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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
        Will Deacon <will.deacon@arm.com>
Subject: [PATCH 4.19 015/105] arm64: Clear OSDLR_EL1 on CPU boot
Date:   Mon, 20 May 2019 14:13:21 +0200
Message-Id: <20190520115248.079427103@linuxfoundation.org>
In-Reply-To: <20190520115247.060821231@linuxfoundation.org>
References: <20190520115247.060821231@linuxfoundation.org>
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From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>

commit 6fda41bf12615ee7c3ddac88155099b1a8cf8d00 upstream.

Some firmwares may reboot CPUs with OS Double Lock set. Make sure that
it is unlocked, in order to use debug exceptions.

Cc: <stable@vger.kernel.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/debug-monitors.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -135,6 +135,7 @@ NOKPROBE_SYMBOL(disable_debug_monitors);
  */
 static int clear_os_lock(unsigned int cpu)
 {
+	write_sysreg(0, osdlr_el1);
 	write_sysreg(0, oslar_el1);
 	isb();
 	return 0;