On Mon, Jul 16, 2012 at 11:34 AM, Nicolas Pitre <[email protected]> wrote: > On Mon, 16 Jul 2012, Colin Cross wrote: > >> vfp_pm_suspend should save the VFP state in suspend after >> any lazy context switch. If it only saves when the VFP is enabled, >> the state can get lost when, on a UP system: >> Thread 1 uses the VFP >> Context switch occurs to thread 2, VFP is disabled but the >> VFP context is not saved >> Thread 2 initiates suspend >> vfp_pm_suspend is called with the VFP disabled, and the unsaved >> VFP context of Thread 1 in the registers >> >> Modify vfp_pm_suspend to save the VFP context whenever >> vfp_current_hw_state is not NULL. >> >> Includes a fix from Ido Yariv <[email protected]>, who pointed out that on >> SMP systems, the state pointer can be pointing to a freed task struct if >> a task exited on another cpu, fixed by using #ifdef CONFIG_SMP in the >> new if clause. >> >> Cc: Russell King <[email protected]> >> Cc: Barry Song <[email protected]> >> Cc: Catalin Marinas <[email protected]> >> Cc: Ido Yariv <[email protected]> >> Cc: Daniel Drake <[email protected]> >> Cc: Will Deacon <[email protected]> >> Signed-off-by: Colin Cross <[email protected]> >> --- >> arch/arm/vfp/vfpmodule.c | 6 ++++++ >> 1 files changed, 6 insertions(+), 0 deletions(-) >> >> diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c >> index 58696192..ce55f05 100644 >> --- a/arch/arm/vfp/vfpmodule.c >> +++ b/arch/arm/vfp/vfpmodule.c >> @@ -457,6 +457,12 @@ static int vfp_pm_suspend(void) >> >> /* disable, just in case */ >> fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); >> + } else if (vfp_current_hw_state[ti->cpu]) { >> +#ifndef CONFIG_SMP >> + fmxr(FPEXC, fpexc | FPEXC_EN); >> + vfp_save_state(vfp_current_hw_state[ti->cpu], fpexc); >> + fmxr(FPEXC, fpexc); >> +#endif >> } > > Couldn't vfp_sync_hwstate() be used here instead?
Not easily, we don't have the thread struct of the thread that is in the vfp hardware. We would have to read vfp_current_hw_state for the current cpu and use container_of to get from struct vfpstate to struct thread_info, and then pass that back in to vfp_sync_hwstate. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
