uprobes/x86: Introduce uprobe_xol_ops->abort() and default_abort_op()

arch_uprobe_abort_xol() calls handle_riprel_post_xol() even if
auprobe->ops != default_xol_ops. This is fine correctness wise, only
default_pre_xol_op() can set UPROBE_FIX_RIP_AX|UPROBE_FIX_RIP_CX and
otherwise handle_riprel_post_xol() is nop.

But this doesn't look clean and this doesn't allow us to move ->fixups
into the union in arch_uprobe. Move this handle_riprel_post_xol() call
into the new default_abort_op() hook and change arch_uprobe_abort_xol()
accordingly.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index f4464b1b9435..b3c2a92cce6c 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -394,6 +394,7 @@ struct uprobe_xol_ops {
         bool    (*emulate)(struct arch_uprobe *, struct pt_regs *);
         int     (*pre_xol)(struct arch_uprobe *, struct pt_regs *);
         int     (*post_xol)(struct arch_uprobe *, struct pt_regs *);
+        void    (*abort)(struct arch_uprobe *, struct pt_regs *);
 };
 
 static inline int sizeof_long(void)
@@ -444,9 +445,15 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs
         return 0;
 }
 
+static void default_abort_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+        handle_riprel_post_xol(auprobe, regs, NULL);
+}
+
 static struct uprobe_xol_ops default_xol_ops = {
         .pre_xol  = default_pre_xol_op,
         .post_xol = default_post_xol_op,
+        .abort    = default_abort_op,
 };
 
 static bool branch_is_call(struct arch_uprobe *auprobe)
@@ -820,10 +827,11 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
         struct uprobe_task *utask = current->utask;
 
-        current->thread.trap_nr = utask->autask.saved_trap_nr;
-        handle_riprel_post_xol(auprobe, regs, NULL);
-        instruction_pointer_set(regs, utask->vaddr);
+        if (auprobe->ops->abort)
+                auprobe->ops->abort(auprobe, regs);
 
+        current->thread.trap_nr = utask->autask.saved_trap_nr;
+        regs->ip = utask->vaddr;
         /* clear TF if it was set by us in arch_uprobe_pre_xol() */
         if (!utask->autask.saved_tf)
                 regs->flags &= ~X86_EFLAGS_TF;