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From:   Will Deacon <will@kernel.org>
To:     gregkh@linuxfoundation.org
Cc:     linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
        "# 4 . 9+" <stable@vger.kernel.org>,
        Aurelien Jarno <aurelien@aurel32.net>,
        Arnd Bergmann <arnd@arndb.de>,
        Dominik Brodowski <linux@dominikbrodowski.net>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Oleg Nesterov <oleg@redhat.com>,
        Catalin Marinas <catalin.marinas@arm.com>
Subject: [PATCH] arm64: compat: Provide definition for COMPAT_SIGMINSTKSZ
Date:   Tue, 30 Jul 2019 10:25:47 +0100
Message-Id: <20190730092547.1284-1-will@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Will Deacon <will.deacon@arm.com>

[ Upstream commit 24951465cbd279f60b1fdc2421b3694405bcff42 ]

arch/arm/ defines a SIGMINSTKSZ of 2k, so we should use the same value
for compat tasks.

Cc: <stable@vger.kernel.org> # 4.9+
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Reported-by: Steve McIntyre <steve.mcintyre@arm.com>
Tested-by: Steve McIntyre <93sam@debian.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---

Aurelien points out that this didn't get selected for -stable despite its
counterpart (22839869f21a ("signal: Introduce COMPAT_SIGMINSTKSZ for use
in compat_sys_sigaltstack")) being backported to 4.9. Oops.

 arch/arm64/include/asm/compat.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h
index 1a037b94eba1..cee28a05ee98 100644
--- a/arch/arm64/include/asm/compat.h
+++ b/arch/arm64/include/asm/compat.h
@@ -159,6 +159,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
 }
 
 #define compat_user_stack_pointer() (user_stack_pointer(task_pt_regs(current)))
+#define COMPAT_MINSIGSTKSZ	2048
 
 static inline void __user *arch_compat_alloc_user_space(long len)
 {
-- 
2.11.0