RE: [PATCH] netxen: memory corruption by netxen_p3_get_mac_addr.

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> -----Original Message-----
> From: santosh prasad nayak [mailto:santoshprasadnayak@xxxxxxxxx]
> Sent: Sunday, March 04, 2012 2:48 PM
> To: Sony Chacko
> Cc: Rajesh Borundia; netdev; Dhananjay Phadke; kernel-
> janitors@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] netxen: memory corruption by
> netxen_p3_get_mac_addr.
> 
> I would like to drop this patch.
> 
> 
> Actually I was trying to simulate the code block by generating assembly
> code
> which looked like  as shown below.  But later I realized it does not
> fit with present scenario.
> Its for different scenario.
> 
> -----------------------------------------------------------------------
> -------------------------------
>  80483cb:	83 ec 2c             	sub    $0x2c,%esp
>  80483ce:	66 c7 44 24 1e e1 2e 	movw   $0x2ee1,0x1e(%esp)
>  80483d5:	66 c7 44 24 1c e1 2e 	movw   $0x2ee1,0x1c(%esp)
>  80483dc:	0f b7 44 24 1c       	movzwl 0x1c(%esp),%eax
>  80483e1:	c1 e0 04             	shl    $0x4,%eax
>  80483e4:	88 44 24 1b          	mov    %al,0x1b(%esp)
>  80483e8:	0f b6 5c 24 1b       	movzbl 0x1b(%esp),%ebx
>  80483ed:	0f b7 4c 24 1c       	movzwl 0x1c(%esp),%ecx
>  80483f2:	0f b7 54 24 1e       	movzwl 0x1e(%esp),%edx
> -----------------------------------------------------------------------
> -------------------------------------
> 
> 
> 
> Following assembly code looks very near to present scenario.
> And  there is no data loss .
> 
> -----------------------------------------------------------------------
> ------------------------
>  804839a:	83 ec 10             	sub    $0x10,%esp
>  804839d:	66 c7 44 24 0e e1 2e 	movw   $0x2ee1,0xe(%esp)
>  80483a4:	66 c7 44 24 0c e1 2e 	movw   $0x2ee1,0xc(%esp)
>  80483ab:	0f b7 44 24 0c       	movzwl 0xc(%esp),%eax
>  80483b0:	ba 00 00 00 00       	mov    $0x0,%edx
>  80483b5:	0f a4 c2 04          	shld   $0x4,%eax,%edx
>  80483b9:	c1 e0 04             	shl    $0x4,%eax
>  80483bc:	89 04 24             	mov    %eax,(%esp)
>  80483bf:	89 54 24 04          	mov    %edx,0x4(%esp)
>  80483c3:	b8 00 00 00 00       	mov    $0x0,%eax
> -----------------------------------------------------------------------
> ----------------------------
> 
> 
> Sorry for the inconvenience.
> 
> 
> Regarding endian issue:
> --------------------------------------
>    Can Rajesh or Dhananjay comment on it ?
>    Is "le64_to_cpu"  there intentionally ??
> 

Yes , le64_to_cpu is intentional the NXRD32/readl will swap the bytes and at lower address
we will have MSB. So while referencing it with byte array we need a extra swap.

Rajesh



> Regards
> santosh
> 
> 
> On Sun, Mar 4, 2012 at 12:05 AM, Dan Carpenter
> <dan.carpenter@xxxxxxxxxx> wrote:
> > On Sat, Mar 03, 2012 at 10:31:27PM +0530, santosh nayak wrote:
> >> From: Santosh Nayak <santoshprasadnayak@xxxxxxxxx>
> >>
> >> 'mac_hi' and 'mac_lo' are 32 bit unsinged int but we are modifing
> >> 64 bit of memory during mac calculation. To fix this issue define
> >> a local variable of 64 bit and do mac calculation.
> >>
> >
> > I'm not seeing any memory corruption.  How do you figure?
> >
> >> Remove 'le64_to_cpu' to fix endian issue.
> >
> > I've add Dhananjay to the CC list to comment on the endian change.
> >
> > regards,
> > dan carpenter
> >
> >>
> >> Signed-off-by: Santosh Nayak <santoshprasadnayak@xxxxxxxxx>
> >> ---
> >>  drivers/net/ethernet/qlogic/netxen/netxen_nic_hw.c |    7 ++++---
> >>  1 files changed, 4 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/net/ethernet/qlogic/netxen/netxen_nic_hw.c
> b/drivers/net/ethernet/qlogic/netxen/netxen_nic_hw.c
> >> index 0f81287..7ea930b 100644
> >> --- a/drivers/net/ethernet/qlogic/netxen/netxen_nic_hw.c
> >> +++ b/drivers/net/ethernet/qlogic/netxen/netxen_nic_hw.c
> >> @@ -1069,7 +1069,8 @@ int netxen_get_flash_mac_addr(struct
> netxen_adapter *adapter, u64 *mac)
> >>
> >>  int netxen_p3_get_mac_addr(struct netxen_adapter *adapter, u64
> *mac)
> >>  {
> >> -     uint32_t crbaddr, mac_hi, mac_lo;
> >> +     uint32_t crbaddr;
> >> +     u64 mac_hi, mac_lo;
> >>       int pci_func = adapter->ahw.pci_func;
> >>
> >>       crbaddr = CRB_MAC_BLOCK_START +
> >> @@ -1079,9 +1080,9 @@ int netxen_p3_get_mac_addr(struct
> netxen_adapter *adapter, u64 *mac)
> >>       mac_hi = NXRD32(adapter, crbaddr+4);
> >>
> >>       if (pci_func & 1)
> >> -             *mac = le64_to_cpu((mac_lo >> 16) | ((u64)mac_hi <<
> 16));
> >> +             *mac = (mac_lo >> 16) | (mac_hi << 16);
> >>       else
> >> -             *mac = le64_to_cpu((u64)mac_lo | ((u64)mac_hi << 32));
> >> +             *mac = mac_lo | (mac_hi << 32);
> >>
> >>       return 0;
> >>  }
> >> --
> >> 1.7.4.4
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe kernel-
> janitors" in
> >> the body of a message to majordomo@xxxxxxxxxxxxxxx
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html


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