7 files changed, 21 insertions, 57 deletions

diff --git a/arch/mips/kernel/r2300_switch.S b/arch/mips/kernel/r2300_switch.S
index 28c2e2e6af73..656bde2e11b1 100644
--- a/arch/mips/kernel/r2300_switch.S
+++ b/arch/mips/kernel/r2300_switch.S
@@ -49,7 +49,8 @@ LEAF(resume)
 #ifndef CONFIG_CPU_HAS_LLSC
         sw      zero, ll_bit
 #endif
-        mfc0    t2, CP0_STATUS
+        mfc0    t1, CP0_STATUS
+        sw      t1, THREAD_STATUS(a0)
         cpu_save_nonscratch a0
         sw      ra, THREAD_REG31(a0)
 
@@ -59,8 +60,8 @@ LEAF(resume)
         lw      t3, TASK_THREAD_INFO(a0)
         lw      t0, TI_FLAGS(t3)
         li      t1, _TIF_USEDFPU
-        and     t1, t0
-        beqz    t1, 1f
+        and     t2, t0, t1
+        beqz    t2, 1f
         nor     t1, zero, t1
 
         and     t0, t0, t1
@@ -73,13 +74,10 @@ LEAF(resume)
         li      t1, ~ST0_CU1
         and     t0, t0, t1
         sw      t0, ST_OFF(t3)
-        /* clear thread_struct CU1 bit */
-        and     t2, t1
 
         fpu_save_single a0, t0                  # clobbers t0
 
 1:
-        sw      t2, THREAD_STATUS(a0)
         /*
          * The order of restoring the registers takes care of the race
          * updating $28, $29 and kernelsp without disabling ints.
diff --git a/arch/mips/kernel/r4k_switch.S b/arch/mips/kernel/r4k_switch.S
index c7698fd9955c..cc566cf12246 100644
--- a/arch/mips/kernel/r4k_switch.S
+++ b/arch/mips/kernel/r4k_switch.S
@@ -48,7 +48,8 @@
 #ifndef CONFIG_CPU_HAS_LLSC
         sw      zero, ll_bit
 #endif
-        mfc0    t2, CP0_STATUS
+        mfc0    t1, CP0_STATUS
+        LONG_S  t1, THREAD_STATUS(a0)
         cpu_save_nonscratch a0
         LONG_S  ra, THREAD_REG31(a0)
 
@@ -58,8 +59,8 @@
         PTR_L   t3, TASK_THREAD_INFO(a0)
         LONG_L  t0, TI_FLAGS(t3)
         li      t1, _TIF_USEDFPU
-        and     t1, t0
-        beqz    t1, 1f
+        and     t2, t0, t1
+        beqz    t2, 1f
         nor     t1, zero, t1
 
         and     t0, t0, t1
@@ -72,13 +73,10 @@
         li      t1, ~ST0_CU1
         and     t0, t0, t1
         LONG_S  t0, ST_OFF(t3)
-        /* clear thread_struct CU1 bit */
-        and     t2, t1
 
         fpu_save_double a0 t0 t1                # c0_status passed in t0
                                                 # clobbers t1
 1:
-        LONG_S  t2, THREAD_STATUS(a0)
 
         /*
          * The order of restoring the registers takes care of the race
diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 8c3c5a5789b0..fa581192de21 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -113,10 +113,10 @@ int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
                  * Save FPU state to signal context. Signal handler
                  * will "inherit" current FPU state.
                  */
+                preempt_disable();
                 own_fpu(1);
-                enable_fp_in_kernel();
                 err |= save_fp_context(sc);
-                disable_fp_in_kernel();
+                preempt_enable();
         }
         return err;
 }
@@ -148,7 +148,10 @@ check_and_restore_fp_context(struct sigcontext __user *sc)
         err = sig = fpcsr_pending(&sc->sc_fpc_csr);
         if (err > 0)
                 err = 0;
+        preempt_disable();
+        own_fpu(0);
         err |= restore_fp_context(sc);
+        preempt_enable();
         return err ?: sig;
 }
 
@@ -187,11 +190,8 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 
         if (used_math) {
                 /* restore fpu context if we have used it before */
-                own_fpu(0);
-                enable_fp_in_kernel();
                 if (!err)
                         err = check_and_restore_fp_context(sc);
-                disable_fp_in_kernel();
         } else {
                 /* signal handler may have used FPU.  Give it up. */
                 lose_fpu(0);
diff --git a/arch/mips/kernel/signal32.c b/arch/mips/kernel/signal32.c
index 151fd2f0893a..53a337cfeb66 100644
--- a/arch/mips/kernel/signal32.c
+++ b/arch/mips/kernel/signal32.c
@@ -209,10 +209,10 @@ static int setup_sigcontext32(struct pt_regs *regs,
                  * Save FPU state to signal context.  Signal handler
                  * will "inherit" current FPU state.
                  */
+                preempt_disable();
                 own_fpu(1);
-                enable_fp_in_kernel();
                 err |= save_fp_context32(sc);
-                disable_fp_in_kernel();
+                preempt_enable();
         }
         return err;
 }
@@ -225,7 +225,10 @@ check_and_restore_fp_context32(struct sigcontext32 __user *sc)
         err = sig = fpcsr_pending(&sc->sc_fpc_csr);
         if (err > 0)
                 err = 0;
+        preempt_disable();
+        own_fpu(0);
         err |= restore_fp_context32(sc);
+        preempt_enable();
         return err ?: sig;
 }
 
@@ -261,11 +264,8 @@ static int restore_sigcontext32(struct pt_regs *regs,
 
         if (used_math) {
                 /* restore fpu context if we have used it before */
-                own_fpu(0);
-                enable_fp_in_kernel();
                 if (!err)
                         err = check_and_restore_fp_context32(sc);
-                disable_fp_in_kernel();
         } else {
                 /* signal handler may have used FPU.  Give it up. */
                 lose_fpu(0);
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 7d76a85422b2..6b356f62289e 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -757,11 +757,12 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 {
         unsigned int cpid;
 
+        die_if_kernel("do_cpu invoked from kernel context!", regs);
+
         cpid = (regs->cp0_cause >> CAUSEB_CE) & 3;
 
         switch (cpid) {
         case 0:
-                die_if_kernel("do_cpu invoked from kernel context!", regs);
                 if (!cpu_has_llsc)
                         if (!simulate_llsc(regs))
                                 return;
@@ -772,9 +773,6 @@ asmlinkage void do_cpu(struct pt_regs *regs)
                 break;
 
         case 1:
-                if (!test_thread_flag(TIF_ALLOW_FP_IN_KERNEL))
-                        die_if_kernel("do_cpu invoked from kernel context!",
-                                      regs);
                 if (used_math())        /* Using the FPU again.  */
                         own_fpu(1);
                 else {                  /* First time FPU user.  */
@@ -782,19 +780,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
                         set_used_math();
                 }
 
-                if (raw_cpu_has_fpu) {
-                        if (test_thread_flag(TIF_ALLOW_FP_IN_KERNEL)) {
-                                local_irq_disable();
-                                if (cpu_has_fpu)
-                                        regs->cp0_status |= ST0_CU1;
-                                /*
-                                 * We must return without enabling
-                                 * interrupts to ensure keep FPU
-                                 * ownership until resume.
-                                 */
-                                return;
-                        }
-                } else {
+                if (!raw_cpu_has_fpu) {
                         int sig;
                         sig = fpu_emulator_cop1Handler(regs,
                                                 &current->thread.fpu, 0);
@@ -836,7 +822,6 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 
         case 2:
         case 3:
-                die_if_kernel("do_cpu invoked from kernel context!", regs);
                 break;
         }
 
diff --git a/include/asm-mips/fpu.h b/include/asm-mips/fpu.h
index 4e12d1f9534f..71436f90203f 100644
--- a/include/asm-mips/fpu.h
+++ b/include/asm-mips/fpu.h
@@ -68,8 +68,6 @@ 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)                                                \
@@ -162,18 +160,4 @@ 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 6cf05f4a4e7e..fbcda8204473 100644
--- a/include/asm-mips/thread_info.h
+++ b/include/asm-mips/thread_info.h
@@ -119,7 +119,6 @@ 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)