text: // SPDX-License-Identifier: GPL-2.0
  /*
   * self test for change_page_attr.
   *
   * Clears the a test pte bit on random pages in the direct mapping,
   * then reverts and compares page tables forwards and afterwards.
   */
  #include <linux/memblock.h>
  #include <linux/kthread.h>
  #include <linux/random.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/mm.h>
  #include <linux/vmalloc.h>
  
  #include <asm/cacheflush.h>
  #include <asm/kdebug.h>
  
  /*
   * Only print the results of the first pass:
   */
  static __read_mostly int print = 1;
  
  enum {
  	NTEST			= 3 * 100,
  	NPAGES			= 100,
  #ifdef CONFIG_X86_64
  	LPS			= (1 << PMD_SHIFT),
  #elif defined(CONFIG_X86_PAE)
  	LPS			= (1 << PMD_SHIFT),
  #else
  	LPS			= (1 << 22),
  #endif
  	GPS			= (1<<30)
  };
  
  #define PAGE_CPA_TEST	__pgprot(_PAGE_CPA_TEST)
  
  static int pte_testbit(pte_t pte)
  {
  	return pte_flags(pte) & _PAGE_SOFTW1;
  }
  
  struct split_state {
  	long lpg, gpg, spg, exec;
  	long min_exec, max_exec;
  };
  
  static int print_split(struct split_state *s)
  {
  	long i, expected, missed = 0;
  	int err = 0;
  
  	s->lpg = s->gpg = s->spg = s->exec = 0;
  	s->min_exec = ~0UL;
  	s->max_exec = 0;
  	for (i = 0; i < max_pfn_mapped; ) {
  		unsigned long addr = (unsigned long)__va(i << PAGE_SHIFT);
  		unsigned int level;
  		pte_t *pte;
  
  		pte = lookup_address(addr, &level);
  		if (!pte) {
  			missed++;
  			i++;
  			continue;
  		}
  
  		if (level == PG_LEVEL_1G && sizeof(long) == 8) {
  			s->gpg++;
  			i += GPS/PAGE_SIZE;
  		} else if (level == PG_LEVEL_2M) {
  			if ((pte_val(*pte) & _PAGE_PRESENT) && !(pte_val(*pte) & _PAGE_PSE)) {
  				printk(KERN_ERR
  					"%lx level %d but not PSE %Lx\n",
  					addr, level, (u64)pte_val(*pte));
  				err = 1;
  			}
  			s->lpg++;
  			i += LPS/PAGE_SIZE;
  		} else {
  			s->spg++;
  			i++;
  		}
  		if (!(pte_val(*pte) & _PAGE_NX)) {
  			s->exec++;
  			if (addr < s->min_exec)
  				s->min_exec = addr;
  			if (addr > s->max_exec)
  				s->max_exec = addr;
  		}
  	}
  	if (print) {
  		printk(KERN_INFO
  			" 4k %lu large %lu gb %lu x %lu[%lx-%lx] miss %lu\n",
  			s->spg, s->lpg, s->gpg, s->exec,
  			s->min_exec != ~0UL ? s->min_exec : 0,
  			s->max_exec, missed);
  	}
  
  	expected = (s->gpg*GPS + s->lpg*LPS)/PAGE_SIZE + s->spg + missed;
  	if (expected != i) {
  		printk(KERN_ERR "CPA max_pfn_mapped %lu but expected %lu\n",
  			max_pfn_mapped, expected);
  		return 1;
  	}
  	return err;
  }
  
  static unsigned long addr[NTEST];
  static unsigned int len[NTEST];
  
  static struct page *pages[NPAGES];
  static unsigned long addrs[NPAGES];
  
  /* Change the global bit on random pages in the direct mapping */
  static int pageattr_test(void)
  {
  	struct split_state sa, sb, sc;
  	unsigned long *bm;
  	pte_t *pte, pte0;
  	int failed = 0;
  	unsigned int level;
  	int i, k;
  	int err;
  
  	if (print)
  		printk(KERN_INFO "CPA self-test:\n");
  
  	bm = vzalloc((max_pfn_mapped + 7) / 8);
  	if (!bm) {
  		printk(KERN_ERR "CPA Cannot vmalloc bitmap\n");
  		return -ENOMEM;
  	}
  
  	failed += print_split(&sa);
  
  	for (i = 0; i < NTEST; i++) {
  		unsigned long pfn = prandom_u32() % max_pfn_mapped;
  
  		addr[i] = (unsigned long)__va(pfn << PAGE_SHIFT);
  		len[i] = prandom_u32() % NPAGES;
  		len[i] = min_t(unsigned long, len[i], max_pfn_mapped - pfn - 1);
  
  		if (len[i] == 0)
  			len[i] = 1;
  
  		pte = NULL;
  		pte0 = pfn_pte(0, __pgprot(0)); /* shut gcc up */
  
  		for (k = 0; k < len[i]; k++) {
  			pte = lookup_address(addr[i] + k*PAGE_SIZE, &level);
  			if (!pte || pgprot_val(pte_pgprot(*pte)) == 0 ||
  			    !(pte_val(*pte) & _PAGE_PRESENT)) {
  				addr[i] = 0;
  				break;
  			}
  			if (k == 0) {
  				pte0 = *pte;
  			} else {
  				if (pgprot_val(pte_pgprot(*pte)) !=
  					pgprot_val(pte_pgprot(pte0))) {
  					len[i] = k;
  					break;
  				}
  			}
  			if (test_bit(pfn + k, bm)) {
  				len[i] = k;
  				break;
  			}
  			__set_bit(pfn + k, bm);
  			addrs[k] = addr[i] + k*PAGE_SIZE;
  			pages[k] = pfn_to_page(pfn + k);
  		}
  		if (!addr[i] || !pte || !k) {
  			addr[i] = 0;
  			continue;
  		}
  
  		switch (i % 3) {
  		case 0:
  			err = change_page_attr_set(&addr[i], len[i], PAGE_CPA_TEST, 0);
  			break;
  
  		case 1:
  			err = change_page_attr_set(addrs, len[1], PAGE_CPA_TEST, 1);
  			break;
  
  		case 2:
  			err = cpa_set_pages_array(pages, len[i], PAGE_CPA_TEST);
  			break;
  		}
  
  
  		if (err < 0) {
  			printk(KERN_ERR "CPA %d failed %d\n", i, err);
  			failed++;
  		}
  
  		pte = lookup_address(addr[i], &level);
  		if (!pte || !pte_testbit(*pte) || pte_huge(*pte)) {
  			printk(KERN_ERR "CPA %lx: bad pte %Lx\n", addr[i],
  				pte ? (u64)pte_val(*pte) : 0ULL);
  			failed++;
  		}
  		if (level != PG_LEVEL_4K) {
  			printk(KERN_ERR "CPA %lx: unexpected level %d\n",
  				addr[i], level);
  			failed++;
  		}
  
  	}
  	vfree(bm);
  
  	failed += print_split(&sb);
  
  	for (i = 0; i < NTEST; i++) {
  		if (!addr[i])
  			continue;
  		pte = lookup_address(addr[i], &level);
  		if (!pte) {
  			printk(KERN_ERR "CPA lookup of %lx failed\n", addr[i]);
  			failed++;
  			continue;
  		}
  		err = change_page_attr_clear(&addr[i], len[i], PAGE_CPA_TEST, 0);
  		if (err < 0) {
  			printk(KERN_ERR "CPA reverting failed: %d\n", err);
  			failed++;
  		}
  		pte = lookup_address(addr[i], &level);
  		if (!pte || pte_testbit(*pte)) {
  			printk(KERN_ERR "CPA %lx: bad pte after revert %Lx\n",
  				addr[i], pte ? (u64)pte_val(*pte) : 0ULL);
  			failed++;
  		}
  
  	}
  
  	failed += print_split(&sc);
  
  	if (failed) {
  		WARN(1, KERN_ERR "NOT PASSED. Please report.\n");
  		return -EINVAL;
  	} else {
  		if (print)
  			printk(KERN_INFO "ok.\n");
  	}
  
  	return 0;
  }
  
  static int do_pageattr_test(void *__unused)
  {
  	while (!kthread_should_stop()) {
  		schedule_timeout_interruptible(HZ*30);
  		if (pageattr_test() < 0)
  			break;
  		if (print)
  			print--;
  	}
  	return 0;
  }
  
  static int start_pageattr_test(void)
  {
  	struct task_struct *p;
  
  	p = kthread_create(do_pageattr_test, NULL, "pageattr-test");
  	if (!IS_ERR(p))
  		wake_up_process(p);
  	else
  		WARN_ON(1);
  
  	return 0;
  }
  device_initcall(start_pageattr_test);
  