uprobes/x86: Introduce push_ret_address()

Extract the "push return address" code from branch_emulate_op() into
the new simple helper, push_ret_address(). It will have more users.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index a8e1d7e47001..df75913acfc0 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -407,6 +407,17 @@ static int default_pre_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
         return 0;
 }
 
+static int push_ret_address(struct pt_regs *regs, unsigned long ip)
+{
+        unsigned long new_sp = regs->sp - sizeof_long();
+
+        if (copy_to_user((void __user *)new_sp, &ip, sizeof_long()))
+                return -EFAULT;
+
+        regs->sp = new_sp;
+        return 0;
+}
+
 /*
  * Adjust the return address pushed by a call insn executed out of line.
  */
@@ -517,7 +528,6 @@ static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
         unsigned long offs = (long)auprobe->branch.offs;
 
         if (branch_is_call(auprobe)) {
-                unsigned long new_sp = regs->sp - sizeof_long();
                 /*
                  * If it fails we execute this (mangled, see the comment in
                  * branch_clear_offset) insn out-of-line. In the likely case
@@ -527,9 +537,8 @@ static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
                  *
                  * But there is corner case, see the comment in ->post_xol().
                  */
-                if (copy_to_user((void __user *)new_sp, &new_ip, sizeof_long()))
+                if (push_ret_address(regs, new_ip))
                         return false;
-                regs->sp = new_sp;
         } else if (!check_jmp_cond(auprobe, regs)) {
                 offs = 0;
         }