[PATCH 4.16 34/47] MIPS: ptrace: Fix PTRACE_PEEKUSR requests for 64-bit FGRs

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Maciej W. Rozycki <macro@xxxxxxxx>

commit c7e814628df65f424fe197dde73bfc67e4a244d7 upstream.

Use 64-bit accesses for 64-bit floating-point general registers with
PTRACE_PEEKUSR, removing the truncation of their upper halves in the
FR=1 mode, caused by commit bbd426f542cb ("MIPS: Simplify FP context
access"), which inadvertently switched them to using 32-bit accesses.

The PTRACE_POKEUSR side is fine as it's never been broken and continues
using 64-bit accesses.

Fixes: bbd426f542cb ("MIPS: Simplify FP context access")
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # 3.15+
Patchwork: https://patchwork.linux-mips.org/patch/19334/
Signed-off-by: James Hogan <jhogan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -818,7 +818,7 @@ long arch_ptrace(struct task_struct *chi
 				break;
 			}
 #endif
-			tmp = get_fpr32(&fregs[addr - FPR_BASE], 0);
+			tmp = get_fpr64(&fregs[addr - FPR_BASE], 0);
 			break;
 		case PC:
 			tmp = regs->cp0_epc;
--- a/arch/mips/kernel/ptrace32.c
+++ b/arch/mips/kernel/ptrace32.c
@@ -109,7 +109,7 @@ long compat_arch_ptrace(struct task_stru
 						addr & 1);
 				break;
 			}
-			tmp = get_fpr32(&fregs[addr - FPR_BASE], 0);
+			tmp = get_fpr64(&fregs[addr - FPR_BASE], 0);
 			break;
 		case PC:
 			tmp = regs->cp0_epc;