From 7f82f1bbba1f762468617387702002c0ca81df0f Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Thu, 4 Feb 2010 21:38:02 +0200 Subject: [PATCH 31/32] ARM: VFP: add support to sync the VFP state of the current thread ARM: VFP: add support to sync the VFP state of the current thread So far vfp_sync_state worked only for threads other than the current one. This worked for tracing other threads, but not for PTRACE_TRACEME. Syncing for the current thread will also be needed by an upcoming patch adding support for VFP context save / restore around signal handlers. For SMP we need get_cpu now, since we have to protect the FPEXC register, other than this things remained the same for threads other than the current. Signed-off-by: Imre Deak Signed-off-by: Bryan Wu --- arch/arm/vfp/vfpmodule.c | 46 +++++++++++++++++++++++++++++++--------------- 1 files changed, 31 insertions(+), 15 deletions(-) diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index aed05bc..f28f45b 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -423,12 +423,19 @@ static inline void vfp_pm_init(void) { } #endif /* CONFIG_PM */ /* - * Synchronise the hardware VFP state of a thread other than current with the - * saved one. This function is used by the ptrace mechanism. + * Synchronise the hardware VFP state of a thread with the saved one. + * This function is used by the ptrace mechanism and the signal handler path. */ -#ifdef CONFIG_SMP void vfp_sync_state(struct thread_info *thread) { + unsigned int cpu = get_cpu(); + u32 fpexc = fmrx(FPEXC); + int vfp_enabled; + int self; + + vfp_enabled = fpexc & FPEXC_EN; + self = thread == current_thread_info(); +#ifdef CONFIG_SMP /* * On SMP systems, the VFP state is automatically saved at every * context switch. We mark the thread VFP state as belonging to a @@ -436,18 +443,22 @@ void vfp_sync_state(struct thread_info *thread) * needed. */ thread->vfpstate.hard.cpu = NR_CPUS; -} -#else -void vfp_sync_state(struct thread_info *thread) -{ - unsigned int cpu = get_cpu(); - u32 fpexc = fmrx(FPEXC); - /* - * If VFP is enabled, the previous state was already saved and - * last_VFP_context updated. + * Only the current thread's saved VFP context can be out-of-date. + * For others there is nothing else to do, since we already ensured + * force loading above. */ - if (fpexc & FPEXC_EN) + if (!self) + goto out; +#endif + /* + * If the VFP is enabled only the current thread's saved VFP + * context can get out-of-date. For other threads the context + * was updated when the current thread started to use the VFP. + * This also means that the context will be reloaded next time + * the thread uses the VFP, so no need to enforce it. + */ + if (vfp_enabled && !self) goto out; if (!last_VFP_context[cpu]) @@ -456,8 +467,14 @@ void vfp_sync_state(struct thread_info *thread) /* * Save the last VFP state on this CPU. */ - fmxr(FPEXC, fpexc | FPEXC_EN); + if (!vfp_enabled) + fmxr(FPEXC, fpexc | FPEXC_EN); vfp_save_state(last_VFP_context[cpu], fpexc); + /* + * Disable VFP in case it was enabled so that the force reload + * can happen. + */ + fpexc &= ~FPEXC_EN; fmxr(FPEXC, fpexc); /* @@ -469,7 +486,6 @@ void vfp_sync_state(struct thread_info *thread) out: put_cpu(); } -#endif #include -- 1.6.6.1