// SPDX-License-Identifier: GPL-2.0

  /*
   * mm/debug.c
   *
   * mm/ specific debug routines.
   *
   */

  #include <linux/kernel.h>
  #include <linux/mm.h>

  #include <linux/trace_events.h>

  #include <linux/memcontrol.h>

  #include <trace/events/mmflags.h>

  #include <linux/migrate.h>

  #include <linux/page_owner.h>

  #include <linux/ctype.h>

  #include "internal.h"

  const char *migrate_reason_names[MR_TYPES] = {

  	"compaction",
  	"memory_failure",
  	"memory_hotplug",
  	"syscall_or_cpuset",
  	"mempolicy_mbind",
  	"numa_misplaced",
  	"cma",
  };

  const struct trace_print_flags pageflag_names[] = {
  	__def_pageflag_names,
  	{0, NULL}
  };
  
  const struct trace_print_flags gfpflag_names[] = {
  	__def_gfpflag_names,
  	{0, NULL}

  };

  const struct trace_print_flags vmaflag_names[] = {
  	__def_vmaflag_names,
  	{0, NULL}

  };

  void __dump_page(struct page *page, const char *reason)

  {

  	struct page *head = compound_head(page);

  	struct address_space *mapping;

  	bool page_poisoned = PagePoisoned(page);

  	bool compound = PageCompound(page);

  	/*
  	 * Accessing the pageblock without the zone lock. It could change to
  	 * "isolate" again in the meantime, but since we are just dumping the
  	 * state for debugging, it should be fine to accept a bit of
  	 * inaccuracy here due to racing.
  	 */
  	bool page_cma = is_migrate_cma_page(page);

  	int mapcount;

  	char *type = "";

  
  	/*
  	 * If struct page is poisoned don't access Page*() functions as that
  	 * leads to recursive loop. Page*() check for poisoned pages, and calls
  	 * dump_page() when detected.
  	 */
  	if (page_poisoned) {

  		pr_warn("page:%px is uninitialized and poisoned", page);

  		goto hex_only;
  	}

  	if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {

  		/*
  		 * Corrupt page, so we cannot call page_mapping. Instead, do a
  		 * safe subset of the steps that page_mapping() does. Caution:
  		 * this will be misleading for tail pages, PageSwapCache pages,
  		 * and potentially other situations. (See the page_mapping()
  		 * implementation for what's missing here.)
  		 */
  		unsigned long tmp = (unsigned long)page->mapping;
  
  		if (tmp & PAGE_MAPPING_ANON)
  			mapping = NULL;
  		else
  			mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);

  		head = page;
  		compound = false;
  	} else {
  		mapping = page_mapping(page);
  	}

  	/*
  	 * Avoid VM_BUG_ON() in page_mapcount().
  	 * page->_mapcount space in struct page is used by sl[aou]b pages to
  	 * encode own info.
  	 */

  	mapcount = PageSlab(head) ? 0 : page_mapcount(page);

  	pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx
  ",

  			page, page_ref_count(head), mapcount, mapping,

  			page_to_pgoff(page), page_to_pfn(page));

  	if (compound) {

  		if (hpage_pincount_available(page)) {

  			pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d
  ",

  					head, compound_order(head),

  					head_compound_mapcount(head),
  					head_compound_pincount(head));

  		} else {

  			pr_warn("head:%p order:%u compound_mapcount:%d
  ",

  					head, compound_order(head),

  					head_compound_mapcount(head));

  		}

  	}

  	if (PageKsm(page))

  		type = "ksm ";

  	else if (PageAnon(page))

  		type = "anon ";

  	else if (mapping) {

  		struct inode *host;

  		const struct address_space_operations *a_ops;

  		struct hlist_node *dentry_first;
  		struct dentry *dentry_ptr;

  		struct dentry dentry;

  		unsigned long ino;

  
  		/*
  		 * mapping can be invalid pointer and we don't want to crash
  		 * accessing it, so probe everything depending on it carefully
  		 */

  		if (get_kernel_nofault(host, &mapping->host) ||
  		    get_kernel_nofault(a_ops, &mapping->a_ops)) {
  			pr_warn("failed to read mapping contents, not a valid kernel address?
  ");

  			goto out_mapping;
  		}
  
  		if (!host) {

  			pr_warn("aops:%ps
  ", a_ops);

  			goto out_mapping;
  		}

  		if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
  		    get_kernel_nofault(ino, &host->i_ino)) {

  			pr_warn("aops:%ps with invalid host inode %px
  ",
  					a_ops, host);

  			goto out_mapping;
  		}
  
  		if (!dentry_first) {

  			pr_warn("aops:%ps ino:%lx
  ", a_ops, ino);

  			goto out_mapping;
  		}
  
  		dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);

  		if (get_kernel_nofault(dentry, dentry_ptr)) {

  			pr_warn("aops:%ps ino:%lx with invalid dentry %px
  ",
  					a_ops, ino, dentry_ptr);

  		} else {
  			/*
  			 * if dentry is corrupted, the %pd handler may still
  			 * crash, but it's unlikely that we reach here with a
  			 * corrupted struct page
  			 */

  			pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"
  ",

  					a_ops, ino, &dentry);

  		}

  	}

  out_mapping:

  	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);

  	pr_warn("%sflags: %#lx(%pGp)%s
  ", type, head->flags, &head->flags,

  		page_cma ? " CMA" : "");

  hex_only:

  	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,

  			sizeof(unsigned long), page,
  			sizeof(struct page), false);

  	if (head != page)
  		print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
  			sizeof(unsigned long), head,
  			sizeof(struct page), false);

  	if (reason)

  		pr_warn("page dumped because: %s
  ", reason);

  #ifdef CONFIG_MEMCG

  	if (!page_poisoned && page->mem_cgroup)

  		pr_warn("page->mem_cgroup:%px
  ", page->mem_cgroup);

  #endif

  }
  
  void dump_page(struct page *page, const char *reason)
  {

  	__dump_page(page, reason);

  	dump_page_owner(page);

  }
  EXPORT_SYMBOL(dump_page);
  
  #ifdef CONFIG_DEBUG_VM

  void dump_vma(const struct vm_area_struct *vma)
  {

  	pr_emerg("vma %px start %px end %px
  "
  		"next %px prev %px mm %px
  "
  		"prot %lx anon_vma %px vm_ops %px
  "
  		"pgoff %lx file %px private_data %px
  "

  		"flags: %#lx(%pGv)
  ",

  		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
  		vma->vm_prev, vma->vm_mm,
  		(unsigned long)pgprot_val(vma->vm_page_prot),
  		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,

  		vma->vm_file, vma->vm_private_data,
  		vma->vm_flags, &vma->vm_flags);

  }
  EXPORT_SYMBOL(dump_vma);

  void dump_mm(const struct mm_struct *mm)
  {

  	pr_emerg("mm %px mmap %px seqnum %llu task_size %lu
  "

  #ifdef CONFIG_MMU

  		"get_unmapped_area %px
  "

  #endif
  		"mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu
  "

  		"pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d
  "

  		"hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx
  "

  		"pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx
  "

  		"start_code %lx end_code %lx start_data %lx end_data %lx
  "
  		"start_brk %lx brk %lx start_stack %lx
  "
  		"arg_start %lx arg_end %lx env_start %lx env_end %lx
  "

  		"binfmt %px flags %lx core_state %px
  "

  #ifdef CONFIG_AIO

  		"ioctx_table %px
  "

  #endif
  #ifdef CONFIG_MEMCG

  		"owner %px "

  #endif

  		"exe_file %px
  "

  #ifdef CONFIG_MMU_NOTIFIER

  		"notifier_subscriptions %px
  "

  #endif
  #ifdef CONFIG_NUMA_BALANCING
  		"numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d
  "
  #endif

  		"tlb_flush_pending %d
  "

  		"def_flags: %#lx(%pGv)
  ",

  		mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,

  #ifdef CONFIG_MMU
  		mm->get_unmapped_area,
  #endif
  		mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
  		mm->pgd, atomic_read(&mm->mm_users),
  		atomic_read(&mm->mm_count),

  		mm_pgtables_bytes(mm),

  		mm->map_count,
  		mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,

  		(u64)atomic64_read(&mm->pinned_vm),

  		mm->data_vm, mm->exec_vm, mm->stack_vm,

  		mm->start_code, mm->end_code, mm->start_data, mm->end_data,
  		mm->start_brk, mm->brk, mm->start_stack,
  		mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
  		mm->binfmt, mm->flags, mm->core_state,
  #ifdef CONFIG_AIO
  		mm->ioctx_table,
  #endif
  #ifdef CONFIG_MEMCG
  		mm->owner,
  #endif
  		mm->exe_file,
  #ifdef CONFIG_MMU_NOTIFIER

  		mm->notifier_subscriptions,

  #endif
  #ifdef CONFIG_NUMA_BALANCING
  		mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
  #endif

  		atomic_read(&mm->tlb_flush_pending),

  		mm->def_flags, &mm->def_flags
  	);

  }

  static bool page_init_poisoning __read_mostly = true;
  
  static int __init setup_vm_debug(char *str)
  {
  	bool __page_init_poisoning = true;
  
  	/*
  	 * Calling vm_debug with no arguments is equivalent to requesting
  	 * to enable all debugging options we can control.
  	 */
  	if (*str++ != '=' || !*str)
  		goto out;
  
  	__page_init_poisoning = false;
  	if (*str == '-')
  		goto out;
  
  	while (*str) {
  		switch (tolower(*str)) {
  		case'p':
  			__page_init_poisoning = true;
  			break;
  		default:
  			pr_err("vm_debug option '%c' unknown. skipped
  ",
  			       *str);
  		}
  
  		str++;
  	}
  out:
  	if (page_init_poisoning && !__page_init_poisoning)
  		pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'
  ");
  
  	page_init_poisoning = __page_init_poisoning;
  
  	return 1;
  }
  __setup("vm_debug", setup_vm_debug);
  
  void page_init_poison(struct page *page, size_t size)
  {
  	if (page_init_poisoning)
  		memset(page, PAGE_POISON_PATTERN, size);
  }
  EXPORT_SYMBOL_GPL(page_init_poison);

  #endif		/* CONFIG_DEBUG_VM */