diff options
| -rw-r--r-- | arch/arm/vfp/vfpmodule.c | 83 |
1 files changed, 62 insertions, 21 deletions
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index 2d7423af119..aed05bc3c2e 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -38,16 +38,72 @@ union vfp_state *last_VFP_context[NR_CPUS]; */ unsigned int VFP_arch; +/* + * Per-thread VFP initialization. + */ +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; + + /* + * Disable VFP to ensure we initialize it first. We must ensure + * that the modification of last_VFP_context[] and hardware disable + * are done for the same CPU and without preemption. + */ + cpu = get_cpu(); + if (last_VFP_context[cpu] == vfp) + last_VFP_context[cpu] = NULL; + fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); + put_cpu(); +} + +static void vfp_thread_release(struct thread_info *thread) +{ + /* release case: Per-thread VFP cleanup. */ + union vfp_state *vfp = &thread->vfpstate; + unsigned int cpu = thread->cpu; + + if (last_VFP_context[cpu] == vfp) + last_VFP_context[cpu] = NULL; +} + +/* + * When this function is called with the following 'cmd's, the following + * is true while this function is being run: + * THREAD_NOFTIFY_SWTICH: + * - the previously running thread will not be scheduled onto another CPU. + * - the next thread to be run (v) will not be running on another CPU. + * - thread->cpu is the local CPU number + * - not preemptible as we're called in the middle of a thread switch + * THREAD_NOTIFY_FLUSH: + * - the thread (v) will be running on the local CPU, so + * v === current_thread_info() + * - thread->cpu is the local CPU number at the time it is accessed, + * but may change at any time. + * - we could be preempted if tree preempt rcu is enabled, so + * it is unsafe to use thread->cpu. + * THREAD_NOTIFY_RELEASE: + * - the thread (v) will not be running on any CPU; it is a dead thread. + * - thread->cpu will be the last CPU the thread ran on, which may not + * be the current CPU. + * - we could be preempted if tree preempt rcu is enabled. + */ static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v) { struct thread_info *thread = v; - union vfp_state *vfp; - __u32 cpu = thread->cpu; if (likely(cmd == THREAD_NOTIFY_SWITCH)) { u32 fpexc = fmrx(FPEXC); #ifdef CONFIG_SMP + unsigned int cpu = thread->cpu; + /* * On SMP, if VFP is enabled, save the old state in * case the thread migrates to a different CPU. The @@ -74,25 +130,10 @@ static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v) return NOTIFY_DONE; } - vfp = &thread->vfpstate; - if (cmd == THREAD_NOTIFY_FLUSH) { - /* - * Per-thread VFP initialisation. - */ - memset(vfp, 0, sizeof(union vfp_state)); - - vfp->hard.fpexc = FPEXC_EN; - vfp->hard.fpscr = FPSCR_ROUND_NEAREST; - - /* - * Disable VFP to ensure we initialise it first. - */ - fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); - } - - /* flush and release case: Per-thread VFP cleanup. */ - if (last_VFP_context[cpu] == vfp) - last_VFP_context[cpu] = NULL; + if (cmd == THREAD_NOTIFY_FLUSH) + vfp_thread_flush(thread); + else + vfp_thread_release(thread); return NOTIFY_DONE; } |