On Fri, 2014-10-24 at 13:13 +0800, [email protected] wrote:
> This is a note to let you know that I've just added the patch titled
> 
>     powerpc/powernv: Fix endian bug in LPC bus debugfs accessors
> 
> to the 3.17-stable tree which can be found at:
>     
> http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

Hi Greg !

Please take it out, it's actually bogus :-(

(And from 3.16 too and any other stable queue it might have landed in)

Michael, can you send a revert to Linus please ?

The original code was fine, I think the bug was actually in the
userspace tool I was using (don't worry, nothing on the field uses that
interface... yet and I can still fix the tool).

Sorry about that.

Ben.

> The filename of the patch is:
>      powerpc-powernv-fix-endian-bug-in-lpc-bus-debugfs-accessors.patch
> and it can be found in the queue-3.17 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <[email protected]> know about it.
> 
> 
> >From bf7588a0859580a45c63cb082825d77c13eca357 Mon Sep 17 00:00:00 2001
> From: Benjamin Herrenschmidt <[email protected]>
> Date: Fri, 3 Oct 2014 17:12:25 +1000
> Subject: powerpc/powernv: Fix endian bug in LPC bus debugfs accessors
> 
> From: Benjamin Herrenschmidt <[email protected]>
> 
> commit bf7588a0859580a45c63cb082825d77c13eca357 upstream.
> 
> When reading from the LPC, the OPAL FW calls return the value via pointer
> to a uint32_t which is always returned big endian. Our internal inb/outb
> implementation byteswaps that fine but our debugfs code is still broken.
> 
> Signed-off-by: Benjamin Herrenschmidt <[email protected]>
> Signed-off-by: Michael Ellerman <[email protected]>
> Signed-off-by: Greg Kroah-Hartman <[email protected]>
> 
> ---
>  arch/powerpc/platforms/powernv/opal-lpc.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> --- a/arch/powerpc/platforms/powernv/opal-lpc.c
> +++ b/arch/powerpc/platforms/powernv/opal-lpc.c
> @@ -191,6 +191,7 @@ static ssize_t lpc_debug_read(struct fil
>  {
>       struct lpc_debugfs_entry *lpc = filp->private_data;
>       u32 data, pos, len, todo;
> +     __be32 bedata;
>       int rc;
>  
>       if (!access_ok(VERIFY_WRITE, ubuf, count))
> @@ -213,9 +214,10 @@ static ssize_t lpc_debug_read(struct fil
>                               len = 2;
>               }
>               rc = opal_lpc_read(opal_lpc_chip_id, lpc->lpc_type, pos,
> -                                &data, len);
> +                                &bedata, len);
>               if (rc)
>                       return -ENXIO;
> +             data = be32_to_cpu(bedata);
>               switch(len) {
>               case 4:
>                       rc = __put_user((u32)data, (u32 __user *)ubuf);
> 
> 
> Patches currently in stable-queue which might be from 
> [email protected] are
> 
> queue-3.17/powerpc-powernv-fix-endian-bug-in-lpc-bus-debugfs-accessors.patch
> queue-3.17/powerpc-iommu-ddw-fix-endianness.patch


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