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>

arch/mips/include/asm/ptrace.h

@@ -47,8 +47,10 @@ struct pt_regs {
 
 struct task_struct;
 
-extern int ptrace_getregs(struct task_struct *child, __s64 __user *data);
-extern int ptrace_setregs(struct task_struct *child, __s64 __user *data);
+extern int ptrace_getregs(struct task_struct *child,
+	struct user_pt_regs __user *data);
+extern int ptrace_setregs(struct task_struct *child,
+	struct user_pt_regs __user *data);
 
 extern int ptrace_getfpregs(struct task_struct *child, __u32 __user *data);
 extern int ptrace_setfpregs(struct task_struct *child, __u32 __user *data);

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

arch/mips/kernel/ptrace.c

@@ -63,7 +63,7 @@ void ptrace_disable(struct task_struct *child)
  * for 32-bit kernels and for 32-bit processes on a 64-bit kernel.
  * Registers are sign extended to fill the available space.
  */
-int ptrace_getregs(struct task_struct *child, __s64 __user *data)
+int ptrace_getregs(struct task_struct *child, struct user_pt_regs __user *data)
 {
 	struct pt_regs *regs;
 	int i;
@@ -74,13 +74,13 @@ int ptrace_getregs(struct task_struct *child, __s64 __user *data)
 	regs = task_pt_regs(child);
 
 	for (i = 0; i < 32; i++)
-		__put_user((long)regs->regs[i], data + i);
-	__put_user((long)regs->lo, data + EF_LO - EF_R0);
-	__put_user((long)regs->hi, data + EF_HI - EF_R0);
-	__put_user((long)regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
-	__put_user((long)regs->cp0_badvaddr, data + EF_CP0_BADVADDR - EF_R0);
-	__put_user((long)regs->cp0_status, data + EF_CP0_STATUS - EF_R0);
-	__put_user((long)regs->cp0_cause, data + EF_CP0_CAUSE - EF_R0);
+		__put_user((long)regs->regs[i], (__s64 __user *)&data->regs[i]);
+	__put_user((long)regs->lo, (__s64 __user *)&data->lo);
+	__put_user((long)regs->hi, (__s64 __user *)&data->hi);
+	__put_user((long)regs->cp0_epc, (__s64 __user *)&data->cp0_epc);
+	__put_user((long)regs->cp0_badvaddr, (__s64 __user *)&data->cp0_badvaddr);
+	__put_user((long)regs->cp0_status, (__s64 __user *)&data->cp0_status);
+	__put_user((long)regs->cp0_cause, (__s64 __user *)&data->cp0_cause);
 
 	return 0;
 }
@@ -90,7 +90,7 @@ int ptrace_getregs(struct task_struct *child, __s64 __user *data)
  * the 64-bit format.  On a 32-bit kernel only the lower order half
  * (according to endianness) will be used.
  */
-int ptrace_setregs(struct task_struct *child, __s64 __user *data)
+int ptrace_setregs(struct task_struct *child, struct user_pt_regs __user *data)
 {
 	struct pt_regs *regs;
 	int i;
@@ -101,10 +101,10 @@ int ptrace_setregs(struct task_struct *child, __s64 __user *data)
 	regs = task_pt_regs(child);
 
 	for (i = 0; i < 32; i++)
-		__get_user(regs->regs[i], data + i);
-	__get_user(regs->lo, data + EF_LO - EF_R0);
-	__get_user(regs->hi, data + EF_HI - EF_R0);
-	__get_user(regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
+		__get_user(regs->regs[i], (__s64 __user *)&data->regs[i]);
+	__get_user(regs->lo, (__s64 __user *)&data->lo);
+	__get_user(regs->hi, (__s64 __user *)&data->hi);
+	__get_user(regs->cp0_epc, (__s64 __user *)&data->cp0_epc);
 
 	/* badvaddr, status, and cause may not be written.  */
 

arch/mips/kernel/ptrace32.c

@@ -256,11 +256,13 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 		}
 
 	case PTRACE_GETREGS:
-		ret = ptrace_getregs(child, (__s64 __user *) (__u64) data);
+		ret = ptrace_getregs(child,
+				(struct user_pt_regs __user *) (__u64) data);
 		break;
 
 	case PTRACE_SETREGS:
-		ret = ptrace_setregs(child, (__s64 __user *) (__u64) data);
+		ret = ptrace_setregs(child,
+				(struct user_pt_regs __user *) (__u64) data);
 		break;
 
 	case PTRACE_GETFPREGS: