![Atsushi Nemoto](/assets/img/avatar_default.png)
The save_fp_context()/restore_fp_context() might sleep on accessing user stack and therefore might lose FPU ownership in middle of them. If these function failed due to "in_atomic" test in do_page_fault, touch the sigcontext area in non-atomic context and retry these save/restore operation. This is a replacement of a (broken) fix which was titled "Allow CpU exception in kernel partially". Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
169 lines
3.4 KiB
C
169 lines
3.4 KiB
C
/*
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* Copyright (C) 2002 MontaVista Software Inc.
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* Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#ifndef _ASM_FPU_H
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#define _ASM_FPU_H
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#include <linux/sched.h>
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#include <linux/thread_info.h>
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#include <asm/mipsregs.h>
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#include <asm/cpu.h>
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#include <asm/cpu-features.h>
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#include <asm/bitops.h>
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#include <asm/processor.h>
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#include <asm/current.h>
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#ifdef CONFIG_MIPS_MT_FPAFF
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#include <asm/mips_mt.h>
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#endif
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struct sigcontext;
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struct sigcontext32;
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extern asmlinkage int (*save_fp_context)(struct sigcontext __user *sc);
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extern asmlinkage int (*restore_fp_context)(struct sigcontext __user *sc);
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extern asmlinkage int (*save_fp_context32)(struct sigcontext32 __user *sc);
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extern asmlinkage int (*restore_fp_context32)(struct sigcontext32 __user *sc);
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extern void fpu_emulator_init_fpu(void);
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extern void _init_fpu(void);
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extern void _save_fp(struct task_struct *);
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extern void _restore_fp(struct task_struct *);
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#if defined(CONFIG_CPU_SB1)
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#define __enable_fpu_hazard() \
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do { \
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asm(".set push \n\t" \
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".set mips64 \n\t" \
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".set noreorder \n\t" \
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"ssnop \n\t" \
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"bnezl $0, .+4 \n\t" \
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"ssnop \n\t" \
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".set pop"); \
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} while (0)
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#else
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#define __enable_fpu_hazard() \
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do { \
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asm("nop;nop;nop;nop"); /* max. hazard */ \
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} while (0)
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#endif
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#define __enable_fpu() \
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do { \
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set_c0_status(ST0_CU1); \
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__enable_fpu_hazard(); \
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} while (0)
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#define __disable_fpu() \
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do { \
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clear_c0_status(ST0_CU1); \
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/* We don't care about the c0 hazard here */ \
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} while (0)
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#define enable_fpu() \
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do { \
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if (cpu_has_fpu) \
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__enable_fpu(); \
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} while (0)
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#define disable_fpu() \
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do { \
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if (cpu_has_fpu) \
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__disable_fpu(); \
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} while (0)
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#define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU)
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static inline int __is_fpu_owner(void)
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{
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return test_thread_flag(TIF_USEDFPU);
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}
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static inline int is_fpu_owner(void)
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{
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return cpu_has_fpu && __is_fpu_owner();
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}
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static inline void __own_fpu(void)
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{
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__enable_fpu();
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KSTK_STATUS(current) |= ST0_CU1;
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set_thread_flag(TIF_USEDFPU);
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}
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static inline void own_fpu_inatomic(int restore)
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{
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if (cpu_has_fpu && !__is_fpu_owner()) {
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__own_fpu();
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if (restore)
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_restore_fp(current);
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}
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}
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static inline void own_fpu(int restore)
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{
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preempt_disable();
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own_fpu_inatomic(restore);
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preempt_enable();
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}
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static inline void lose_fpu(int save)
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{
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preempt_disable();
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if (is_fpu_owner()) {
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if (save)
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_save_fp(current);
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KSTK_STATUS(current) &= ~ST0_CU1;
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clear_thread_flag(TIF_USEDFPU);
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__disable_fpu();
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}
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preempt_enable();
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}
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static inline void init_fpu(void)
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{
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preempt_disable();
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if (cpu_has_fpu) {
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__own_fpu();
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_init_fpu();
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} else {
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fpu_emulator_init_fpu();
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}
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preempt_enable();
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}
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static inline void save_fp(struct task_struct *tsk)
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{
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if (cpu_has_fpu)
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_save_fp(tsk);
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}
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static inline void restore_fp(struct task_struct *tsk)
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{
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if (cpu_has_fpu)
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_restore_fp(tsk);
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}
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static inline fpureg_t *get_fpu_regs(struct task_struct *tsk)
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{
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if (tsk == current) {
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preempt_disable();
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if (is_fpu_owner())
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_save_fp(current);
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preempt_enable();
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}
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return tsk->thread.fpu.fpr;
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}
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#endif /* _ASM_FPU_H */
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