[MIPS] FPU ownership management & preemption fixes

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

4 files changed, 48 insertions, 11 deletions

diff --git a/include/asm-mips/cpu-features.h b/include/asm-mips/cpu-features.h
index eadca266f159..5e4bed123b48 100644
--- a/include/asm-mips/cpu-features.h
+++ b/include/asm-mips/cpu-features.h
@@ -40,6 +40,9 @@
 #endif
 #ifndef cpu_has_fpu
 #define cpu_has_fpu             (current_cpu_data.options & MIPS_CPU_FPU)
+#define raw_cpu_has_fpu         (raw_current_cpu_data.options & MIPS_CPU_FPU)
+#else
+#define raw_cpu_has_fpu         cpu_has_fpu
 #endif
 #ifndef cpu_has_32fpr
 #define cpu_has_32fpr           (cpu_data[0].options & MIPS_CPU_32FPR)
diff --git a/include/asm-mips/cpu-info.h b/include/asm-mips/cpu-info.h
index 610d0cdeaa9e..22fe8453fcc7 100644
--- a/include/asm-mips/cpu-info.h
+++ b/include/asm-mips/cpu-info.h
@@ -87,6 +87,7 @@ struct cpuinfo_mips {
 
 extern struct cpuinfo_mips cpu_data[];
 #define current_cpu_data cpu_data[smp_processor_id()]
+#define raw_current_cpu_data cpu_data[raw_smp_processor_id()]
 
 extern void cpu_probe(void);
 extern void cpu_report(void);
diff --git a/include/asm-mips/fpu.h b/include/asm-mips/fpu.h
index efef843b93f0..4e12d1f9534f 100644
--- a/include/asm-mips/fpu.h
+++ b/include/asm-mips/fpu.h
@@ -27,11 +27,11 @@
 struct sigcontext;
 struct sigcontext32;
 
-extern asmlinkage int (*save_fp_context)(struct sigcontext *sc);
-extern asmlinkage int (*restore_fp_context)(struct sigcontext *sc);
+extern asmlinkage int (*save_fp_context)(struct sigcontext __user *sc);
+extern asmlinkage int (*restore_fp_context)(struct sigcontext __user *sc);
 
-extern asmlinkage int (*save_fp_context32)(struct sigcontext32 *sc);
-extern asmlinkage int (*restore_fp_context32)(struct sigcontext32 *sc);
+extern asmlinkage int (*save_fp_context32)(struct sigcontext32 __user *sc);
+extern asmlinkage int (*restore_fp_context32)(struct sigcontext32 __user *sc);
 
 extern void fpu_emulator_init_fpu(void);
 extern void _init_fpu(void);
@@ -68,6 +68,8 @@ do {									\
         /* We don't care about the c0 hazard here  */                   \
 } while (0)
 
+#define __fpu_enabled() (read_c0_status() & ST0_CU1)
+
 #define enable_fpu()                                                    \
 do {                                                                    \
         if (cpu_has_fpu)                                                \
@@ -93,31 +95,47 @@ static inline int is_fpu_owner(void)
         return cpu_has_fpu && __is_fpu_owner();
 }
 
-static inline void own_fpu(void)
+static inline void __own_fpu(void)
 {
-        if (cpu_has_fpu) {
-                __enable_fpu();
-                KSTK_STATUS(current) |= ST0_CU1;
-                set_thread_flag(TIF_USEDFPU);
+        __enable_fpu();
+        KSTK_STATUS(current) |= ST0_CU1;
+        set_thread_flag(TIF_USEDFPU);
+}
+
+static inline void own_fpu(int restore)
+{
+        preempt_disable();
+        if (cpu_has_fpu && !__is_fpu_owner()) {
+                __own_fpu();
+                if (restore)
+                        _restore_fp(current);
         }
+        preempt_enable();
 }
 
-static inline void lose_fpu(void)
+static inline void lose_fpu(int save)
 {
-        if (cpu_has_fpu) {
+        preempt_disable();
+        if (is_fpu_owner()) {
+                if (save)
+                        _save_fp(current);
                 KSTK_STATUS(current) &= ~ST0_CU1;
                 clear_thread_flag(TIF_USEDFPU);
                 __disable_fpu();
         }
+        preempt_enable();
 }
 
 static inline void init_fpu(void)
 {
+        preempt_disable();
         if (cpu_has_fpu) {
+                __own_fpu();
                 _init_fpu();
         } else {
                 fpu_emulator_init_fpu();
         }
+        preempt_enable();
 }
 
 static inline void save_fp(struct task_struct *tsk)
@@ -144,4 +162,18 @@ static inline fpureg_t *get_fpu_regs(struct task_struct *tsk)
         return tsk->thread.fpu.fpr;
 }
 
+static inline void enable_fp_in_kernel(void)
+{
+        set_thread_flag(TIF_ALLOW_FP_IN_KERNEL);
+        /* make sure CU1 and FPU ownership are consistent */
+        if (!__is_fpu_owner() && __fpu_enabled())
+                __disable_fpu();
+}
+
+static inline void disable_fp_in_kernel(void)
+{
+        BUG_ON(!__is_fpu_owner() && __fpu_enabled());
+        clear_thread_flag(TIF_ALLOW_FP_IN_KERNEL);
+}
+
 #endif /* _ASM_FPU_H */
diff --git a/include/asm-mips/thread_info.h b/include/asm-mips/thread_info.h
index fbcda8204473..6cf05f4a4e7e 100644
--- a/include/asm-mips/thread_info.h
+++ b/include/asm-mips/thread_info.h
@@ -119,6 +119,7 @@ register struct thread_info *__current_thread_info __asm__("$28");
 #define TIF_POLLING_NRFLAG      17      /* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE              18
 #define TIF_FREEZE              19
+#define TIF_ALLOW_FP_IN_KERNEL  20
 #define TIF_SYSCALL_TRACE       31      /* syscall trace active */
 
 #define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)