MIPS: Fix ptrace(2) PTRACE_PEEKUSR and PTRACE_POKEUSR accesses to o32 FGRs

BugLink: https://bugs.launchpad.net/bugs/1775771

commit 9a3a92cc upstream.

Check the TIF_32BIT_FPREGS task setting of the tracee rather than the
tracer in determining the layout of floating-point general registers in
the floating-point context, correcting access to odd-numbered registers
for o32 tracees where the setting disagrees between the two processes.

Fixes: 597ce172 ("MIPS: Support for 64-bit FP with O32 binaries")
Signed-off-by: Maciej W. Rozycki <macro@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.14+
Signed-off-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

arch/mips/kernel/ptrace.c

@@ -830,7 +830,7 @@ long arch_ptrace(struct task_struct *child, long request,
 			fregs = get_fpu_regs(child);
 
 #ifdef CONFIG_32BIT
-			if (test_thread_flag(TIF_32BIT_FPREGS)) {
+			if (test_tsk_thread_flag(child, TIF_32BIT_FPREGS)) {
 				/*
 				 * The odd registers are actually the high
 				 * order bits of the values stored in the even
@@ -919,7 +919,7 @@ long arch_ptrace(struct task_struct *child, long request,
 
 			init_fp_ctx(child);
 #ifdef CONFIG_32BIT
-			if (test_thread_flag(TIF_32BIT_FPREGS)) {
+			if (test_tsk_thread_flag(child, TIF_32BIT_FPREGS)) {
 				/*
 				 * The odd registers are actually the high
 				 * order bits of the values stored in the even

arch/mips/kernel/ptrace32.c

@@ -97,7 +97,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 				break;
 			}
 			fregs = get_fpu_regs(child);
-			if (test_thread_flag(TIF_32BIT_FPREGS)) {
+			if (test_tsk_thread_flag(child, TIF_32BIT_FPREGS)) {
 				/*
 				 * The odd registers are actually the high
 				 * order bits of the values stored in the even
@@ -203,7 +203,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 				       sizeof(child->thread.fpu));
 				child->thread.fpu.fcr31 = 0;
 			}
-			if (test_thread_flag(TIF_32BIT_FPREGS)) {
+			if (test_tsk_thread_flag(child, TIF_32BIT_FPREGS)) {
 				/*
 				 * The odd registers are actually the high
 				 * order bits of the values stored in the even