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

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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: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2010-02-06 11:36:23 +00:00
parent 54cb3dbb4a
commit ad187f9561
3 changed files with 29 additions and 5 deletions
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3
arch/arm/include/asm/thread_info.h
View File

@ -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

6
arch/arm/kernel/ptrace.c
View File

@ -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

25
arch/arm/vfp/vfpmodule.c
View File

@ -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);
/*