linux/drivers/ras/cec.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 15:07:57 +01:00
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2017-2019 Borislav Petkov, SUSE Labs.
*/
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/ras.h>
#include <linux/kernel.h>
#include <linux/workqueue.h>
#include <asm/mce.h>
#include "debugfs.h"
/*
* RAS Correctable Errors Collector
*
* This is a simple gadget which collects correctable errors and counts their
* occurrence per physical page address.
*
* We've opted for possibly the simplest data structure to collect those - an
* array of the size of a memory page. It stores 512 u64's with the following
* structure:
*
* [63 ... PFN ... 12 | 11 ... generation ... 10 | 9 ... count ... 0]
*
* The generation in the two highest order bits is two bits which are set to 11b
* on every insertion. During the course of each entry's existence, the
* generation field gets decremented during spring cleaning to 10b, then 01b and
* then 00b.
*
* This way we're employing the natural numeric ordering to make sure that newly
* inserted/touched elements have higher 12-bit counts (which we've manufactured)
* and thus iterating over the array initially won't kick out those elements
* which were inserted last.
*
* Spring cleaning is what we do when we reach a certain number CLEAN_ELEMS of
* elements entered into the array, during which, we're decaying all elements.
* If, after decay, an element gets inserted again, its generation is set to 11b
* to make sure it has higher numerical count than other, older elements and
* 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 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
* signal to its callers to log the error.
*
* To the question why we've chosen a page and moving elements around with
* memmove(), it is because it is a very simple structure to handle and max data
* movement is 4K which on highly optimized modern CPUs is almost unnoticeable.
* We wanted to avoid the pointer traversal of more complex structures like a
* linked list or some sort of a balancing search tree.
*
* Deleting an element takes O(n) but since it is only a single page, it should
* be fast enough and it shouldn't happen all too often depending on error
* patterns.
*/
#undef pr_fmt
#define pr_fmt(fmt) "RAS: " fmt
/*
* We use DECAY_BITS bits of PAGE_SHIFT bits for counting decay, i.e., how long
* elements have stayed in the array without having been accessed again.
*/
#define DECAY_BITS 2
#define DECAY_MASK ((1ULL << DECAY_BITS) - 1)
#define MAX_ELEMS (PAGE_SIZE / sizeof(u64))
/*
* Threshold amount of inserted elements after which we start spring
* cleaning.
*/
#define CLEAN_ELEMS (MAX_ELEMS >> DECAY_BITS)
/* Bits which count the number of errors happened in this 4K page. */
#define COUNT_BITS (PAGE_SHIFT - DECAY_BITS)
#define COUNT_MASK ((1ULL << COUNT_BITS) - 1)
#define FULL_COUNT_MASK (PAGE_SIZE - 1)
/*
* u64: [ 63 ... 12 | DECAY_BITS | COUNT_BITS ]
*/
#define PFN(e) ((e) >> PAGE_SHIFT)
#define DECAY(e) (((e) >> COUNT_BITS) & DECAY_MASK)
#define COUNT(e) ((unsigned int)(e) & COUNT_MASK)
#define FULL_COUNT(e) ((e) & (PAGE_SIZE - 1))
static struct ce_array {
u64 *array; /* container page */
unsigned int n; /* number of elements in the array */
unsigned int decay_count; /*
* number of element insertions/increments
* since the last spring cleaning.
*/
u64 pfns_poisoned; /*
* number of PFNs which got poisoned.
*/
u64 ces_entered; /*
* The number of correctable errors
* entered into the collector.
*/
u64 decays_done; /*
* Times we did spring cleaning.
*/
union {
struct {
__u32 disabled : 1, /* cmdline disabled */
__resv : 31;
};
__u32 flags;
};
} ce_arr;
static DEFINE_MUTEX(ce_mutex);
static u64 dfs_pfn;
/* Amount of errors after which we offline */
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 */
#define CEC_DECAY_MIN_INTERVAL 1 * 60 * 60 /* 1h */
#define CEC_DECAY_MAX_INTERVAL 30 * 24 * 60 * 60 /* one month */
static struct delayed_work cec_work;
static u64 decay_interval = CEC_DECAY_DEFAULT_INTERVAL;
/*
* Decrement decay value. We're using DECAY_BITS bits to denote decay of an
* element in the array. On insertion and any access, it gets reset to max.
*/
static void do_spring_cleaning(struct ce_array *ca)
{
int i;
for (i = 0; i < ca->n; i++) {
u8 decay = DECAY(ca->array[i]);
if (!decay)
continue;
decay--;
ca->array[i] &= ~(DECAY_MASK << COUNT_BITS);
ca->array[i] |= (decay << COUNT_BITS);
}
ca->decay_count = 0;
ca->decays_done++;
}
/*
* @interval in seconds
*/
static void cec_mod_work(unsigned long interval)
{
unsigned long iv;
iv = interval * HZ;
mod_delayed_work(system_wq, &cec_work, round_jiffies(iv));
}
static void cec_work_fn(struct work_struct *work)
{
mutex_lock(&ce_mutex);
do_spring_cleaning(&ce_arr);
mutex_unlock(&ce_mutex);
cec_mod_work(decay_interval);
}
/*
* @to: index of the smallest element which is >= then @pfn.
*
* Return the index of the pfn if found, otherwise negative value.
*/
static int __find_elem(struct ce_array *ca, u64 pfn, unsigned int *to)
{
int min = 0, max = ca->n - 1;
u64 this_pfn;
while (min <= max) {
int i = (min + max) >> 1;
this_pfn = PFN(ca->array[i]);
if (this_pfn < pfn)
min = i + 1;
else if (this_pfn > pfn)
max = i - 1;
else if (this_pfn == pfn) {
if (to)
*to = i;
return i;
}
}
/*
* When the loop terminates without finding @pfn, min has the index of
* the element slot where the new @pfn should be inserted. The loop
* terminates when min > max, which means the min index points to the
* bigger element while the max index to the smaller element, in-between
* which the new @pfn belongs to.
*
* For more details, see exercise 1, Section 6.2.1 in TAOCP, vol. 3.
*/
if (to)
*to = min;
return -ENOKEY;
}
static int find_elem(struct ce_array *ca, u64 pfn, unsigned int *to)
{
WARN_ON(!to);
if (!ca->n) {
*to = 0;
return -ENOKEY;
}
return __find_elem(ca, pfn, to);
}
static void del_elem(struct ce_array *ca, int idx)
{
/* Save us a function call when deleting the last element. */
if (ca->n - (idx + 1))
memmove((void *)&ca->array[idx],
(void *)&ca->array[idx + 1],
(ca->n - (idx + 1)) * sizeof(u64));
ca->n--;
}
static u64 del_lru_elem_unlocked(struct ce_array *ca)
{
unsigned int min = FULL_COUNT_MASK;
int i, min_idx = 0;
for (i = 0; i < ca->n; i++) {
unsigned int this = FULL_COUNT(ca->array[i]);
if (min > this) {
min = this;
min_idx = i;
}
}
del_elem(ca, min_idx);
return PFN(ca->array[min_idx]);
}
/*
* We return the 0th pfn in the error case under the assumption that it cannot
* be poisoned and excessive CEs in there are a serious deal anyway.
*/
static u64 __maybe_unused del_lru_elem(void)
{
struct ce_array *ca = &ce_arr;
u64 pfn;
if (!ca->n)
return 0;
mutex_lock(&ce_mutex);
pfn = del_lru_elem_unlocked(ca);
mutex_unlock(&ce_mutex);
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 = 0;
int count, ret = 0;
/*
* We can be called very early on the identify_cpu() path where we are
* not initialized yet. We ignore the error for simplicity.
*/
if (!ce_arr.array || ce_arr.disabled)
return -ENODEV;
mutex_lock(&ce_mutex);
ca->ces_entered++;
/* Array full, free the LRU slot. */
if (ca->n == MAX_ELEMS)
WARN_ON(!del_lru_elem_unlocked(ca));
ret = find_elem(ca, pfn, &to);
if (ret < 0) {
/*
* Shift range [to-end] to make room for one more element.
*/
memmove((void *)&ca->array[to + 1],
(void *)&ca->array[to],
(ca->n - to) * sizeof(u64));
ca->array[to] = pfn << PAGE_SHIFT;
ca->n++;
}
/* Add/refresh element generation and increment count */
ca->array[to] |= DECAY_MASK << COUNT_BITS;
ca->array[to]++;
/* 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)) {
pr_warn("CEC: Invalid pfn: 0x%llx\n", pfn);
} else {
/* We have reached max count for this page, soft-offline it. */
pr_err("Soft-offlining pfn: 0x%llx\n", pfn);
memory_failure_queue(pfn, MF_SOFT_OFFLINE);
ca->pfns_poisoned++;
}
del_elem(ca, to);
/*
* Return a >0 value to callers, to denote that we've reached
* the offlining threshold.
*/
ret = 1;
goto unlock;
}
ca->decay_count++;
if (ca->decay_count >= CLEAN_ELEMS)
do_spring_cleaning(ca);
WARN_ON_ONCE(sanity_check(ca));
unlock:
mutex_unlock(&ce_mutex);
return ret;
}
static int u64_get(void *data, u64 *val)
{
*val = *(u64 *)data;
return 0;
}
static int pfn_set(void *data, u64 val)
{
*(u64 *)data = 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)
{
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 action_threshold_set(void *data, u64 val)
{
*(u64 *)data = val;
if (val > COUNT_MASK)
val = COUNT_MASK;
action_threshold = val;
return 0;
}
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;
int i;
mutex_lock(&ce_mutex);
seq_printf(m, "{ n: %d\n", ca->n);
for (i = 0; i < ca->n; i++) {
u64 this = PFN(ca->array[i]);
seq_printf(m, " %3d: [%016llx|%s|%03llx]\n",
i, this, bins[DECAY(ca->array[i])], COUNT(ca->array[i]));
}
seq_printf(m, "}\n");
seq_printf(m, "Stats:\nCEs: %llu\nofflined pages: %llu\n",
ca->ces_entered, ca->pfns_poisoned);
seq_printf(m, "Flags: 0x%x\n", ca->flags);
seq_printf(m, "Decay interval: %lld seconds\n", decay_interval);
seq_printf(m, "Decays: %lld\n", ca->decays_done);
seq_printf(m, "Action threshold: %lld\n", action_threshold);
mutex_unlock(&ce_mutex);
return 0;
}
static int array_open(struct inode *inode, struct file *filp)
{
return single_open(filp, array_dump, NULL);
}
static const struct file_operations array_ops = {
.owner = THIS_MODULE,
.open = array_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int __init create_debugfs_nodes(void)
{
struct dentry *d, *pfn, *decay, *count, *array;
d = debugfs_create_dir("cec", ras_debugfs_dir);
if (!d) {
pr_warn("Error creating cec debugfs node!\n");
return -1;
}
decay = debugfs_create_file("decay_interval", S_IRUSR | S_IWUSR, d,
&decay_interval, &decay_interval_ops);
if (!decay) {
pr_warn("Error creating decay_interval debugfs node!\n");
goto err;
}
count = debugfs_create_file("action_threshold", S_IRUSR | S_IWUSR, d,
&action_threshold, &action_threshold_ops);
if (!count) {
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;
err:
debugfs_remove_recursive(d);
return 1;
}
void __init cec_init(void)
{
if (ce_arr.disabled)
return;
ce_arr.array = (void *)get_zeroed_page(GFP_KERNEL);
if (!ce_arr.array) {
pr_err("Error allocating CE array page!\n");
return;
}
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);
pr_info("Correctable Errors collector initialized.\n");
}
int __init parse_cec_param(char *str)
{
if (!str)
return 0;
if (*str == '=')
str++;
if (!strcmp(str, "cec_disable"))
ce_arr.disabled = 1;
else
return 0;
return 1;
}