diff options
Diffstat (limited to 'arch/arm/vfp/vfpmodule.c')
| -rw-r--r-- | arch/arm/vfp/vfpmodule.c | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index b68efe643a12..63de164c7fc7 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -56,6 +56,34 @@ extern unsigned int VFP_arch_feroceon __alias(VFP_arch); union vfp_state *vfp_current_hw_state[NR_CPUS]; /* + * Claim ownership of the VFP unit. + * + * The caller may change VFP registers until vfp_state_release() is called. + * + * local_bh_disable() is used to disable preemption and to disable VFP + * processing in softirq context. On PREEMPT_RT kernels local_bh_disable() is + * not sufficient because it only serializes soft interrupt related sections + * via a local lock, but stays preemptible. Disabling preemption is the right + * choice here as bottom half processing is always in thread context on RT + * kernels so it implicitly prevents bottom half processing as well. + */ +static void vfp_state_hold(void) +{ + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_bh_disable(); + else + preempt_disable(); +} + +static void vfp_state_release(void) +{ + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_bh_enable(); + else + preempt_enable(); +} + +/* * Is 'thread's most up to date state stored in this CPUs hardware? * Must be called from non-preemptible context. */ @@ -837,7 +865,7 @@ void kernel_neon_begin(void) unsigned int cpu; u32 fpexc; - local_bh_disable(); + vfp_state_hold(); /* * Kernel mode NEON is only allowed outside of hardirq context with @@ -868,7 +896,7 @@ void kernel_neon_end(void) { /* Disable the NEON/VFP unit. */ fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); - local_bh_enable(); + vfp_state_release(); } EXPORT_SYMBOL(kernel_neon_end); |