From 037f0eed57c3f35367ac32275e45f24e297549e9 Mon Sep 17 00:00:00 2001 From: Kevin Hao Date: Sun, 14 Jul 2013 17:02:05 +0800 Subject: [PATCH] powerpc: Make flush_fp_to_thread() nop when CONFIG_PPC_FPU is disabled In the current kernel, the function flush_fp_to_thread() is not dependent on CONFIG_PPC_FPU. So most invocations of this function is not wrapped by CONFIG_PPC_FPU. Even through we don't really save the FPRs to the thread struct if CONFIG_PPC_FPU is not enabled, but there does have some runtime overhead such as the check for tsk->thread.regs and preempt disable and enable. It really make no sense to do that. So make it a nop when CONFIG_PPC_FPU is disabled. Also remove the wrapped #ifdef CONFIG_PPC_FPU when invoking this function. Signed-off-by: Kevin Hao Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/switch_to.h | 7 ++++++- arch/powerpc/kernel/process.c | 2 ++ arch/powerpc/math-emu/math.c | 3 +-- 3 files changed, 9 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h index 33e1cd8..39cf0f6 100644 --- a/arch/powerpc/include/asm/switch_to.h +++ b/arch/powerpc/include/asm/switch_to.h @@ -19,7 +19,6 @@ extern struct task_struct *_switch(struct thread_struct *prev, extern void giveup_fpu(struct task_struct *); extern void load_up_fpu(void); extern void enable_kernel_fp(void); -extern void flush_fp_to_thread(struct task_struct *); extern void enable_kernel_altivec(void); extern void load_up_altivec(struct task_struct *); extern int emulate_altivec(struct pt_regs *); @@ -37,6 +36,12 @@ static inline void discard_lazy_cpu_state(void) } #endif +#ifdef CONFIG_PPC_FPU +extern void flush_fp_to_thread(struct task_struct *); +#else +static inline void flush_fp_to_thread(struct task_struct *t) { } +#endif + #ifdef CONFIG_ALTIVEC extern void flush_altivec_to_thread(struct task_struct *); extern void giveup_altivec(struct task_struct *); diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index c517dbe..0ec255a 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -74,6 +74,7 @@ struct task_struct *last_task_used_vsx = NULL; struct task_struct *last_task_used_spe = NULL; #endif +#ifdef CONFIG_PPC_FPU /* * Make sure the floating-point register state in the * the thread_struct is up to date for task tsk. @@ -107,6 +108,7 @@ void flush_fp_to_thread(struct task_struct *tsk) } } EXPORT_SYMBOL_GPL(flush_fp_to_thread); +#endif void enable_kernel_fp(void) { diff --git a/arch/powerpc/math-emu/math.c b/arch/powerpc/math-emu/math.c index 49eb2ac..bc90162 100644 --- a/arch/powerpc/math-emu/math.c +++ b/arch/powerpc/math-emu/math.c @@ -7,6 +7,7 @@ #include #include +#include #include #include @@ -433,9 +434,7 @@ do_mathemu(struct pt_regs *regs) * is flushed into the thread_struct before attempting * emulation */ -#ifdef CONFIG_PPC_FPU flush_fp_to_thread(current); -#endif eflag = func(op0, op1, op2, op3); -- 2.7.4