Messages in this thread | | | From | Peng Fan <> | Subject | RE: [PATCH] arm: l2c: unlock ways when in non-secure mode | Date | Mon, 27 Nov 2017 09:43:41 +0000 |
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Hi Russell,
> -----Original Message----- > From: Russell King - ARM Linux [mailto:linux@armlinux.org.uk] > Sent: Monday, November 27, 2017 5:20 PM > To: Peng Fan <peng.fan@nxp.com> > Cc: linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; > van.freenix@gmail.com; Mark Rutland <mark.rutland@arm.com>; Thomas > Gleixner <tglx@linutronix.de>; Chris Brandt <chris.brandt@renesas.com>; Will > Deacon <will.deacon@arm.com> > Subject: Re: [PATCH] arm: l2c: unlock ways when in non-secure mode > > On Sun, Nov 26, 2017 at 11:56:10PM +0000, Peng Fan wrote: > > Hi Russell, > > > > > Subject: Re: [PATCH] arm: l2c: unlock ways when in non-secure mode > > > > > > On Sun, Nov 26, 2017 at 08:25:30PM +0800, Peng Fan wrote: > > > > To boot Linux in Non-secure mode with l2x0, the l2x0 controller is > > > > enabled in secure mode and ways locked to make it seems L2 cache > > > > disabled during linux boot process. So during l2x0 initialization, > > > > need to unlock the ways to make l2x0 could cache data/inst. > > > > > > Why was this chosen instead of doing what everyone else does? > > > > I am not aware of how other platform handles the l2x0 unlock in non > > secure mode. Could you please share with me what others choose? > > That's not what I was asking. > > Everyone else provides a way for the l2x0 controller to be enabled and disabled > from non-secure mode.
Thanks for the information. I see that some platforms implements l2c_write_sec.
> > Why have you decided to enable the l2x0 controller and leave it enabled, and > then lock down all the cache ways - which means you need the kernel to do > something entirely different for your platform.
Currently we are running OP-TEE on i.MX6/7 with Linux in non-secure mode. See In https://github.com/OP-TEE/optee_os/blob/master/core/arch/arm/kernel/generic_entry_a32.S#L428 Pl310 is enabled. And In https://github.com/OP-TEE/optee_os/blob/master/core/arch/arm/kernel/generic_entry_a32.S#L461 pl310 locked before returning back to Linux.
I see ti platform not enabled pl310 in OP-TEE, leaving Linux to enable it. platform-sam/stm/ zynq7k/imx Have pl310 enabled in OP-TEE.
I could switch to use l2c_write_sec dedicated for i.MX. But I think this patch is also a valid point. What do you suggest?
Thanks, Peng.
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