drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validationgrafted

amdgpu_dm_create_validate_stream_for_sink() walks encoding_order[] and
uses the first encoding that validates. YCbCr 4:4:4 is listed before
RGB, so an HDMI sink that advertises 4:4:4 gets YCbCr 4:4:4 whenever the
"color format" property is left at AUTO, even though RGB fits the same
link.

That contradicts the documented AUTO behaviour for HDMI in enum
drm_connector_color_format (RGB, falling back to YCbCr 4:2:0 only when
the bandwidth is not available or the mode is 4:2:0-only), which the
amdgpu implementation of the property also describes. It also leaves
the "Broadcast RGB" property without effect on such sinks, since the
quantization range it selects only applies to RGB output.

Try RGB first. The mask still holds every encoding the sink supports,
so a mode that cannot carry RGB falls back exactly as before.

For reference, v7.2 picked RGB here unless YCbCr 4:4:4 was forced
through debugfs, while earlier kernels picked YCbCr 4:4:4 for any HDMI
sink that advertised it.

Fixes: 0b0ff65d3ca1 ("drm/amd/display: Refactor stream validation")
Suggested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Assisted-by: Claude Code:claude-fable-5-1
Signed-off-by: Adrian Betschart <adrian.betschart@cinemaone.ch>
Reviewed-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7)

1 files changed, 885 insertions, 0 deletions

diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
new file mode 100644
index 000000000..3eca2ef64
--- /dev/null
+++ b/drivers/misc/lkdtm/bugs.c
@@ -0,0 +1,885 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This is for all the tests related to logic bugs (e.g. bad dereferences,
+ * bad alignment, bad loops, bad locking, bad scheduling, deep stacks, and
+ * lockups) along with other things that don't fit well into existing LKDTM
+ * test source files.
+ */
+#include "lkdtm.h"
+#include <linux/cpu.h>
+#include <linux/efi.h>
+#include <linux/list.h>
+#include <linux/hrtimer.h>
+#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task_stack.h>
+#include <linux/slab.h>
+#include <linux/stop_machine.h>
+#include <linux/uaccess.h>
+
+#if IS_ENABLED(CONFIG_X86_32) && !IS_ENABLED(CONFIG_UML)
+#include <asm/desc.h>
+#endif
+
+struct lkdtm_list {
+	struct list_head node;
+};
+
+/*
+ * Make sure our attempts to over run the kernel stack doesn't trigger
+ * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
+ * recurse past the end of THREAD_SIZE by default.
+ */
+#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
+#define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2)
+#else
+#define REC_STACK_SIZE (THREAD_SIZE / 8UL)
+#endif
+#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
+
+static int recur_count = REC_NUM_DEFAULT;
+
+static DEFINE_SPINLOCK(lock_me_up);
+
+/*
+ * Make sure compiler does not optimize this function or stack frame away:
+ * - function marked noinline
+ * - stack variables are marked volatile
+ * - stack variables are written (memset()) and read (buf[..] passed as arg)
+ * - function may have external effects (memzero_explicit())
+ * - no tail recursion possible
+ */
+static int noinline recursive_loop(int remaining)
+{
+	volatile char buf[REC_STACK_SIZE];
+	volatile int ret;
+
+	memset((void *)buf, remaining & 0xFF, sizeof(buf));
+	if (!remaining)
+		ret = 0;
+	else
+		ret = recursive_loop((int)buf[remaining % sizeof(buf)] - 1);
+	memzero_explicit((void *)buf, sizeof(buf));
+	return ret;
+}
+
+/* If the depth is negative, use the default, otherwise keep parameter. */
+void __init lkdtm_bugs_init(int *recur_param)
+{
+	if (*recur_param < 0)
+		*recur_param = recur_count;
+	else
+		recur_count = *recur_param;
+}
+
+static void lkdtm_PANIC(void)
+{
+	panic("dumptest");
+}
+
+static int panic_stop_irqoff_fn(void *arg)
+{
+	atomic_t *v = arg;
+
+	/*
+	 * As stop_machine() disables interrupts, all CPUs within this function
+	 * have interrupts disabled and cannot take a regular IPI.
+	 *
+	 * The last CPU which enters here will trigger a panic, and as all CPUs
+	 * cannot take a regular IPI, we'll only be able to stop secondaries if
+	 * smp_send_stop() or crash_smp_send_stop() uses an NMI.
+	 */
+	if (atomic_inc_return(v) == num_online_cpus())
+		panic("panic stop irqoff test");
+
+	for (;;)
+		cpu_relax();
+}
+
+static void lkdtm_PANIC_STOP_IRQOFF(void)
+{
+	atomic_t v = ATOMIC_INIT(0);
+	stop_machine(panic_stop_irqoff_fn, &v, cpu_online_mask);
+}
+
+static bool wait_for_panic;
+
+static enum hrtimer_restart panic_in_hardirq(struct hrtimer *timer)
+{
+	panic("from hard IRQ context");
+
+	wait_for_panic = false;
+	return HRTIMER_NORESTART;
+}
+
+static void lkdtm_PANIC_IN_HARDIRQ(void)
+{
+	struct hrtimer timer;
+
+	wait_for_panic = true;
+	hrtimer_setup_on_stack(&timer, panic_in_hardirq,
+			       CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
+	hrtimer_start(&timer, us_to_ktime(100), HRTIMER_MODE_REL_HARD);
+
+	while (READ_ONCE(wait_for_panic))
+		cpu_relax();
+
+	hrtimer_cancel(&timer);
+}
+
+static void lkdtm_BUG(void)
+{
+	BUG();
+}
+
+static bool wait_for_bug;
+
+static enum hrtimer_restart bug_in_hardirq(struct hrtimer *timer)
+{
+	BUG();
+
+	wait_for_bug = false;
+	return HRTIMER_NORESTART;
+}
+
+static void lkdtm_BUG_IN_HARDIRQ(void)
+{
+	struct hrtimer timer;
+
+	wait_for_bug = true;
+	hrtimer_setup_on_stack(&timer, bug_in_hardirq,
+			       CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
+	hrtimer_start(&timer, us_to_ktime(100), HRTIMER_MODE_REL_HARD);
+
+	while (READ_ONCE(wait_for_bug))
+		cpu_relax();
+
+	hrtimer_cancel(&timer);
+}
+
+static int warn_counter;
+
+static void lkdtm_WARNING(void)
+{
+	WARN_ON(++warn_counter);
+}
+
+static void lkdtm_WARNING_MESSAGE(void)
+{
+	WARN(1, "Warning message trigger count: %d\n", ++warn_counter);
+}
+
+static void lkdtm_EXCEPTION(void)
+{
+	*((volatile int *) 0) = 0;
+}
+
+static void lkdtm_LOOP(void)
+{
+	for (;;)
+		;
+}
+
+static void lkdtm_EXHAUST_STACK(void)
+{
+	pr_info("Calling function with %lu frame size to depth %d ...\n",
+		REC_STACK_SIZE, recur_count);
+	recursive_loop(recur_count);
+	pr_info("FAIL: survived without exhausting stack?!\n");
+}
+
+static noinline void __lkdtm_CORRUPT_STACK(void *stack)
+{
+	memset(stack, '\xff', 64);
+}
+
+/* This should trip the stack canary, not corrupt the return address. */
+static noinline void lkdtm_CORRUPT_STACK(void)
+{
+	/* Use default char array length that triggers stack protection. */
+	char data[8] __aligned(sizeof(void *));
+
+	pr_info("Corrupting stack containing char array ...\n");
+	__lkdtm_CORRUPT_STACK((void *)&data);
+}
+
+/* Same as above but will only get a canary with -fstack-protector-strong */
+static noinline void lkdtm_CORRUPT_STACK_STRONG(void)
+{
+	union {
+		unsigned short shorts[4];
+		unsigned long *ptr;
+	} data __aligned(sizeof(void *));
+
+	pr_info("Corrupting stack containing union ...\n");
+	__lkdtm_CORRUPT_STACK((void *)&data);
+}
+
+static pid_t stack_pid;
+static unsigned long stack_addr;
+
+static void lkdtm_REPORT_STACK(void)
+{
+	volatile uintptr_t magic;
+	pid_t pid = task_pid_nr(current);
+
+	if (pid != stack_pid) {
+		pr_info("Starting stack offset tracking for pid %d\n", pid);
+		stack_pid = pid;
+		stack_addr = (uintptr_t)&magic;
+	}
+
+	pr_info("Stack offset: %d\n", (int)(stack_addr - (uintptr_t)&magic));
+}
+
+static pid_t stack_canary_pid;
+static unsigned long stack_canary;
+static unsigned long stack_canary_offset;
+
+static noinline void __lkdtm_REPORT_STACK_CANARY(void *stack)
+{
+	int i = 0;
+	pid_t pid = task_pid_nr(current);
+	unsigned long *canary = (unsigned long *)stack;
+	unsigned long current_offset = 0, init_offset = 0;
+
+	/* Do our best to find the canary in a 16 word window ... */
+	for (i = 1; i < 16; i++) {
+		canary = (unsigned long *)stack + i;
+#ifdef CONFIG_STACKPROTECTOR
+		if (*canary == current->stack_canary)
+			current_offset = i;
+		if (*canary == init_task.stack_canary)
+			init_offset = i;
+#endif
+	}
+
+	if (current_offset == 0) {
+		/*
+		 * If the canary doesn't match what's in the task_struct,
+		 * we're either using a global canary or the stack frame
+		 * layout changed.
+		 */
+		if (init_offset != 0) {
+			pr_err("FAIL: global stack canary found at offset %ld (canary for pid %d matches init_task's)!\n",
+			       init_offset, pid);
+		} else {
+			pr_warn("FAIL: did not correctly locate stack canary :(\n");
+			pr_expected_config(CONFIG_STACKPROTECTOR);
+		}
+
+		return;
+	} else if (init_offset != 0) {
+		pr_warn("WARNING: found both current and init_task canaries nearby?!\n");
+	}
+
+	canary = (unsigned long *)stack + current_offset;
+	if (stack_canary_pid == 0) {
+		stack_canary = *canary;
+		stack_canary_pid = pid;
+		stack_canary_offset = current_offset;
+		pr_info("Recorded stack canary for pid %d at offset %ld\n",
+			stack_canary_pid, stack_canary_offset);
+	} else if (pid == stack_canary_pid) {
+		pr_warn("ERROR: saw pid %d again -- please use a new pid\n", pid);
+	} else {
+		if (current_offset != stack_canary_offset) {
+			pr_warn("ERROR: canary offset changed from %ld to %ld!?\n",
+				stack_canary_offset, current_offset);
+			return;
+		}
+
+		if (*canary == stack_canary) {
+			pr_warn("FAIL: canary identical for pid %d and pid %d at offset %ld!\n",
+				stack_canary_pid, pid, current_offset);
+		} else {
+			pr_info("ok: stack canaries differ between pid %d and pid %d at offset %ld.\n",
+				stack_canary_pid, pid, current_offset);
+			/* Reset the test. */
+			stack_canary_pid = 0;
+		}
+	}
+}
+
+static void lkdtm_REPORT_STACK_CANARY(void)
+{
+	/* Use default char array length that triggers stack protection. */
+	char data[8] __aligned(sizeof(void *)) = { };
+
+	__lkdtm_REPORT_STACK_CANARY((void *)&data);
+}
+
+static void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)
+{
+	static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5};
+	u32 *p;
+	u32 val = 0x12345678;
+
+	p = (u32 *)(data + 1);
+	if (*p == 0)
+		val = 0x87654321;
+	*p = val;
+
+	if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
+		pr_err("XFAIL: arch has CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS\n");
+}
+
+static void lkdtm_SOFTLOCKUP(void)
+{
+	preempt_disable();
+	for (;;)
+		cpu_relax();
+}
+
+static void lkdtm_HARDLOCKUP(void)
+{
+	local_irq_disable();
+	for (;;)
+		cpu_relax();
+}
+
+static void __lkdtm_SMP_CALL_LOCKUP(void *unused)
+{
+	for (;;)
+		cpu_relax();
+}
+
+static void lkdtm_SMP_CALL_LOCKUP(void)
+{
+	unsigned int cpu, target;
+
+	cpus_read_lock();
+
+	cpu = get_cpu();
+	target = cpumask_any_but(cpu_online_mask, cpu);
+
+	if (target >= nr_cpu_ids) {
+		pr_err("FAIL: no other online CPUs\n");
+		goto out_put_cpus;
+	}
+
+	smp_call_function_single(target, __lkdtm_SMP_CALL_LOCKUP, NULL, 1);
+
+	pr_err("FAIL: did not hang\n");
+
+out_put_cpus:
+	put_cpu();
+	cpus_read_unlock();
+}
+
+static void lkdtm_SPINLOCKUP(void)
+{
+	/* Must be called twice to trigger. */
+	spin_lock(&lock_me_up);
+	/* Let sparse know we intended to exit holding the lock. */
+	__release(&lock_me_up);
+}
+
+static void __noreturn lkdtm_HUNG_TASK(void)
+{
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	schedule();
+	BUG();
+}
+
+static volatile unsigned int huge = INT_MAX - 2;
+static volatile unsigned int ignored;
+
+static void lkdtm_OVERFLOW_SIGNED(void)
+{
+	int value;
+
+	value = huge;
+	pr_info("Normal signed addition ...\n");
+	value += 1;
+	ignored = value;
+
+	pr_info("Overflowing signed addition ...\n");
+	value += 4;
+	ignored = value;
+}
+
+
+static void lkdtm_OVERFLOW_UNSIGNED(void)
+{
+	unsigned int value;
+
+	value = huge;
+	pr_info("Normal unsigned addition ...\n");
+	value += 1;
+	ignored = value;
+
+	pr_info("Overflowing unsigned addition ...\n");
+	value += 4;
+	ignored = value;
+}
+
+/* Intentionally using unannotated flex array definition. */
+struct array_bounds_flex_array {
+	int one;
+	int two;
+	char data[];
+};
+
+struct array_bounds {
+	int one;
+	int two;
+	char data[8];
+	int three;
+};
+
+static void lkdtm_ARRAY_BOUNDS(void)
+{
+	struct array_bounds_flex_array *not_checked;
+	struct array_bounds *checked;
+	volatile int i;
+
+	not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL);
+	checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL);
+	if (!not_checked || !checked) {
+		kfree(not_checked);
+		kfree(checked);
+		return;
+	}
+
+	pr_info("Array access within bounds ...\n");
+	/* For both, touch all bytes in the actual member size. */
+	for (i = 0; i < sizeof(checked->data); i++)
+		checked->data[i] = 'A';
+	/*
+	 * For the uninstrumented flex array member, also touch 1 byte
+	 * beyond to verify it is correctly uninstrumented.
+	 */
+	for (i = 0; i < 2; i++)
+		not_checked->data[i] = 'A';
+
+	pr_info("Array access beyond bounds ...\n");
+	for (i = 0; i < sizeof(checked->data) + 1; i++)
+		checked->data[i] = 'B';
+
+	kfree(not_checked);
+	kfree(checked);
+	pr_err("FAIL: survived array bounds overflow!\n");
+	if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
+		pr_expected_config(CONFIG_UBSAN_TRAP);
+	else
+		pr_expected_config(CONFIG_UBSAN_BOUNDS);
+}
+
+struct lkdtm_cb_fam {
+	unsigned long flags;
+	int count;
+	int array[] __counted_by(count);
+};
+
+static volatile int element_count = 4;
+
+static void lkdtm_FAM_BOUNDS(void)
+{
+	struct lkdtm_cb_fam *inst;
+
+	inst = kzalloc_flex(*inst, array, element_count + 1);
+	if (!inst) {
+		pr_err("FAIL: could not allocate test struct!\n");
+		return;
+	}
+
+	inst->count = element_count;
+	pr_info("Array access within bounds ...\n");
+	inst->array[1] = element_count;
+	ignored = inst->array[1];
+
+	pr_info("Array access beyond bounds ...\n");
+	inst->array[element_count] = element_count;
+	ignored = inst->array[element_count];
+
+	kfree(inst);
+
+	pr_err("FAIL: survived access of invalid flexible array member index!\n");
+
+	if (!IS_ENABLED(CONFIG_CC_HAS_COUNTED_BY))
+		pr_warn("This is expected since this %s was built with a compiler that does not support __counted_by\n",
+			lkdtm_kernel_info);
+	else if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
+		pr_expected_config(CONFIG_UBSAN_TRAP);
+	else
+		pr_expected_config(CONFIG_UBSAN_BOUNDS);
+}
+
+struct lkdtm_extra {
+	short a, b;
+	u16 sixteen;
+	u32 bigger;
+	u64 biggest;
+};
+
+struct lkdtm_cb_ptr {
+	int a, b, c;
+	int nr_extra;
+	char *buf __counted_by_ptr(len);
+	size_t len;
+	struct lkdtm_extra *extra __counted_by_ptr(nr_extra);
+};
+
+static noinline void check_ptr_len(struct lkdtm_cb_ptr *p, size_t len)
+{
+	if (__member_size(p->buf) != len)
+		pr_err("FAIL: could not determine size of inst->buf: %zu\n",
+			__member_size(p->buf));
+	else
+		pr_info("good: inst->buf length is %zu\n", len);
+}
+
+static void lkdtm_PTR_BOUNDS(void)
+{
+	struct lkdtm_cb_ptr *inst;
+
+	inst = kzalloc_obj(*inst);
+	if (!inst) {
+		pr_err("FAIL: could not allocate struct lkdtm_cb_ptr!\n");
+		return;
+	}
+
+	inst->buf = kzalloc(element_count, GFP_KERNEL);
+	if (!inst->buf) {
+		pr_err("FAIL: could not allocate inst->buf!\n");
+		return;
+	}
+	inst->len = element_count;
+
+	/* Double element_count */
+	inst->extra = kzalloc_objs(*inst->extra, element_count * 2);
+	inst->nr_extra = element_count * 2;
+
+	pr_info("Pointer access within bounds ...\n");
+	check_ptr_len(inst, 4);
+	/* All 4 bytes */
+	inst->buf[0] = 'A';
+	inst->buf[1] = 'B';
+	inst->buf[2] = 'C';
+	inst->buf[3] = 'D';
+	/* Halfway into the array */
+	inst->extra[element_count].biggest = 0x1000;
+
+	pr_info("Pointer access beyond bounds ...\n");
+	ignored = inst->extra[inst->nr_extra].b;
+
+	kfree(inst->extra);
+	kfree(inst->buf);
+	kfree(inst);
+
+	pr_err("FAIL: survived access of invalid pointer member offset!\n");
+
+	if (!IS_ENABLED(CONFIG_CC_HAS_COUNTED_BY_PTR))
+		pr_warn("This is expected since this %s was built with a compiler that does not support __counted_by_ptr\n",
+			lkdtm_kernel_info);
+	else if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
+		pr_expected_config(CONFIG_UBSAN_TRAP);
+	else
+		pr_expected_config(CONFIG_UBSAN_BOUNDS);
+}
+
+static void lkdtm_CORRUPT_LIST_ADD(void)
+{
+	/*
+	 * Initially, an empty list via LIST_HEAD:
+	 *	test_head.next = &test_head
+	 *	test_head.prev = &test_head
+	 */
+	LIST_HEAD(test_head);
+	struct lkdtm_list good, bad;
+	void *target[2] = { };
+	void *redirection = &target;
+
+	pr_info("attempting good list addition\n");
+
+	/*
+	 * Adding to the list performs these actions:
+	 *	test_head.next->prev = &good.node
+	 *	good.node.next = test_head.next
+	 *	good.node.prev = test_head
+	 *	test_head.next = good.node
+	 */
+	list_add(&good.node, &test_head);
+
+	pr_info("attempting corrupted list addition\n");
+	/*
+	 * In simulating this "write what where" primitive, the "what" is
+	 * the address of &bad.node, and the "where" is the address held
+	 * by "redirection".
+	 */
+	test_head.next = redirection;
+	list_add(&bad.node, &test_head);
+
+	if (target[0] == NULL && target[1] == NULL)
+		pr_err("Overwrite did not happen, but no BUG?!\n");
+	else {
+		pr_err("list_add() corruption not detected!\n");
+		pr_expected_config(CONFIG_LIST_HARDENED);
+	}
+}
+
+static void lkdtm_CORRUPT_LIST_DEL(void)
+{
+	LIST_HEAD(test_head);
+	struct lkdtm_list item;
+	void *target[2] = { };
+	void *redirection = &target;
+
+	list_add(&item.node, &test_head);
+
+	pr_info("attempting good list removal\n");
+	list_del(&item.node);
+
+	pr_info("attempting corrupted list removal\n");
+	list_add(&item.node, &test_head);
+
+	/* As with the list_add() test above, this corrupts "next". */
+	item.node.next = redirection;
+	list_del(&item.node);
+
+	if (target[0] == NULL && target[1] == NULL)
+		pr_err("Overwrite did not happen, but no BUG?!\n");
+	else {
+		pr_err("list_del() corruption not detected!\n");
+		pr_expected_config(CONFIG_LIST_HARDENED);
+	}
+}
+
+/* Test that VMAP_STACK is actually allocating with a leading guard page */
+static void lkdtm_STACK_GUARD_PAGE_LEADING(void)
+{
+	const unsigned char *stack = task_stack_page(current);
+	const unsigned char *ptr = stack - 1;
+	volatile unsigned char byte;
+
+	pr_info("attempting bad read from page below current stack\n");
+
+	byte = *ptr;
+
+	pr_err("FAIL: accessed page before stack! (byte: %x)\n", byte);
+}
+
+/* Test that VMAP_STACK is actually allocating with a trailing guard page */
+static void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
+{
+	const unsigned char *stack = task_stack_page(current);
+	const unsigned char *ptr = stack + THREAD_SIZE;
+	volatile unsigned char byte;
+
+	pr_info("attempting bad read from page above current stack\n");
+
+	byte = *ptr;
+
+	pr_err("FAIL: accessed page after stack! (byte: %x)\n", byte);
+}
+
+static void lkdtm_UNSET_SMEP(void)
+{
+#if IS_ENABLED(CONFIG_X86_64) && !IS_ENABLED(CONFIG_UML)
+#define MOV_CR4_DEPTH	64
+	void (*direct_write_cr4)(unsigned long val);
+	unsigned char *insn;
+	unsigned long cr4;
+	int i;
+
+	cr4 = native_read_cr4();
+
+	if ((cr4 & X86_CR4_SMEP) != X86_CR4_SMEP) {
+		pr_err("FAIL: SMEP not in use\n");
+		return;
+	}
+	cr4 &= ~(X86_CR4_SMEP);
+
+	pr_info("trying to clear SMEP normally\n");
+	native_write_cr4(cr4);
+	if (cr4 == native_read_cr4()) {
+		pr_err("FAIL: pinning SMEP failed!\n");
+		cr4 |= X86_CR4_SMEP;
+		pr_info("restoring SMEP\n");
+		native_write_cr4(cr4);
+		return;
+	}
+	pr_info("ok: SMEP did not get cleared\n");
+
+	/*
+	 * To test the post-write pinning verification we need to call
+	 * directly into the middle of native_write_cr4() where the
+	 * cr4 write happens, skipping any pinning. This searches for
+	 * the cr4 writing instruction.
+	 */
+	insn = (unsigned char *)native_write_cr4;
+	OPTIMIZER_HIDE_VAR(insn);
+	for (i = 0; i < MOV_CR4_DEPTH; i++) {
+		/* mov %rdi, %cr4 */
+		if (insn[i] == 0x0f && insn[i+1] == 0x22 && insn[i+2] == 0xe7)
+			break;
+		/* mov %rdi,%rax; mov %rax, %cr4 */
+		if (insn[i]   == 0x48 && insn[i+1] == 0x89 &&
+		    insn[i+2] == 0xf8 && insn[i+3] == 0x0f &&
+		    insn[i+4] == 0x22 && insn[i+5] == 0xe0)
+			break;
+	}
+	if (i >= MOV_CR4_DEPTH) {
+		pr_info("ok: cannot locate cr4 writing call gadget\n");
+		return;
+	}
+	direct_write_cr4 = (void *)(insn + i);
+
+	pr_info("trying to clear SMEP with call gadget\n");
+	direct_write_cr4(cr4);
+	if (native_read_cr4() & X86_CR4_SMEP) {
+		pr_info("ok: SMEP removal was reverted\n");
+	} else {
+		pr_err("FAIL: cleared SMEP not detected!\n");
+		cr4 |= X86_CR4_SMEP;
+		pr_info("restoring SMEP\n");
+		native_write_cr4(cr4);
+	}
+#else
+	pr_err("XFAIL: this test is x86_64-only\n");
+#endif
+}
+
+static void lkdtm_DOUBLE_FAULT(void)
+{
+#if IS_ENABLED(CONFIG_X86_32) && !IS_ENABLED(CONFIG_UML)
+	/*
+	 * Trigger #DF by setting the stack limit to zero.  This clobbers
+	 * a GDT TLS slot, which is okay because the current task will die
+	 * anyway due to the double fault.
+	 */
+	struct desc_struct d = {
+		.type = 3,	/* expand-up, writable, accessed data */
+		.p = 1,		/* present */
+		.d = 1,		/* 32-bit */
+		.g = 0,		/* limit in bytes */
+		.s = 1,		/* not system */
+	};
+
+	local_irq_disable();
+	write_gdt_entry(get_cpu_gdt_rw(smp_processor_id()),
+			GDT_ENTRY_TLS_MIN, &d, DESCTYPE_S);
+
+	/*
+	 * Put our zero-limit segment in SS and then trigger a fault.  The
+	 * 4-byte access to (%esp) will fault with #SS, and the attempt to
+	 * deliver the fault will recursively cause #SS and result in #DF.
+	 * This whole process happens while NMIs and MCEs are blocked by the
+	 * MOV SS window.  This is nice because an NMI with an invalid SS
+	 * would also double-fault, resulting in the NMI or MCE being lost.
+	 */
+	asm volatile ("movw %0, %%ss; addl $0, (%%esp)" ::
+		      "r" ((unsigned short)(GDT_ENTRY_TLS_MIN << 3)));
+
+	pr_err("FAIL: tried to double fault but didn't die\n");
+#else
+	pr_err("XFAIL: this test is ia32-only\n");
+#endif
+}
+
+#ifdef CONFIG_ARM64
+static noinline void change_pac_parameters(void)
+{
+	if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) {
+		/* Reset the keys of current task */
+		ptrauth_thread_init_kernel(current);
+		ptrauth_thread_switch_kernel(current);
+	}
+}
+#endif
+
+static noinline void lkdtm_CORRUPT_PAC(void)
+{
+#ifdef CONFIG_ARM64
+#define CORRUPT_PAC_ITERATE	10
+	int i;
+
+	if (!IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
+		pr_err("FAIL: kernel not built with CONFIG_ARM64_PTR_AUTH_KERNEL\n");
+
+	if (!system_supports_address_auth()) {
+		pr_err("FAIL: CPU lacks pointer authentication feature\n");
+		return;
+	}
+
+	pr_info("changing PAC parameters to force function return failure...\n");
+	/*
+	 * PAC is a hash value computed from input keys, return address and
+	 * stack pointer. As pac has fewer bits so there is a chance of
+	 * collision, so iterate few times to reduce the collision probability.
+	 */
+	for (i = 0; i < CORRUPT_PAC_ITERATE; i++)
+		change_pac_parameters();
+
+	pr_err("FAIL: survived PAC changes! Kernel may be unstable from here\n");
+#else
+	pr_err("XFAIL: this test is arm64-only\n");
+#endif
+}
+
+static void __maybe_unused lkdtm_EFI_RUNTIME_CRASH(void)
+{
+	static unsigned long size __ro_after_init = sizeof(efi_char16_t);
+	efi_status_t status;
+
+	if (!efi.get_next_variable ||
+	    !efi_enabled(EFI_RUNTIME_SERVICES) ||
+	    !efi_rt_services_supported(EFI_RT_SUPPORTED_GET_NEXT_VARIABLE_NAME)) {
+		pr_err("FAIL: EFI GetNextVariableName() is not available\n");
+		return;
+	}
+
+	/*
+	 * Provoke a fault by asking the firmware to write to a read-only
+	 * variable.
+	 */
+	status = efi.get_next_variable(&size, L"", &(efi_guid_t){});
+
+	if (status != EFI_ABORTED || efi_enabled(EFI_RUNTIME_SERVICES))
+		pr_err("FAIL: EFI GetNextVariable() did not abort (%#lx)\n",
+		       status);
+}
+
+static struct crashtype crashtypes[] = {
+	CRASHTYPE(PANIC),
+	CRASHTYPE(PANIC_STOP_IRQOFF),
+	CRASHTYPE(PANIC_IN_HARDIRQ),
+	CRASHTYPE(BUG),
+	CRASHTYPE(BUG_IN_HARDIRQ),
+	CRASHTYPE(WARNING),
+	CRASHTYPE(WARNING_MESSAGE),
+	CRASHTYPE(EXCEPTION),
+	CRASHTYPE(LOOP),
+	CRASHTYPE(EXHAUST_STACK),
+	CRASHTYPE(CORRUPT_STACK),
+	CRASHTYPE(CORRUPT_STACK_STRONG),
+	CRASHTYPE(REPORT_STACK),
+	CRASHTYPE(REPORT_STACK_CANARY),
+	CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
+	CRASHTYPE(SOFTLOCKUP),
+	CRASHTYPE(HARDLOCKUP),
+	CRASHTYPE(SMP_CALL_LOCKUP),
+	CRASHTYPE(SPINLOCKUP),
+	CRASHTYPE(HUNG_TASK),
+	CRASHTYPE(OVERFLOW_SIGNED),
+	CRASHTYPE(OVERFLOW_UNSIGNED),
+	CRASHTYPE(ARRAY_BOUNDS),
+	CRASHTYPE(FAM_BOUNDS),
+	CRASHTYPE(PTR_BOUNDS),
+	CRASHTYPE(CORRUPT_LIST_ADD),
+	CRASHTYPE(CORRUPT_LIST_DEL),
+	CRASHTYPE(STACK_GUARD_PAGE_LEADING),
+	CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
+	CRASHTYPE(UNSET_SMEP),
+	CRASHTYPE(DOUBLE_FAULT),
+	CRASHTYPE(CORRUPT_PAC),
+#ifdef CONFIG_EFI
+	CRASHTYPE(EFI_RUNTIME_CRASH),
+#endif
+};
+
+struct crashtype_category bugs_crashtypes = {
+	.crashtypes = crashtypes,
+	.len	    = ARRAY_SIZE(crashtypes),
+};