/* SPDX-License-Identifier: GPL-2.0 */
/*
 * page allocation tagging
 */
#ifndef _LINUX_PGALLOC_TAG_H
#define _LINUX_PGALLOC_TAG_H

#include <linux/alloc_tag.h>

#ifdef CONFIG_MEM_ALLOC_PROFILING

#include <linux/page_ext.h>

extern struct page_ext_operations page_alloc_tagging_ops;
extern unsigned long alloc_tag_ref_mask;
extern int alloc_tag_ref_offs;
extern struct alloc_tag_kernel_section kernel_tags;

DECLARE_STATIC_KEY_FALSE(mem_profiling_compressed);

typedef u16     pgalloc_tag_idx;

union pgtag_ref_handle {
        union codetag_ref *ref; /* reference in page extension */
        struct page *page;      /* reference in page flags */
};

/* Reserved indexes */
#define CODETAG_ID_NULL         0
#define CODETAG_ID_EMPTY        1
#define CODETAG_ID_FIRST        2

#ifdef CONFIG_MODULES

extern struct alloc_tag_module_section module_tags;

static inline struct alloc_tag *module_idx_to_tag(pgalloc_tag_idx idx)
{
        return &module_tags.first_tag[idx - kernel_tags.count];
}

static inline pgalloc_tag_idx module_tag_to_idx(struct alloc_tag *tag)
{
        return CODETAG_ID_FIRST + kernel_tags.count + (tag - module_tags.first_tag);
}

#else /* CONFIG_MODULES */

static inline struct alloc_tag *module_idx_to_tag(pgalloc_tag_idx idx)
{
        pr_warn("invalid page tag reference %lu\n", (unsigned long)idx);
        return NULL;
}

static inline pgalloc_tag_idx module_tag_to_idx(struct alloc_tag *tag)
{
        pr_warn("invalid page tag 0x%lx\n", (unsigned long)tag);
        return CODETAG_ID_NULL;
}

#endif /* CONFIG_MODULES */

static inline void idx_to_ref(pgalloc_tag_idx idx, union codetag_ref *ref)
{
        switch (idx) {
        case (CODETAG_ID_NULL):
                ref->ct = NULL;
                break;
        case (CODETAG_ID_EMPTY):
                set_codetag_empty(ref);
                break;
        default:
                idx -= CODETAG_ID_FIRST;
                ref->ct = idx < kernel_tags.count ?
                        &kernel_tags.first_tag[idx].ct :
                        &module_idx_to_tag(idx)->ct;
                break;
        }
}

static inline pgalloc_tag_idx ref_to_idx(union codetag_ref *ref)
{
        struct alloc_tag *tag;

        if (!ref->ct)
                return CODETAG_ID_NULL;

        if (is_codetag_empty(ref))
                return CODETAG_ID_EMPTY;

        tag = ct_to_alloc_tag(ref->ct);
        if (tag >= kernel_tags.first_tag && tag < kernel_tags.first_tag + kernel_tags.count)
                return CODETAG_ID_FIRST + (tag - kernel_tags.first_tag);

        return module_tag_to_idx(tag);
}



/* Should be called only if mem_alloc_profiling_enabled() */
static inline bool get_page_tag_ref(struct page *page, union codetag_ref *ref,
                                    union pgtag_ref_handle *handle)
{
        if (!page)
                return false;

        if (static_key_enabled(&mem_profiling_compressed)) {
                pgalloc_tag_idx idx;

                idx = (page->flags.f >> alloc_tag_ref_offs) &
                        alloc_tag_ref_mask;
                idx_to_ref(idx, ref);
                handle->page = page;
        } else {
                struct page_ext *page_ext;
                union codetag_ref *tmp;

                page_ext = page_ext_get(page);
                if (!page_ext)
                        return false;

                tmp = (union codetag_ref *)page_ext_data(page_ext, &page_alloc_tagging_ops);
                ref->ct = tmp->ct;
                handle->ref = tmp;
        }

        return true;
}

static inline void put_page_tag_ref(union pgtag_ref_handle handle)
{
        if (WARN_ON(!handle.ref))
                return;

        if (!static_key_enabled(&mem_profiling_compressed))
                page_ext_put((void *)handle.ref - page_alloc_tagging_ops.offset);
}

static inline void update_page_tag_ref(union pgtag_ref_handle handle, union codetag_ref *ref)
{
        if (static_key_enabled(&mem_profiling_compressed)) {
                struct page *page = handle.page;
                unsigned long old_flags;
                unsigned long flags;
                unsigned long idx;

                if (WARN_ON(!page || !ref))
                        return;

                idx = (unsigned long)ref_to_idx(ref);
                idx = (idx & alloc_tag_ref_mask) << alloc_tag_ref_offs;
                do {
                        old_flags = READ_ONCE(page->flags.f);
                        flags = old_flags;
                        flags &= ~(alloc_tag_ref_mask << alloc_tag_ref_offs);
                        flags |= idx;
                } while (unlikely(!try_cmpxchg(&page->flags.f, &old_flags, flags)));
        } else {
                if (WARN_ON(!handle.ref || !ref))
                        return;

                handle.ref->ct = ref->ct;
        }
}

/* Should be called only if mem_alloc_profiling_enabled() */
void __clear_page_tag_ref(struct page *page);

static inline void clear_page_tag_ref(struct page *page)
{
        if (mem_alloc_profiling_enabled())
                __clear_page_tag_ref(page);
}

/* Should be called only if mem_alloc_profiling_enabled() */
static inline struct alloc_tag *__pgalloc_tag_get(struct page *page)
{
        struct alloc_tag *tag = NULL;
        union pgtag_ref_handle handle;
        union codetag_ref ref;

        if (get_page_tag_ref(page, &ref, &handle)) {
                alloc_tag_sub_check(&ref);
                if (ref.ct)
                        tag = ct_to_alloc_tag(ref.ct);
                put_page_tag_ref(handle);
        }

        return tag;
}

static inline struct alloc_tag *pgalloc_tag_get(struct page *page)
{
        if (mem_alloc_profiling_enabled())
                return __pgalloc_tag_get(page);
        return NULL;
}

void pgalloc_tag_split(struct folio *folio, int old_order, int new_order);
void pgalloc_tag_swap(struct folio *new, struct folio *old);

void __init alloc_tag_sec_init(void);

#else /* CONFIG_MEM_ALLOC_PROFILING */

static inline void clear_page_tag_ref(struct page *page) {}
static inline void alloc_tag_sec_init(void) {}
static inline void pgalloc_tag_split(struct folio *folio, int old_order, int new_order) {}
static inline void pgalloc_tag_swap(struct folio *new, struct folio *old) {}
static inline struct alloc_tag *pgalloc_tag_get(struct page *page) { return NULL; }

#endif /* CONFIG_MEM_ALLOC_PROFILING */

#endif /* _LINUX_PGALLOC_TAG_H */