Messages in this thread Patch in this message | | | Date | Tue, 7 Nov 2017 01:51:56 -0800 | From | tip-bot for Josh Poimboeuf <> | Subject | [tip:core/objtool] objtool: Add a comment for the unreachable annotation macros |
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Commit-ID: d0c2e691d1cbe43662df3a08a4933f13acc352c3 Gitweb: https://git.kernel.org/tip/d0c2e691d1cbe43662df3a08a4933f13acc352c3 Author: Josh Poimboeuf <jpoimboe@redhat.com> AuthorDate: Mon, 6 Nov 2017 07:17:37 -0600 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Tue, 7 Nov 2017 10:48:22 +0100
objtool: Add a comment for the unreachable annotation macros
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> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1570e48d9f87e0fc6f0126c32e7e1de6e109cb67.1509974104.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- include/linux/compiler.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 2027104..f8734fc 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -187,6 +187,11 @@ 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" \
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