FAILED: patch "[PATCH] powerpc: Avoid clang warnings around setjmp and longjmp" failed to apply to 5.4-stable tree

FAILED: patch "[PATCH] powerpc: Avoid clang warnings around setjmp and longjmp" failed to apply to 5.4-stable tree

[gregkh]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c9029ef9c95765e7b63c4d9aa780674447db1ec0 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <natechancellor@gmail.com>
Date: Mon, 18 Nov 2019 21:57:11 -0700
Subject: [PATCH] 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 16c1c5a19519..378f6108a414 100644
--- 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 f142570ad860..c3842dbeb1b7 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

Re: FAILED: patch "[PATCH] powerpc: Avoid clang warnings around setjmp and longjmp" failed to apply to 5.4-stable tree

[Sasha Levin]

On Sun, Dec 15, 2019 at 06:11:28PM +0100, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 5.4-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From c9029ef9c95765e7b63c4d9aa780674447db1ec0 Mon Sep 17 00:00:00 2001
>From: Nathan Chancellor <natechancellor@gmail.com>
>Date: Mon, 18 Nov 2019 21:57:11 -0700
>Subject: [PATCH] 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

Adjusted for code movement in 793b08e2efff ("powerpc/kexec: Move kexec
files into a dedicated subdir.") and queued for 5.4-4.14.

-- 
Thanks,
Sasha