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Commit ad187f95 authored by Russell King's avatar Russell King
Browse files

ARM: vfp ptrace: no point flushing hw context for PTRACE_GETVFPREGS 



If we're only reading the VFP context via the ptrace call, there's
no need to invalidate the hardware context - we only need to do that
on PTRACE_SETVFPREGS.  This allows more efficient monitoring of a
traced task.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 54cb3dbb

arch/arm/include/asm/thread_info.h

+2 −1
Original line number Diff line number Diff line
@@ -115,7 +115,8 @@ extern void iwmmxt_task_restore(struct thread_info *, void *); 
extern void iwmmxt_task_release(struct thread_info *);

extern void iwmmxt_task_switch(struct thread_info *);



extern void vfp_sync_state(struct thread_info *thread);

extern void vfp_sync_hwstate(struct thread_info *);

extern void vfp_flush_hwstate(struct thread_info *);



#endif

arch/arm/kernel/ptrace.c

+4 −2
Original line number Diff line number Diff line
@@ -700,7 +700,7 @@ static int ptrace_getvfpregs(struct task_struct *tsk, void __user *data) 
	union vfp_state *vfp = &thread->vfpstate;

	struct user_vfp __user *ufp = data;



	vfp_sync_state(thread);

	vfp_sync_hwstate(thread);



	/* copy the floating point registers */

	if (copy_to_user(&ufp->fpregs, &vfp->hard.fpregs,
@@ -723,7 +723,7 @@ static int ptrace_setvfpregs(struct task_struct *tsk, void __user *data) 
	union vfp_state *vfp = &thread->vfpstate;

	struct user_vfp __user *ufp = data;



	vfp_sync_state(thread);

	vfp_sync_hwstate(thread);



	/* copy the floating point registers */

	if (copy_from_user(&vfp->hard.fpregs, &ufp->fpregs,
@@ -734,6 +734,8 @@ static int ptrace_setvfpregs(struct task_struct *tsk, void __user *data) 
	if (get_user(vfp->hard.fpscr, &ufp->fpscr))

		return -EFAULT;



	vfp_flush_hwstate(thread);



	return 0;

}

#endif

arch/arm/vfp/vfpmodule.c

+23 −2
Original line number Diff line number Diff line
@@ -430,7 +430,11 @@ static inline void vfp_pm_init(void) { } 
 * saved one. This function is used by the ptrace mechanism.

 */

#ifdef CONFIG_SMP

void vfp_sync_state(struct thread_info *thread)

void vfp_sync_hwstate(struct thread_info *thread)

{

}



void vfp_flush_hwstate(struct thread_info *thread)

{

	/*

	 * On SMP systems, the VFP state is automatically saved at every
@@ -441,7 +445,7 @@ void vfp_sync_state(struct thread_info *thread) 
	thread->vfpstate.hard.cpu = NR_CPUS;

}

#else

void vfp_sync_state(struct thread_info *thread)

void vfp_sync_hwstate(struct thread_info *thread)

{

	unsigned int cpu = get_cpu();
@@ -457,6 +461,23 @@ void vfp_sync_state(struct thread_info *thread) 
		 */

		fmxr(FPEXC, fpexc | FPEXC_EN);

		vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN);

		fmxr(FPEXC, fpexc);

	}



	put_cpu();

}



void vfp_flush_hwstate(struct thread_info *thread)

{

	unsigned int cpu = get_cpu();



	/*

	 * If the thread we're interested in is the current owner of the

	 * hardware VFP state, then we need to save its state.

	 */

	if (last_VFP_context[cpu] == &thread->vfpstate) {

		u32 fpexc = fmrx(FPEXC);



		fmxr(FPEXC, fpexc & ~FPEXC_EN);



		/*