linux-kernel - [PATCH 0/6] arm: don't call addr_limit_user

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Message-ID: <20200720155441.GA13067@lst.de>
Date:   Mon, 20 Jul 2020 17:54:41 +0200
From:   Christoph Hellwig <hch@....de>
To:     Nick Hu <nickhu@...estech.com>, Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-arch@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 0/6] arm: don't call addr_limit_user_check for nommu

On arm nommu kernel use the same constant for USER_DS and KERNEL_DS,
and seqment_eq always returns false.  With the current check in
addr_limit_user_check that works by accident, but when replacing
seqment_eq with uaccess_kerne it will fail.  Just remove the not
needed check entirely.

Signed-off-by: Christoph Hellwig <hch@....de>
Reported-by: Guenter Roeck <linux@...ck-us.net>
---

Andrew: this should preferably go before the other patches in this
series.

 arch/arm/kernel/signal.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index ab2568996ddb0c..c9dc912b83f012 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -713,7 +713,9 @@ struct page *get_signal_page(void)
 /* Defer to generic check */
 asmlinkage void addr_limit_check_failed(void)
 {
+#ifdef CONFIG_MMU
 	addr_limit_user_check();
+#endif
 }
 
 #ifdef CONFIG_DEBUG_RSEQ
-- 
2.27.0