> -----Original Message----- > From: Wood Scott-B07421 > Sent: Friday, March 08, 2013 12:38 AM > To: Jia Hongtao-B38951 > Cc: David Laight; Wood Scott-B07421; linuxppc-dev@lists.ozlabs.org; > Stuart Yoder > Subject: Re: [PATCH V4] powerpc/85xx: Add machine check handler to fix > PCIe erratum on mpc85xx > > On 03/07/2013 02:06:05 AM, Jia Hongtao-B38951 wrote: > > Here is the ideas from Scott: > > " > > > + if (is_in_pci_mem_space(addr)) { > > > + inst = *(unsigned int *)regs->nip; > > > > Be careful about taking a fault here. A simple TLB miss should be > > safe given that we shouldn't be accessing PCIe in the middle of > > exception code, but what if the mapping has gone away (e.g. a > > userspace driver had its code munmap()ed or swapped out)? What if > > permissions allow execute but not read (not sure if Linux will allow > > this, but the hardware does)? > > > > What if it happened in a KVM guest? You can't access guest addresses > > directly. > > " > > That means you need to be careful about how you read the instruction, not > that you shouldn't do it at all. > > -Scott
I agree. Do you have a more secure way to get the instruction? Or what should be done to avoid permission break issue? Thanks. -Hongtao _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev