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From: Will McVicker <willmcvicker@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: Nathan Chancellor <natechancellor@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Andrei Vagin <avagin@gmail.com>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	kernel-team@android.com, Will McVicker <willmcvicker@google.com>
Subject: [PATCH] arm64: Fix off-by-one vdso trampoline return value
Date: Thu, 12 Nov 2020 00:14:22 +0000	[thread overview]
Message-ID: <20201112001422.340449-1-willmcvicker@google.com> (raw)

Depending on your host nm version, the generated header
`include/generated/vdso32-offsets.h` may have the bottom bit set for the
thumb vdso offset addresses (as observed when using llvm-nm). This
results in an additional +1 for thumb vdso trampoline return values
since compat_setup_return() already includes `vdso_trampoline + thumb`.
As a result, I see a SIGBUS error when running the LTP test
syscalls.rt_sigaction01. To fix this, let's clear the bottom bit of the
vdso_offset in the VDSO_SYMBOL macro.

Test: LTP test syscalls.rt_sigaction01
Fixes: f01703b3d2e6 ("arm64: compat: Get sigreturn trampolines from vDSO")
Signed-off-by: Will McVicker <willmcvicker@google.com>
---
 arch/arm64/include/asm/vdso.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/vdso.h b/arch/arm64/include/asm/vdso.h
index f99dcb94b438..a7384379e8e1 100644
--- a/arch/arm64/include/asm/vdso.h
+++ b/arch/arm64/include/asm/vdso.h
@@ -23,7 +23,7 @@
 
 #define VDSO_SYMBOL(base, name)						   \
 ({									   \
-	(void *)(vdso_offset_##name - VDSO_LBASE + (unsigned long)(base)); \
+	(void *)((vdso_offset_##name & ~1UL) - VDSO_LBASE + (unsigned long)(base)); \
 })
 
 #endif /* !__ASSEMBLY__ */
-- 
2.29.2.299.gdc1121823c-goog


             reply	other threads:[~2020-11-12  1:37 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12  0:14 Will McVicker [this message]
2020-11-12  1:00 ` [PATCH] arm64: Fix off-by-one vdso trampoline return value Nick Desaulniers
2020-11-12  1:07   ` Nick Desaulniers
2020-11-12  2:14   ` Nick Desaulniers
2020-11-12 10:12 ` Will Deacon
2020-11-12 18:51   ` William Mcvicker
2020-11-16 22:55     ` William Mcvicker

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