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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2018-01-23 05:07:46 +0100 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-01-23 19:24:19 +0100 |
| commit | e2ac83d74a4d753cea88407e65136c84a0cb60b2 (patch) | |
| tree | 2ccc7c642996b201c6f4f6e908a05879f695ac82 /arch/x86/kernel/Makefile | |
| parent | Linux 4.15-rc9 (diff) | |
| download | linux-e2ac83d74a4d753cea88407e65136c84a0cb60b2.tar.xz linux-e2ac83d74a4d753cea88407e65136c84a0cb60b2.zip | |
x86/ftrace: Fix ORC unwinding from ftrace handlers
Steven Rostedt discovered that the ftrace stack tracer is broken when
it's used with the ORC unwinder. The problem is that objtool is
instructed by the Makefile to ignore the ftrace_64.S code, so it doesn't
generate any ORC data for it.
Fix it by making the asm code objtool-friendly:
- Objtool doesn't like the fact that save_mcount_regs pushes RBP at the
beginning, but it's never restored (directly, at least). So just skip
the original RBP push, which is only needed for frame pointers anyway.
- Annotate some functions as normal callable functions with
ENTRY/ENDPROC.
- Add an empty unwind hint to return_to_handler(). The return address
isn't on the stack, so there's nothing ORC can do there. It will just
punt in the unlikely case it tries to unwind from that code.
With all that fixed, remove the OBJECT_FILES_NON_STANDARD Makefile
annotation so objtool can read the file.
Link: http://lkml.kernel.org/r/20180123040746.ih4ep3tk4pbjvg7c@treble
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'arch/x86/kernel/Makefile')
| -rw-r--r-- | arch/x86/kernel/Makefile | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 81bb565f4497..7e2baf7304ae 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -29,10 +29,13 @@ KASAN_SANITIZE_stacktrace.o := n KASAN_SANITIZE_paravirt.o := n OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o := y -OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y OBJECT_FILES_NON_STANDARD_test_nx.o := y OBJECT_FILES_NON_STANDARD_paravirt_patch_$(BITS).o := y +ifdef CONFIG_FRAME_POINTER +OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y +endif + # If instrumentation of this dir is enabled, boot hangs during first second. # Probably could be more selective here, but note that files related to irqs, # boot, dumpstack/stacktrace, etc are either non-interesting or can lead to |