// 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\n",
                        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\n",
                                        head, compound_order(head),
                                        head_compound_mapcount(head),
                                        head_compound_pincount(head));
                } else {
                        pr_warn("head:%p order:%u compound_mapcount:%d\n",
                                        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?\n");
                        goto out_mapping;
                }

                if (!host) {
                        pr_warn("aops:%ps\n", 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\n",
                                        a_ops, host);
                        goto out_mapping;
                }

                if (!dentry_first) {
                        pr_warn("aops:%ps ino:%lx\n", 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\n",
                                        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\"\n",
                                        a_ops, ino, &dentry);
                }
        }
out_mapping:
        BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);

        pr_warn("%sflags: %#lx(%pGp)%s\n", 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\n", reason);

#ifdef CONFIG_MEMCG
        if (!page_poisoned && page->memcg_data)
                pr_warn("pages's memcg:%lx\n", page->memcg_data);
#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\n"
                "next %px prev %px mm %px\n"
                "prot %lx anon_vma %px vm_ops %px\n"
                "pgoff %lx file %px private_data %px\n"
                "flags: %#lx(%pGv)\n",
                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\n"
#ifdef CONFIG_MMU
                "get_unmapped_area %px\n"
#endif
                "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
                "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
                "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
                "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
                "start_code %lx end_code %lx start_data %lx end_data %lx\n"
                "start_brk %lx brk %lx start_stack %lx\n"
                "arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
                "binfmt %px flags %lx core_state %px\n"
#ifdef CONFIG_AIO
                "ioctx_table %px\n"
#endif
#ifdef CONFIG_MEMCG
                "owner %px "
#endif
                "exe_file %px\n"
#ifdef CONFIG_MMU_NOTIFIER
                "notifier_subscriptions %px\n"
#endif
#ifdef CONFIG_NUMA_BALANCING
                "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
#endif
                "tlb_flush_pending %d\n"
                "def_flags: %#lx(%pGv)\n",

                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\n",
                               *str);
                }

                str++;
        }
out:
        if (page_init_poisoning && !__page_init_poisoning)
                pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");

        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 */