diff options
Diffstat (limited to 'arch/arm/vfp')
| -rw-r--r-- | arch/arm/vfp/vfphw.S | 43 | ||||
| -rw-r--r-- | arch/arm/vfp/vfpmodule.c | 98 |
2 files changed, 86 insertions, 55 deletions
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index 404538ae591d..2d30c7f6edd3 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -82,19 +82,22 @@ ENTRY(vfp_support_entry) ldr r4, [r3, r11, lsl #2] @ vfp_current_hw_state pointer bic r5, r1, #FPEXC_EX @ make sure exceptions are disabled cmp r4, r10 @ this thread owns the hw context? +#ifndef CONFIG_SMP + @ For UP, checking that this thread owns the hw context is + @ sufficient to determine that the hardware state is valid. beq vfp_hw_state_valid + @ On UP, we lazily save the VFP context. As a different + @ thread wants ownership of the VFP hardware, save the old + @ state if there was a previous (valid) owner. + VFPFMXR FPEXC, r5 @ enable VFP, disable any pending @ exceptions, so we can get at the @ rest of it -#ifndef CONFIG_SMP - @ Save out the current registers to the old thread state - @ No need for SMP since this is not done lazily - DBGSTR1 "save old state %p", r4 - cmp r4, #0 - beq no_old_VFP_process + cmp r4, #0 @ if the vfp_current_hw_state is NULL + beq vfp_reload_hw @ then the hw state needs reloading VFPFSTMIA r4, r5 @ save the working registers VFPFMRX r5, FPSCR @ current status #ifndef CONFIG_CPU_FEROCEON @@ -107,11 +110,33 @@ ENTRY(vfp_support_entry) 1: #endif stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2 - @ and point r4 at the word at the - @ start of the register dump +vfp_reload_hw: + +#else + @ For SMP, if this thread does not own the hw context, then we + @ need to reload it. No need to save the old state as on SMP, + @ we always save the state when we switch away from a thread. + bne vfp_reload_hw + + @ This thread has ownership of the current hardware context. + @ However, it may have been migrated to another CPU, in which + @ case the saved state is newer than the hardware context. + @ Check this by looking at the CPU number which the state was + @ last loaded onto. + ldr ip, [r10, #VFP_CPU] + teq ip, r11 + beq vfp_hw_state_valid + +vfp_reload_hw: + @ We're loading this threads state into the VFP hardware. Update + @ the CPU number which contains the most up to date VFP context. + str r11, [r10, #VFP_CPU] + + VFPFMXR FPEXC, r5 @ enable VFP, disable any pending + @ exceptions, so we can get at the + @ rest of it #endif -no_old_VFP_process: DBGSTR1 "load state %p", r10 str r10, [r3, r11, lsl #2] @ update the vfp_current_hw_state pointer @ Load the saved state back into the VFP diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index 3640351171b8..08ff93fa533c 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -35,18 +35,51 @@ void vfp_null_entry(void); void (*vfp_vector)(void) = vfp_null_entry; /* + * Dual-use variable. + * Used in startup: set to non-zero if VFP checks fail + * After startup, holds VFP architecture + */ +unsigned int VFP_arch; + +/* * The pointer to the vfpstate structure of the thread which currently * owns the context held in the VFP hardware, or NULL if the hardware * context is invalid. + * + * For UP, this is sufficient to tell which thread owns the VFP context. + * However, for SMP, we also need to check the CPU number stored in the + * saved state too to catch migrations. */ union vfp_state *vfp_current_hw_state[NR_CPUS]; /* - * Dual-use variable. - * Used in startup: set to non-zero if VFP checks fail - * After startup, holds VFP architecture + * Is 'thread's most up to date state stored in this CPUs hardware? + * Must be called from non-preemptible context. */ -unsigned int VFP_arch; +static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread) +{ +#ifdef CONFIG_SMP + if (thread->vfpstate.hard.cpu != cpu) + return false; +#endif + return vfp_current_hw_state[cpu] == &thread->vfpstate; +} + +/* + * Force a reload of the VFP context from the thread structure. We do + * this by ensuring that access to the VFP hardware is disabled, and + * clear last_VFP_context. Must be called from non-preemptible context. + */ +static void vfp_force_reload(unsigned int cpu, struct thread_info *thread) +{ + if (vfp_state_in_hw(cpu, thread)) { + fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); + vfp_current_hw_state[cpu] = NULL; + } +#ifdef CONFIG_SMP + thread->vfpstate.hard.cpu = NR_CPUS; +#endif +} /* * Per-thread VFP initialization. @@ -60,6 +93,9 @@ static void vfp_thread_flush(struct thread_info *thread) 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 @@ -90,6 +126,9 @@ static void vfp_thread_copy(struct thread_info *thread) vfp_sync_hwstate(parent); thread->vfpstate = parent->vfpstate; +#ifdef CONFIG_SMP + thread->vfpstate.hard.cpu = NR_CPUS; +#endif } /* @@ -135,17 +174,8 @@ static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v) * case the thread migrates to a different CPU. The * restoring is done lazily. */ - if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) { + if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) vfp_save_state(vfp_current_hw_state[cpu], fpexc); - vfp_current_hw_state[cpu]->hard.cpu = cpu; - } - /* - * Thread migration, just force the reloading of the - * state on the new CPU in case the VFP registers - * contain stale data. - */ - if (thread->vfpstate.hard.cpu != cpu) - vfp_current_hw_state[cpu] = NULL; #endif /* @@ -449,15 +479,15 @@ static void vfp_pm_init(void) static inline void vfp_pm_init(void) { } #endif /* CONFIG_PM */ +/* + * Ensure that the VFP state stored in 'thread->vfpstate' is up to date + * with the hardware state. + */ void vfp_sync_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 (vfp_current_hw_state[cpu] == &thread->vfpstate) { + if (vfp_state_in_hw(cpu, thread)) { u32 fpexc = fmrx(FPEXC); /* @@ -471,36 +501,13 @@ void vfp_sync_hwstate(struct thread_info *thread) put_cpu(); } +/* Ensure that the thread reloads the hardware VFP state on the next use. */ 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 (vfp_current_hw_state[cpu] == &thread->vfpstate) { - u32 fpexc = fmrx(FPEXC); + vfp_force_reload(cpu, thread); - fmxr(FPEXC, fpexc & ~FPEXC_EN); - - /* - * Set the context to NULL to force a reload the next time - * the thread uses the VFP. - */ - vfp_current_hw_state[cpu] = NULL; - } - -#ifdef CONFIG_SMP - /* - * For SMP we still have to take care of the case where the thread - * migrates to another CPU and then back to the original CPU on which - * the last VFP user is still the same thread. Mark the thread VFP - * state as belonging to a non-existent CPU so that the saved one will - * be reloaded in the above case. - */ - thread->vfpstate.hard.cpu = NR_CPUS; -#endif put_cpu(); } @@ -519,8 +526,7 @@ static int vfp_hotplug(struct notifier_block *b, unsigned long action, void *hcpu) { if (action == CPU_DYING || action == CPU_DYING_FROZEN) { - unsigned int cpu = (long)hcpu; - vfp_current_hw_state[cpu] = NULL; + vfp_force_reload((long)hcpu, current_thread_info()); } else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN) vfp_enable(NULL); return NOTIFY_OK; |