On Tue, 2014-10-07 at 22:08 -0500, Jia Hongtao-B38951 wrote:

quoted

-----Original Message-----
From: Wood Scott-B07421
Sent: Tuesday, September 30, 2014 2:36 AM
To: Guenter Roeck
Cc: Benjamin Herrenschmidt; Paul Mackerras; Michael Ellerman; linuxppc-
dev@lists.ozlabs.org; linux-kernel@vger.kernel.org; Jojy G Varghese;
Guenter Roeck; Jia Hongtao-B38951
Subject: Re: [PATCH] powerpc/fsl: Add support for pci(e) machine check
exception on E500MC / E5500

On Mon, 2014-09-29 at 09:48 -0700, Guenter Roeck wrote:

quoted

From: Jojy G Varghese <redacted>

For E500MC and E5500, a machine check exception in pci(e) memory space
crashes the kernel.

Testing shows that the MCAR(U) register is zero on a MC exception for
the
E5500 core. At the same time, DEAR register has been found to have the
address of the faulty load address during an MC exception for this core.

This fix changes the current behavior to fixup the result register and
instruction pointers in the case of a load operation on a faulty PCI
address.

The changes are:
- Added the hook to pci machine check handing to the e500mc machine

check

quoted

  exception handler.
- For the E5500 core, load faulting address from SPRN_DEAR register.
  As mentioned above, this is necessary because the E5500 core does not
  report the fault address in the MCAR register.

Cc: Scott Wood <redacted>
Signed-off-by: Jojy G Varghese <redacted> [Guenter Roeck:
updated description]
Signed-off-by: Guenter Roeck <redacted>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 arch/powerpc/kernel/traps.c   | 3 ++-
 arch/powerpc/sysdev/fsl_pci.c | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 0dc43f9..ecb709b 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c

@@ -494,7 +494,8 @@ int machine_check_e500mc(struct pt_regs *regs)
 	int recoverable = 1;

 	if (reason & MCSR_LD) {
-		recoverable = fsl_rio_mcheck_exception(regs);
+		recoverable = fsl_rio_mcheck_exception(regs) ||
+			fsl_pci_mcheck_exception(regs);
 		if (recoverable == 1)
 			goto silent_out;
 	}

diff --git a/arch/powerpc/sysdev/fsl_pci.c

b/arch/powerpc/sysdev/fsl_pci.c index c507767..bdb956b 100644

--- a/arch/powerpc/sysdev/fsl_pci.c
+++ b/arch/powerpc/sysdev/fsl_pci.c

@@ -1021,6 +1021,11 @@ int fsl_pci_mcheck_exception(struct pt_regs

*regs)  #endif
 	addr += mfspr(SPRN_MCAR);

+#ifdef CONFIG_E5500_CPU
+	if (mfspr(SPRN_EPCR) & SPRN_EPCR_ICM)
+		addr = PFN_PHYS(vmalloc_to_pfn((void *)mfspr(SPRN_DEAR)));

#endif

Kconfig tells you what hardware is supported, not what hardware you're
actually running on.

Jia Hongtao, do you know anything about this issue?  Is there an erratum?

Sorry for the late response, I just return from my vacation.
I don't know this issue.

quoted

What chips are affected by the the erratum covered by
<http://patchwork.ozlabs.org/patch/240239/>?

MPC8544, MPC8548, MPC8572 are affected by this erratum.

What is the erratum number?

I checked P4080 which using e500mc and no such erratum is found.

What is the erratum behavior, and how does it differ from the problem
that Jojy and Guenter are trying to solve?

-Scott