linux-kernel - [PATCH v3 3/5] arm64: vdso32: Fix compilation warning

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Date:   Thu, 26 Sep 2019 22:43:40 +0100
From:   Vincenzo Frascino <vincenzo.frascino@....com>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     vincenzo.frascino@....com, ard.biesheuvel@...aro.org,
        ndesaulniers@...gle.com, catalin.marinas@....com, will@...nel.org,
        tglx@...utronix.de
Subject: [PATCH v3 3/5] arm64: vdso32: Fix compilation warning

As reported by Will Deacon the following compilation warning appears
during the compilation of the vdso32:

In file included from ./arch/arm64/include/asm/thread_info.h:17:0,
                 from ./include/linux/thread_info.h:38,
                 from ./arch/arm64/include/asm/preempt.h:5,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:51,
                 from ./include/linux/seqlock.h:36,
                 from ./include/linux/time.h:6,
                 from .../work/linux/lib/vdso/gettimeofday.c:7,
                 from <command-line>:0:
./arch/arm64/include/asm/memory.h: In function ‘__tag_set’:
./arch/arm64/include/asm/memory.h:233:15: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]
  u64 __addr = (u64)addr & ~__tag_shifted(0xff);
               ^
In file included from ./arch/arm64/include/asm/pgtable-hwdef.h:8:0,
                 from ./arch/arm64/include/asm/processor.h:34,
                 from ./arch/arm64/include/asm/elf.h:118,
                 from ./include/linux/elf.h:5,
                 from ./include/linux/elfnote.h:62,
                 from arch/arm64/kernel/vdso32/note.c:11:
./arch/arm64/include/asm/memory.h: In function ‘__tag_set’:
./arch/arm64/include/asm/memory.h:233:15: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]
  u64 __addr = (u64)addr & ~__tag_shifted(0xff);
               ^

This happens because few 64 bit compilation headers are included during
the generation of vdso32.

Fix the issue redefining the __tag_set function.

Note: This fix is meant to be temporary, a more comprehensive solution
based on the refactoring of the generic headers will be provided with a
future patch set. At that point it will be possible to revert this patch.

Cc: Will Deacon <will@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
---
 arch/arm64/include/asm/memory.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index b61b50bf68b1..c61b2eb50a3b 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -228,11 +228,14 @@ static inline unsigned long kaslr_offset(void)
 #define __tag_get(addr)		0
 #endif /* CONFIG_KASAN_SW_TAGS */
 
+#ifdef __aarch64__
+/* Do not attempt to compile this code with compat vdso */
 static inline const void *__tag_set(const void *addr, u8 tag)
 {
 	u64 __addr = (u64)addr & ~__tag_shifted(0xff);
 	return (const void *)(__addr | __tag_shifted(tag));
 }
+#endif
 
 /*
  * Physical vs virtual RAM address space conversion.  These are
-- 
2.23.0