diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2014-05-08 11:20:23 +0200 |
|---|---|---|
| committer | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2014-05-08 11:31:57 +0200 |
| commit | 005f78cd88494457ed38ce817f4e3fe5d372f0cb (patch) | |
| tree | f41fff97609ae7c98bc9841bd85b60a3aa892c08 /arch/arm64/include/asm | |
| parent | c51f92693c35c141cf7d9b7e2fcbb81128324eb4 (diff) | |
arm64: defer reloading a task's FPSIMD state to userland resume
If a task gets scheduled out and back in again and nothing has touched
its FPSIMD state in the mean time, there is really no reason to reload
it from memory. Similarly, repeated calls to kernel_neon_begin() and
kernel_neon_end() will preserve and restore the FPSIMD state every time.
This patch defers the FPSIMD state restore to the last possible moment,
i.e., right before the task returns to userland. If a task does not return to
userland at all (for any reason), the existing FPSIMD state is preserved
and may be reused by the owning task if it gets scheduled in again on the
same CPU.
This patch adds two more functions to abstract away from straight FPSIMD
register file saves and restores:
- fpsimd_restore_current_state -> ensure current's FPSIMD state is loaded
- fpsimd_flush_task_state -> invalidate live copies of a task's FPSIMD state
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Diffstat (limited to 'arch/arm64/include/asm')
| -rw-r--r-- | arch/arm64/include/asm/fpsimd.h | 5 | ||||
| -rw-r--r-- | arch/arm64/include/asm/thread_info.h | 4 |
2 files changed, 8 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index f4e524b67e91..7a900142dbc8 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -37,6 +37,8 @@ struct fpsimd_state { u32 fpcr; }; }; + /* the id of the last cpu to have restored this state */ + unsigned int cpu; }; #if defined(__KERNEL__) && defined(CONFIG_COMPAT) @@ -59,8 +61,11 @@ extern void fpsimd_thread_switch(struct task_struct *next); extern void fpsimd_flush_thread(void); extern void fpsimd_preserve_current_state(void); +extern void fpsimd_restore_current_state(void); extern void fpsimd_update_current_state(struct fpsimd_state *state); +extern void fpsimd_flush_task_state(struct task_struct *target); + #endif #endif diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 720e70b66ffd..4a1ca1cfb2f8 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -100,6 +100,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_SIGPENDING 0 #define TIF_NEED_RESCHED 1 #define TIF_NOTIFY_RESUME 2 /* callback before returning to user */ +#define TIF_FOREIGN_FPSTATE 3 /* CPU's FP state is not current's */ #define TIF_SYSCALL_TRACE 8 #define TIF_POLLING_NRFLAG 16 #define TIF_MEMDIE 18 /* is terminating due to OOM killer */ @@ -112,10 +113,11 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) +#define _TIF_FOREIGN_FPSTATE (1 << TIF_FOREIGN_FPSTATE) #define _TIF_32BIT (1 << TIF_32BIT) #define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ - _TIF_NOTIFY_RESUME) + _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE) #endif /* __KERNEL__ */ #endif /* __ASM_THREAD_INFO_H */ |