Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc

[cascardo/linux.git] / arch / mips / kernel / process.c

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 92880ce..813ed78 100644 (file)
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -73,14 +73,6 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
        regs->regs[29] = sp;
 }
 
-void exit_thread(void)
-{
-}
-
-void flush_thread(void)
-{
-}
-
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
        /*
@@ -353,7 +345,7 @@ static int get_frame_info(struct mips_frame_info *info)
                return 0;
        if (info->pc_offset < 0) /* leaf */
                return 1;
-       /* prologue seems boggus... */
+       /* prologue seems bogus... */
 err:
        return -1;
 }
@@ -455,7 +447,7 @@ unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
                    *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
                        regs = (struct pt_regs *)*sp;
                        pc = regs->cp0_epc;
-                       if (__kernel_text_address(pc)) {
+                       if (!user_mode(regs) && __kernel_text_address(pc)) {
                                *sp = regs->regs[29];
                                *ra = regs->regs[31];
                                return pc;
@@ -580,11 +572,19 @@ int mips_get_process_fp_mode(struct task_struct *task)
        return value;
 }
 
+static void prepare_for_fp_mode_switch(void *info)
+{
+       struct mm_struct *mm = info;
+
+       if (current->mm == mm)
+               lose_fpu(1);
+}
+
 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 {
        const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
-       unsigned long switch_count;
        struct task_struct *t;
+       int max_users;
 
        /* Check the value is valid */
        if (value & ~known_bits)
@@ -601,6 +601,9 @@ int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
        if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6)
                return -EOPNOTSUPP;
 
+       /* Proceed with the mode switch */
+       preempt_disable();
+
        /* Save FP & vector context, then disable FPU & MSA */
        if (task->signal == current->signal)
                lose_fpu(1);
@@ -610,31 +613,17 @@ int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
        smp_mb__after_atomic();
 
        /*
-        * If there are multiple online CPUs then wait until all threads whose
-        * FP mode is about to change have been context switched. This approach
-        * allows us to only worry about whether an FP mode switch is in
-        * progress when FP is first used in a tasks time slice. Pretty much all
-        * of the mode switch overhead can thus be confined to cases where mode
-        * switches are actually occurring. That is, to here. However for the
-        * thread performing the mode switch it may take a while...
+        * If there are multiple online CPUs then force any which are running
+        * threads in this process to lose their FPU context, which they can't
+        * regain until fp_mode_switching is cleared later.
         */
        if (num_online_cpus() > 1) {
-               spin_lock_irq(&task->sighand->siglock);
-
-               for_each_thread(task, t) {
-                       if (t == current)
-                               continue;
+               /* No need to send an IPI for the local CPU */
+               max_users = (task->mm == current->mm) ? 1 : 0;
 
-                       switch_count = t->nvcsw + t->nivcsw;
-
-                       do {
-                               spin_unlock_irq(&task->sighand->siglock);
-                               cond_resched();
-                               spin_lock_irq(&task->sighand->siglock);
-                       } while ((t->nvcsw + t->nivcsw) == switch_count);
-               }
-
-               spin_unlock_irq(&task->sighand->siglock);
+               if (atomic_read(&current->mm->mm_users) > max_users)
+                       smp_call_function(prepare_for_fp_mode_switch,
+                                         (void *)current->mm, 1);
        }
 
        /*
@@ -659,6 +648,7 @@ int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 
        /* Allow threads to use FP again */
        atomic_set(&task->mm->context.fp_mode_switching, 0);
+       preempt_enable();
 
        return 0;
 }