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MIPS: Stub asm/fpu.h functions

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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: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21006/
Cc: linux-mips@linux-mips.org
This commit is contained in:
Paul Burton 2018-11-07 23:14:04 +00:00
parent b372e83b67
commit 9ec55930e0
No known key found for this signature in database
GPG Key ID: 3EA79FACB57500DD
1 changed files with 82 additions and 3 deletions
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85
arch/mips/include/asm/fpu.h
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@ -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 */