Unverified Commit 9ec55930 authored by Paul Burton's avatar Paul Burton
Browse files

MIPS: Stub asm/fpu.h functions 



Provide stub versions of functions in asm/fpu.h when
CONFIG_MIPS_FP_SUPPORT=n. Two approaches are taken to the functions
provided:

  - Functions which can safely be called when FP is not enabled provide
    stubs which return an error where appropriate or are simple no-ops.

  - Functions which should only ever be called in cases where
    cpu_has_fpu is true or the FPU was successfully enabled are declared
    extern & annotated with __compiletime_error() to detect cases in
    which they are called incorrectly.

Signed-off-by: default avatarPaul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21006/
Cc: linux-mips@linux-mips.org
parent b372e83b

arch/mips/include/asm/fpu.h

+82 −3
Original line number Diff line number Diff line
@@ -30,9 +30,6 @@ 
#include <asm/mips_mt.h>

#endif



extern void _save_fp(struct task_struct *);

extern void _restore_fp(struct task_struct *);



/*

 * This enum specifies a mode in which we want the FPU to operate, for cores

 * which implement the Status.FR bit. Note that the bottom bit of the value
@@ -47,6 +44,11 @@ enum fpu_mode { 
#define FPU_FR_MASK		0x1

};



#ifdef CONFIG_MIPS_FP_SUPPORT



extern void _save_fp(struct task_struct *);

extern void _restore_fp(struct task_struct *);



#define __disable_fpu()							\

do {									\

	clear_c0_status(ST0_CU1);					\
@@ -250,4 +252,81 @@ static inline union fpureg *get_fpu_regs(struct task_struct *tsk) 
	return tsk->thread.fpu.fpr;

}



#else /* !CONFIG_MIPS_FP_SUPPORT */



/*

 * When FP support is disabled we provide only a minimal set of stub functions

 * to avoid callers needing to care too much about CONFIG_MIPS_FP_SUPPORT.

 */



static inline int __enable_fpu(enum fpu_mode mode)

{

	return SIGILL;

}



static inline void __disable_fpu(void)

{

	/* no-op */

}





static inline int is_fpu_owner(void)

{

	return 0;

}



static inline void clear_fpu_owner(void)

{

	/* no-op */

}



static inline int own_fpu_inatomic(int restore)

{

	return SIGILL;

}



static inline int own_fpu(int restore)

{

	return SIGILL;

}



static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)

{

	/* no-op */

}



static inline void lose_fpu(int save)

{

	/* no-op */

}



static inline bool init_fp_ctx(struct task_struct *target)

{

	return false;

}



/*

 * The following functions should only be called in paths where we know that FP

 * support is enabled, typically a path where own_fpu() or __enable_fpu() have

 * returned successfully. When CONFIG_MIPS_FP_SUPPORT=n it is known at compile

 * time that this should never happen, so calls to these functions should be

 * optimized away & never actually be emitted.

 */



extern void save_fp(struct task_struct *tsk)

	__compiletime_error("save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");



extern void _save_fp(struct task_struct *)

	__compiletime_error("_save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");



extern void restore_fp(struct task_struct *tsk)

	__compiletime_error("restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");



extern void _restore_fp(struct task_struct *)

	__compiletime_error("_restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");



extern union fpureg *get_fpu_regs(struct task_struct *tsk)

	__compiletime_error("get_fpu_regs() should not be called when CONFIG_MIPS_FP_SUPPORT=n");



#endif /* !CONFIG_MIPS_FP_SUPPORT */

#endif /* _ASM_FPU_H */

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