recipes/linux/linux-omap-psp-2.6.32/0031-ARM-VFP-add-support-to-sync-the-VFP-state-of-the-cur.patch

   1 From 06408a83f74dde1c827749912fa53c7118f84822 Mon Sep 17 00:00:00 2001
   2 From: Imre Deak <imre.deak@nokia.com>
   3 Date: Thu, 4 Feb 2010 21:38:02 +0200
   4 Subject: [PATCH 31/42] ARM: VFP: add support to sync the VFP state of the current thread
   5
   6 ARM: VFP: add support to sync the VFP state of the current thread
   7
   8 So far vfp_sync_state worked only for threads other than the current
   9 one. This worked for tracing other threads, but not for PTRACE_TRACEME.
  10 Syncing for the current thread will also be needed by an upcoming patch
  11 adding support for VFP context save / restore around signal handlers.
  12
  13 For SMP we need get_cpu now, since we have to protect the FPEXC
  14 register, other than this things remained the same for threads other
  15 than the current.
  16
  17 Signed-off-by: Imre Deak <imre.deak@nokia.com>
  18 Signed-off-by: Bryan Wu <bryan.wu@canonical.com>
  19 ---
  20  arch/arm/vfp/vfpmodule.c |   46 +++++++++++++++++++++++++++++++---------------
  21  1 files changed, 31 insertions(+), 15 deletions(-)
  22
  23 diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
  24 index aed05bc..f28f45b 100644
  25 --- a/arch/arm/vfp/vfpmodule.c
  26 +++ b/arch/arm/vfp/vfpmodule.c
  27 @@ -423,12 +423,19 @@ static inline void vfp_pm_init(void) { }
  28  #endif /* CONFIG_PM */
  29
  30  /*
  31 - * Synchronise the hardware VFP state of a thread other than current with the
  32 - * saved one. This function is used by the ptrace mechanism.
  33 + * Synchronise the hardware VFP state of a thread with the saved one.
  34 + * This function is used by the ptrace mechanism and the signal handler path.
  35   */
  36 -#ifdef CONFIG_SMP
  37  void vfp_sync_state(struct thread_info *thread)
  38  {
  39 +       unsigned int cpu = get_cpu();
  40 +       u32 fpexc = fmrx(FPEXC);
  41 +       int vfp_enabled;
  42 +       int self;
  43 +
  44 +       vfp_enabled = fpexc & FPEXC_EN;
  45 +       self = thread == current_thread_info();
  46 +#ifdef CONFIG_SMP
  47         /*
  48          * On SMP systems, the VFP state is automatically saved at every
  49          * context switch. We mark the thread VFP state as belonging to a
  50 @@ -436,18 +443,22 @@ void vfp_sync_state(struct thread_info *thread)
  51          * needed.
  52          */
  53         thread->vfpstate.hard.cpu = NR_CPUS;
  54 -}
  55 -#else
  56 -void vfp_sync_state(struct thread_info *thread)
  57 -{
  58 -       unsigned int cpu = get_cpu();
  59 -       u32 fpexc = fmrx(FPEXC);
  60 -
  61         /*
  62 -        * If VFP is enabled, the previous state was already saved and
  63 -        * last_VFP_context updated.
  64 +        * Only the current thread's saved VFP context can be out-of-date.
  65 +        * For others there is nothing else to do, since we already ensured
  66 +        * force loading above.
  67          */
  68 -       if (fpexc & FPEXC_EN)
  69 +       if (!self)
  70 +               goto out;
  71 +#endif
  72 +       /*
  73 +        * If the VFP is enabled only the current thread's saved VFP
  74 +        * context can get out-of-date. For other threads the context
  75 +        * was updated when the current thread started to use the VFP.
  76 +        * This also means that the context will be reloaded next time
  77 +        * the thread uses the VFP, so no need to enforce it.
  78 +        */
  79 +       if (vfp_enabled && !self)
  80                 goto out;
  81
  82         if (!last_VFP_context[cpu])
  83 @@ -456,8 +467,14 @@ void vfp_sync_state(struct thread_info *thread)
  84         /*
  85          * Save the last VFP state on this CPU.
  86          */
  87 -       fmxr(FPEXC, fpexc | FPEXC_EN);
  88 +       if (!vfp_enabled)
  89 +               fmxr(FPEXC, fpexc | FPEXC_EN);
  90         vfp_save_state(last_VFP_context[cpu], fpexc);
  91 +       /*
  92 +        * Disable VFP in case it was enabled so that the force reload
  93 +        * can happen.
  94 +        */
  95 +       fpexc &= ~FPEXC_EN;
  96         fmxr(FPEXC, fpexc);
  97
  98         /*
  99 @@ -469,7 +486,6 @@ void vfp_sync_state(struct thread_info *thread)
 100  out:
 101         put_cpu();
 102  }
 103 -#endif
 104
 105  #include <linux/smp.h>
 106
 107 --
 108 1.6.6.1
 109