1 files changed, 24 insertions, 6 deletions

diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 510452812594..7da6e324dd35 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -46,6 +46,26 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/syscalls.h>
 
+static void init_fp_ctx(struct task_struct *target)
+{
+        /* If FP has been used then the target already has context */
+        if (tsk_used_math(target))
+                return;
+
+        /* Begin with data registers set to all 1s... */
+        memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
+
+        /* ...and FCSR zeroed */
+        target->thread.fpu.fcr31 = 0;
+
+        /*
+         * Record that the target has "used" math, such that the context
+         * just initialised, and any modifications made by the caller,
+         * aren't discarded.
+         */
+        set_stopped_child_used_math(target);
+}
+
 /*
  * Called by kernel/ptrace.c when detaching..
  *
@@ -142,6 +162,7 @@ int ptrace_setfpregs(struct task_struct *child, __u32 __user *data)
         if (!access_ok(VERIFY_READ, data, 33 * 8))
                 return -EIO;
 
+        init_fp_ctx(child);
         fregs = get_fpu_regs(child);
 
         for (i = 0; i < 32; i++) {
@@ -439,6 +460,8 @@ static int fpr_set(struct task_struct *target,
 
         /* XXX fcr31  */
 
+        init_fp_ctx(target);
+
         if (sizeof(target->thread.fpu.fpr[i]) == sizeof(elf_fpreg_t))
                 return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                                           &target->thread.fpu,
@@ -660,12 +683,7 @@ long arch_ptrace(struct task_struct *child, long request,
                 case FPR_BASE ... FPR_BASE + 31: {
                         union fpureg *fregs = get_fpu_regs(child);
 
-                        if (!tsk_used_math(child)) {
-                                /* FP not yet used  */
-                                memset(&child->thread.fpu, ~0,
-                                       sizeof(child->thread.fpu));
-                                child->thread.fpu.fcr31 = 0;
-                        }
+                        init_fp_ctx(child);
 #ifdef CONFIG_32BIT
                         if (test_thread_flag(TIF_32BIT_FPREGS)) {
                                 /*