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authorKevin Hao <haokexin@gmail.com>2013-07-14 17:02:05 +0800
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-08-14 14:59:44 +1000
commit037f0eed57c3f35367ac32275e45f24e297549e9 (patch)
tree87dbec64efb721dae5fd8b0a5c2b634f882631dd /arch
parent662499d04b6bc73d0ecab0ab876bacd5bbe7d6a7 (diff)
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 <haokexin@gmail.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/include/asm/switch_to.h7
-rw-r--r--arch/powerpc/kernel/process.c2
-rw-r--r--arch/powerpc/math-emu/math.c3
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 33e1cd82358..39cf0f6cc37 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 c517dbe705f..0ec255a81c6 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 49eb2ac08fd..bc901623d8d 100644
--- a/arch/powerpc/math-emu/math.c
+++ b/arch/powerpc/math-emu/math.c
@@ -7,6 +7,7 @@
#include <asm/uaccess.h>
#include <asm/reg.h>
+#include <asm/switch_to.h>
#include <asm/sfp-machine.h>
#include <math-emu/double.h>
@@ -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);