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From:   Pi-Hsun Shih <pihsun@chromium.org>
Cc:     Pi-Hsun Shih <pihsun@chromium.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Dominik Brodowski <linux@dominikbrodowski.net>,
        Dave Martin <dave.martin@arm.com>,
        linux-arm-kernel@lists.infradead.org (moderated list:ARM64 PORT
        (AARCH64 ARCHITECTURE)), linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] arm64: Mirror arm for small unimplemented compat syscalls
Date:   Thu,  3 Jan 2019 15:45:47 +0800
Message-Id: <20190103074550.217421-1-pihsun@chromium.org>
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Sender: linux-kernel-owner@vger.kernel.org
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For syscall number smaller than 0xf0000, arm calls sys_ni_syscall
instead of arm_syscall in arch/arm/kernel/entry-common.S, which returns
-ENOSYS instead of raising SIGILL. Mirror this behavior for compat
syscalls in arm64.

Fixes: 532826f3712b607 ("arm64: Mirror arm for unimplemented compat
syscalls")
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
---
 arch/arm64/kernel/syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index 8f3371415642ad..95fd8c7ec8a171 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -21,7 +21,7 @@ asmlinkage long do_ni_syscall(struct pt_regs *regs)
 {
 #ifdef CONFIG_COMPAT
 	long ret;
-	if (is_compat_task()) {
+	if (is_compat_task() && regs->regs[7] >= __ARM_NR_COMPAT_BASE) {
 		ret = compat_arm_syscall(regs);
 		if (ret != -ENOSYS)
 			return ret;
-- 
2.20.1.415.g653613c723-goog