MIPS: ptrace: Avoid smp_processor_id() when retrieving FPU IR

Whenever ptrace attempts to retrieve the FPU implementation register it
accesses it through current_cpu_data, which calls smp_processor_id().
Since the code may execute with preemption enabled, this can trigger
a warning. Fix this by using boot_cpu_data to get the IR instead.

Signed-off-by: Alex Smith <alex@alex-smith.me.uk>
Cc: <stable@vger.kernel.org> # v3.15+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7449/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 3 insertions, 3 deletions

diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index f639ccd5060c..6063b112a6aa 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -129,7 +129,7 @@ int ptrace_getfpregs(struct task_struct *child, __u32 __user *data)
         }
 
         __put_user(child->thread.fpu.fcr31, data + 64);
-        __put_user(current_cpu_data.fpu_id, data + 65);
+        __put_user(boot_cpu_data.fpu_id, data + 65);
 
         return 0;
 }
@@ -480,7 +480,7 @@ long arch_ptrace(struct task_struct *child, long request,
                         break;
                 case FPC_EIR:
                         /* implementation / version register */
-                        tmp = current_cpu_data.fpu_id;
+                        tmp = boot_cpu_data.fpu_id;
                         break;
                 case DSP_BASE ... DSP_BASE + 5: {
                         dspreg_t *dregs;
diff --git a/arch/mips/kernel/ptrace32.c b/arch/mips/kernel/ptrace32.c
index b40c3ca60ee5..a83fb730b387 100644
--- a/arch/mips/kernel/ptrace32.c
+++ b/arch/mips/kernel/ptrace32.c
@@ -129,7 +129,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                         break;
                 case FPC_EIR:
                         /* implementation / version register */
-                        tmp = current_cpu_data.fpu_id;
+                        tmp = boot_cpu_data.fpu_id;
                         break;
                 case DSP_BASE ... DSP_BASE + 5: {
                         dspreg_t *dregs;