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u32 ret;
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asm volatile("xchg %[ret], %[m], %[val]"
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: [ret] "=&r"(ret), "=m"(*m)
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: "m"(*m), [m] "r"(m), [val] "r"(val)
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: "memory");
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return ret;
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}
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static inline unsigned long __xchg(unsigned long x,
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volatile void *ptr,
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int size)
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{
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switch(size) {
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case 4:
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return xchg_u32(x, ptr);
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default:
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__xchg_called_with_bad_pointer();
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return x;
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}
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}
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static inline unsigned long __cmpxchg_u32(volatile int *m, unsigned long old,
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unsigned long new)
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{
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__u32 ret;
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asm volatile(
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"1: ssrf 5\n"
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" ld.w %[ret], %[m]\n"
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" cp.w %[ret], %[old]\n"
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" brne 2f\n"
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" stcond %[m], %[new]\n"
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" brne 1b\n"
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"2:\n"
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: [ret] "=&r"(ret), [m] "=m"(*m)
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: "m"(m), [old] "ir"(old), [new] "r"(new)
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: "memory", "cc");
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return ret;
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}
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extern unsigned long __cmpxchg_u64_unsupported_on_32bit_kernels(
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volatile int * m, unsigned long old, unsigned long new);
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#define __cmpxchg_u64 __cmpxchg_u64_unsupported_on_32bit_kernels
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/* This function doesn't exist, so you'll get a linker error
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if something tries to do an invalid cmpxchg(). */
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extern void __cmpxchg_called_with_bad_pointer(void);
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#define __HAVE_ARCH_CMPXCHG 1
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static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
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unsigned long new, int size)
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{
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switch (size) {
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case 4:
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return __cmpxchg_u32(ptr, old, new);
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case 8:
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return __cmpxchg_u64(ptr, old, new);
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}
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__cmpxchg_called_with_bad_pointer();
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return old;
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}
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#define cmpxchg(ptr, old, new) \
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((typeof(*(ptr)))__cmpxchg((ptr), (unsigned long)(old), \
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(unsigned long)(new), \
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sizeof(*(ptr))))
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struct pt_regs;
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void NORET_TYPE die(const char *str, struct pt_regs *regs, long err);
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void _exception(long signr, struct pt_regs *regs, int code,
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unsigned long addr);
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#define arch_align_stack(x) (x)
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#endif /* __ASM_AVR32_SYSTEM_H */
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