powerpc/ftrace: Fix nop of modules on 64bit LE (ABIv2)

There is a bug in the handling of the function entry when we are nopping
out a branch from a module in ftrace.

We compare the result of module_trampoline_target() with the value of
ppc_function_entry(), and expect them to be true. But they never will
be.

module_trampoline_target() will always return the global entry point of
the function, whereas ppc_function_entry() will always return the local.

Fix it by using the newly added ppc_global_function_entry().

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index 8fc0c1742498..96efc664b49d 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -105,7 +105,7 @@ __ftrace_make_nop(struct module *mod,
                   struct dyn_ftrace *rec, unsigned long addr)
 {
         unsigned int op;
-        unsigned long ptr;
+        unsigned long entry, ptr;
         unsigned long ip = rec->ip;
         void *tramp;
 
@@ -136,10 +136,11 @@ __ftrace_make_nop(struct module *mod,
 
         pr_devel("trampoline target %lx", ptr);
 
+        entry = ppc_global_function_entry((void *)addr);
         /* This should match what was called */
-        if (ptr != ppc_function_entry((void *)addr)) {
+        if (ptr != entry) {
                 printk(KERN_ERR "addr %lx does not match expected %lx\n",
-                        ptr, ppc_function_entry((void *)addr));
+                        ptr, entry);
                 return -EINVAL;
         }