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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_release(struct thread_info *);
extern void iwmmxt_task_switch(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 #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; union vfp_state *vfp = &thread->vfpstate;
struct user_vfp __user *ufp = data; struct user_vfp __user *ufp = data;
vfp_sync_state(thread); vfp_sync_hwstate(thread);
/* copy the floating point registers */ /* copy the floating point registers */
if (copy_to_user(&ufp->fpregs, &vfp->hard.fpregs, 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; union vfp_state *vfp = &thread->vfpstate;
struct user_vfp __user *ufp = data; struct user_vfp __user *ufp = data;
vfp_sync_state(thread); vfp_sync_hwstate(thread);
/* copy the floating point registers */ /* copy the floating point registers */
if (copy_from_user(&vfp->hard.fpregs, &ufp->fpregs, 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)) if (get_user(vfp->hard.fpscr, &ufp->fpscr))
return -EFAULT; return -EFAULT;
vfp_flush_hwstate(thread);
return 0; return 0;
} }
#endif #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. * saved one. This function is used by the ptrace mechanism.
*/ */
#ifdef CONFIG_SMP #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 * 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; thread->vfpstate.hard.cpu = NR_CPUS;
} }
#else #else
void vfp_sync_state(struct thread_info *thread) void vfp_sync_hwstate(struct thread_info *thread)
{ {
unsigned int cpu = get_cpu(); unsigned int cpu = get_cpu();
@@ -457,6 +461,23 @@ void vfp_sync_state(struct thread_info *thread)
*/ */
fmxr(FPEXC, fpexc | FPEXC_EN); fmxr(FPEXC, fpexc | FPEXC_EN);
vfp_save_state(&thread->vfpstate, 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); fmxr(FPEXC, fpexc & ~FPEXC_EN);
/* /*