Messages in this thread Patch in this message | | | From | Josh Poimboeuf <> | Subject | [PATCH 1/2] objtool: Add a comment for the unreachable annotation macros | Date | Mon, 6 Nov 2017 07:17:37 -0600 |
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Add a comment for the unreachable annotation macros to explain their purpose and the '__COUNTER__' label hack.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> --- include/linux/compiler.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 3672353a0acd..b863e5ad91a3 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -88,6 +88,11 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, /* Unreachable code */ #ifdef CONFIG_STACK_VALIDATION +/* + * These macros help objtool understand GCC code flow for unreachable code. + * The __COUNTER__ based labels are a hack to make each instance of the macros + * unique, to convince GCC not to merge duplicate inline asm statements. + */ #define annotate_reachable() ({ \ asm("%c0:\n\t" \ ".pushsection .discard.reachable\n\t" \ -- 2.13.6
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