powerpc: Avoid clang warnings around setjmp and longjmp

Commit aea447141c7e ("powerpc: Disable -Wbuiltin-requires-header when
setjmp is used") disabled -Wbuiltin-requires-header because of a
warning about the setjmp and longjmp declarations.

r367387 in clang added another diagnostic around this, complaining
that there is no jmp_buf declaration.

  In file included from ../arch/powerpc/xmon/xmon.c:47:
  ../arch/powerpc/include/asm/setjmp.h:10:13: error: declaration of
  built-in function 'setjmp' requires the declaration of the 'jmp_buf'
  type, commonly provided in the header <setjmp.h>.
  [-Werror,-Wincomplete-setjmp-declaration]
  extern long setjmp(long *);
              ^
  ../arch/powerpc/include/asm/setjmp.h:11:13: error: declaration of
  built-in function 'longjmp' requires the declaration of the 'jmp_buf'
  type, commonly provided in the header <setjmp.h>.
  [-Werror,-Wincomplete-setjmp-declaration]
  extern void longjmp(long *, long);
              ^
  2 errors generated.

We are not using the standard library's longjmp/setjmp implementations
for obvious reasons; make this clear to clang by using -ffreestanding
on these files.

Cc: stable@vger.kernel.org # 4.14+
Suggested-by: Segher Boessenkool <segher@kernel.crashing.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191119045712.39633-3-natechancellor@gmail.com

diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile
index 16c1c5a1951980f0b35ab0a12f0df6eeca350146..378f6108a41469e5bf145a7536daf60923f9f19e 100644 (file)
--- a/arch/powerpc/kexec/Makefile
+++ b/arch/powerpc/kexec/Makefile
@@ -3,8 +3,8 @@
 # Makefile for the linux kernel.
 #
 
-# Disable clang warning for using setjmp without setjmp.h header
-CFLAGS_crash.o         += $(call cc-disable-warning, builtin-requires-header)
+# Avoid clang warnings around longjmp/setjmp declarations
+CFLAGS_crash.o += -ffreestanding
 
 obj-y                          += core.o crash.o core_$(BITS).o
 

diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile
index f142570ad86066ef90b4896d4f478528f4fa4eae..c3842dbeb1b75e568c6548a39a6045810ea54a3a 100644 (file)
--- a/arch/powerpc/xmon/Makefile
+++ b/arch/powerpc/xmon/Makefile
@@ -1,8 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 # Makefile for xmon
 
-# Disable clang warning for using setjmp without setjmp.h header
-subdir-ccflags-y := $(call cc-disable-warning, builtin-requires-header)
+# Avoid clang warnings around longjmp/setjmp declarations
+subdir-ccflags-y := -ffreestanding
 
 GCOV_PROFILE := n
 KCOV_INSTRUMENT := n