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compiler.h: update definition of unreachable()

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Fixes the objtool warning seen with Clang:
arch/x86/mm/fault.o: warning: objtool: no_context()+0x220: unreachable
instruction

Fixes commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h
mutually exclusive")

Josh noted that the fallback definition was meant to work around a
pre-gcc-4.6 bug. GCC still needs to work around
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365, so compiler-gcc.h
defines its own version of unreachable().  Clang and ICC can use this
shared definition.

Link: https://github.com/ClangBuiltLinux/linux/issues/204
Suggested-by: Andy Lutomirski <luto@amacapital.net>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
This commit is contained in:
ndesaulniers@google.com 2018-10-15 10:22:21 -07:00 committed by Miguel Ojeda
parent f0604f6303
commit fe0640eb30
1 changed files with 4 additions and 1 deletions
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5
include/linux/compiler.h
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@ -124,7 +124,10 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
# define ASM_UNREACHABLE
#endif
#ifndef unreachable
# define unreachable() do { annotate_reachable(); do { } while (1); } while (0)
# define unreachable() do { \
annotate_unreachable(); \
__builtin_unreachable(); \
} while (0)
#endif
/*