tree 04bad7718ceab3cf4a6f6479a0295f4bfedab8e7
parent dfc382a19a2478768ef09d1c745b116e4fca9b4e
author Michael Ellerman <mpe@ellerman.id.au> 1402985734 +1000
committer Benjamin Herrenschmidt <benh@kernel.crashing.org> 1403582741 +1000

powerpc/ftrace: Fix inverted check of create_branch()

In commit 24a1bdc35, "Fix ABIv2 issues with __ftrace_make_call", Anton
changed the logic that creates and patches the branch, and added a
thinko in the check of create_branch(). create_branch() returns the
instruction that was generated, so if we get zero then it succeeded.

The result is we can't ftrace modules:

  Branch out of range
  WARNING: at ../kernel/trace/ftrace.c:1638
  ftrace failed to modify [<d000000004ba001c>] fuse_req_init_context+0x1c/0x90 [fuse]

We should probably fix patch_instruction() to do that check and make the
API saner, but that's a separate patch. For now just invert the test.

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