[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>

1 files changed, 37 insertions, 47 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 18f56a9dbcfa..7d76a85422b2 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -610,16 +610,6 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
         if (fcr31 & FPU_CSR_UNI_X) {
                 int sig;
 
-                preempt_disable();
-
-#ifdef CONFIG_PREEMPT
-                if (!is_fpu_owner()) {
-                        /* We might lose fpu before disabling preempt... */
-                        own_fpu();
-                        BUG_ON(!used_math());
-                        restore_fp(current);
-                }
-#endif
                 /*
                  * Unimplemented operation exception.  If we've got the full
                  * software emulator on-board, let's use it...
@@ -630,18 +620,12 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
                  * register operands before invoking the emulator, which seems
                  * a bit extreme for what should be an infrequent event.
                  */
-                save_fp(current);
                 /* Ensure 'resume' not overwrite saved fp context again. */
-                lose_fpu();
-
-                preempt_enable();
+                lose_fpu(1);
 
                 /* Run the emulator */
                 sig = fpu_emulator_cop1Handler (regs, &current->thread.fpu, 1);
 
-                preempt_disable();
-
-                own_fpu();      /* Using the FPU again.  */
                 /*
                  * We can't allow the emulated instruction to leave any of
                  * the cause bit set in $fcr31.
@@ -649,9 +633,7 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
                 current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X;
 
                 /* Restore the hardware register state */
-                restore_fp(current);
-
-                preempt_enable();
+                own_fpu(1);     /* Using the FPU again.  */
 
                 /* If something went wrong, signal */
                 if (sig)
@@ -775,12 +757,11 @@ 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;
@@ -791,21 +772,30 @@ asmlinkage void do_cpu(struct pt_regs *regs)
                 break;
 
         case 1:
-                preempt_disable();
-
-                own_fpu();
-                if (used_math()) {      /* Using the FPU again.  */
-                        restore_fp(current);
-                } else {                        /* First time FPU user.  */
+                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.  */
                         init_fpu();
                         set_used_math();
                 }
 
-                if (cpu_has_fpu) {
-                        preempt_enable();
+                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 {
                         int sig;
-                        preempt_enable();
                         sig = fpu_emulator_cop1Handler(regs,
                                                 &current->thread.fpu, 0);
                         if (sig)
@@ -1259,26 +1249,26 @@ static inline void mips_srs_init(void)
 /*
  * This is used by native signal handling
  */
-asmlinkage int (*save_fp_context)(struct sigcontext *sc);
-asmlinkage int (*restore_fp_context)(struct sigcontext *sc);
+asmlinkage int (*save_fp_context)(struct sigcontext __user *sc);
+asmlinkage int (*restore_fp_context)(struct sigcontext __user *sc);
 
-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 fpu_emulator_save_context(struct sigcontext *sc);
-extern asmlinkage int fpu_emulator_restore_context(struct sigcontext *sc);
+extern asmlinkage int fpu_emulator_save_context(struct sigcontext __user *sc);
+extern asmlinkage int fpu_emulator_restore_context(struct sigcontext __user *sc);
 
 #ifdef CONFIG_SMP
-static int smp_save_fp_context(struct sigcontext *sc)
+static int smp_save_fp_context(struct sigcontext __user *sc)
 {
-        return cpu_has_fpu
+        return raw_cpu_has_fpu
                ? _save_fp_context(sc)
                : fpu_emulator_save_context(sc);
 }
 
-static int smp_restore_fp_context(struct sigcontext *sc)
+static int smp_restore_fp_context(struct sigcontext __user *sc)
 {
-        return cpu_has_fpu
+        return raw_cpu_has_fpu
                ? _restore_fp_context(sc)
                : fpu_emulator_restore_context(sc);
 }
@@ -1306,14 +1296,14 @@ static inline void signal_init(void)
 /*
  * This is used by 32-bit signal stuff on the 64-bit kernel
  */
-asmlinkage int (*save_fp_context32)(struct sigcontext32 *sc);
-asmlinkage int (*restore_fp_context32)(struct sigcontext32 *sc);
+asmlinkage int (*save_fp_context32)(struct sigcontext32 __user *sc);
+asmlinkage int (*restore_fp_context32)(struct sigcontext32 __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 asmlinkage int fpu_emulator_save_context32(struct sigcontext32 *sc);
-extern asmlinkage int fpu_emulator_restore_context32(struct sigcontext32 *sc);
+extern asmlinkage int fpu_emulator_save_context32(struct sigcontext32 __user *sc);
+extern asmlinkage int fpu_emulator_restore_context32(struct sigcontext32 __user *sc);
 
 static inline void signal32_init(void)
 {