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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Robert Richter <rrichter@marvell.com>,
	Borislav Petkov <bp@suse.de>,
	"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
	James Morse <james.morse@arm.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Tony Luck <tony.luck@intel.com>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.3 072/344] EDAC/mc: Fix grain_bits calculation
Date: Thu,  3 Oct 2019 17:50:37 +0200
Message-ID: <20191003154547.235446511@linuxfoundation.org> (raw)
In-Reply-To: <20191003154540.062170222@linuxfoundation.org>

From: Robert Richter <rrichter@marvell.com>

[ Upstream commit 3724ace582d9f675134985727fd5e9811f23c059 ]

The grain in EDAC is defined as "minimum granularity for an error
report, in bytes". The following calculation of the grain_bits in
edac_mc is wrong:

	grain_bits = fls_long(e->grain) + 1;

Where grain_bits is defined as:

	grain = 1 << grain_bits

Example:

	grain = 8	# 64 bit (8 bytes)
	grain_bits = fls_long(8) + 1
	grain_bits = 4 + 1 = 5

	grain = 1 << grain_bits
	grain = 1 << 5 = 32

Replace it with the correct calculation:

	grain_bits = fls_long(e->grain - 1);

The example gives now:

	grain_bits = fls_long(8 - 1)
	grain_bits = fls_long(7)
	grain_bits = 3

	grain = 1 << 3 = 8

Also, check if the hardware reports a reasonable grain != 0 and fallback
with a warning to 1 byte granularity otherwise.

 [ bp: massage a bit. ]

Signed-off-by: Robert Richter <rrichter@marvell.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20190624150758.6695-2-rrichter@marvell.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/edac/edac_mc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 64922c8fa7e3b..d899d86897d06 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -1235,9 +1235,13 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
 	if (p > e->location)
 		*(p - 1) = '\0';
 
-	/* Report the error via the trace interface */
-	grain_bits = fls_long(e->grain) + 1;
+	/* Sanity-check driver-supplied grain value. */
+	if (WARN_ON_ONCE(!e->grain))
+		e->grain = 1;
+
+	grain_bits = fls_long(e->grain - 1);
 
+	/* Report the error via the trace interface */
 	if (IS_ENABLED(CONFIG_RAS))
 		trace_mc_event(type, e->msg, e->label, e->error_count,
 			       mci->mc_idx, e->top_layer, e->mid_layer,
-- 
2.20.1




       reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191003154540.062170222@linuxfoundation.org>
2019-10-03 15:50 ` Greg Kroah-Hartman [this message]
2019-10-03 15:50 ` [PATCH 5.3 083/344] EDAC/altera: Use the proper type for the IRQ status bits Greg Kroah-Hartman
2019-10-03 15:50 ` [PATCH 5.3 091/344] RAS: Fix prototype warnings Greg Kroah-Hartman
2019-10-03 15:50 ` [PATCH 5.3 092/344] RAS: Build debugfs.o only when enabled in Kconfig Greg Kroah-Hartman
2019-10-03 15:51 ` [PATCH 5.3 144/344] EDAC/amd64: Support more than two controllers for chip selects handling Greg Kroah-Hartman
2019-10-03 15:51 ` [PATCH 5.3 147/344] EDAC/amd64: Recognize DRAM device type ECC capability Greg Kroah-Hartman
2019-10-03 15:51 ` [PATCH 5.3 148/344] EDAC/amd64: Decode syndrome before translating address Greg Kroah-Hartman

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