[PATCH 5.3 168/180] powerpc: Avoid clang warnings around setjmp and longjmp

[Greg Kroah-Hartman]

From: Nathan Chancellor <natechancellor@xxxxxxxxx>

[ Upstream commit c9029ef9c95765e7b63c4d9aa780674447db1ec0 ]

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@xxxxxxxxxxxxxxx # 4.14+
Suggested-by: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191119045712.39633-3-natechancellor@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/powerpc/kernel/Makefile | 4 ++--
 arch/powerpc/xmon/Makefile   | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 56dfa7a2a6f2a..61527f1d4d05b 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -5,8 +5,8 @@
 
 CFLAGS_ptrace.o		+= -DUTS_MACHINE='"$(UTS_MACHINE)"'
 
-# 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
 
 ifdef CONFIG_PPC64
 CFLAGS_prom_init.o	+= $(NO_MINIMAL_TOC)
diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile
index f142570ad8606..c3842dbeb1b75 100644
--- 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
-- 
2.20.1