Module: xenomai-3
Branch: next
Commit: 29bf6e13adbd7d15e4be7f20aaac1d7c6fabee6b
URL:    
http://git.xenomai.org/?p=xenomai-3.git;a=commit;h=29bf6e13adbd7d15e4be7f20aaac1d7c6fabee6b

Author: Gilles Chanteperdrix <gilles.chanteperd...@xenomai.org>
Date:   Fri Oct 30 17:14:00 2015 +0100

cobalt/arm64: attempt at fixing fpu switch

Return to eager switching, since user-space applications use FPU
registers even when not using the FPU, but use an auxiliary backup area
when the "TIF_FOREIGN_FPSTATE" bit is set, in order to avoid clobbering
the saved FPU state.

---

 .../cobalt/arch/arm64/include/asm/xenomai/thread.h |   14 +++--
 kernel/cobalt/arch/arm64/thread.c                  |   54 +++++---------------
 2 files changed, 25 insertions(+), 43 deletions(-)

diff --git a/kernel/cobalt/arch/arm64/include/asm/xenomai/thread.h 
b/kernel/cobalt/arch/arm64/include/asm/xenomai/thread.h
index 9055e58..4b247ac 100644
--- a/kernel/cobalt/arch/arm64/include/asm/xenomai/thread.h
+++ b/kernel/cobalt/arch/arm64/include/asm/xenomai/thread.h
@@ -24,6 +24,7 @@
 struct xnarchtcb {
        struct xntcb core;
 #ifdef CONFIG_XENO_ARCH_FPU
+       struct fpsimd_state xnfpsimd_state;
        struct fpsimd_state *fpup;
 #define xnarch_fpu_ptr(tcb)     ((tcb)->fpup)
 #endif
@@ -67,7 +68,10 @@ static inline void xnarch_init_root_tcb(struct xnthread 
*thread)
 
 void xnarch_init_shadow_tcb(struct xnthread *thread);
 
-int xnarch_fault_fpu_p(struct ipipe_trap_data *d);
+static inline int xnarch_fault_fpu_p(struct ipipe_trap_data *d)
+{
+       return xnarch_fault_trap(d) == IPIPE_TRAP_FPU_ACC;
+}
 
 void xnarch_leave_root(struct xnthread *root);
 
@@ -75,8 +79,12 @@ void xnarch_save_fpu(struct xnthread *thread);
 
 void xnarch_switch_fpu(struct xnthread *from, struct xnthread *thread);
 
-int xnarch_handle_fpu_fault(struct xnthread *from, 
-                       struct xnthread *to, struct ipipe_trap_data *d);
+static inline int
+xnarch_handle_fpu_fault(struct xnthread *from,
+                       struct xnthread *to, struct ipipe_trap_data *d)
+{
+       return 0;
+}
 
 #else /* !CONFIG_XENO_ARCH_FPU */
 
diff --git a/kernel/cobalt/arch/arm64/thread.c 
b/kernel/cobalt/arch/arm64/thread.c
index 2238751..b987e09 100644
--- a/kernel/cobalt/arch/arm64/thread.c
+++ b/kernel/cobalt/arch/arm64/thread.c
@@ -6,6 +6,7 @@
  * 
  * ARM64 port
  *   Copyright (C) 2015 Dmitriy Cherkasov <dmit...@mperpetuo.com>
+ *   Copyright (C) 2015 Gilles Chanteperdrix <g...@xenomai.org>
  *
  * Xenomai is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by
@@ -41,7 +42,7 @@
 static inline unsigned long get_cpacr(void)
 {
        unsigned long result;
-       __asm__ __volatile__("mrs %0, cpacr_el1": "=r"(result));
+       __asm__ ("mrs %0, cpacr_el1": "=r"(result));
        return result;
 }
 
@@ -53,21 +54,20 @@ static inline void set_cpacr(long val)
                : /* */ : "r"(val));
 }
 
-static void enable_fpsimd(void)
+static inline void enable_fpsimd(void)
 {
-       unsigned long cpacr = get_cpacr();
-       cpacr |= FPSIMD_EN;
-       set_cpacr(cpacr);
+       set_cpacr(get_cpacr() | FPSIMD_EN);
 }
 
-int xnarch_fault_fpu_p(struct ipipe_trap_data *d)
+static inline struct fpsimd_state *get_fpu_owner(struct xnarchtcb *rootcb)
 {
-       return (d->exception == IPIPE_TRAP_FPU_ACC);
-}
+       struct task_struct *curr = rootcb->core.host_task;
 
-static inline struct fpsimd_state *get_fpu_owner(struct xnarchtcb *tcb)
-{
-       return &(tcb->core.tsp->fpsimd_state);
+       if (test_ti_thread_flag(task_thread_info(curr), TIF_FOREIGN_FPSTATE))
+               /* Foreign fpu state, use auxiliary backup area */
+               return &rootcb->xnfpsimd_state;
+
+       return &curr->thread.fpsimd_state;
 }
 
 void xnarch_leave_root(struct xnthread *root)
@@ -76,13 +76,6 @@ void xnarch_leave_root(struct xnthread *root)
        rootcb->fpup = get_fpu_owner(rootcb);
 }
 
-void xnarch_save_fpu(struct xnthread *thread)
-{
-       struct xnarchtcb *tcb = &(thread->tcb);
-       if (xnarch_fpu_ptr(tcb))
-               fpsimd_save_state(tcb->fpup);
-}
-
 void xnarch_switch_fpu(struct xnthread *from, struct xnthread *to)
 {
        struct fpsimd_state *const from_fpup = from ? from->tcb.fpup : NULL;
@@ -93,35 +86,16 @@ void xnarch_switch_fpu(struct xnthread *from, struct 
xnthread *to)
        if (from_fpup == to_fpup)
                return;
 
-       if (from_fpup)
-               fpsimd_save_state(from_fpup);
+       fpsimd_save_state(from_fpup);
 
        fpsimd_load_state(to_fpup);
-}
-
-int xnarch_handle_fpu_fault(struct xnthread *from, 
-                       struct xnthread *to, struct ipipe_trap_data *d)
-{
-       spl_t s;
-
-       /* FPU should already be enabled for XNFPU tasks. */
-       if (xnthread_test_state(to, XNFPU))
-               BUG();
-
-       xnlock_get_irqsave(&nklock, s);
-       xnthread_set_state(to, XNFPU);
-       xnlock_put_irqrestore(&nklock, s);
-
-       xnarch_switch_fpu(from, to);
-
-       return 1;
+       to_fpup->cpu = ipipe_processor_id();
 }
 
 void xnarch_init_shadow_tcb(struct xnthread *thread)
 {
        struct xnarchtcb *tcb = xnthread_archtcb(thread);
-       tcb->fpup = &(tcb->core.host_task->thread.fpsimd_state);
-       xnthread_clear_state(thread, XNFPU);
+       tcb->fpup = &tcb->core.host_task->thread.fpsimd_state;
 }
 
 #endif /* CONFIG_XENO_ARCH_FPU */


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