On Wed, 2017-09-06 at 19:31 +0000, Leo Li wrote:
> > -----Original Message-----
> > From: York Sun
> > Sent: Wednesday, September 06, 2017 10:38 AM
> > To: Joakim Tjernlund <joakim.tjernl...@infinera.com>; linuxppc-
> > d...@lists.ozlabs.org; Leo Li <leoyang...@nxp.com>
> > Subject: Re: Machine Check in P2010(e500v2)
> >
> > Scott is no longer with Freescale/NXP. Adding Leo.
> >
> > On 09/05/2017 01:40 AM, Joakim Tjernlund wrote:
> > > So after some debugging I found this bug:
> > > @@ -996,7 +998,7 @@ int fsl_pci_mcheck_exception(struct pt_regs *regs)
> > > if (is_in_pci_mem_space(addr)) {
> > > if (user_mode(regs)) {
> > > pagefault_disable();
> > > - ret = get_user(regs->nip, &inst);
> > > + ret = get_user(inst, (__u32 __user
> > > + *)regs->nip);
> > > pagefault_enable();
> > > } else {
> > > ret = probe_kernel_address(regs->nip, inst);
> > >
> > > However, the kernel still locked up after fixing that.
> > > Now I wonder why this fixup is there in the first place? The routine
> > > will not really fixup the insn, just return 0xffffffff for the failing
> > > read and then advance the process NIP.
>
> You are right. The code here only gives 0xffffffff to the load instructions
> and continue with the next instruction when the load instruction is causing
> the machine check. This will prevent a system lockup when reading from
> PCI/RapidIO device which is link down.
>
> I don't know what is actual problem in your case. Maybe it is a write
> instruction instead of read? Or the code is in a infinite loop waiting for
> a valid read result? Are you able to do some further debugging with the NIP
> correctly printed?
>
According to the MC it is a Read and the NIP also leads to a read in the
program.
ATM, I have disabled the fixup but I will enable that again.
Question, is it safe add a small printk when this MC happens(after fixing up)?
I need to see that
it has happened as the error is somewhat random.
Jocke
> Regards,
> Leo
>
> > >
> > > Removing the fixup does not help either, kernel still locks up:
> > > [ 28.170532] Machine check in kernel mode.
> > > [ 28.174538] Caused by (from MCSR=10008):
> > > [ 28.182804] Bus - Read Data Bus Error: DAR:b7013000
> > > [ 28.197079] Oops: Machine check, sig: 7 [#1]
> > > [ 28.201343] P1010 RDB
> > > [ 28.203608] Modules linked in: linux_bcm_knet(PO) linux_user_bde(PO)
> >
> > linux_kernel_bde(PO)
> > > [ 28.211796] CPU: 0 PID: 470 Comm: emxp2_hw_bl Tainted: P O
> >
> > 4.1.38+ #201
> > > [ 28.219540] task: db16ed10 ti: df122000 task.ti: df122000
> > > [ 28.224935] NIP: 10a4e2f4 LR: 10a4e404 CTR: 10046c38
> > > [ 28.229896] REGS: df123f10 TRAP: 0204 Tainted: P O
> > > (4.1.38+)
> > > [ 28.236942] MSR: 0002d000 <CE,EE,PR,ME> CR: 44002428 XER: 00000000
> > > [ 28.243306] DEAR: b7013000 ESR: 00000000
> > > GPR00: 10a4e404 bfab2730 b7b354a0 132f9fa8 07006000 07000000
> >
> > 00000000
> > > 132f9fd8
> > > GPR08: b6fd5000 b6fe5000 0003e000 bfab2720 24004424 11d6cf7c 00000000
> > > 00000000
> > > GPR16: 10f6e29c 10f6c872 10f6db01 0000b541 0000b541 11d92fcc 00000011
> > > 00000001
> > > GPR24: 01a5bd3e 132ffbf0 11d60000 00000000 07006000 00000000 132f9fa8
> >
> > 00000000
> > > [ 28.275547] NIP [10a4e2f4] 0x10a4e2f4
> > > [ 28.279204] LR [10a4e404] 0x10a4e404
> > > [ 28.282772] Call Trace:
> > > [ 28.285213] ---[ end trace 9f8b64ab1e83f449 ]---
> > > [ 28.289825]
> > >
> > >
> > > Jocke
> > >
> > > On Fri, 2017-09-01 at 13:32 +0200, Joakim Tjernlund wrote:
> > > > I am trying to debug a Machine Check for a P2010 (e500v2) CPU:
> > > >
> > > > [ 28.111816] Caused by (from MCSR=10008): Bus - Read Data Bus Error
> > > > [ 28.117998] Oops: Machine check, sig: 7 [#1]
> > > > [ 28.122263] P1010 RDB
> > > > [ 28.124529] Modules linked in: linux_bcm_knet(PO) linux_user_bde(PO)
> >
> > linux_kernel_bde(PO)
> > > > [ 28.132718] CPU: 0 PID: 470 Comm: emxp2_hw_bl Tainted: P O
> >
> > 4.1.38+ #49
> > > > [ 28.140376] task: db16cd10 ti: df128000 task.ti: df128000
> > > > [ 28.145770] NIP: 00000000 LR: 10a4e404 CTR: 10046c38
> > > > [ 28.150730] REGS: df129f10 TRAP: 0204 Tainted: P O
> > > > (4.1.38+)
> > > > [ 28.157776] MSR: 0002d000 <CE,EE,PR,ME> CR: 44002428 XER: 00000000
> > > > [ 28.164140] DEAR: b7187000 ESR: 00000000
> > > > GPR00: 10a4e404 bf86ea30 b7ca94a0 132f9fa8 07006000 07000000
> >
> > 00000000
> > > > 132f9fd8
> > > > GPR08: b7149000 b7159000 0003e000 bf86ea20 24004424 11d6cf7c
> >
> > 00000000
> > > > 00000000
> > > > GPR16: 10f6e29c 10f6c872 10f6db01 0000b541 0000b541 11d92fcc
> >
> > 00000011
> > > > 00000001
> > > > GPR24: 01a4d12d 132ffbf0 11d60000 00000000 07006000 00000000
> >
> > 132f9fa8 00000000
> > > > [ 28.196375] NIP [00000000] (null)
> > > > [ 28.199859] LR [10a4e404] 0x10a4e404
> > > > [ 28.203426] Call Trace:
> > > > [ 28.205866] ---[ end trace f456255ddf9bee83 ]---
> > > >
> > > > I cannot figure out why NIP is NULL ? It LOOKs like NIP is set to
> > > > MCSRR0 early on but maybe it is lost somehow?
> > > >
> > > > Anyhow, looking at entry_32.S:
> > > > .globl mcheck_transfer_to_handler
> > > > mcheck_transfer_to_handler:
> > > > mfspr r0,SPRN_DSRR0
> > > > stw r0,_DSRR0(r11)
> > > > mfspr r0,SPRN_DSRR1
> > > > stw r0,_DSRR1(r11)
> > > > /* fall through */
> > > >
> > > > .globl debug_transfer_to_handler
> > > > debug_transfer_to_handler:
> > > > mfspr r0,SPRN_CSRR0
> > > > stw r0,_CSRR0(r11)
> > > > mfspr r0,SPRN_CSRR1
> > > > stw r0,_CSRR1(r11)
> > > > /* fall through */
> > > >
> > > > .globl crit_transfer_to_handler
> > > > crit_transfer_to_handler:
> > > >
> > > > It looks odd that DSRRx is assigned in mcheck and CSRRx in debug and
> > > > crit has none. Should not this assigment be shifted down one level?
> > > >
> > > > Jocke
>
>
