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>

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 4e33a35..0ba4cfb 100644 (file)
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -681,7 +681,6 @@ static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
                        continue;
 
                if (auprobe->insn[i] == 0x90) {
-                       regs->ip = uprobe_get_swbp_addr(regs);
                        regs->ip += i + 1;
                        return true;
                }

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 04c104a..f1b8078 100644 (file)
--- 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);
 }

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index e668024..17d9b2b 100644 (file)
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -492,7 +492,7 @@ static void uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
                return;
 
        entry = ring_buffer_event_data(event);
-       entry->ip = uprobe_get_swbp_addr(task_pt_regs(current));
+       entry->ip = instruction_pointer(task_pt_regs(current));
        data = (u8 *)&entry[1];
        for (i = 0; i < tu->nr_args; i++)
                call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
@@ -667,7 +667,7 @@ static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
        if (!entry)
                goto out;
 
-       entry->ip = uprobe_get_swbp_addr(task_pt_regs(current));
+       entry->ip = instruction_pointer(task_pt_regs(current));
        data = (u8 *)&entry[1];
        for (i = 0; i < tu->nr_args; i++)
                call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);