[PATCH] x86/boot: Add -Wno-pointer-sign to KBUILD_CFLAGS

* [PATCH] x86/boot: Add -Wno-pointer-sign to KBUILD_CFLAGS
@ 2018-10-13  1:07 Nathan Chancellor
  2018-10-14  9:18 ` [tip:x86/urgent] " tip-bot for Nathan Chancellor
  0 siblings, 1 reply; 2+ messages in thread
From: Nathan Chancellor @ 2018-10-13  1:07 UTC (permalink / raw)
  To: Thomas Gleixner, Ingo Molnar, Borislav Petkov
  Cc: H. Peter Anvin, x86, linux-kernel, Nick Desaulniers, Nathan Chancellor

When compiling the kernel with Clang, this warning appears even though
it is disabled for the whole kernel because this folder has its own set
of KBUILD_CFLAGS. It was disabled before the beginning of git history.

In file included from arch/x86/boot/compressed/kaslr.c:29:
In file included from arch/x86/boot/compressed/misc.h:21:
In file included from ./include/linux/elf.h:5:
In file included from ./arch/x86/include/asm/elf.h:77:
In file included from ./arch/x86/include/asm/vdso.h:11:
In file included from ./include/linux/mm_types.h:9:
In file included from ./include/linux/spinlock.h:88:
In file included from ./arch/x86/include/asm/spinlock.h:43:
In file included from ./arch/x86/include/asm/qrwlock.h:6:
./include/asm-generic/qrwlock.h:101:53: warning: passing 'u32 *' (aka
'unsigned int *') to parameter of type 'int *' converts between pointers
to integer types with different sign [-Wpointer-sign]
        if (likely(atomic_try_cmpxchg_acquire(&lock->cnts, &cnts, _QW_LOCKED)))
                                                           ^~~~~
./include/linux/compiler.h:76:40: note: expanded from macro 'likely'
# define likely(x)      __builtin_expect(!!(x), 1)
                                            ^
./include/asm-generic/atomic-instrumented.h:69:66: note: passing
argument to parameter 'old' here
static __always_inline bool atomic_try_cmpxchg(atomic_t *v, int *old, int new)
                                                                 ^

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---

There has been some discussion around whether KBUILD_CFLAGS should be
overwritten in the folder (few examples linked below). In the meantime,
there is precedent for taking top level disabled warnings and adding
them here, thus this patch.

* https://lore.kernel.org/lkml/CAKwvOdmXcztP542kADhyJYN2=Fk3qyXif_MCs=kqPGE8QtTjvQ@mail.gmail.com/
* https://lore.kernel.org/lkml/56442061-7f55-878d-5b26-7cdd14e901d2@zytor.com/

 arch/x86/boot/compressed/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 28764dacf018..466f66c8a7f8 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -37,6 +37,7 @@ KBUILD_CFLAGS += $(call cc-option,-ffreestanding)
 KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
 KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
 KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
+KBUILD_CFLAGS += -Wno-pointer-sign
 
 KBUILD_AFLAGS  := $(KBUILD_CFLAGS) -D__ASSEMBLY__
 GCOV_PROFILE := n
-- 
2.19.1


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