From e123d36f95b22fea6ebfc8afd609bfac871c0d73 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 9 Jul 2011 17:41:33 +0100 Subject: ARM: vfp: ensure that thread flushing works if preempted Prevent a preemption event causing the initialized VFP state being overwritten by ensuring that the VFP hardware access is disabled prior to starting initialization. We can then do this in safety while still allowing preemption to occur. Change-Id: I93922d95f641aa989b2acefe009a656e27d4d9bf Signed-off-by: Russell King Signed-off-by: Lanchon --- arch/arm/vfp/vfpmodule.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index 9245b86..fe2913c 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -90,24 +90,27 @@ static void vfp_thread_flush(struct thread_info *thread) union vfp_state *vfp = &thread->vfpstate; unsigned int cpu; - memset(vfp, 0, sizeof(union vfp_state)); - - vfp->hard.fpexc = FPEXC_EN; - vfp->hard.fpscr = FPSCR_ROUND_NEAREST; -#ifdef CONFIG_SMP - vfp->hard.cpu = NR_CPUS; -#endif - /* * Disable VFP to ensure we initialize it first. We must ensure - * that the modification of vfp_current_hw_state[] and hardware disable - * are done for the same CPU and without preemption. + * that the modification of vfp_current_hw_state[] and hardware + * disable are done for the same CPU and without preemption. + * + * Do this first to ensure that preemption won't overwrite our + * state saving should access to the VFP be enabled at this point. */ cpu = get_cpu(); if (vfp_current_hw_state[cpu] == vfp) vfp_current_hw_state[cpu] = NULL; fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); put_cpu(); + + memset(vfp, 0, sizeof(union vfp_state)); + + vfp->hard.fpexc = FPEXC_EN; + vfp->hard.fpscr = FPSCR_ROUND_NEAREST; +#ifdef CONFIG_SMP + vfp->hard.cpu = NR_CPUS; +#endif } static void vfp_thread_exit(struct thread_info *thread) -- cgit v1.1