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From: Robert Richter <rrichter@marvell.com>
To: Borislav Petkov <bp@alien8.de>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Tony Luck <tony.luck@intel.com>
Cc: James Morse <james.morse@arm.com>,
	Robert Richter <rrichter@marvell.com>,
	"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Mauro Carvalho Chehab" <mchehab+samsung@kernel.org>
Subject: [PATCH v2 10/20] EDAC, ghes: Fix grain calculation
Date: Wed, 6 Nov 2019 09:33:23 +0000
Message-ID: <20191106093239.25517-11-rrichter@marvell.com> (raw)
In-Reply-To: <20191106093239.25517-1-rrichter@marvell.com>

The current code to convert a physical address mask to a grain
(defined as granularity in bytes) is:

	e->grain = ~(mem_err->physical_addr_mask & ~PAGE_MASK);

This is broken in several ways:

1) It calculates to wrong grain values. E.g., a physical address mask
of ~0xfff should give a grain of 0x1000. Without considering
PAGE_MASK, there is an off-by-one. Things are worse when also
filtering it with ~PAGE_MASK. This will calculate to a grain with the
upper bits set. In the example it even calculates to ~0.

2) The grain does not depend on and is unrelated to the kernel's
page-size. The page-size only matters when unmapping memory in
memory_failure(). Smaller grains are wrongly rounded up to the
page-size, on architectures with a configurable page-size (e.g. arm64)
this could round up to the even bigger page-size of the hypervisor.

Fix this with:

	e->grain = ~mem_err->physical_addr_mask + 1;

The grain_bits are defined as:

	grain = 1 << grain_bits;

Change also the grain_bits calculation accordingly, it is the same
formula as in edac_mc.c now and the code can be unified.

The value in ->physical_addr_mask coming from firmware is assumed to
be contiguous, but this is not sanity-checked. However, in case the
mask is non-contiguous, a conversion to grain_bits effectively
converts the grain bit mask to a power of 2 by rounding up.

Suggested-by: James Morse <james.morse@arm.com>
Signed-off-by: Robert Richter <rrichter@marvell.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
---
 drivers/edac/ghes_edac.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
index 944c9d2f0eef..4acb456c20f7 100644
--- a/drivers/edac/ghes_edac.c
+++ b/drivers/edac/ghes_edac.c
@@ -230,6 +230,7 @@ void ghes_edac_report_mem_error(int sev, struct cper_sec_mem_err *mem_err)
 	/* Cleans the error report buffer */
 	memset(e, 0, sizeof (*e));
 	e->error_count = 1;
+	e->grain = 1;
 	strcpy(e->label, "unknown label");
 	e->msg = pvt->msg;
 	e->other_detail = pvt->other_detail;
@@ -325,7 +326,7 @@ void ghes_edac_report_mem_error(int sev, struct cper_sec_mem_err *mem_err)
 
 	/* Error grain */
 	if (mem_err->validation_bits & CPER_MEM_VALID_PA_MASK)
-		e->grain = ~(mem_err->physical_addr_mask & ~PAGE_MASK);
+		e->grain = ~mem_err->physical_addr_mask + 1;
 
 	/* Memory error location, mapped on e->location */
 	p = e->location;
@@ -441,8 +442,13 @@ void ghes_edac_report_mem_error(int sev, struct cper_sec_mem_err *mem_err)
 	if (p > pvt->other_detail)
 		*(p - 1) = '\0';
 
+	/* Sanity-check driver-supplied grain value. */
+	if (WARN_ON_ONCE(!e->grain))
+		e->grain = 1;
+
+	grain_bits = fls_long(e->grain - 1);
+
 	/* Generate the trace event */
-	grain_bits = fls_long(e->grain);
 	snprintf(pvt->detail_location, sizeof(pvt->detail_location),
 		 "APEI location: %s %s", e->location, e->other_detail);
 	trace_mc_event(type, e->msg, e->label, e->error_count,
-- 
2.20.1


  parent reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06  9:32 [PATCH v2 00/20] EDAC: Rework edac_mc and ghes drivers Robert Richter
2019-11-06  9:33 ` [PATCH v2 01/20] EDAC: Replace EDAC_DIMM_PTR() macro with edac_get_dimm() function Robert Richter
2019-11-09  7:23   ` Mauro Carvalho Chehab
2019-11-06  9:33 ` [PATCH v2 02/20] EDAC: Remove EDAC_DIMM_OFF() macro Robert Richter
2019-11-09  7:27   ` Mauro Carvalho Chehab
2019-11-06  9:33 ` [PATCH v2 03/20] EDAC: Introduce mci_for_each_dimm() iterator Robert Richter
2019-11-10 11:37   ` Borislav Petkov
2019-11-06  9:33 ` [PATCH v2 04/20] EDAC, mc: Do not BUG_ON() in edac_mc_alloc() Robert Richter
2019-11-06  9:33 ` [PATCH v2 05/20] EDAC, mc: Remove needless zero string termination Robert Richter
2019-11-09  7:28   ` Mauro Carvalho Chehab
2019-11-09 10:11   ` Borislav Petkov
2019-11-06  9:33 ` [PATCH v2 06/20] EDAC, mc: Reduce indentation level in edac_mc_handle_error() Robert Richter
2019-11-06  9:33 ` [PATCH v2 07/20] EDAC, mc: Rename iterator variable to idx Robert Richter
2019-11-09 10:21   ` Borislav Petkov
2019-11-06  9:33 ` [PATCH v2 08/20] EDAC: Remove misleading comment in struct edac_raw_error_desc Robert Richter
2019-11-06  9:33 ` [PATCH v2 09/20] EDAC, ghes: Use standard kernel macros for page calculations Robert Richter
2019-11-06  9:33 ` Robert Richter [this message]
2019-11-06  9:33 ` [PATCH v2 11/20] EDAC, ghes: Remove intermediate buffer pvt->detail_location Robert Richter
2019-11-06  9:33 ` [PATCH v2 12/20] EDAC, ghes: Unify trace_mc_event() code with edac_mc driver Robert Richter
2019-11-06  9:33 ` [PATCH v2 13/20] EDAC, Documentation: Describe CPER module definition and DIMM ranks Robert Richter
2019-11-06  9:33 ` [PATCH v2 14/20] EDAC, mc: Remove per layer counters Robert Richter
2019-11-09  7:40   ` Mauro Carvalho Chehab
2019-11-18 20:30     ` Robert Richter
2019-11-06  9:33 ` [PATCH v2 15/20] EDAC, mc: Split edac_mc_alloc() into smaller functions Robert Richter
2019-11-06  9:33 ` [PATCH v2 16/20] EDAC, mc: Reorder functions edac_mc_alloc*() Robert Richter
2019-11-06  9:33 ` [PATCH v2 17/20] EDAC, mc: Rework edac_raw_mc_handle_error() to use struct dimm_info Robert Richter
2019-11-06  9:33 ` [PATCH v2 18/20] EDAC: Store error type in struct edac_raw_error_desc Robert Richter
2019-11-09  7:30   ` Mauro Carvalho Chehab
2019-11-06  9:33 ` [PATCH v2 19/20] EDAC, mc: Determine mci pointer from the error descriptor Robert Richter
2019-11-06  9:33 ` [PATCH v2 20/20] EDAC, mc: Create new function edac_inc_csrow() Robert Richter
2019-11-09  7:32   ` Mauro Carvalho Chehab
2019-11-10 14:51 ` [PATCH v2 00/20] EDAC: Rework edac_mc and ghes drivers Borislav Petkov
2019-11-11 15:49   ` Robert Richter

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