[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 eadca266f15..5e4bed123b4 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 610d0cdeaa9..22fe8453fcc 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 efef843b93f..4e12d1f9534 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 fbcda820447..6cf05f4a4e7 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)