linux-kernel - [PATCH 3.19.y-ckt 079/170] EDAC/sb_edac: Fix computation of channel address

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Message-Id: <1459558456-24452-80-git-send-email-kamal@canonical.com>
Date:	Fri,  1 Apr 2016 17:52:45 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Tony Luck <tony.luck@...el.com>, Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-edac@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 079/170] EDAC/sb_edac: Fix computation of channel address

3.19.8-ckt18 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: "Luck, Tony" <tony.luck@...el.com>

commit eb1af3b71f9d83e45f2fd2fd649356e98e1c582c upstream.

Large memory Haswell-EX systems with multiple DIMMs per channel were
sometimes reporting the wrong DIMM.

Found three problems:

 1) Debug printouts for socket and channel interleave were not interpreting
    the register fields correctly. The socket interleave field is a 2^X
    value (0=1, 1=2, 2=4, 3=8). The channel interleave is X+1 (0=1, 1=2,
    2=3. 3=4).

 2) Actual use of the socket interleave value didn't interpret as 2^X

 3) Conversion of address to channel address was complicated, and wrong.

Signed-off-by: Tony Luck <tony.luck@...el.com>
Acked-by: Aristeu Rozanski <arozansk@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mauro Carvalho Chehab <mchehab@....samsung.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-edac@...r.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/edac/sb_edac.c | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/drivers/edac/sb_edac.c b/drivers/edac/sb_edac.c
index 1acf57b..0af67b5 100644
--- a/drivers/edac/sb_edac.c
+++ b/drivers/edac/sb_edac.c
@@ -1043,8 +1043,8 @@ static void get_memory_layout(const struct mem_ctl_info *mci)
 		edac_dbg(0, "TAD#%d: up to %u.%03u GB (0x%016Lx), socket interleave %d, memory interleave %d, TGT: %d, %d, %d, %d, reg=0x%08x\n",
 			 n_tads, gb, (mb*1000)/1024,
 			 ((u64)tmp_mb) << 20L,
-			 (u32)TAD_SOCK(reg),
-			 (u32)TAD_CH(reg),
+			 (u32)(1 << TAD_SOCK(reg)),
+			 (u32)TAD_CH(reg) + 1,
 			 (u32)TAD_TGT0(reg),
 			 (u32)TAD_TGT1(reg),
 			 (u32)TAD_TGT2(reg),
@@ -1316,7 +1316,7 @@ static int get_memory_error_data(struct mem_ctl_info *mci,
 	}
 
 	ch_way = TAD_CH(reg) + 1;
-	sck_way = TAD_SOCK(reg) + 1;
+	sck_way = 1 << TAD_SOCK(reg);
 
 	if (ch_way == 3)
 		idx = addr >> 6;
@@ -1373,7 +1373,7 @@ static int get_memory_error_data(struct mem_ctl_info *mci,
 		 n_tads,
 		 addr,
 		 limit,
-		 (u32)TAD_SOCK(reg),
+		 sck_way,
 		 ch_way,
 		 offset,
 		 idx,
@@ -1388,18 +1388,12 @@ static int get_memory_error_data(struct mem_ctl_info *mci,
 			offset, addr);
 		return -EINVAL;
 	}
-	addr -= offset;
-	/* Store the low bits [0:6] of the addr */
-	ch_addr = addr & 0x7f;
-	/* Remove socket wayness and remove 6 bits */
-	addr >>= 6;
-	addr = div_u64(addr, sck_xch);
-#if 0
-	/* Divide by channel way */
-	addr = addr / ch_way;
-#endif
-	/* Recover the last 6 bits */
-	ch_addr |= addr << 6;
+
+	ch_addr = addr - offset;
+	ch_addr >>= (6 + shiftup);
+	ch_addr /= ch_way * sck_way;
+	ch_addr <<= (6 + shiftup);
+	ch_addr |= addr & ((1 << (6 + shiftup)) - 1);
 
 	/*
 	 * Step 3) Decode rank
-- 
2.7.4