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From:   Vincenzo Frascino <vincenzo.frascino@arm.com>
To:     linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
        linux-kselftest@vger.kernel.org
Cc:     catalin.marinas@arm.com, will.deacon@arm.com, arnd@arndb.de,
        linux@armlinux.org.uk, ralf@linux-mips.org, paul.burton@mips.com,
        daniel.lezcano@linaro.org, tglx@linutronix.de, salyzyn@android.com,
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        sthotton@marvell.com, andre.przywara@arm.com, luto@kernel.org,
        john.stultz@linaro.org
Subject: [PATCH] arm64: vdso: Fix ABI regression in compat vdso
Date:   Wed, 10 Jul 2019 14:04:52 +0100
Message-Id: <20190710130452.44111-1-vincenzo.frascino@arm.com>
In-Reply-To: <20190621095252.32307-11-vincenzo.frascino@arm.com>
References: <20190621095252.32307-11-vincenzo.frascino@arm.com>
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Prior to the introduction of Unified vDSO support and compat layer for
vDSO on arm64, AT_SYSINFO_EHDR was not defined for compat tasks.
In the current implementation, AT_SYSINFO_EHDR is defined even if the
compat vdso layer is not built and this causes a regression in the
expected behavior of the ABI.

Restore the ABI behavior making sure that AT_SYSINFO_EHDR for compat
tasks is defined only when CONFIG_GENERIC_COMPAT_VDSO and
CONFIG_COMPAT_VDSO are enabled.

Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/include/asm/elf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 3c7037c6ba9b..b7992bb9d414 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -202,7 +202,7 @@ typedef compat_elf_greg_t		compat_elf_gregset_t[COMPAT_ELF_NGREG];
 ({									\
 	set_thread_flag(TIF_32BIT);					\
  })
-#ifdef CONFIG_GENERIC_COMPAT_VDSO
+#if defined(CONFIG_COMPAT_VDSO) && defined(CONFIG_GENERIC_COMPAT_VDSO)
 #define COMPAT_ARCH_DLINFO						\
 do {									\
 	/*								\
-- 
2.22.0