From mboxrd@z Thu Jan 1 00:00:00 1970 From: lorenzo.pieralisi@arm.com (Lorenzo Pieralisi) Date: Mon, 3 Jul 2017 10:44:39 +0100 Subject: [PATCH] arm64: use readq() instead of readl() to read 64bit entry_point In-Reply-To: <20170626131625.79059-1-luc.vanoostenryck@gmail.com> References: <20170626131625.79059-1-luc.vanoostenryck@gmail.com> Message-ID: <20170703094439.GA19119@red-moon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Jun 26, 2017 at 03:16:25PM +0200, Luc Van Oostenryck wrote: > Here the entrypoint, declared as a 64 bit integer, is read from > a pointer to 64bit integer but the read is done via readl_relaxed() > which is for 32bit quantities. > > All the high bits will thus be lost which change the meaning > of the test against zero done later. > > Fix this by using readq_relaxed() instead as it should be for > 64bit quantities. > > Signed-off-by: Luc Van Oostenryck > > --- > > !!! Warning !!! > I don't have the HW to test this, nor have I read the ACPI specs. > This is only compile tested. > --- > arch/arm64/kernel/acpi_parking_protocol.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Patch is correct but as Mark already mentioned I would like some testing done on systems that rely on the parking protocol (hopefully FW clears the entry point correctly but I want to understand if this patch would trigger regressions that would force us to add quirks around it - even if we know this patch does the right thing from a kernel perspective). Acked-by: Lorenzo Pieralisi > diff --git a/arch/arm64/kernel/acpi_parking_protocol.c b/arch/arm64/kernel/acpi_parking_protocol.c > index 1f5655cd9..f35e80aad 100644 > --- a/arch/arm64/kernel/acpi_parking_protocol.c > +++ b/arch/arm64/kernel/acpi_parking_protocol.c > @@ -125,7 +125,7 @@ static void acpi_parking_protocol_cpu_postboot(void) > struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox; > __le64 entry_point; > > - entry_point = readl_relaxed(&mailbox->entry_point); > + entry_point = readq_relaxed(&mailbox->entry_point); > /* > * Check if firmware has cleared the entry_point as expected > * by the protocol specification. > -- > 2.13.0 >