MIPS: ptrace: Fix user pt_regs definition, use in ptrace_{get, set}regs()

In uapi/asm/ptrace.h, a user version of pt_regs is defined wrapped in
ifndef __KERNEL__. This structure definition does not match anything
used by any kernel API, in particular it does not match the format used
by PTRACE_{GET,SET}REGS.

Therefore, replace the structure definition with one matching what is
used by PTRACE_{GET,SET}REGS. The format used by these is the same for
both 32-bit and 64-bit.

Also, change the implementation of PTRACE_{GET,SET}REGS to use this new
structure definition. The structure is renamed to user_pt_regs when
__KERNEL__ is defined to avoid conflicts with the kernel's own pt_regs.

Signed-off-by: Alex Smith <alex@alex-smith.me.uk>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7457/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/uapi/asm/ptrace.h b/arch/mips/include/uapi/asm/ptrace.h
index b26f7e3..bbcfb8b 100644
--- a/arch/mips/include/uapi/asm/ptrace.h
+++ b/arch/mips/include/uapi/asm/ptrace.h
@@ -22,24 +22,27 @@
 #define DSP_CONTROL	77
 #define ACX		78
 
-#ifndef __KERNEL__
 /*
- * This struct defines the way the registers are stored on the stack during a
- * system call/exception. As usual the registers k0/k1 aren't being saved.
+ * This struct defines the registers as used by PTRACE_{GET,SET}REGS. The
+ * format is the same for both 32- and 64-bit processes. Registers for 32-bit
+ * processes are sign extended.
  */
+#ifdef __KERNEL__
+struct user_pt_regs {
+#else
 struct pt_regs {
+#endif
 	/* Saved main processor registers. */
-	unsigned long regs[32];
+	__u64 regs[32];
 
 	/* Saved special registers. */
-	unsigned long cp0_status;
-	unsigned long hi;
-	unsigned long lo;
-	unsigned long cp0_badvaddr;
-	unsigned long cp0_cause;
-	unsigned long cp0_epc;
+	__u64 lo;
+	__u64 hi;
+	__u64 cp0_epc;
+	__u64 cp0_badvaddr;
+	__u64 cp0_status;
+	__u64 cp0_cause;
 } __attribute__ ((aligned (8)));
-#endif /* __KERNEL__ */
 
 /* Arbitrarily choose the same ptrace numbers as used by the Sparc code. */
 #define PTRACE_GETREGS		12