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Diffstat (limited to 'arch/mips/kernel/process.c')
-rw-r--r--arch/mips/kernel/process.c46
1 files changed, 22 insertions, 24 deletions
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index eddd5fd6f..d83730cd2 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -455,7 +455,7 @@ 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 +580,19 @@ 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 +609,9 @@ 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 +621,17 @@ 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 occuring. 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;
-
- switch_count = t->nvcsw + t->nivcsw;
+ /* No need to send an IPI for the local CPU */
+ max_users = (task->mm == current->mm) ? 1 : 0;
- 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 +656,7 @@ 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;
}