| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 10/44] arm64: Clear OSDLR_EL1 on CPU boot | Date | Mon, 20 May 2019 14:13:59 +0200 |
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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 @@ -132,6 +132,7 @@ 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;
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