arm64: rockchip_defconfig: enable CONFIG_PHY_ROCKCHIP_DP

[firefly-linux-kernel-4.4.55.git] / arch / arm64 / kernel / ftrace.c

diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index c851be795080336938f4826cc0608234b0e34bfa..ebecf9aa33d12da8a564ea0314f59a71b89e64a0 100644 (file)
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -29,12 +29,11 @@ static int ftrace_modify_code(unsigned long pc, u32 old, u32 new,
 
        /*
         * Note:
-        * Due to modules and __init, code can disappear and change,
-        * we need to protect against faulting as well as code changing.
-        * We do this by aarch64_insn_*() which use the probe_kernel_*().
-        *
-        * No lock is held here because all the modifications are run
-        * through stop_machine().
+        * We are paranoid about modifying text, as if a bug were to happen, it
+        * could cause us to read or write to someplace that could cause harm.
+        * Carefully read and modify the code with aarch64_insn_*() which uses
+        * probe_kernel_*(), and make sure what we read is what we expected it
+        * to be before modifying it.
         */
        if (validate) {
                if (aarch64_insn_read((void *)pc, &replaced))
@@ -93,6 +92,11 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
        return ftrace_modify_code(pc, old, new, true);
 }
 
+void arch_ftrace_update_code(int command)
+{
+       ftrace_modify_all_code(command);
+}
+
 int __init ftrace_dyn_arch_init(void)
 {
        return 0;
@@ -125,23 +129,20 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
         * on other archs. It's unlikely on AArch64.
         */
        old = *parent;
-       *parent = return_hooker;
 
        trace.func = self_addr;
        trace.depth = current->curr_ret_stack + 1;
 
        /* Only trace if the calling function expects to */
-       if (!ftrace_graph_entry(&trace)) {
-               *parent = old;
+       if (!ftrace_graph_entry(&trace))
                return;
-       }
 
        err = ftrace_push_return_trace(old, self_addr, &trace.depth,
                                       frame_pointer);
-       if (err == -EBUSY) {
-               *parent = old;
+       if (err == -EBUSY)
                return;
-       }
+       else
+               *parent = return_hooker;
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE