(EXT) RE: [RFC PATCH] PCI: imx6: Handle the abort from user-space

[Alexander Stein]

Am Freitag, 28. Januar 2022, 10:25:11 CET schrieb Hongxing Zhu:
> > -----Original Message-----
> > From: Francesco Dolcini <francesco.dolcini at toradex.com>
> > Sent: 2022年1月28日 16:29
> > To: Hongxing Zhu <hongxing.zhu at nxp.com>; Lucas Stach
> > <l.stach at pengutronix.de>; Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>;
> > Rob
 Herring <robh at kernel.org>; Krzysztof Wilczyński <kw at linux.com>;
> > Sascha Hauer <s.hauer at pengutronix.de>; Pengutronix Kernel Team
> > <kernel at pengutronix.de>; Fabio Estevam <festevam at gmail.com>;
> > dl-linux-imx <linux-imx at nxp.com>; Jason Liu <jason.hui.liu at nxp.com>
> > Cc: linux-pci at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> > linux-kernel at vger.kernel.org; Bjorn Helgaas <bhelgaas at google.com>; Shawn
> > Guo <shawnguo at kernel.org>; Francesco Dolcini
> > <francesco.dolcini at toradex.com>
> > Subject: [RFC PATCH] PCI: imx6: Handle the abort from user-space
> > 
> > From: Jason Liu <jason.hui.liu at nxp.com>
> > 
> > The driver install one hook to handle the external abort, but issue is
> > that if the
 abort introduced from user space code, the following code
> > unsigned long instr = *(unsigned long *)pc; which will created another
> > data-abort(page domain fault) if CONFIG_CPU_SW_DOMAIN_PAN.
> > 
> > The patch does not intent to use copy_from_user and then do the hack due
> > to
 the security consideration. In fact, we can just return and report
> > the external abort to user-space.
> > 
> > Signed-off-by: Jason Liu <jason.hui.liu at nxp.com>
> > Reviewed-by: Richard Zhu <hongxing.zhu at nxp.com>
> > Signed-off-by: Francesco Dolcini <francesco.dolcini at toradex.com>
> > ---
> > We have this patch from NXP downstream kernel [1] in our kernel branch
> > [2]
> > since a long time, to me it would make sense to upstream it. Any concern?
> > 
> > [1]
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsource.
> > codeaurora.org%2Fexternal%2Fimxsupport%2Flinux-imx%2Fcommit%2F%3Fid
> > %3D62dfb2fb953463dd1b6710567c9e174672a98f24&data=04%7C01%7
> > Chongxing.zhu%40nxp.com%7Ccbe193ab4c3e4ad11bcb08d9e2384a1f%7C68
> > 6ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637789553659549198%7
> > CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBT
> > iI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=Mwhx8DFF7EDJdpqTsHT
> > %2BBAGzhQadDOqcgJnVjeoi1yk%3D&reserved=0
> > [2]
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.tora
> > 
> > dex.com%2Fcgit%2Flinux-toradex.git%2Fcommit%2F%3Fid%3D2b42547cf659f
> > 979be2defdff6a99f921b33d0f1&data=04%7C01%7Chongxing.zhu%40nx
> > p.com%7Ccbe193ab4c3e4ad11bcb08d9e2384a1f%7C686ea1d3bc2b4c6fa92c
> > d99c5c301635%7C0%7C0%7C637789553659549198%7CUnknown%7CTWFp
> > bGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI
> > 6Mn0%3D%7C3000&sdata=QEW1frh8WacCzniWo4ng1cy3Z1UZ9uMRFw
> > GBKuIh7zE%3D&reserved=0
> > ---
> > 
> >  drivers/pci/controller/dwc/pci-imx6.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > 
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 6974bd5aa116..6b178a29e253 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -27,6 +27,7 @@
> > 
> >  #include <linux/resource.h>
> >  #include <linux/signal.h>
> >  #include <linux/types.h>
> > 
> > +#include <linux/uaccess.h>
> 
> 
> [Richard Zhu] Thanks for your kindly help.
> This header include is not required actually, please remove it.

It should be <linux/ptrace.h> instead, for using user_mode().
Best regards,
Alexander


> >  #include <linux/interrupt.h>
> >  #include <linux/reset.h>
> >  #include <linux/phy/phy.h>
> > 
> > @@ -297,8 +298,15 @@ static int imx6q_pcie_abort_handler(unsigned long
> > addr,
> > 
> >  		unsigned int fsr, struct pt_regs *regs)  {
> >  	
> >  	unsigned long pc = instruction_pointer(regs);
> > 
> > -	unsigned long instr = *(unsigned long *)pc;
> > -	int reg = (instr >> 12) & 15;
> > +	unsigned long instr;
> > +	int reg;
> > +
> > +	/* if the abort from user-space, just return and report it */
> > +	if (user_mode(regs))
> > +		return 1;
> > +
> > +	instr = *(unsigned long *)pc;
> > +	reg = (instr >> 12) & 15;
> > 
> > 
> >  	/*
> >  	
> >  	 * If the instruction being executed was a read,
> > 
> > --
> > 2.25.1
> 
>