9411ec60c2
We expect that a kernel with CONFIG_FPU=y can still support no-FPU machines. To do so, the kernel should first examine the existence of a FPU, then do nothing if a FPU does exist; otherwise, it should disable/bypass all FPU-related functions. In this patch, a new global variable, has_fpu, is created and determined when parsing the hardware capability from device tree during booting. This variable is used in those FPU-related functions. Signed-off-by: Alan Kao <alankao@andestech.com> Cc: Greentime Hu <greentime@andestech.com> Cc: Vincent Chen <vincentc@andestech.com> Cc: Zong Li <zong@andestech.com> Cc: Nick Hu <nickhu@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
80 lines
2.1 KiB
C
80 lines
2.1 KiB
C
/*
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* Copyright (C) 2012 Regents of the University of California
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef _ASM_RISCV_SWITCH_TO_H
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#define _ASM_RISCV_SWITCH_TO_H
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#include <asm/processor.h>
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#include <asm/ptrace.h>
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#include <asm/csr.h>
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#ifdef CONFIG_FPU
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extern void __fstate_save(struct task_struct *save_to);
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extern void __fstate_restore(struct task_struct *restore_from);
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static inline void __fstate_clean(struct pt_regs *regs)
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{
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regs->sstatus |= (regs->sstatus & ~(SR_FS)) | SR_FS_CLEAN;
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}
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static inline void fstate_save(struct task_struct *task,
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struct pt_regs *regs)
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{
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if ((regs->sstatus & SR_FS) == SR_FS_DIRTY) {
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__fstate_save(task);
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__fstate_clean(regs);
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}
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}
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static inline void fstate_restore(struct task_struct *task,
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struct pt_regs *regs)
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{
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if ((regs->sstatus & SR_FS) != SR_FS_OFF) {
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__fstate_restore(task);
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__fstate_clean(regs);
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}
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}
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static inline void __switch_to_aux(struct task_struct *prev,
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struct task_struct *next)
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{
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struct pt_regs *regs;
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regs = task_pt_regs(prev);
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if (unlikely(regs->sstatus & SR_SD))
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fstate_save(prev, regs);
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fstate_restore(next, task_pt_regs(next));
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}
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extern bool has_fpu;
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#else
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#define has_fpu false
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#define fstate_save(task, regs) do { } while (0)
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#define fstate_restore(task, regs) do { } while (0)
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#define __switch_to_aux(__prev, __next) do { } while (0)
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#endif
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extern struct task_struct *__switch_to(struct task_struct *,
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struct task_struct *);
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#define switch_to(prev, next, last) \
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do { \
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struct task_struct *__prev = (prev); \
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struct task_struct *__next = (next); \
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if (has_fpu) \
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__switch_to_aux(__prev, __next); \
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((last) = __switch_to(__prev, __next)); \
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} while (0)
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#endif /* _ASM_RISCV_SWITCH_TO_H */
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