Merge tag 'char-misc-4.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc updates from Greg KH:
 "Here is the big set of char/misc driver patches for 4.17-rc1.

  There are a lot of little things in here, nothing huge, but all
  important to the different hardware types involved:

   -  thunderbolt driver updates

   -  parport updates (people still care...)

   -  nvmem driver updates

   -  mei updates (as always)

   -  hwtracing driver updates

   -  hyperv driver updates

   -  extcon driver updates

   -  ... and a handful of even smaller driver subsystem and individual
      driver updates

  All of these have been in linux-next with no reported issues"

* tag 'char-misc-4.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (149 commits)
  hwtracing: Add HW tracing support menu
  intel_th: Add ACPI glue layer
  intel_th: Allow forcing host mode through drvdata
  intel_th: Pick up irq number from resources
  intel_th: Don't touch switch routing in host mode
  intel_th: Use correct method of finding hub
  intel_th: Add SPDX GPL-2.0 header to replace GPLv2 boilerplate
  stm class: Make dummy's master/channel ranges configurable
  stm class: Add SPDX GPL-2.0 header to replace GPLv2 boilerplate
  MAINTAINERS: Bestow upon myself the care for drivers/hwtracing
  hv: add SPDX license id to Kconfig
  hv: add SPDX license to trace
  Drivers: hv: vmbus: do not mark HV_PCIE as perf_device
  Drivers: hv: vmbus: respect what we get from hv_get_synint_state()
  /dev/mem: Avoid overwriting "err" in read_mem()
  eeprom: at24: use SPDX identifier instead of GPL boiler-plate
  eeprom: at24: simplify the i2c functionality checking
  eeprom: at24: fix a line break
  eeprom: at24: tweak newlines
  eeprom: at24: refactor at24_probe()
  ...

1 files changed, 401 insertions, 0 deletions

diff --git a/drivers/misc/lkdtm/refcount.c b/drivers/misc/lkdtm/refcount.c
new file mode 100644
index 000000000000..0a146b32da13
--- /dev/null
+++ b/drivers/misc/lkdtm/refcount.c
@@ -0,0 +1,401 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This is for all the tests related to refcount bugs (e.g. overflow,
+ * underflow, reaching zero untested, etc).
+ */
+#include "lkdtm.h"
+#include <linux/refcount.h>
+
+#ifdef CONFIG_REFCOUNT_FULL
+#define REFCOUNT_MAX		(UINT_MAX - 1)
+#define REFCOUNT_SATURATED	UINT_MAX
+#else
+#define REFCOUNT_MAX		INT_MAX
+#define REFCOUNT_SATURATED	(INT_MIN / 2)
+#endif
+
+static void overflow_check(refcount_t *ref)
+{
+	switch (refcount_read(ref)) {
+	case REFCOUNT_SATURATED:
+		pr_info("Overflow detected: saturated\n");
+		break;
+	case REFCOUNT_MAX:
+		pr_warn("Overflow detected: unsafely reset to max\n");
+		break;
+	default:
+		pr_err("Fail: refcount wrapped to %d\n", refcount_read(ref));
+	}
+}
+
+/*
+ * A refcount_inc() above the maximum value of the refcount implementation,
+ * should at least saturate, and at most also WARN.
+ */
+void lkdtm_REFCOUNT_INC_OVERFLOW(void)
+{
+	refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX - 1);
+
+	pr_info("attempting good refcount_inc() without overflow\n");
+	refcount_dec(&over);
+	refcount_inc(&over);
+
+	pr_info("attempting bad refcount_inc() overflow\n");
+	refcount_inc(&over);
+	refcount_inc(&over);
+
+	overflow_check(&over);
+}
+
+/* refcount_add() should behave just like refcount_inc() above. */
+void lkdtm_REFCOUNT_ADD_OVERFLOW(void)
+{
+	refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX - 1);
+
+	pr_info("attempting good refcount_add() without overflow\n");
+	refcount_dec(&over);
+	refcount_dec(&over);
+	refcount_dec(&over);
+	refcount_dec(&over);
+	refcount_add(4, &over);
+
+	pr_info("attempting bad refcount_add() overflow\n");
+	refcount_add(4, &over);
+
+	overflow_check(&over);
+}
+
+/* refcount_inc_not_zero() should behave just like refcount_inc() above. */
+void lkdtm_REFCOUNT_INC_NOT_ZERO_OVERFLOW(void)
+{
+	refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX);
+
+	pr_info("attempting bad refcount_inc_not_zero() overflow\n");
+	if (!refcount_inc_not_zero(&over))
+		pr_warn("Weird: refcount_inc_not_zero() reported zero\n");
+
+	overflow_check(&over);
+}
+
+/* refcount_add_not_zero() should behave just like refcount_inc() above. */
+void lkdtm_REFCOUNT_ADD_NOT_ZERO_OVERFLOW(void)
+{
+	refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX);
+
+	pr_info("attempting bad refcount_add_not_zero() overflow\n");
+	if (!refcount_add_not_zero(6, &over))
+		pr_warn("Weird: refcount_add_not_zero() reported zero\n");
+
+	overflow_check(&over);
+}
+
+static void check_zero(refcount_t *ref)
+{
+	switch (refcount_read(ref)) {
+	case REFCOUNT_SATURATED:
+		pr_info("Zero detected: saturated\n");
+		break;
+	case REFCOUNT_MAX:
+		pr_warn("Zero detected: unsafely reset to max\n");
+		break;
+	case 0:
+		pr_warn("Still at zero: refcount_inc/add() must not inc-from-0\n");
+		break;
+	default:
+		pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref));
+	}
+}
+
+/*
+ * A refcount_dec(), as opposed to a refcount_dec_and_test(), when it hits
+ * zero it should either saturate (when inc-from-zero isn't protected)
+ * or stay at zero (when inc-from-zero is protected) and should WARN for both.
+ */
+void lkdtm_REFCOUNT_DEC_ZERO(void)
+{
+	refcount_t zero = REFCOUNT_INIT(2);
+
+	pr_info("attempting good refcount_dec()\n");
+	refcount_dec(&zero);
+
+	pr_info("attempting bad refcount_dec() to zero\n");
+	refcount_dec(&zero);
+
+	check_zero(&zero);
+}
+
+static void check_negative(refcount_t *ref, int start)
+{
+	/*
+	 * CONFIG_REFCOUNT_FULL refuses to move a refcount at all on an
+	 * over-sub, so we have to track our starting position instead of
+	 * looking only at zero-pinning.
+	 */
+	if (refcount_read(ref) == start) {
+		pr_warn("Still at %d: refcount_inc/add() must not inc-from-0\n",
+			start);
+		return;
+	}
+
+	switch (refcount_read(ref)) {
+	case REFCOUNT_SATURATED:
+		pr_info("Negative detected: saturated\n");
+		break;
+	case REFCOUNT_MAX:
+		pr_warn("Negative detected: unsafely reset to max\n");
+		break;
+	default:
+		pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref));
+	}
+}
+
+/* A refcount_dec() going negative should saturate and may WARN. */
+void lkdtm_REFCOUNT_DEC_NEGATIVE(void)
+{
+	refcount_t neg = REFCOUNT_INIT(0);
+
+	pr_info("attempting bad refcount_dec() below zero\n");
+	refcount_dec(&neg);
+
+	check_negative(&neg, 0);
+}
+
+/*
+ * A refcount_dec_and_test() should act like refcount_dec() above when
+ * going negative.
+ */
+void lkdtm_REFCOUNT_DEC_AND_TEST_NEGATIVE(void)
+{
+	refcount_t neg = REFCOUNT_INIT(0);
+
+	pr_info("attempting bad refcount_dec_and_test() below zero\n");
+	if (refcount_dec_and_test(&neg))
+		pr_warn("Weird: refcount_dec_and_test() reported zero\n");
+
+	check_negative(&neg, 0);
+}
+
+/*
+ * A refcount_sub_and_test() should act like refcount_dec_and_test()
+ * above when going negative.
+ */
+void lkdtm_REFCOUNT_SUB_AND_TEST_NEGATIVE(void)
+{
+	refcount_t neg = REFCOUNT_INIT(3);
+
+	pr_info("attempting bad refcount_sub_and_test() below zero\n");
+	if (refcount_sub_and_test(5, &neg))
+		pr_warn("Weird: refcount_sub_and_test() reported zero\n");
+
+	check_negative(&neg, 3);
+}
+
+static void check_from_zero(refcount_t *ref)
+{
+	switch (refcount_read(ref)) {
+	case 0:
+		pr_info("Zero detected: stayed at zero\n");
+		break;
+	case REFCOUNT_SATURATED:
+		pr_info("Zero detected: saturated\n");
+		break;
+	case REFCOUNT_MAX:
+		pr_warn("Zero detected: unsafely reset to max\n");
+		break;
+	default:
+		pr_info("Fail: zero not detected, incremented to %d\n",
+			refcount_read(ref));
+	}
+}
+
+/*
+ * A refcount_inc() from zero should pin to zero or saturate and may WARN.
+ * Only CONFIG_REFCOUNT_FULL provides this protection currently.
+ */
+void lkdtm_REFCOUNT_INC_ZERO(void)
+{
+	refcount_t zero = REFCOUNT_INIT(0);
+
+	pr_info("attempting safe refcount_inc_not_zero() from zero\n");
+	if (!refcount_inc_not_zero(&zero)) {
+		pr_info("Good: zero detected\n");
+		if (refcount_read(&zero) == 0)
+			pr_info("Correctly stayed at zero\n");
+		else
+			pr_err("Fail: refcount went past zero!\n");
+	} else {
+		pr_err("Fail: Zero not detected!?\n");
+	}
+
+	pr_info("attempting bad refcount_inc() from zero\n");
+	refcount_inc(&zero);
+
+	check_from_zero(&zero);
+}
+
+/*
+ * A refcount_add() should act like refcount_inc() above when starting
+ * at zero.
+ */
+void lkdtm_REFCOUNT_ADD_ZERO(void)
+{
+	refcount_t zero = REFCOUNT_INIT(0);
+
+	pr_info("attempting safe refcount_add_not_zero() from zero\n");
+	if (!refcount_add_not_zero(3, &zero)) {
+		pr_info("Good: zero detected\n");
+		if (refcount_read(&zero) == 0)
+			pr_info("Correctly stayed at zero\n");
+		else
+			pr_err("Fail: refcount went past zero\n");
+	} else {
+		pr_err("Fail: Zero not detected!?\n");
+	}
+
+	pr_info("attempting bad refcount_add() from zero\n");
+	refcount_add(3, &zero);
+
+	check_from_zero(&zero);
+}
+
+static void check_saturated(refcount_t *ref)
+{
+	switch (refcount_read(ref)) {
+	case REFCOUNT_SATURATED:
+		pr_info("Saturation detected: still saturated\n");
+		break;
+	case REFCOUNT_MAX:
+		pr_warn("Saturation detected: unsafely reset to max\n");
+		break;
+	default:
+		pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref));
+	}
+}
+
+/*
+ * A refcount_inc() from a saturated value should at most warn about
+ * being saturated already.
+ */
+void lkdtm_REFCOUNT_INC_SATURATED(void)
+{
+	refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
+
+	pr_info("attempting bad refcount_inc() from saturated\n");
+	refcount_inc(&sat);
+
+	check_saturated(&sat);
+}
+
+/* Should act like refcount_inc() above from saturated. */
+void lkdtm_REFCOUNT_DEC_SATURATED(void)
+{
+	refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
+
+	pr_info("attempting bad refcount_dec() from saturated\n");
+	refcount_dec(&sat);
+
+	check_saturated(&sat);
+}
+
+/* Should act like refcount_inc() above from saturated. */
+void lkdtm_REFCOUNT_ADD_SATURATED(void)
+{
+	refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
+
+	pr_info("attempting bad refcount_dec() from saturated\n");
+	refcount_add(8, &sat);
+
+	check_saturated(&sat);
+}
+
+/* Should act like refcount_inc() above from saturated. */
+void lkdtm_REFCOUNT_INC_NOT_ZERO_SATURATED(void)
+{
+	refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
+
+	pr_info("attempting bad refcount_inc_not_zero() from saturated\n");
+	if (!refcount_inc_not_zero(&sat))
+		pr_warn("Weird: refcount_inc_not_zero() reported zero\n");
+
+	check_saturated(&sat);
+}
+
+/* Should act like refcount_inc() above from saturated. */
+void lkdtm_REFCOUNT_ADD_NOT_ZERO_SATURATED(void)
+{
+	refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
+
+	pr_info("attempting bad refcount_add_not_zero() from saturated\n");
+	if (!refcount_add_not_zero(7, &sat))
+		pr_warn("Weird: refcount_add_not_zero() reported zero\n");
+
+	check_saturated(&sat);
+}
+
+/* Should act like refcount_inc() above from saturated. */
+void lkdtm_REFCOUNT_DEC_AND_TEST_SATURATED(void)
+{
+	refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
+
+	pr_info("attempting bad refcount_dec_and_test() from saturated\n");
+	if (refcount_dec_and_test(&sat))
+		pr_warn("Weird: refcount_dec_and_test() reported zero\n");
+
+	check_saturated(&sat);
+}
+
+/* Should act like refcount_inc() above from saturated. */
+void lkdtm_REFCOUNT_SUB_AND_TEST_SATURATED(void)
+{
+	refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
+
+	pr_info("attempting bad refcount_sub_and_test() from saturated\n");
+	if (refcount_sub_and_test(8, &sat))
+		pr_warn("Weird: refcount_sub_and_test() reported zero\n");
+
+	check_saturated(&sat);
+}
+
+/* Used to time the existing atomic_t when used for reference counting */
+void lkdtm_ATOMIC_TIMING(void)
+{
+	unsigned int i;
+	atomic_t count = ATOMIC_INIT(1);
+
+	for (i = 0; i < INT_MAX - 1; i++)
+		atomic_inc(&count);
+
+	for (i = INT_MAX; i > 0; i--)
+		if (atomic_dec_and_test(&count))
+			break;
+
+	if (i != 1)
+		pr_err("atomic timing: out of sync up/down cycle: %u\n", i - 1);
+	else
+		pr_info("atomic timing: done\n");
+}
+
+/*
+ * This can be compared to ATOMIC_TIMING when implementing fast refcount
+ * protections. Looking at the number of CPU cycles tells the real story
+ * about performance. For example:
+ *    cd /sys/kernel/debug/provoke-crash
+ *    perf stat -B -- cat <(echo REFCOUNT_TIMING) > DIRECT
+ */
+void lkdtm_REFCOUNT_TIMING(void)
+{
+	unsigned int i;
+	refcount_t count = REFCOUNT_INIT(1);
+
+	for (i = 0; i < INT_MAX - 1; i++)
+		refcount_inc(&count);
+
+	for (i = INT_MAX; i > 0; i--)
+		if (refcount_dec_and_test(&count))
+			break;
+
+	if (i != 1)
+		pr_err("refcount: out of sync up/down cycle: %u\n", i - 1);
+	else
+		pr_info("refcount timing: done\n");
+}