uprobes: Change handle_swbp() to expose bp_vaddr to handler_chain()

Change handle_swbp() to set regs->ip = bp_vaddr in advance, this is
what consumer->handler() needs but uprobe_get_swbp_addr() is not
exported.

This also simplifies the code and makes it more consistent across
the supported architectures. handle_swbp() becomes the only caller
of uprobe_get_swbp_addr().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

1 files changed, 7 insertions, 8 deletions

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 04c104ad9522..f1b807831fc2 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1504,6 +1504,10 @@ static void handle_swbp(struct pt_regs *regs)
                 }
                 return;
         }
+
+        /* change it in advance for ->handler() and restart */
+        instruction_pointer_set(regs, bp_vaddr);
+
         /*
          * TODO: move copy_insn/etc into _register and remove this hack.
          * After we hit the bp, _unregister + _register can install the
@@ -1511,14 +1515,14 @@ static void handle_swbp(struct pt_regs *regs)
          */
         smp_rmb(); /* pairs with wmb() in install_breakpoint() */
         if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
-                goto restart;
+                goto out;
 
         utask = current->utask;
         if (!utask) {
                 utask = add_utask();
                 /* Cannot allocate; re-execute the instruction. */
                 if (!utask)
-                        goto restart;
+                        goto out;
         }
 
         handler_chain(uprobe, regs);
@@ -1531,12 +1535,7 @@ static void handle_swbp(struct pt_regs *regs)
                 return;
         }
 
-restart:
-        /*
-         * cannot singlestep; cannot skip instruction;
-         * re-execute the instruction.
-         */
-        instruction_pointer_set(regs, bp_vaddr);
+        /* can_skip_sstep() succeeded, or restart if can't singlestep */
 out:
         put_uprobe(uprobe);
 }