linux-kernel - [PATCH 1/1] AMD64_EDAC: Fix incorrect wrap arounds due to left shift beyond 32 bits.

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Message-ID: <1376958472-2150-2-git-send-email-Aravind.Gopalakrishnan@amd.com>
Date:	Mon, 19 Aug 2013 19:27:52 -0500
From:	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
To:	<tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
	<dougthompson@...ssion.com>, <bp@...en8.de>, <bhelgaas@...gle.com>,
	<jbeulich@...e.com>, <linux-kernel@...r.kernel.org>,
	<linux-edac@...r.kernel.org>, <linux-pci@...r.kernel.org>
CC:	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
Subject: [PATCH 1/1] AMD64_EDAC: Fix incorrect wrap arounds due to left shift beyond 32 bits.

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.Gopalakrishnan@....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);
+	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. */
@@ -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);
-- 
1.7.10.4


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