ptrace, x86: Add improved regset APIx86/ptrace

3 files changed, 40 insertions, 8 deletions

diff --git a/include/linux/regset.h b/include/linux/regset.h
index 8e0c9febf495f5..8b07102e104a94 100644
--- a/include/linux/regset.h
+++ b/include/linux/regset.h
@@ -195,15 +195,34 @@ struct user_regset_view {
  * implementation is machine-dependent but its interface is universal.
  */
 /**
- * task_user_regset_view - Return the process's native regset view.
+ * task_user_regset_view - Return a guess for the process's regset view.
  * @tsk: a thread of the process in question
  *
- * Return the &struct user_regset_view that is native for the given process.
- * For example, what it would access when it called ptrace().
- * Throughout the life of the process, this only changes at exec.
+ * Return the &struct user_regset_view that is use used by the historically
+ * broken PTRACE_GET/SETREGSET APIs and by core dumps for the given process.
+ *
+ * This function is inherently defective for ptrace(), as there is no way
+ * to ensure that it returns the regset that the caller expects.  For
+ * example, on x86_64, a task's native regset view is always the x86_64
+ * view, but ptrace() has no way to request it.
  */
 const struct user_regset_view *task_user_regset_view(struct task_struct *tsk);
 
+/**
+ * task_machine_regset_view - Return the requested regset view for a process.
+ * @tsk: a thread of the process in question
+ *
+ * Return the requested &struct user_regset_view if valid for the target
+ * task or an error.
+ */
+#ifndef task_get_regset_view
+static inline const struct user_regset_view *
+task_machine_regset_view(task_struct *tsk, u16 e_machine)
+{
+	return ERR_PTR(-EINVAL);
+}
+#endif
+
 
 /*
  * These are helpers for writing regset get/set functions in arch code.
diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index fb810650900029..3b4edc8e6f2c73 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -65,6 +65,17 @@ struct ptrace_peeksiginfo_args {
 #define PTRACE_SETSIGMASK	0x420b
 
 #define PTRACE_SECCOMP_GET_FILTER	0x420c
+#define PTRACE_GETREGSET2	0x420f
+#define PTRACE_SETREGSET2	0x4210
+
+struct ptrace_regset2 {
+	__u64 uptr;		/* pointer to user buffer */
+	__u64 ulen;		/* size of user bufer */
+
+	__u32 e_machine;	/* ELF machine of the requested regset view */
+	__u32 regset_type;	/* regset type within the requested view */
+};
+
 
 /* Read signals from a shared (process wide) queue */
 #define PTRACE_PEEKSIGINFO_SHARED	(1 << 0)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index d49bfa1e53e6b4..e869239209bb05 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -807,10 +807,10 @@ find_regset(const struct user_regset_view *view, unsigned int type)
 	return NULL;
 }
 
-static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
+static int ptrace_regset(struct task_struct *task, int req,
+			 const struct user_regset_view *view, unsigned int type,
 			 struct iovec *kiov)
 {
-	const struct user_regset_view *view = task_user_regset_view(task);
 	const struct user_regset *regset = find_regset(view, type);
 	int regset_no;
 
@@ -1038,7 +1038,8 @@ int ptrace_request(struct task_struct *child, long request,
 		    __get_user(kiov.iov_len, &uiov->iov_len))
 			return -EFAULT;
 
-		ret = ptrace_regset(child, request, addr, &kiov);
+		ret = ptrace_regset(child, request,
+				    task_user_regset_view(child), addr, &kiov);
 		if (!ret)
 			ret = __put_user(kiov.iov_len, &uiov->iov_len);
 		break;
@@ -1207,7 +1208,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 		kiov.iov_base = compat_ptr(ptr);
 		kiov.iov_len = len;
 
-		ret = ptrace_regset(child, request, addr, &kiov);
+		ret = ptrace_regset(child, request,
+				    task_user_regset_view(child), addr, &kiov);
 		if (!ret)
 			ret = __put_user(kiov.iov_len, &uiov->iov_len);
 		break;