4.9-stable patches

[thirdparty/kernel/stable-queue.git] / releases / 3.16.3 / mips-ptrace-avoid-smp_processor_id-when-retrieving-fpu-ir.patch

From 656ff9bef08c19a6471b49528dacb4cbbeb1e537 Mon Sep 17 00:00:00 2001
From: Alex Smith <alex@alex-smith.me.uk>
Date: Wed, 23 Jul 2014 14:40:06 +0100
Subject: MIPS: ptrace: Avoid smp_processor_id() when retrieving FPU IR

From: Alex Smith <alex@alex-smith.me.uk>

commit 656ff9bef08c19a6471b49528dacb4cbbeb1e537 upstream.

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: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7449/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/kernel/ptrace.c   |    4 ++--
 arch/mips/kernel/ptrace32.c |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -129,7 +129,7 @@ int ptrace_getfpregs(struct task_struct
 	}
 
 	__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;
 }
@@ -611,7 +611,7 @@ long arch_ptrace(struct task_struct *chi
 			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;
--- a/arch/mips/kernel/ptrace32.c
+++ b/arch/mips/kernel/ptrace32.c
@@ -129,7 +129,7 @@ long compat_arch_ptrace(struct task_stru
 			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;