| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20200810080625.1428045-1-elver@google.com>
Date: Mon, 10 Aug 2020 10:06:25 +0200
From: Marco Elver <elver@...gle.com>
To: elver@...gle.com, paulmck@...nel.org
Cc: kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org
Subject: [PATCH] kcsan: Optimize debugfs stats counters
Remove kcsan_counter_inc/dec() functions, as they perform no other
logic, and are no longer needed.
This avoids several calls in kcsan_setup_watchpoint() and
kcsan_found_watchpoint(), as well as lets the compiler warn us about
potential out-of-bounds accesses as the array's size is known at all
usage sites at compile-time.
Signed-off-by: Marco Elver <elver@...gle.com>
---
kernel/kcsan/core.c | 22 +++++++++++-----------
kernel/kcsan/debugfs.c | 21 +++++----------------
kernel/kcsan/kcsan.h | 12 ++++++------
kernel/kcsan/report.c | 2 +-
4 files changed, 23 insertions(+), 34 deletions(-)
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index 23d0c4e4cd3a..c3b19e4a089a 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -351,13 +351,13 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr,
* already removed the watchpoint, or another thread consumed
* the watchpoint before this thread.
*/
- kcsan_counter_inc(KCSAN_COUNTER_REPORT_RACES);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_REPORT_RACES]);
}
if ((type & KCSAN_ACCESS_ASSERT) != 0)
- kcsan_counter_inc(KCSAN_COUNTER_ASSERT_FAILURES);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ASSERT_FAILURES]);
else
- kcsan_counter_inc(KCSAN_COUNTER_DATA_RACES);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_DATA_RACES]);
user_access_restore(flags);
}
@@ -398,7 +398,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
goto out;
if (!check_encodable((unsigned long)ptr, size)) {
- kcsan_counter_inc(KCSAN_COUNTER_UNENCODABLE_ACCESSES);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_UNENCODABLE_ACCESSES]);
goto out;
}
@@ -413,12 +413,12 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
* with which should_watch() returns true should be tweaked so
* that this case happens very rarely.
*/
- kcsan_counter_inc(KCSAN_COUNTER_NO_CAPACITY);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_NO_CAPACITY]);
goto out_unlock;
}
- kcsan_counter_inc(KCSAN_COUNTER_SETUP_WATCHPOINTS);
- kcsan_counter_inc(KCSAN_COUNTER_USED_WATCHPOINTS);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_SETUP_WATCHPOINTS]);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_USED_WATCHPOINTS]);
/*
* Read the current value, to later check and infer a race if the data
@@ -520,16 +520,16 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
* increment this counter.
*/
if (is_assert && value_change == KCSAN_VALUE_CHANGE_TRUE)
- kcsan_counter_inc(KCSAN_COUNTER_ASSERT_FAILURES);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ASSERT_FAILURES]);
kcsan_report(ptr, size, type, value_change, KCSAN_REPORT_RACE_SIGNAL,
watchpoint - watchpoints);
} else if (value_change == KCSAN_VALUE_CHANGE_TRUE) {
/* Inferring a race, since the value should not have changed. */
- kcsan_counter_inc(KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN]);
if (is_assert)
- kcsan_counter_inc(KCSAN_COUNTER_ASSERT_FAILURES);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ASSERT_FAILURES]);
if (IS_ENABLED(CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN) || is_assert)
kcsan_report(ptr, size, type, KCSAN_VALUE_CHANGE_TRUE,
@@ -542,7 +542,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
* reused after this point.
*/
remove_watchpoint(watchpoint);
- kcsan_counter_dec(KCSAN_COUNTER_USED_WATCHPOINTS);
+ atomic_long_dec(&kcsan_counters[KCSAN_COUNTER_USED_WATCHPOINTS]);
out_unlock:
if (!kcsan_interrupt_watcher)
raw_local_irq_restore(irq_flags);
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index 6c4914fa2fad..3c8093a371b1 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -17,10 +17,7 @@
#include "kcsan.h"
-/*
- * Statistics counters.
- */
-static atomic_long_t counters[KCSAN_COUNTER_COUNT];
+atomic_long_t kcsan_counters[KCSAN_COUNTER_COUNT];
static const char *const counter_names[] = {
[KCSAN_COUNTER_USED_WATCHPOINTS] = "used_watchpoints",
[KCSAN_COUNTER_SETUP_WATCHPOINTS] = "setup_watchpoints",
@@ -53,16 +50,6 @@ static struct {
};
static DEFINE_SPINLOCK(report_filterlist_lock);
-void kcsan_counter_inc(enum kcsan_counter_id id)
-{
- atomic_long_inc(&counters[id]);
-}
-
-void kcsan_counter_dec(enum kcsan_counter_id id)
-{
- atomic_long_dec(&counters[id]);
-}
-
/*
* The microbenchmark allows benchmarking KCSAN core runtime only. To run
* multiple threads, pipe 'microbench=<iters>' from multiple tasks into the
@@ -206,8 +193,10 @@ static int show_info(struct seq_file *file, void *v)
/* show stats */
seq_printf(file, "enabled: %i\n", READ_ONCE(kcsan_enabled));
- for (i = 0; i < KCSAN_COUNTER_COUNT; ++i)
- seq_printf(file, "%s: %ld\n", counter_names[i], atomic_long_read(&counters[i]));
+ for (i = 0; i < KCSAN_COUNTER_COUNT; ++i) {
+ seq_printf(file, "%s: %ld\n", counter_names[i],
+ atomic_long_read(&kcsan_counters[i]));
+ }
/* show filter functions, and filter type */
spin_lock_irqsave(&report_filterlist_lock, flags);
diff --git a/kernel/kcsan/kcsan.h b/kernel/kcsan/kcsan.h
index 763d6d08d94b..7619c245e080 100644
--- a/kernel/kcsan/kcsan.h
+++ b/kernel/kcsan/kcsan.h
@@ -8,6 +8,7 @@
#ifndef _KERNEL_KCSAN_KCSAN_H
#define _KERNEL_KCSAN_KCSAN_H
+#include <linux/atomic.h>
#include <linux/kcsan.h>
/* The number of adjacent watchpoints to check. */
@@ -27,6 +28,10 @@ extern bool kcsan_enabled;
*/
void kcsan_debugfs_init(void);
+/*
+ * Statistics counters displayed via debugfs; should only be modified in
+ * slow-paths.
+ */
enum kcsan_counter_id {
/*
* Number of watchpoints currently in use.
@@ -79,12 +84,7 @@ enum kcsan_counter_id {
KCSAN_COUNTER_COUNT, /* number of counters */
};
-
-/*
- * Increment/decrement counter with given id; avoid calling these in fast-path.
- */
-extern void kcsan_counter_inc(enum kcsan_counter_id id);
-extern void kcsan_counter_dec(enum kcsan_counter_id id);
+extern atomic_long_t kcsan_counters[KCSAN_COUNTER_COUNT];
/*
* Returns true if data races in the function symbol that maps to func_addr
diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index 15add93ff12e..3add0d9b252c 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -556,7 +556,7 @@ static bool prepare_report_consumer(unsigned long *flags,
* If the actual accesses to not match, this was a false
* positive due to watchpoint encoding.
*/
- kcsan_counter_inc(KCSAN_COUNTER_ENCODING_FALSE_POSITIVES);
+ atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ENCODING_FALSE_POSITIVES]);
goto discard;
}
--
2.28.0.236.gb10cc79966-goog
Powered by blists - more mailing lists