On Mon, Aug 19, 2013 at 07:27:52PM -0500, Aravind Gopalakrishnan wrote:
> Link to the bug report:
> http://marc.info/?l=linux-edac&m=137692201732220&w=2
>
> dct_base and dct_limit obtain 32 bit register values when they read their
> respective pci config space registers. A left shift beyond 32 bits will
> cause them to wrap around. Similar case for chan_addr as can be seen from
> the bug report. In the patch, we rectify this by casting chan_addr to u64
> and by comparing dct_base and dct_limit against (sys_addr >> 27)
>
> Tested on F15h, M30h with ECC turned on and works fine.
>
> Signed-off-by: Aravind Gopalakrishnan <aravind.gopalakrish...@amd.com>
>
> diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
> index b86228c..eb4793e 100644
> --- a/drivers/edac/amd64_edac.c
> +++ b/drivers/edac/amd64_edac.c
> @@ -1558,11 +1558,12 @@ static int f15_m30h_match_to_this_node(struct
> amd64_pvt *pvt, unsigned range,
> }
>
> /* Verify sys_addr is within DCT Range. */
> - dct_base = (dct_sel_baseaddr(pvt) << 27);
> - dct_limit = (((dct_cont_limit_reg >> 11) & 0x1FFF) << 27) | 0x7FFFFFF;
> + dct_base = dct_sel_baseaddr(pvt);
This can't be correct.
So the original patch takes the shifted dct_base while your change
doesn't anymore...
> + dct_limit = (dct_cont_limit_reg >> 11) & 0x1FFF;
>
> if (!(dct_cont_base_reg & BIT(0)) &&
> - !(dct_base <= sys_addr && dct_limit >= sys_addr))
> + !(dct_base <= (sys_addr >> 27) &&
> + dct_limit >= (sys_addr >> 27)))
... and while this comparison shifts sys_addr to use the proper bits,
the code does this assignment later:
chan_offset = dct_base;
Now, chan_offset has the << 27 version of dct_base which makes the following
calculation wrong:
chan_addr = sys_addr - chan_offset;
because sys_addr is the full 64-bit, unshifted value.
The right thing to do would be to do:
chan_offset = dct_base << 27;
Or am I missing something?
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
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