compiler.h: update definition of unreachable()

fe0640eb · [email protected] <[email protected]> · 2018-10-15 10:22:21 -07:00

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 <[email protected]>
Suggested-by: Josh Poimboeuf <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Signed-off-by: Nick Desaulniers <[email protected]>
Signed-off-by: Miguel Ojeda <[email protected]>

Commit: fe0640eb30b7da261ae84d252ed9ed3c7e68dfd8
Parents: f0604f63

Changes

1 files changed · +4 −1

File	Status	Add	Del	Content
include/linux/compiler.h	modified	+4	−1	View file

include/linux/compiler.h

View file

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index b5fb034..2e0b632 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -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
 
 /*