amd64_edac: Fix incorrect wraparounds

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 (link below). In the patch, we rectify this by
casting chan_addr to u64 and by comparing dct_base and dct_limit against
properly shifted sys_addr in order to compare the correct bits.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Link: http://lkml.kernel.org/r/20130819132302.GA12171@elgon.mountain
Signed-off-by: Borislav Petkov <bp@suse.de>

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 = (u64) dct_sel_baseaddr(pvt);
+	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)))
 		return -EINVAL;
 
 	/* Verify number of dct's that participate in channel interleaving. */
@@ -1584,7 +1585,7 @@ static int f15_m30h_match_to_this_node(struct amd64_pvt *pvt, unsigned range,
 	if (leg_mmio_hole && (sys_addr >= BIT_64(32)))
 		chan_offset = dhar_offset;
 	else
-		chan_offset = dct_base;
+		chan_offset = dct_base << 27;
 
 	chan_addr = sys_addr - chan_offset;
 
@@ -1614,7 +1615,7 @@ static int f15_m30h_match_to_this_node(struct amd64_pvt *pvt, unsigned range,
 		amd64_read_pci_cfg(pvt->F1,
 				   DRAM_CONT_HIGH_OFF + (int) channel * 4,
 				   &tmp);
-		chan_addr +=  ((tmp >> 11) & 0xfff) << 27;
+		chan_addr +=  (u64) ((tmp >> 11) & 0xfff) << 27;
 	}
 
 	f15h_select_dct(pvt, channel);