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-rw-r--r--drivers/ras/cec.c132
1 files changed, 81 insertions, 51 deletions
diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index 673f8a128397..5d545806d930 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -1,4 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2017-2019 Borislav Petkov, SUSE Labs.
+ */
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
@@ -37,9 +40,9 @@
* thus emulate an an LRU-like behavior when deleting elements to free up space
* in the page.
*
- * When an element reaches it's max count of count_threshold, we try to poison
- * it by assuming that errors triggered count_threshold times in a single page
- * are excessive and that page shouldn't be used anymore. count_threshold is
+ * When an element reaches it's max count of action_threshold, we try to poison
+ * it by assuming that errors triggered action_threshold times in a single page
+ * are excessive and that page shouldn't be used anymore. action_threshold is
* initialized to COUNT_MASK which is the maximum.
*
* That error event entry causes cec_add_elem() to return !0 value and thus
@@ -122,7 +125,7 @@ static DEFINE_MUTEX(ce_mutex);
static u64 dfs_pfn;
/* Amount of errors after which we offline */
-static unsigned int count_threshold = COUNT_MASK;
+static u64 action_threshold = COUNT_MASK;
/* Each element "decays" each decay_interval which is 24hrs by default. */
#define CEC_DECAY_DEFAULT_INTERVAL 24 * 60 * 60 /* 24 hrs */
@@ -276,11 +279,39 @@ static u64 __maybe_unused del_lru_elem(void)
return pfn;
}
+static bool sanity_check(struct ce_array *ca)
+{
+ bool ret = false;
+ u64 prev = 0;
+ int i;
+
+ for (i = 0; i < ca->n; i++) {
+ u64 this = PFN(ca->array[i]);
+
+ if (WARN(prev > this, "prev: 0x%016llx <-> this: 0x%016llx\n", prev, this))
+ ret = true;
+
+ prev = this;
+ }
+
+ if (!ret)
+ return ret;
+
+ pr_info("Sanity check dump:\n{ n: %d\n", ca->n);
+ for (i = 0; i < ca->n; i++) {
+ u64 this = PFN(ca->array[i]);
+
+ pr_info(" %03d: [%016llx|%03llx]\n", i, this, FULL_COUNT(ca->array[i]));
+ }
+ pr_info("}\n");
+
+ return ret;
+}
int cec_add_elem(u64 pfn)
{
struct ce_array *ca = &ce_arr;
- unsigned int to;
+ unsigned int to = 0;
int count, ret = 0;
/*
@@ -294,6 +325,7 @@ int cec_add_elem(u64 pfn)
ca->ces_entered++;
+ /* Array full, free the LRU slot. */
if (ca->n == MAX_ELEMS)
WARN_ON(!del_lru_elem_unlocked(ca));
@@ -306,24 +338,17 @@ int cec_add_elem(u64 pfn)
(void *)&ca->array[to],
(ca->n - to) * sizeof(u64));
- ca->array[to] = (pfn << PAGE_SHIFT) |
- (DECAY_MASK << COUNT_BITS) | 1;
-
+ ca->array[to] = pfn << PAGE_SHIFT;
ca->n++;
-
- ret = 0;
-
- goto decay;
}
- count = COUNT(ca->array[to]);
-
- if (count < count_threshold) {
- ca->array[to] |= (DECAY_MASK << COUNT_BITS);
- ca->array[to]++;
+ /* Add/refresh element generation and increment count */
+ ca->array[to] |= DECAY_MASK << COUNT_BITS;
+ ca->array[to]++;
- ret = 0;
- } else {
+ /* Check action threshold and soft-offline, if reached. */
+ count = COUNT(ca->array[to]);
+ if (count >= action_threshold) {
u64 pfn = ca->array[to] >> PAGE_SHIFT;
if (!pfn_valid(pfn)) {
@@ -338,20 +363,21 @@ int cec_add_elem(u64 pfn)
del_elem(ca, to);
/*
- * Return a >0 value to denote that we've reached the offlining
- * threshold.
+ * Return a >0 value to callers, to denote that we've reached
+ * the offlining threshold.
*/
ret = 1;
goto unlock;
}
-decay:
ca->decay_count++;
if (ca->decay_count >= CLEAN_ELEMS)
do_spring_cleaning(ca);
+ WARN_ON_ONCE(sanity_check(ca));
+
unlock:
mutex_unlock(&ce_mutex);
@@ -369,45 +395,48 @@ static int pfn_set(void *data, u64 val)
{
*(u64 *)data = val;
- return cec_add_elem(val);
+ cec_add_elem(val);
+
+ return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(pfn_ops, u64_get, pfn_set, "0x%llx\n");
static int decay_interval_set(void *data, u64 val)
{
- *(u64 *)data = val;
-
if (val < CEC_DECAY_MIN_INTERVAL)
return -EINVAL;
if (val > CEC_DECAY_MAX_INTERVAL)
return -EINVAL;
+ *(u64 *)data = val;
decay_interval = val;
cec_mod_work(decay_interval);
+
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(decay_interval_ops, u64_get, decay_interval_set, "%lld\n");
-static int count_threshold_set(void *data, u64 val)
+static int action_threshold_set(void *data, u64 val)
{
*(u64 *)data = val;
if (val > COUNT_MASK)
val = COUNT_MASK;
- count_threshold = val;
+ action_threshold = val;
return 0;
}
-DEFINE_DEBUGFS_ATTRIBUTE(count_threshold_ops, u64_get, count_threshold_set, "%lld\n");
+DEFINE_DEBUGFS_ATTRIBUTE(action_threshold_ops, u64_get, action_threshold_set, "%lld\n");
+
+static const char * const bins[] = { "00", "01", "10", "11" };
static int array_dump(struct seq_file *m, void *v)
{
struct ce_array *ca = &ce_arr;
- u64 prev = 0;
int i;
mutex_lock(&ce_mutex);
@@ -416,11 +445,8 @@ static int array_dump(struct seq_file *m, void *v)
for (i = 0; i < ca->n; i++) {
u64 this = PFN(ca->array[i]);
- seq_printf(m, " %03d: [%016llx|%03llx]\n", i, this, FULL_COUNT(ca->array[i]));
-
- WARN_ON(prev > this);
-
- prev = this;
+ seq_printf(m, " %3d: [%016llx|%s|%03llx]\n",
+ i, this, bins[DECAY(ca->array[i])], COUNT(ca->array[i]));
}
seq_printf(m, "}\n");
@@ -433,7 +459,7 @@ static int array_dump(struct seq_file *m, void *v)
seq_printf(m, "Decay interval: %lld seconds\n", decay_interval);
seq_printf(m, "Decays: %lld\n", ca->decays_done);
- seq_printf(m, "Action threshold: %d\n", count_threshold);
+ seq_printf(m, "Action threshold: %lld\n", action_threshold);
mutex_unlock(&ce_mutex);
@@ -463,18 +489,6 @@ static int __init create_debugfs_nodes(void)
return -1;
}
- pfn = debugfs_create_file("pfn", S_IRUSR | S_IWUSR, d, &dfs_pfn, &pfn_ops);
- if (!pfn) {
- pr_warn("Error creating pfn debugfs node!\n");
- goto err;
- }
-
- array = debugfs_create_file("array", S_IRUSR, d, NULL, &array_ops);
- if (!array) {
- pr_warn("Error creating array debugfs node!\n");
- goto err;
- }
-
decay = debugfs_create_file("decay_interval", S_IRUSR | S_IWUSR, d,
&decay_interval, &decay_interval_ops);
if (!decay) {
@@ -482,13 +496,27 @@ static int __init create_debugfs_nodes(void)
goto err;
}
- count = debugfs_create_file("count_threshold", S_IRUSR | S_IWUSR, d,
- &count_threshold, &count_threshold_ops);
+ count = debugfs_create_file("action_threshold", S_IRUSR | S_IWUSR, d,
+ &action_threshold, &action_threshold_ops);
if (!count) {
- pr_warn("Error creating count_threshold debugfs node!\n");
+ pr_warn("Error creating action_threshold debugfs node!\n");
+ goto err;
+ }
+
+ if (!IS_ENABLED(CONFIG_RAS_CEC_DEBUG))
+ return 0;
+
+ pfn = debugfs_create_file("pfn", S_IRUSR | S_IWUSR, d, &dfs_pfn, &pfn_ops);
+ if (!pfn) {
+ pr_warn("Error creating pfn debugfs node!\n");
goto err;
}
+ array = debugfs_create_file("array", S_IRUSR, d, NULL, &array_ops);
+ if (!array) {
+ pr_warn("Error creating array debugfs node!\n");
+ goto err;
+ }
return 0;
@@ -509,8 +537,10 @@ void __init cec_init(void)
return;
}
- if (create_debugfs_nodes())
+ if (create_debugfs_nodes()) {
+ free_page((unsigned long)ce_arr.array);
return;
+ }
INIT_DELAYED_WORK(&cec_work, cec_work_fn);
schedule_delayed_work(&cec_work, CEC_DECAY_DEFAULT_INTERVAL);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.