From: Nick Desaulniers <ndesaulniers@google.com>
To: unlisted-recipients:; (no To-header on input)
Cc: zijun_hu@htc.com, akpm@linux-foundation.org,
ghackmann@google.com, dianders@chromium.org, srhines@google.com,
pirama@google.com, Nick Desaulniers <ndesaulniers@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Laura Abbott <labbott@redhat.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com>,
Alexander Popov <alex.popov@linux.com>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] arm64: avoid overflow in VA_START and PAGE_OFFSET
Date: Thu, 3 Aug 2017 10:11:16 -0700 [thread overview]
Message-ID: <20170803171117.107992-1-ndesaulniers@google.com> (raw)
In-Reply-To: <20170803132035.gixd7m7oxtehpquu@yury-thinkpad>
The bitmask used to define these values produces overflow, as seen by
this compiler warning:
arch/arm64/kernel/head.S:47:8: warning:
integer overflow in preprocessor expression
#elif (PAGE_OFFSET & 0x1fffff) != 0
^~~~~~~~~~~
arch/arm64/include/asm/memory.h:52:46: note:
expanded from macro 'PAGE_OFFSET'
#define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS -
1))
~~~~~~~~~~~~~~~~~~ ^
It would be preferrable to use GENMASK_ULL() instead, but it's not set
up to be used from assembly (the UL() macro token pastes UL suffixes
when not included in assembly sources).
Suggested-by: Yury Norov <ynorov@caviumnetworks.com>
Suggested-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/arm64/include/asm/memory.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 32f82723338a..dde717a31dee 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -64,8 +64,9 @@
* TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.
*/
#define VA_BITS (CONFIG_ARM64_VA_BITS)
-#define VA_START (UL(0xffffffffffffffff) << VA_BITS)
-#define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
+#define VA_START ((UL(0xffffffffffffffff) >> VA_BITS) << VA_BITS)
+#define PAGE_OFFSET ((UL(0xffffffffffffffff) >> (VA_BITS - 1)) \
+ << (VA_BITS - 1))
#define KIMAGE_VADDR (MODULES_END)
#define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
#define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE)
--
2.14.0.rc1.383.gd1ce394fe2-goog
next prev parent reply other threads:[~2017-08-03 17:11 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-02 22:51 [PATCH 1/2] bitops: Avoid integer overflow warning in GENMASK_ULL Matthias Kaehlcke
2017-08-02 22:51 ` [PATCH 2/2] arm64: Define PAGE_OFFSET using GENMASK_ULL Matthias Kaehlcke
2017-08-02 23:13 ` Nick Desaulniers
2017-08-02 23:19 ` Nick Desaulniers
2017-08-02 23:44 ` Matthias Kaehlcke
2017-08-03 13:20 ` Yury Norov
2017-08-03 17:11 ` Nick Desaulniers [this message]
2017-08-03 17:20 ` [PATCH] arm64: avoid overflow in VA_START and PAGE_OFFSET Ard Biesheuvel
2017-08-03 17:53 ` Nick Desaulniers
2017-08-03 18:03 ` [PATCH v2] " Nick Desaulniers
2017-08-04 2:26 ` [PATCH 2/2] arm64: Define PAGE_OFFSET using GENMASK_ULL kbuild test robot
2017-08-03 13:24 ` [PATCH 1/2] bitops: Avoid integer overflow warning in GENMASK_ULL Yury Norov
2017-08-03 17:03 ` Matthias Kaehlcke
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