x86: compat_ptrace_request

This adds a compat_ptrace_request that is the analogue of ptrace_request
for the things that 32-on-64 ptrace implementations can share in common.
So far there are just a couple of requests handled generically.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 42 insertions, 0 deletions

diff --git a/include/linux/compat.h b/include/linux/compat.h
index ba29d4c5964..a907fbede6c 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -243,6 +243,10 @@ asmlinkage long compat_sys_migrate_pages(compat_pid_t pid,
                 compat_ulong_t maxnode, const compat_ulong_t __user *old_nodes,
                 const compat_ulong_t __user *new_nodes);
 
+extern int compat_ptrace_request(struct task_struct *child,
+                                 compat_long_t request,
+                                 compat_ulong_t addr, compat_ulong_t data);
+
 /*
  * epoll (fs/eventpoll.c) compat bits follow ...
  */
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index e6a99d2793b..ed1c3d56c2c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -607,3 +607,41 @@ int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
         return (copied == sizeof(data)) ? 0 : -EIO;
 }
+
+#ifdef CONFIG_COMPAT
+#include <linux/compat.h>
+
+int compat_ptrace_request(struct task_struct *child, compat_long_t request,
+                          compat_ulong_t addr, compat_ulong_t data)
+{
+        compat_ulong_t __user *datap = compat_ptr(data);
+        compat_ulong_t word;
+        int ret;
+
+        switch (request) {
+        case PTRACE_PEEKTEXT:
+        case PTRACE_PEEKDATA:
+                ret = access_process_vm(child, addr, &word, sizeof(word), 0);
+                if (ret != sizeof(word))
+                        ret = -EIO;
+                else
+                        ret = put_user(word, datap);
+                break;
+
+        case PTRACE_POKETEXT:
+        case PTRACE_POKEDATA:
+                ret = access_process_vm(child, addr, &data, sizeof(data), 1);
+                ret = (ret != sizeof(data) ? -EIO : 0);
+                break;
+
+        case PTRACE_GETEVENTMSG:
+                ret = put_user((compat_ulong_t) child->ptrace_message, datap);
+                break;
+
+        default:
+                ret = ptrace_request(child, request, addr, data);
+        }
+
+        return ret;
+}
+#endif  /* CONFIG_COMPAT */