powerpc: Add attributes for setjmp/longjmp

commit aa497d4352414aad22e792b35d0aaaa12bbc37c5 upstream.

The setjmp function should be declared as "returns_twice", or bad
things can happen[1]. This does not actually change generated code in
my testing.

The longjmp function should be declared as "noreturn", so that the
compiler can optimise calls to it better. This makes the generated
code a little shorter.

1: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-returns_005ftwice-function-attribute

Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c02ce4a573f3bac907e2c70957a2d1275f910013.1567605586.git.segher@kernel.crashing.org
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/include/asm/setjmp.h b/arch/powerpc/include/asm/setjmp.h
index 279d03a1eec625b12d93632ce7586796835bee97..d930f5607ef251b6af3723bd3dd95fab4d6f8f1e 100644 (file)
--- a/arch/powerpc/include/asm/setjmp.h
+++ b/arch/powerpc/include/asm/setjmp.h
@@ -12,7 +12,7 @@
 
 #define JMP_BUF_LEN    23
 
-extern long setjmp(long *);
-extern void longjmp(long *, long);
+extern long setjmp(long *) __attribute__((returns_twice));
+extern void longjmp(long *, long) __attribute__((noreturn));
 
 #endif /* _ASM_POWERPC_SETJMP_H */